Stryker scope extends to GameCult.Caching.Tests; CultElementIds survivors killed or recorded (mutation-testing-scope) (#163)

.github/workflows/cultmesh-portability.yml

@@ -25,7 +25,9 @@ jobs:
   reactive-and-resource-lifetime:
     name: ${{ matrix.os }} reactive semantics and leases
     runs-on: ${{ matrix.os }}
-    timeout-minutes: 30
+    # The job dies at the lower of this value and the forge runner's own cap, which Eureka is raising from 30 to 60 minutes
+    # (run 1378 carried 60 and was still cancelled at 30:02); the two must both say 60 before a full run can finish.
+    timeout-minutes: 60
     strategy:
       fail-fast: false
       matrix:
@@ -45,17 +47,41 @@ jobs:
         with:
           dotnet-version: 10.0.x
 
+      # The forge runner image (catthehacker/ubuntu:act-latest) carries Node 24 and Python 3.12 on PATH, and these two
+      # setup actions downloaded them again from github.com anyway (about 2.7 and 2.8 minutes, run 639) because the
+      # image's tool cache is not the one they read. They run only where the image does not carry the tools (the
+      # workflow_dispatch Windows leg); the check below fails a Linux image that stops carrying them.
       - name: Set up Node.js
+        if: runner.os != 'Linux'
         uses: actions/setup-node@v4
         with:
           node-version: 24
           cache: npm
 
       - name: Set up Python
+        if: runner.os != 'Linux'
         uses: actions/setup-python@v5
         with:
           python-version: "3.12"
 
+      - name: Check the image carries Node 24 and Python 3.12
+        if: runner.os == 'Linux'
+        shell: bash
+        run: |
+          set -euo pipefail
+          node --version | grep -E '^v24\.'
+          python --version | grep -E '^Python 3\.12\.'
+
+      # The image's Python is distro-managed (PEP 668): pip refuses to install into it, so the Linux leg installs the
+      # CultLib packages into a venv under RUNNER_TEMP that later steps find first on PATH.
+      - name: Create the Python environment
+        if: runner.os == 'Linux'
+        shell: bash
+        run: |
+          set -euo pipefail
+          python -m venv "$RUNNER_TEMP/venv"
+          echo "$RUNNER_TEMP/venv/bin" >> "$GITHUB_PATH"
+
       - name: Install TypeScript workspace dependencies
         run: npm install --no-package-lock
 
@@ -132,7 +158,7 @@ jobs:
       # (only the interop example built, inside the C# store tests). The target directory is under RUNNER_TEMP, away from the checkout.
       - name: Verify the CultCache document owner with the Rust cache
         shell: bash
-        run: CARGO_TARGET_DIR="$RUNNER_TEMP/cultcache-rs-target" cargo test --manifest-path packages/cultcache-rs/Cargo.toml
+        run: CARGO_TARGET_DIR="$RUNNER_TEMP/cultcache-rs-target" cargo test --locked --manifest-path packages/cultcache-rs/Cargo.toml
 
       # tests/GameCult.Caching.Tests, the C# reference cache's own suite (about 1,260 tests, under a minute), ran in no
       # forge workflow; only the Mesh tests above exercised the reference.

.github/workflows/cultnet-interop.yml

@@ -29,6 +29,12 @@ jobs:
     steps:
       - name: Check out CultLib
         uses: actions/checkout@v4
+        with:
+          # packages/cultnet-py/tests/test_declared_dependency_ranges.py reads the cultcache-py
+          # release tags and their file contents with `git show`; a shallow checkout has no tags
+          # and the test skips itself.
+          fetch-depth: 0
+          fetch-tags: true
 
       - name: Set up .NET
         uses: actions/setup-dotnet@v4
@@ -129,10 +135,10 @@ jobs:
           python -m unittest discover -s packages/cultmesh-py/tests
 
       - name: Verify Rust RUDP reliability
-        run: cargo test --manifest-path packages/cultnet-rs/Cargo.toml rudp
+        run: cargo test --locked --manifest-path packages/cultnet-rs/Cargo.toml rudp
 
       - name: Verify Rust CultMesh runtime-local surface
-        run: cargo test --manifest-path packages/cultmesh-rs/Cargo.toml
+        run: cargo test --locked --manifest-path packages/cultmesh-rs/Cargo.toml
 
       - name: Verify C# RUDP reliability
         run: dotnet test tests/GameCult.Networking.Tests/GameCult.Networking.Tests.csproj --filter "FullyQualifiedName~Rudp"

README.md

@@ -212,8 +212,8 @@ identity-owned C# session after provider route replacement.
 Rust package tests:
 
 ```powershell
-cargo test --manifest-path packages/cultcache-rs/Cargo.toml
-cargo test --manifest-path packages/cultnet-rs/Cargo.toml
+cargo test --locked --manifest-path packages/cultcache-rs/Cargo.toml
+cargo test --locked --manifest-path packages/cultnet-rs/Cargo.toml
 ```
 
 Kotlin package build:

contracts/cultmesh/content-acceptance-vectors.json

@@ -899,23 +899,23 @@
     {
       "label": "trailing_nil",
       "inputBase64": "mqNhL2KlYXNzZXShMdlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQCvYXBwbGljYXRpb24veC10oXSRlNlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQAAoWuRoXiBoWuhdsA=",
-      "accepted": true,
-      "reencodedBase64": "mqNhL2KlYXNzZXShMdlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQCvYXBwbGljYXRpb24veC10oXSRldlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQAAoWugkaF4gaFroXY=",
-      "recordKey": "mesh:cdn:artifact:a-b:1:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+      "accepted": false,
+      "reencodedBase64": null,
+      "recordKey": null
     },
     {
       "label": "trailing_reserved_code",
       "inputBase64": "mqNhL2KlYXNzZXShMdlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQCvYXBwbGljYXRpb24veC10oXSRlNlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQAAoWuRoXiBoWuhdsE=",
-      "accepted": true,
-      "reencodedBase64": "mqNhL2KlYXNzZXShMdlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQCvYXBwbGljYXRpb24veC10oXSRldlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQAAoWugkaF4gaFroXY=",
-      "recordKey": "mesh:cdn:artifact:a-b:1:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+      "accepted": false,
+      "reencodedBase64": null,
+      "recordKey": null
     },
     {
       "label": "trailing_truncated_array",
       "inputBase64": "mqNhL2KlYXNzZXShMdlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQCvYXBwbGljYXRpb24veC10oXSRlNlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQAAoWuRoXiBoWuhdpI=",
-      "accepted": true,
-      "reencodedBase64": "mqNhL2KlYXNzZXShMdlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQCvYXBwbGljYXRpb24veC10oXSRldlAZTNiMGM0NDI5OGZjMWMxNDlhZmJmNGM4OTk2ZmI5MjQyN2FlNDFlNDY0OWI5MzRjYTQ5NTk5MWI3ODUyYjg1NQAAoWugkaF4gaFroXY=",
-      "recordKey": "mesh:cdn:artifact:a-b:1:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+      "accepted": false,
+      "reencodedBase64": null,
+      "recordKey": null
     },
     {
       "label": "top_nil",

contracts/cultnet/governance/fork-card.md

@@ -26,13 +26,15 @@ All documents are CultNet map-mode: every key written, nil where absent, closed
 
 ### card
 
-`{schemaVersion, fork_id, title, context, options[{id, text}], recommendation, depends[], leans, flag, raised_in, deciders[], status, ruling, ruled_from[], order, options_hash}`.
+`{schemaVersion, fork_id, title, context, options[{id, text}], recommendation, depends[], leans, flag, raised_in, raised_at, deciders[], decider_count, status, ruling, ruled_from[], order, options_hash}`.
 
 - `fork_id`: the mind's `question` key, `<campaign>:question:<label>`.
 - **Hashed (the shown members):** `title`, `context`, `options` (each `{id, text}`, in shown order), `recommendation` (an option id, **never nil**: the stored `question` requires `recommended`), `depends` (strings, each one of the stored question's `depends` lines verbatim, at most 8, each at most 1000 UTF-8 bytes (the stored `Line`), in shown order, empty when none; the stored kind holds prose lines, so a line may read like a reference such as `campaign:kind:label` but is hashed as the text it is).
-- **Not hashed:** `fork_id` (bound beside the hash), `leans` (an option id or nil), `flag`, `raised_in`, `deciders`, `status` (`open` or `closed`), `ruling` (the ruling id when a ruling closed the fork; nil when the card is open, and nil on a closed card whose question was withdrawn or otherwise resolved with no ruling), `ruled_from` (answer ids a ruling has been admitted from; non-empty only on a closed card), `order`, and `options_hash` itself.
-- **`deciders` is read-only data.** The list is set outside the Mind, through Bifrost's admin path, and **Bifrost sends it per call**: Huginn keeps no copy (M5). The card projection copies the list the call carried. **The list holds one to 64 ids** (Huginn's bound), on the card and in the per-call list alike (vectors `deciders_at_the_cap_of_64`, `deciders_65`); the per-call list has no schema here, so the bound is stated for the cut that builds it. A question's own `audience` may only narrow it. A Mind never writes it, so a Mind cannot add itself and answer its own fork.
-- Rules a schema cannot say, each with a negative vector: a `depends` line is at most 1000 UTF-8 bytes (the schema bounds 8 lines and 1000 characters; bytes need the rule); option ids are unique; `order` is unique among a Mind's cards (a list with two cards on one `order` is refused, naming both fork ids); `recommendation` and `leans` name an option; deciders are unique; an open card names no `ruling` and its `ruled_from` is empty (a ruling that answers a fork closes it); `ruled_from` is non-empty only when `ruling` is set; a closed card may name no ruling (the question was withdrawn, superseded or deferred: step 6 reads `status`, not the ruling); `options_hash` equals the hash of the shown members.
+- **Not hashed:** `fork_id` (bound beside the hash), `leans` (an option id or nil), `flag`, `raised_in`, `raised_at` (the instant the question was first admitted, an RFC3339 instant string as `answered_at`, or nil when the mind holds no admission time, as for a card projected before the field; the key is always written; it never moves when the question is edited; age is the client's: now minus `raised_at`), `deciders`, `decider_count` (the number of deciders of the call, set beside `deciders`; neither it nor the emptiness of `deciders` enters the hash, so the hash a non-decider recomputes is a decider's), `status` (`open` or `closed`), `ruling` (the ruling id when a ruling closed the fork; nil when the card is open, and nil on a closed card whose question was withdrawn or otherwise resolved with no ruling), `ruled_from` (answer ids a ruling has been admitted from; non-empty only on a closed card), `order`, and `options_hash` itself.
+- **`deciders` is read-only data.** The list is set outside the Mind, through Bifrost's admin path, and **Bifrost sends it per call**: Huginn keeps no copy (M5). The card projection copies the list the call carried. **The per-call list holds one to 64 ids** (Huginn's bound; vectors `deciders_at_the_cap_of_64`, `deciders_65`); the per-call list has no schema here, so the bound is stated for the cut that builds it. **`decider_count` is the size of that list, an integer 1 to 64, always written** (vectors `decider_count_missing`, `_zero`, `_65`, `_string`, `_null`). A fork with no decider is still refused, now as `decider_count` 0. **`deciders` holds that list for a decider and is empty for a reader who is not one: empty means "the ids are withheld from this reader", never "no deciders"** (vector `withheld_deciders`). Rule R-card: when `deciders` is non-empty it holds exactly `decider_count` ids; a visible list is whole (vectors `decider_count_fewer_than_the_ids`, `decider_count_more_than_the_ids_shown`). A question's own `audience` may only narrow it. A Mind never writes it, so a Mind cannot add itself and answer its own fork.
+- Rules a schema cannot say, each with a negative vector: a `depends` line is at most 1000 UTF-8 bytes (the schema bounds 8 lines and 1000 characters; bytes need the rule); option ids are unique; `order` is unique among a Mind's cards (a list with two cards on one `order` is refused, naming both fork ids); `recommendation` and `leans` name an option; deciders are unique; an open card names no `ruling` and its `ruled_from` is empty (a ruling that answers a fork closes it); `ruled_from` is non-empty only when `ruling` is set; a closed card may name no ruling (the question was withdrawn, superseded or deferred: step 6 reads `status`, not the ruling); `options_hash` equals the hash of the shown members; R-card (above); R-answer-result: `answer_result.answer.answerer` is never nil, being the sender's own stamped account (vector `answer_result_with_a_nil_answerer`); R-record, R-entry and R-list ("Reader views" below).
+
+**Reader views.** A card and its record are shown in one of two views. The **decider view** carries the ids: `deciders` whole, every `answerer` named, and the counts equal to the ids. The **non-decider view** withholds them: `deciders` empty, every `answerer` nil, the counts kept (`decider_count`; `answerer_count` on the record). Who is a decider is Huginn's decision, not this contract's: a reader is a decider exactly when the call's subject is byte-equal to one of the call's deciders (`eureka-substrate:ruling:desk-read-visibility-withheld-ids`); Huginn's door withholds, Bifrost cannot (the card is opaque to it). There is no viewer flag on any document: the view is read off whether `deciders` is empty. This contract carries both views and refuses a view that leaks: R-record: if every `answerer` is named, `answerer_count` is the number of distinct ids; if all are nil and there is at least one answer, `answerer_count` is between 1 and the number of answers; with no answers it is 0 (vectors `answerer_count_disagrees_with_the_ids`, `answerer_count_counts_answers_not_people`, `withheld_count_over_the_answers`, `withheld_count_zero_over_answers`, `withheld_count_over_no_answers`); R-entry, the leak rule: an entry with `deciders` non-empty names every answerer, an entry with `deciders` empty names none (vectors `decider_card_with_withheld_answers`, `withheld_card_with_named_answers`, `withheld_card_with_a_named_answerer_among_nils`); R-list: all entries of one page agree on the view (vector `a_page_mixes_views`). The view does not move the page: `non_decider_page` has the counts, order, cursor and stamp of the decider page it twins, and the vectors' no-leak check finds no id string in a non-decider vector's bytes. `options_hash` is the same in both views, and the bound-answer and `stale_fork` machinery is untouched.
 
 ### Options hash (canonical bytes)
 
@@ -65,7 +67,9 @@ The stamped `authority` field of a stored answer is an **attribution**: the role
 
 `received_at` is Huginn's admission time; "first" means first by admission order (the `n<seq>` ordinal), never by `answered_at`. `claim_in_future` is true when `answered_at` is more than five minutes after `received_at`: accepted but flagged. It is a function of the two stored values, so the writer compares against the `received_at` it stores, at the precision it stores it (a flag decided against an unrounded clock and a stored second-truncated `received_at` disagrees with the document it sits in). **Not stored, and no answer id:** a body refused at step 1 or 2 (Bifrost; it never reaches Huginn), and a body naming an unknown fork (step 3; Huginn answers it from its stored forks, but with no question there is nothing to key a record under). Each gets a `refusal` and is dropped. A malformed body is therefore never stored, and neither is an unknown fork. Every refusal from step 4 on is stored. **`unavailable`** (503) is not a refusal and not in the refusal set: Bifrost answers it when the second door or Huginn did not answer after the auth steps and the body shape passed (a bad body is still refused first). **It says the outcome is NOT CONFIRMED, never that nothing was stored**: a timeout after the request reached Huginn may have stored it. It carries no answer id. The desk retries the same request with the same `request_id` and learns the outcome: the stored one if Huginn had it, a fresh one if not. It covers **calls 1 and 2 as well as the answer POST** when Huginn cannot be reached (Transport; a read has no outcome to confirm, so a retry is plain). `retryAfterSeconds` is nil when Bifrost has no hint.
 
-**The mind's record and this document.** Huginn keeps the answer as its own record kind (`epiphany.pipeline.desk_answer.v2`, key `<campaign>:desk_answer:<question-label>.n<seq>`, the outcome as one externally tagged value, the fork as `fork`). The second door projects it to this document and nothing else crosses: `answer_id` is the key's `n<seq>` part, `fork_id` is the stored `fork`, the tagged outcome flattens into `outcome`, `of`, `retracts` and `code`, and the six refusal codes are spelt as in the schema (snake_case; the record's enum spells them in the mind's own PascalCase). On the wire an answer is named by its `n<seq>` alone, always inside the fork whose `fork_id` the document carries; a runtime that holds the full record key converts at the door, in one place. `body_sha256` and any other digest Huginn keeps to decide "same body" stay in the record: Huginn alone decides a replay or a `request_id_conflict` and Bifrost never compares bodies, so no digest is a field of this document. A digest is a valid way to decide it only if it covers `fork_id`, `options_hash`, `answer.choice`, `answer.note`, `retracted`, `retracts` and `answered_at` (every field of the request but `request_id`), is computed by Huginn and never read from a client.
+**The record.** `record` is `{schemaVersion, fork_id, options_hash, counted_answer_id, answerer_count, answers[]}`. `answerer_count` is an integer of at least 0: the number of distinct answerer ids over every stored answer of the fork, refusals included (a refusal stores the stamped answerer too), and it is the same number in both views (vectors `answerer_count_missing`, `_negative`, `_null`). `answers[].answerer` is a string or nil (nil only in the non-decider view).
+
+**The mind's record and this document.** Huginn keeps the answer as its own record kind (`epiphany.pipeline.desk_answer.v2`, key `<campaign>:desk_answer:<question-label>.n<seq>`, the outcome as one externally tagged value, the fork as `fork`). The second door projects it to this document and nothing else crosses: `answer_id` is the key's `n<seq>` part, `fork_id` is the stored `fork`, the tagged outcome flattens into `outcome`, `of`, `retracts` and `code`, and the six refusal codes are spelt as in the schema (snake_case; the record's enum spells them in the mind's own PascalCase). On the wire an answer is named by its `n<seq>` alone, always inside the fork whose `fork_id` the document carries; a runtime that holds the full record key converts at the door, in one place. Huginn's stored `desk_answer` keeps a non-nil `answerer`; nil exists only in a record projected to a non-decider. `body_sha256` and any other digest Huginn keeps to decide "same body" stay in the record: Huginn alone decides a replay or a `request_id_conflict` and Bifrost never compares bodies, so no digest is a field of this document. A digest is a valid way to decide it only if it covers `fork_id`, `options_hash`, `answer.choice`, `answer.note`, `retracted`, `retracts` and `answered_at` (every field of the request but `request_id`), is computed by Huginn and never read from a client.
 
 **Huginn's digest, pinned in the vectors (`bodyDigests`; informative, not a wire document).** SHA-256 of one compact JSON object as `serde_json::to_string` writes it (UTF-8, no spaces), lowercase hex, keys in this order, `null` for a missing value, strings verbatim: `fork`, `options_hash`, `answered_at`, `choice`, `note`, `retracts` (the **full stored key** `<campaign>:desk_answer:<label>.n<seq>`: the door converts the wire's `n<seq>` before the digest), then, **only for the three illegal forms** (R1: a retraction carrying an answer, a retraction naming no target, a plain answer carrying a target), `illegal_retraction: true` and `retracted: true|false`. `request_id` is not in it. A plain answer and a legal retraction carry neither trailing key, so their digests are the ones Huginn main pins (`8a4d5b2e`, `9f807538`) and do not move. `9f807538` is pinned for a target no door produces (`Q1.1`); the golden for the real legal retraction is the door's form, the wire's `n1` converted to `Q1.n1` (`84576840`, vector `legal_retraction_door_form`, also main-valid). Source: Eureka's `desk-body-digest-order-20261110.md`, computed with `sha256sum`; the generator, the C# suite and the TypeScript suite recompute every digest from the input fields. **Status:** the three `retracted` goldens (`935cab1a`, `82b24ccc`, `34ef86ed`, and `79eee623` for form (i) with a null target) are the form of `cut-desk-digest-retracted.r2`, merged as Huginn #30. Eureka reports that these four and the door-form legal retraction (`84576840`) reproduce byte for byte on Huginn main `f0ca504` (the #30 fix); that run is hers, reported to us, and was not rerun here. Before #30, Huginn main (`7ea11b4`) wrote `illegal_retraction` alone, so forms (i) and (iii) collided there (`69074cc6`, pinned as `illegal_i_and_iii_alike_on_main`). The wire contract does not wait on it: the conflict scenarios are pinned in `scenarios`.
 
@@ -113,8 +117,8 @@ Source: the desk's client needs (Ratatoskr PR #24 section 12, `ratatoskr-desk-sp
 - **M1.** `{mind}` is looked up in a **fixed configured list** of Mind ids, each mapped in configuration to that Mind's socket on the peer-checked door. The segment is percent-decoded once and compared, ordinally, with the list's ids: no case folding, trimming or Unicode normalisation, and a decoding failure is a miss. It is **never joined into a path, a socket name or a query**, so a value off the list opens nothing (`../x`, `a/b`, `a%2fb`, `eureka%00`, a 4 KB string, `GAMECULT-CHAT` for `gamecult-chat`, a trailing space, bytes that are not UTF-8: all unknown, 404, no socket opened).
 - **M2.** An unknown Mind gets **the same refusal as an unknown fork**: `fork_unknown`, 404, the same bytes (the document's `error` names neither the Mind nor the fork). The list of Minds is not probeable. Auth is judged first, so a caller without a valid token, scope or Active membership learns nothing about which Minds exist.
 - **M3.** On the POST the route's Mind must hold `fork_id`: step 3 is judged against **that Mind's** stored forks, so a `fork_id` the route's Mind does not hold is `fork_unknown` and nothing is stored, in either Mind. A fork cannot be answered through another Mind's route. A body that names `mind` is `body_unknown_field`: the Mind is the route's.
-- **M4.** Scopes are **not per Mind**: `desk.read` and `desk.answer` open the routes of every configured Mind; every reader sees every fork's card and outcome, and which forks a caller may answer is the decider list.
-- **M5. The decider list is sent per call.** Bifrost holds the admin-set list and sends it with **every answer, read and list request** to Huginn, as a typed field on the same peer-checked door; Huginn keeps no copy of it. Because it travels with read and list too, a projected card's `deciders` is the list of that call, and step 5 judges an answer against the list the same call carried. It comes only from Bifrost's admin-set state: never from a Mind and never from any request body a client controls: no HTTP field, header or query parameter on any desk route sets or extends it, and a body naming `deciders` is `body_unknown_field` (scenario `M5_...`). A request carrying it from a Mind's own door or session is refused. **This is Bifrost and Huginn work and no vector here can test it** (the typed field and the door's wire are pending, open choice 3); the rule is stated so that the cut that builds the request has it. (Heimdall's ruling, #minds 2026-11-10 19:26Z; it replaces the earlier reading of a list Huginn receives once and holds.) **Envelope names:** the desk's envelope on that door uses the names this page uses, `mind`, `authority`, `subject` and `deciders`, with no conversion at the door (Eureka, #minds 2026-11-10 19:58Z); `deciders` is a per-call list of short ids at the envelope's top level beside `subject`, never inside the request body, and Huginn keeps no copy.
+- **M4.** Scopes are **not per Mind**: `desk.read` and `desk.answer` open the routes of every configured Mind; every reader sees every fork's card and outcome (a non-decider sees no account id, "Reader views"), and which forks a caller may answer is the decider list.
+- **M5. The decider list is sent per call.** Bifrost holds the admin-set list and sends it with **every answer, read and list request** to Huginn, as a typed field on the same peer-checked door; Huginn keeps no copy of it. Because it travels with read and list too, a projected card's `deciders` is the list of that call for a decider and empty for a reader who is not one, with `decider_count` travelling with both views, and step 5 judges an answer against the list the same call carried. It comes only from Bifrost's admin-set state: never from a Mind and never from any request body a client controls: no HTTP field, header or query parameter on any desk route sets or extends it, and a body naming `deciders` is `body_unknown_field` (scenario `M5_...`). A request carrying it from a Mind's own door or session is refused. **This is Bifrost and Huginn work and no vector here can test it** (the typed field and the door's wire are pending, open choice 3); the rule is stated so that the cut that builds the request has it. (Heimdall's ruling, #minds 2026-11-10 19:26Z; it replaces the earlier reading of a list Huginn receives once and holds.) **Envelope names:** the desk's envelope on that door uses the names this page uses, `mind`, `authority`, `subject` and `deciders`, with no conversion at the door (Eureka, #minds 2026-11-10 19:58Z); `deciders` is a per-call list of short ids at the envelope's top level beside `subject`, never inside the request body, and Huginn keeps no copy.
 
 Calls 1 and 2 are enough for a read-only desk. Every response is the pinned MessagePack document or its JSON form with the same keys (open choice 1 of `vote-api.md`: the media type is unsettled).
 
@@ -122,7 +126,7 @@ Calls 1 and 2 are enough for a read-only desk. Every response is the pinned Mess
 
 **List.** `list_request`: `{mind, status, cursor, limit}`. `mind` is the route's `{mind}`, a Mind id from the configured list. `status` is `open`, `recorded` or nil for both; `recorded` means a closed card. Cards come **newest first by `order`**. `order` is the card's unique rank per Mind: an integer from 0 that never changes once the card exists, later questions only appending (Huginn derives it from the Mind's questions sorted by admission ordinal, then key). A Mind never holds two cards of one `order`; a list or card set that does is refused, and the refusal names both fork ids. 0 is legal, but no cursor names it (`c0` fails the cursor pattern): a page ending at order 1 returns `c1`, and the next page returns the order-0 card alone with `next_cursor` nil. `limit` is 0 to 50; **`limit` 0 returns no entries, only the counts and the stamp**, which is what "N open" on the Mind's header needs. `cursor` is nil or `c<N>`: the cards whose `order` is below N; a client treats it as opaque and sends back the `next_cursor` it was given. `list`: `{mind, stamp, open_count, recorded_count, forks[entry], next_cursor}`. The counts cover every card the viewer may see, whatever `status` and `cursor` asked for. `stamp` is `s<N>`, N the receiver's last-seen Huginn admission ordinal for the Mind's desk documents: the same stamp means the same state, so a desk polls `limit` 0 and fetches bodies only when the stamp moves. `next_cursor` is nil on the last page. **A page may hold fewer than `limit` entries** when the next entry would push the encoded response past the receiver's response budget (Huginn: 65536 bytes); it then holds at least one, `next_cursor` is `c<order of the last entry returned>` so the next page resumes below it, and the counts and the stamp are those of the full list, unchanged. **`fork_too_large`** (HTTP 422) refuses a page whose **first** entry alone is past the budget: 422 because the request is well formed and authorised but names a resource the list cannot carry, and 413 is for a request body that is too large, which this is not; retrying returns the same refusal. Its `error` names the fork id and its `order`, for example `fork_too_large: fork <fork_id> (order <n>) alone is past the response budget`. **A refusal's `error` text is informational and not pinned**: the contract pins the code, the HTTP status, that the text names the fork id (and the order on a list), and the `c<order>` continuation on a list; the vectors' wording is a sample, and the judges check those four things, not the bytes of the text. The client continues the list with cursor `c<n>`, the cards strictly below that order, which skips this fork; it is then readable only by id (the read route returns the whole entry, and refuses with the same code only when that entry alone is past the cap, see Read); `c<n>` is valid only when n is at least 1, so for order 0 there is nothing below and the client has reached the end. `limit` 0 returns no entries and never refuses. (Ruled by Persona, 2026-11-11.) An `entry` is `{card, record}`: the card and its `record` (the answers with their outcomes and the derived `counted_answer_id`).
 
-**Read.** `read_request` is `{mind, fork_id}`; the response is the `entry` for one fork of that Mind. Its `card.options_hash` is **computed by the server** from the five shown members as in "Options hash" and the client recomputes it from what it rendered; a card whose hash is not the hash of its members is no card (negative vector `card_hash_wrong`). The record's `fork_id` and `options_hash` are the card's, and `counted_answer_id` is derived, not copied (negative vectors for each). Every `desk.read` holder sees every fork's card and outcome in a configured Mind; only a decider's notes depend on the caller, going to callers in the admin-set `deciders` list, which Bifrost enforces at the door (ruling `desk-read-visibility`, option (c)); `fork_unknown` is only for a fork id that does not exist under the route's Mind (an unknown Mind answers the same, M2), so no fork is ever hidden by it, and a caller without `desk.read` is refused by the auth order above (`insufficient_scope`) before any lookup. **Bifrost applies visibility at the door; Huginn returns the whole record to the door.** Every `desk.read` holder sees cards and outcomes; notes (a decider's own words) only go to callers in the admin-set `deciders` list. The read and list shapes are unchanged and carry no audience field (`eureka-substrate:question:desk-read-visibility`, Heimdall's option (c)). **A read is refused `fork_too_large` (422) when the whole entry is past the reply cap** (Huginn's daemon caps every reply at 65536 bytes; the cap, not the page budget, is what a read meets). Its `error` names the fork id and has no order and no cursor to carry, because there is nothing to continue with (sample: `fork_too_large: fork <fork_id> alone is past the response budget`) (vector `transport.readTooLarge`; the cap is in no vector). **The answer route meets the same cap:** when an answer is `stale_fork`, Bifrost re-reads the current card to attach it, and if that read is past the cap the answer is refused `fork_too_large` (422) with the read form of the text, the same document as a read. Huginn has already stored the answer as `Refused(stale_fork)`, as for any stale answer, and it is never counted; the client is told `fork_too_large` instead of receiving the current card, and a replay of the same `request_id` gets the same 422 while the fork stays oversize. It is never `unavailable` (vector `transport.answerTooLarge`). A stripped read serves a decider's `note` as `note: null`, never omitted (map-mode: every key is written); `desk_answer.note` is already nullable in the schema, so a served record validates as it stands.
+**Read.** `read_request` is `{mind, fork_id}`; the response is the `entry` for one fork of that Mind. Its `card.options_hash` is **computed by the server** from the five shown members as in "Options hash" and the client recomputes it from what it rendered; a card whose hash is not the hash of its members is no card (negative vector `card_hash_wrong`). The record's `fork_id` and `options_hash` are the card's, and `counted_answer_id` is derived, not copied (negative vectors for each). Every `desk.read` holder sees every fork's card and outcome in a configured Mind; only a decider's notes depend on the caller, going to callers in the admin-set `deciders` list, which Bifrost enforces at the door (ruling `desk-read-visibility`, option (c)); `fork_unknown` is only for a fork id that does not exist under the route's Mind (an unknown Mind answers the same, M2), so no fork is ever hidden by it, and a caller without `desk.read` is refused by the auth order above (`insufficient_scope`) before any lookup. **Huginn withholds account ids from a reader who is not a decider and returns counts ("Reader views"); Bifrost still strips notes.** Every `desk.read` holder sees cards and outcomes; notes (a decider's own words) only go to callers in the admin-set `deciders` list. The read and list shapes are unchanged and carry no audience field (`eureka-substrate:question:desk-read-visibility`, Heimdall's option (c)). **A read is refused `fork_too_large` (422) when the whole entry is past the reply cap** (Huginn's daemon caps every reply at 65536 bytes; the cap, not the page budget, is what a read meets). Its `error` names the fork id and has no order and no cursor to carry, because there is nothing to continue with (sample: `fork_too_large: fork <fork_id> alone is past the response budget`) (vector `transport.readTooLarge`; the cap is in no vector). **The answer route meets the same cap:** when an answer is `stale_fork`, Bifrost re-reads the current card to attach it, and if that read is past the cap the answer is refused `fork_too_large` (422) with the read form of the text, the same document as a read. Huginn has already stored the answer as `Refused(stale_fork)`, as for any stale answer, and it is never counted; the client is told `fork_too_large` instead of receiving the current card, and a replay of the same `request_id` gets the same 422 while the fork stays oversize. It is never `unavailable` (vector `transport.answerTooLarge`). A stripped read serves a decider's `note` as `note: null`, never omitted (map-mode: every key is written); `desk_answer.note` is already nullable in the schema, so a served record validates as it stands.
 
 **Answer.** The body is the `answer_request` and nothing else a client may set: `fork_id`, `options_hash`, `answer`, `answered_at`, `request_id` (plus `retracted` and `retracts`, written `false` and nil unless the call retracts). The response is the stored outcome: `Counted`, `Revision`, `Retraction`, or `Refused` with its code, and the **`counted_answer_id`** the fork has once this call is applied (`n<seq>` or nil; derived as in "The counted answer is derived", the same value the `record` projection carries, so the desk needs no second read). A replay returns the stored outcome with the `counted_answer_id` current at the retry, not the one it had when first stored. **A `stale_fork` refusal carries the current card** in `answer_result.card`, so the desk can show the new fork without another read. Nothing is stored for a step 1 or 2 refusal, an unknown fork (or an unknown Mind, or a fork another Mind holds) or a `request_id_conflict`. `unavailable` promises nothing either way.
 
@@ -149,7 +153,9 @@ The old desk (`index.html`) read `questions/<id>` and wrote `answers/<id>` in a
 | `status` open or closed, `ruling` | derived from the resolution (status is never written): any resolution of the question closes it; the ruling is the one that answered it | `status`, `ruling`, both a projection (`ruling` is nil on an open card and on a card closed with no ruling) |
 | `order` | none (unique rank per Mind, from 0) | `order` |
 | none | `raised_in`, `asked_on` | `raised_in`; `asked_on` is not carried |
+| none | the question's admission time (no timestamp in the old format; `asked_on` is a date and stays uncarried) | `raised_at`, an instant or nil, not hashed |
 | none | none | `deciders` (outside the Mind), `ruled_from`, `options_hash` |
+| none | none | `decider_count`, `answerer_count` (counts that stand in for withheld ids) |
 | answer `{choice: key or null, note, question, updatedAt}`, one mutable document per question | none | `answer_request` then an append-only `desk_answer` |
 | `note`: her words verbatim | | `answer.note`, verbatim |
 | "Clear pick": `choice` back to null so the note stands alone | | an `answer` with `choice` nil and `note` set, as the first answer or as a `Revision` |
@@ -178,6 +184,8 @@ Option B, **Bifrost receives the answer and Huginn stores it** (the design in th
 - `request_id` (on the request and the stored `desk_answer`) and `request_id_conflict` are this page's: his file has no idempotency key, and a retry after `unavailable` needs one. Eureka's `desk_answer` kind and Huginn's request type must carry it.
 - Transport: the routes, the `{mind}` segment, the scopes, the audience and the auth order are his rulings (4.1 to 4.3a); the documents (list, read, `unavailable`) are this page's. The note limit is 4000 UTF-8 bytes here, as his 1.1 leaves the unit unsaid.
 - The recommendation is never nil. The binding file's earlier vectors D and E used a nil recommendation; its updated D and E use `"a"`, as here.
+- `raised_at` (2026-11-11) is the desk-feed addition (Bifrost PR 67): a required key, an instant or nil, outside `options_hash` (the five hashed members and every digest are unchanged; vectors `raised_at_nil`, `raised_at_epoch_integer`, `raised_at_date_only`, `raised_at_missing`). The card is spec-authored and no runtime deploys it, so the schema id stays `gamecult.fork.card.v0`.
+- Reader views (2026-11-11) are the desk-feed addition behind Huginn PR 56 and `eureka-substrate:ruling:desk-read-visibility-withheld-ids`: the card gains `decider_count` and `deciders` may be empty; the record gains `answerer_count` and `answerer` may be nil, the counts beside the collections they summarise (not on the list envelope, which neither the read entry nor the `stale_fork` card travels in). `options_hash` and every digest are unchanged. The schema ids stay `gamecult.fork.card.v0` and `gamecult.fork.record.v0` for the same reason as `raised_at`.
 - Hash vectors: A, B, C, D, E, F and G of the binding file are reproduced digest for digest by the Python generator, the C# suite and the TypeScript suite (the generator prints `same` for each; none differs).
 
 ## Open choices
@@ -186,7 +194,7 @@ Option B, **Bifrost receives the answer and Huginn stores it** (the design in th
 2. NFC across runtimes relies on each runtime's normaliser; a pinned table, as `write-receipt.md` does for letters, would remove the reliance. The risk is only for code points assigned after a runtime's Unicode version.
 3. How Huginn learns the verified subject: the second door's authenticated context (the peer credential names Bifrost the service, not the member), so the subject must travel beside the request. This contract has no envelope for it.
 4. Whether `fork_unknown` and shape refusals should leave an audit record somewhere other than a `desk_answer`.
-5. Whether `leans` and `flag`, which the booth shows, should join the hash. The binding file's five members do not include them; a changed lean would not make an answer stale.
+5. Whether `leans` and `flag`, which the booth shows, should join the hash. The binding file's five members do not include them; a changed lean would not make an answer stale. `raised_at` is immutable, so it was kept out of the hash for the same reason it need not be in: it can never make a shown card stale.
 6. What the person sees of a retracted counted answer when the next answer counts: this contract only says the count moves.
 7. `received_at` is not in the binding file's stored fields; it is kept for `claim_in_future` and could be dropped if the `n<seq>` answer ordinal alone decided answer order.
 8. The stamped `authority` field is an attribution, not an authority (above); renaming it `attribution` would say so, at the price of a new key the door must also refuse in a body.
@@ -195,3 +203,4 @@ Option B, **Bifrost receives the answer and Huginn stores it** (the design in th
 11. While a known Mind's door is down its routes answer `unavailable` (503) and an unknown Mind answers `fork_unknown` (404), so the two are distinguishable for that period. M2 makes them identical only when every door is up; making them identical when one is down means answering `unavailable` for any `{mind}` not on the list, which tells a client nothing about which Minds exist but also hides a typo. Heimdall's to rule; the vectors do not pin it.
 12. A fork's answers are unbounded in number, so a fork's entry can grow past the reply cap and become unreadable (`fork_too_large` on read, and on list when it is the first entry of a page). Whether the contract should cap the answers per fork is for Persona and Heimdall to rule; nothing here decides it.
 13. The read form of `fork_too_large` is a target, not current behaviour: Huginn's door answers an over-cap read as `Refused(ResponseTooLarge{bytes, limit})`, which carries no fork id and is not `fork_too_large`. Bifrost maps it to `fork_too_large` (422) using the route's `fork_id`; until it does, a read past the cap reaches the client as 503 `unavailable`. The same holds for the answer route: a `stale_fork` answer whose card re-read is past the cap is a Bifrost target too (`fork_too_large` 422 over a stored `Refused(stale_fork)`), and until it is built the client sees 503 `unavailable`.
+14. What a non-decider can still infer: the card's `status` and `order`, the `authority` role on each answer (a role, not an id, and the ruling leaves it whole), and `answerer_count`. Whether a role plus a count is too much to show is Eureka's ruling to revisit.

contracts/cultnet/governance/fork-card.schema.json

@@ -70,7 +70,9 @@
         "leans",
         "flag",
         "raised_in",
+        "raised_at",
         "deciders",
+        "decider_count",
         "status",
         "ruling",
         "ruled_from",
@@ -143,15 +145,30 @@
             }
           ]
         },
+        "raised_at": {
+          "oneOf": [
+            {
+              "$ref": "#/$defs/instant"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        },
         "deciders": {
           "type": "array",
-          "minItems": 1,
+          "minItems": 0,
           "items": {
             "type": "string",
             "minLength": 1
           },
           "maxItems": 64
         },
+        "decider_count": {
+          "type": "integer",
+          "minimum": 1,
+          "maximum": 64
+        },
         "status": {
           "enum": [
             "open",
@@ -373,7 +390,14 @@
           "type": "boolean"
         },
         "answerer": {
-          "$ref": "#/$defs/id"
+          "oneOf": [
+            {
+              "$ref": "#/$defs/id"
+            },
+            {
+              "type": "null"
+            }
+          ]
         },
         "authority": {
           "$ref": "#/$defs/id"
@@ -459,7 +483,14 @@
           "type": "boolean"
         },
         "answerer": {
-          "$ref": "#/$defs/id"
+          "oneOf": [
+            {
+              "$ref": "#/$defs/id"
+            },
+            {
+              "type": "null"
+            }
+          ]
         },
         "authority": {
           "$ref": "#/$defs/id"
@@ -531,7 +562,14 @@
           "type": "boolean"
         },
         "answerer": {
-          "$ref": "#/$defs/id"
+          "oneOf": [
+            {
+              "$ref": "#/$defs/id"
+            },
+            {
+              "type": "null"
+            }
+          ]
         },
         "authority": {
           "$ref": "#/$defs/id"
@@ -631,7 +669,14 @@
           "type": "boolean"
         },
         "answerer": {
-          "$ref": "#/$defs/id"
+          "oneOf": [
+            {
+              "$ref": "#/$defs/id"
+            },
+            {
+              "type": "null"
+            }
+          ]
         },
         "authority": {
           "$ref": "#/$defs/id"
@@ -735,6 +780,7 @@
         "fork_id",
         "options_hash",
         "counted_answer_id",
+        "answerer_count",
         "answers"
       ],
       "properties": {
@@ -757,6 +803,10 @@
             }
           ]
         },
+        "answerer_count": {
+          "type": "integer",
+          "minimum": 0
+        },
         "answers": {
           "type": "array",
           "items": {

docs/cultcache-union-parity-map.md

@@ -259,7 +259,7 @@ landed in `ead5260c`, Python in `5618d8dd`, Rust in `c028c511`. TypeScript is no
 | Runtime | Owner of the decision (constant and walker) | Doors routed through it |
 |---|---|---|
 | C# | `CultPayloadDepth.Check` (`src/GameCult.Caching.MessagePack/CultPayloadDepth.cs`), limit `CultMessagePackSecurity.MaximumPayloadDepth`. MessagePack's own graph counter is set to the same value as a backstop only. | Write: `CultDocumentMessagePackSerialization.SerializeUntyped`. Read: `DeserializeUntyped`. The cache store (`SerializePayload`/`DeserializePayload`), the directory store, `CultMesh` and single-file documents all call those two; C# has no separate raw-envelope or prepared-batch door. |
-| Rust | `cultcache_rs::check_payload_depth` and `MAX_PAYLOAD_DEPTH` (`packages/cultcache-rs/src/lib.rs`). | Read: `decode_payload` (get, list, `validate_envelope`/`put_envelope`, `finish_prepared_entry`). Write: `put`/`prepare_entry`/`prepare_entry_named` reach it through `finish_prepared_entry`, which decodes what it just encoded. Raw envelope: `put_raw_envelope`, the door CultMesh network puts use (`cultmesh-rs` `lib.rs`, two call sites). Prepared batch: `put_prepared_batch` via `require_payload_depth`. cultnet-rs: every free-form or skippable wire payload decodes through `cultcache_rs::decode_payload` (message decode in `contracts.rs`, `provider_session`, `media_stream_wire`, `replication`, `service_identity`). |
+| Rust | `check_record_payload` (private; depth, then no bytes after the first value) over `first_value_end`, and `MAX_PAYLOAD_DEPTH`; `cultcache_rs::check_payload_depth` is the depth-only probe for outside callers (`packages/cultcache-rs/src/lib.rs`). | Read: `decode_payload` (get, list, `validate_envelope`/`put_envelope`, `finish_prepared_entry`). Write: `put`/`prepare_entry`/`prepare_entry_named` reach it through `finish_prepared_entry`, which decodes what it just encoded. Raw envelope: `put_raw_envelope`, the door CultMesh network puts use (`cultmesh-rs` `lib.rs`, two call sites). Prepared batch: `put_prepared_batch` via `require_record_payload`. Load: `pull_all_backing_stores` and `load_soa` run `require_record_payload` on every record, so a store holding a payload past the bound (or with bytes after it) is refused at load, and the cache then refuses every write and removal (`CultCacheLoadRefused`) until a load succeeds. cultnet-rs: every free-form or skippable wire payload decodes through `cultcache_rs::decode_payload` (message decode in `contracts.rs`, `provider_session`, `media_stream_wire`, `replication`, `service_identity`). |
 | Python | `_refuse_past_depth_limit` and `MAX_PAYLOAD_DEPTH` (`packages/cultcache-py/src/cultcache_py/documents.py`); a msgpack `StackError` on read maps to the same error. | `DocumentDefinition.encode_payload` (write) and `decode_payload` (read). `CultCache.put`, `put_envelope`, `put_envelopes` and load-time hydration go through them; there is no raw-envelope door. cultmesh-py round trips call the same pair. |
 
 - **Doors deliberately not routed.** cultnet-rs `idunn_lifecycle_brake`, `provider_health_contracts` and

docs/document-variants-cut.md

@@ -1609,7 +1609,7 @@ The one door per runtime, and who walks through it:
 - **Shared paths.** cultnet-ts reaches the header decision only through `readSingleFileStore` (AUTH:4, :321) and checks only record count, schema id and type. cultnet-ts therefore needs a cultcache-ts release that exports it, which is the release that ships with this change; the manifests move to that version then (c0-ships-with-c2a), not before.
 - **Cut line.** `merge-r1` h3 (Rust) and h4 (TS, cultnet-ts); spec `cut-merge-r1.r3` authority map.
 - **Pinned by.** `tests/vectors/document-variants-c2a/readability/manifest.txt`, walked by `StoreReadabilityTests.OpenReadsExactlyTheFilesTheVectorsSayItReads` (C#), `CultMeshSingleFileReadabilityTests.AWriteReplacesAFileExactlyWhenItReads` (Mesh), `a_file_is_replaced_exactly_when_it_reads` (RS:5132), "SingleFileMessagePackBackingStore replaces a file exactly when it reads" (TS test :2321) and `test_single_file_replaces_a_file_exactly_when_it_reads` (Python). AUTH cases: `packages/cultnet-ts/test/idunn-runtime-authority.test.ts`. Declared divergences in the manifest: `legacy-envelopes.bin` (C# refuses; the others read and replace it) and `variant-slot-v3.bin` (C# reads; the others refuse).
-- **Known gaps.** `variants:follow_up:c0-bad-canonical-in-manifest` (`current-catalog-bad-canonical.msgpack` is not in the manifest; TS reads it, Rust refuses). `variants:follow_up:legacy-vectors-all-runtimes` (the three `legacy-catalog-*` c0 vectors have a verdict only in C# tests; all four runtimes refuse them, probed). `variants:follow_up:range-check-in-ci` (`npm run test:pack:ts` builds every admitted tag and checks exports, but `.github/workflows/publish-packages.yml` does not run it).
+- **Known gaps.** `variants:follow_up:range-check-in-ci` (`npm run test:pack:ts` builds every admitted tag and checks exports, but `.github/workflows/publish-packages.yml` does not run it).
 
 ### B. Existence and links (what "nothing at the path" means)
 
@@ -1620,7 +1620,7 @@ The one door per runtime, and who walks through it:
 - **Shared paths.** Open, flush, commit, `ReadDurable`, `ReplaceDurable`. Rust `pull_all` RS:1243 also checks `is_absent` on the store and on the lock path before it takes the shared lock; that skips lock creation only, and the verdict stays with the reader.
 - **Cut line.** `merge-r1` h2 (C#) and h4/h6 (TS `readStoreBytes`); `mesh-single-file-reader` h1.
 - **Pinned by.** C#: `StoreReadabilityTests` `ADanglingFileLinkIsAnIoErrorOnOpenNotAnEmptyStore` :208, `ADanglingDirectoryLinkIsAnIoErrorOnOpenNotAnEmptyStore` :185, and the commit variants :196, :219. Mesh: `ADanglingLinkIsAnIoErrorOnTypedWriteRawWriteAndReadNeverAMissingFile` :107 and `OnlyNothingAtThePathIsAMissingFile` :134 (`CultMeshSingleFileStoreTests.cs`). Rust: `a_dangling_symlink_at_the_store_path_is_an_error_and_nothing_is_written` RS:5832. TS: "readStoreBytes reports nothing at the path only when the lstat finds nothing too".
-- **Known gaps.** The writer side still tolerates a dangling link: Rust `write_all_unlocked` RS:992-996 and TS `pushAll` TS:94-100 replace it on a whole-store write (`variants:follow_up:writer-dangling-link-tolerance`, owner `c2a-write-set`). What a replace does to a live link is `variants:follow_up:store-replace-cut` item 2. Windows junction behavior was proven at `42f05f66` and `b1ff2dcb`, not at the final head.
+- **Known gaps.** The writer no longer tolerates a dangling link: the reader's refusal stands for every write, whole-store `pushAll` included (Rust `a_push_all_through_a_dangling_link_is_refused_like_push_and_writes_nothing`, TS `a pushAll through a dangling link is refused like push`; `variants:follow_up:writer-dangling-link-tolerance`). What a replace does to a live link is `variants:follow_up:store-replace-cut` item 2. Windows junction behavior was proven at `42f05f66` and `b1ff2dcb`, not at the final head.
 
 ### C. Zero-byte file
 
@@ -1640,7 +1640,7 @@ The one door per runtime, and who walks through it:
 - **Shared paths.** Open, commit, Mesh read and write.
 - **Cut line.** `mesh-single-file-reader` h1 (the C# clause). Rust, TS and Python were correct by construction of their reads.
 - **Pinned by.** C#: `ADirectoryAtTheStorePathIsAnIoErrorOnOpenAndOnCommitNotAnEmptyStore` (`StoreReadabilityTests.cs:236`). Mesh: `ADirectoryAtThePathIsAnIoErrorOnReadAndWriteAndIsLeftAlone` (:149). Rust: `a_write_over_a_directory_stops_at_the_read_and_leaves_no_staging_file` RS:5726.
-- **Known gaps.** TS and Python have no test for a directory at the store path. No follow-up is registered; the natural home is `write-set-vectors` with the other readability pins.
+- **Known gaps.** None open. The `@directory` manifest row is walked by all four runtimes: every operation including delete is refused and leaves the directory untouched; Rust pins an I/O failure rather than a typed unreadable store.
 
 ### E. Lock
 
@@ -1672,7 +1672,7 @@ The one door per runtime, and who walks through it:
 - **Shared paths.** TS `pushAll` and Rust `push_all` only.
 - **Cut line.** `merge-r1` h4 (TS) and h6 (Rust).
 - **Pinned by.** The manifest walks run a soft flush over every vector in TS (the `softPushAll` operation, TS test :2336) and Rust (`soft_push_all`, RS:5149), each with an absent and a dangling-link case; `a_soft_push_all_writes_where_nothing_is_and_refuses_a_dangling_link` RS:6019.
-- **Known gaps.** C# and Python have no soft decision, and the C# Mesh flag is dead; no follow-up is registered (h6 `undone` names it). `writer-dangling-link-tolerance` applies to the non-soft branch.
+- **Known gaps.** C# and Python have no soft decision, and the C# Mesh flag is dead; no follow-up is registered (h6 `undone` names it). `writer-dangling-link-tolerance` is settled: the non-soft branch refuses a dangling link too.
 
 ### What no cut owns yet
 

docs/mutation-testing.md

@@ -3,7 +3,7 @@
 CultLib measures its C# test suites with Stryker.NET, pinned as a repo-local
 tool in `dotnet-tools.json`. Coverage is added project by project; a project
 with no `stryker-config.json` next to its test project has not been scoped
-yet (see "Follow-ups" below for what's outstanding).
+yet (see "Scope and follow-ups" below for what's outstanding).
 
 ## Running it
 
@@ -126,14 +126,17 @@ project as precedent for the `vstest` caveat itself - that caveat is
 `mtp`-runner-specific and documented above for `static readonly` field
 initializers, and GameCult.Geometry has never actually hit it.
 
-## Follow-ups
+## Scope and follow-ups
 
-CultMath.Tests and GameCult.Geometry.Tests are the only projects currently
-scoped. GameCult.Geometry's `stryker-config.json` has no `test-runner`
-entry: the project is NUnit 4 with `NUnit3TestAdapter` and
+CultMath.Tests, GameCult.Geometry.Tests and GameCult.Caching.Tests are the
+projects currently scoped. GameCult.Geometry's `stryker-config.json` has no
+`test-runner` entry: the project is NUnit 4 with `NUnit3TestAdapter` and
 `Microsoft.NET.Test.Sdk`, so Stryker's default `vstest` runner applies
 directly (no `mtp` workaround needed, unlike CultMath.Tests's xunit.v3
-suite).
+suite). GameCult.Caching.Tests is the same shape (NUnit, default `vstest`)
+and its `stryker-config.json` is driven the same way, by the repo-local
+`dotnet-stryker` tool: `dotnet tool restore` once, then `dotnet tool run
+dotnet-stryker` from `tests/GameCult.Caching.Tests`.
 
 GameCult.Geometry has only ever been run `--since:`-scoped to the cut that
 added surface nets; a full-project baseline (running mutation against all of
@@ -151,7 +154,81 @@ file, anything under `Fixtures/`) loses `--since` line-level scoping for that
 run; a future cut whose diff is C#-only, against a base commit that already
 has `stryker-config.json`, should scope correctly.
 
-`GameCult.Caching`, `GameCult.Mesh` (+ `.Quic`, `.Quic.Native`),
+### GameCult.Caching.Tests
+
+`tests/GameCult.Caching.Tests/stryker-config.json` mutates all of
+`src/GameCult.Caching` (the project is `GameCult.Caching.csproj`; Standard
+mutation level, `break` 0, the same thresholds as Geometry). Caching was
+scoped before Networking because its suite is deterministic and quick (1415
+tests, about 40 s) over about 7.8k lines of source, where GameCult.Networking
+is about 20k lines and its tests lean on socket timing, so a mutant timing out
+there says little about the test. A full Caching run is about 2,900 candidate
+mutants (3,602 created, minus 730 that fail to compile) at about 2 s each,
+about 1.5 hours; run it detached and read the JSON report,
+never as one attached session.
+
+The first measurement was a narrow pass over the three files that carry the
+store-replace and element-id machinery, from `tests/GameCult.Caching.Tests`:
+
+```bash
+dotnet tool run dotnet-stryker \
+  -m '**/src/GameCult.Caching/StoreReplace.cs' \
+  -m '**/src/GameCult.Caching/CultStoreLinks.cs' \
+  -m '**/src/GameCult.Caching/CultElementIds.cs'
+```
+
+A clean single run of that command tested 243 mutants and scored 86.79% in
+9 minutes 55 seconds. The first measurement of it overlapped two Stryker
+runs, so its numbers (and the 114 survivors it showed for `CultElementIds.cs`,
+where tests that kill a mutant by hand reported `Survived` or `Timeout`) are
+not measurements and are not quoted here. Never run two Stryker runs against
+one checkout at once, and check `ps` before starting one. A clean single run
+on `CultElementIds.cs` alone, after the tests below, tested 228 mutants: 208
+`Killed`, 8 `Timeout`, 12 `Survived`, a score of 94.74%. The 12th survivor
+was 321, which the throwing-enumerator case in `ListsOfValuesHoldNoIds` now
+kills; the other 11 are equivalent mutants. With that case a clean single run
+on `CultElementIds.cs` is 209 `Killed`, 8 `Timeout`, 11 `Survived`, 95.18%.
+
+Real gaps that run exposed, each now pinned by `ElementIdWalkTests` (and each
+failing when its mutant is applied by hand): the order of the id path (the
+codec refuses at the first type MessagePack cannot allow, so order is what an
+error names first; `Append` to `Prepend` at 163, 167 and 180); the
+union-cycle guard in `ConcreteTypes` (248; the mutant is a stack overflow, so
+the red is a crashed test host: a depth guard would need production code in
+`ConcreteTypes`, since the recursion is private and a stack overflow cannot be
+caught by the test, so the regression test is left to crash loudly); a list of values reporting that it holds an
+id (`Holds`, 322); `[Key]` read through an override (`KeyOf`, 583); and the
+`IsWrittenWhole` and `IsKeyed` predicates (629 to 631 and 636: formatter,
+`[MessagePackObject]` and `KeyAsPropertyName` inherited from a base, and the
+`[DataContract]` without `[MessagePackObject]` and `||` arms).
+
+Equivalent survivors in `CultElementIds.cs` (11), each hand-checked against the full
+suite; none can be told apart by any test:
+
+- 142, 251, 636 (second arm), 506 (`IsDefined(UnionAttribute, false)` to
+  `true`): `UnionAttribute` is `Inherited = false`, so its `inherit` argument
+  changes nothing. Likewise 630's `DataContractAttribute` `inherit` argument
+  (`DataContractAttribute` is `Inherited = false`).
+- 264, 542: `group.First()` to `FirstOrDefault()` over `GroupBy` groups, which
+  are never empty.
+- 491: `new StringBuilder(bytes.Length * 2)` to `/ 2` changes only the initial
+  capacity.
+- 578: removing the `Nullable.GetUnderlyingType` unwrap in `WalksAsOwner`;
+  `Classify` unwraps nullables itself, so the unwrap is dead. A cut
+  candidate, not a test gap.
+- 645, 657: `Append(type)` to `Prepend(type)` in `ElementTypeOf` and
+  `MapTypes`; `type` matches only when it is itself `IEnumerable<>`,
+  `IDictionary<,>` or `IReadOnlyDictionary<,>`, and none of those has a second
+  matching interface, so the position of `type` never decides the answer.
+
+The Windows-only P/Invoke group is exercised only on Windows: its mutants are
+`NoCoverage` on Linux and are a target for a Windows-leg mutation run, not a
+Linux gap or a finding. `StoreReplace.cs` line 45 is a different case: its
+negated `IsOSPlatform(Windows)` mutant is `Survived` on Linux, because the
+negated branch calls `ReplaceWindows`, whose `DllNotFound` fallback gives the
+same result.
+
+`GameCult.Mesh` (+ `.Quic`, `.Quic.Native`),
 `GameCult.Networking` (+ `.WebSockets`), and the non-.NET runtimes
 (`cultcache-rs/py/ts`, `cultmesh-*`, `cultnet-*`) each still need their own
 `stryker-config.json` (or ecosystem-equivalent tool: `cargo-mutants` for

docs/start/README.md

@@ -124,7 +124,7 @@ The test imports from `../src/index` where the block reads `@gamecult/cultcache-
 Same shape with `derive(DatabaseEntry)`: slots are `#[cultcache(key = N)]`, so the `.cc` payload is the
 slot-indexed array the C# runtime writes. The source is
 [`packages/cultcache-rs/tests/first_call.rs`](../../packages/cultcache-rs/tests/first_call.rs), run by
-`cargo test --test first_call` in `packages/cultcache-rs`; a second test in that file fails if the block
+`cargo test --locked --test first_call` in `packages/cultcache-rs`; a second test in that file fails if the block
 below stops matching the file. The Rust runtime has no name lookup, so the read-back is by key. More:
 `packages/cultcache-rs/README.md`.
 
@@ -341,7 +341,7 @@ async function firstCall() {
 ### Rust CultNet first call
 
 Source: [`packages/cultnet-rs/tests/first_call.rs`](../../packages/cultnet-rs/tests/first_call.rs), run by
-`cargo test --test first_call` in `packages/cultnet-rs`. More: `packages/cultnet-rs/README.md`.
+`cargo test --locked --test first_call` in `packages/cultnet-rs`. More: `packages/cultnet-rs/README.md`.
 
 ```rust
 use std::net::{TcpListener, TcpStream};

docs/write-ownership-map.md

@@ -33,13 +33,16 @@ Probes: scratch tests in this worktree, removed. C# filtered runs on Starfire (o
 
 | Probe | C# | TypeScript | Rust | Python |
 |---|---|---|---|---|
-| P1 cache {A,B}: B at k, then A at k | **C**: B's record replaced, k now A's id | C, and **both** records live at k | C, both live at k | C, both live at k |
-| P2 cache {A} only, store holds B at k, write A at k | R `CultSchemaConflictException` (B is foreign, carried) | R at load: "No schema is registered for persisted schema id" | R at load, same | R at load: "Unknown persisted document type" |
+| P1 cache {A,B}: B at k, then A at k | **C**: B's record replaced, k now A's id | R `SchemaConflictError` (cultcache-ts: one record per key) | R `SchemaConflictError` naming k, A not written (leaf cut) | R `SchemaConflictError`, A's write refused, B kept (was C, both live) |
+| P2 cache {A} only, store holds B at k, write A at k | R `CultSchemaConflictException` (B is foreign, carried) | R `SchemaConflictError` at write (foreign loads, carried; cultcache-ts) | R `SchemaConflictError` (B loads as foreign, carried; leaf cut) | R `SchemaConflictError` (B is foreign, carried; the load admits it; was R at load) |
 | P3 cacheless `WriteDocument<A>` over B, registry null / {A} / {A,B} | R / R / R | no cacheless write | no cacheless write | no cacheless write |
 | P4 cache {A,B}: remove k and upsert A at k in one batch | C (k is A's) | n/a | n/a | n/a |
 | P5 cache {A,B}: remove, then add in a second commit | C | n/a | n/a | n/a |
 | P6 N2 over an N1 record (undeclared name drift), cache {N2} / cacheless reg {N2} | C restamped / C restamped | not probed | not probed | C (cache) |
 
+The C#-written probe the leaves are held to is `tests/vectors/key-identity` (12 rows: retype, foreign carry, key in two stores), walked by
+`KeyIdentityVectorTests`; each leaf cut corrects its own column above.
+
 What this establishes:
 
 - C#: one record per key. The only path that retypes is the cache arm (P1): `CacheBackingStore.RefuseUndeclared`
@@ -52,12 +55,22 @@ What this establishes:
 - Retype as remove plus add already works in the cache (P4, P5); the cut adds no new primitive.
 - Directory store: its own judge (`DirectoryMessagePackBackingStore.cs:287-306`) asks `Registry.Owns` for every key,
   upserts included. It must take the same per-key rule.
-- TypeScript, Rust, Python: records are keyed by `(type, key)` (Rust `entries: BTreeMap<(String, String), _>`,
-  `lib.rs:2659`; TS `#entryId(definition.type, key)`, `cult-cache.ts:323`; Python sorts and stores by `(type, key)`).
-  A write of A at k never meets B's record: both live at k (P1). None carries a foreign record; a store holding an
-  unregistered type does not load (P2). So no leaf has a "write meets another type's record" path to fix. Bringing the
-  ruling to the leaves first needs C#'s key identity (one record per key) and C#'s foreign carry, which are parity changes
-  of the leaves' store model, not a write-ownership rule. Owned by the new follow-up `variants:follow_up:leaf-key-identity-parity`.
+- TypeScript and Python: records are keyed by `(type, key)` (TS `#entryId(definition.type, key)`, `cult-cache.ts:323`;
+  Python sorts and stores by `(type, key)`). A write of A at k never meets B's record: both live at k (P1). Neither carries
+  a foreign record; a store holding an unregistered type does not load (P2). So neither has a "write meets another type's
+  record" path to fix: bringing the ruling to them first needs C#'s key identity (one record per key) and C#'s foreign
+  carry, parity changes of their store model, not a write-ownership rule (follow-up `variants:follow_up:leaf-key-identity-parity`).
+- Rust is that follow-up's first leaf cut (`cut-leaf-key-identity-rs`). The cache keeps its `(type, key)` map; one judge
+  (`refuse_retype`) refuses another registered type at a key the cache holds, or any write at a key a store carries
+  foreign, on every write path, pull and SoA load, comparing types, not the ids envelopes claim. At a key the cache does not
+  hold (a fresh key, or one another writer filled after this cache's pull) the single-file store's commit guard judges by
+  the stored and claimed schema ids, so an envelope claiming another registered type's id is refused earlier, at every
+  envelope admission (`refuse_claimed_id`, the pull's own `resolve_registered_type` lookup); an id naming no registered type
+  passes, trusted as claimed: an envelope under such an id can replace another writer's record stored under it at a key
+  this cache does not hold, or be served as another type by a reader that registers the type the id names (Soul g8a, g8c,
+  open: which ids a Rust type owns is not declared to CultCache). Store-level writers called directly (`push`,
+  `insert_entry_if_absent`, compare-and-swap) trust the claimed id.
+  The cache carries an unregistered type's records as foreign and walks the vector's 12 rows.
 - Interop (unproven): a Python store holding A and B at k fails C# decode first on payload encoding (Python's
   lambda-defined document wrote JSON payloads), so what C# does with two records at one key was not reached.
 
@@ -94,8 +107,8 @@ Authority map (also in the spec):
 - `variants:follow_up:public-store-writes-behind-cache`: **leave**. It asks who may stage behind an attached cache (API
   shape); this cut changes what any staging is judged by. No collision: direct `Push`/`CommitBatch` reach the same on-disk
   judge, so they get the per-key rule for free. Hands must not give direct staging a different predicate.
-- `variants:follow_up:writer-dangling-link-tolerance`: **leave**. Rust/TS whole-store `push_all` reading a dangling link is
-  a reader/writer tolerance question, not ownership; this cut touches no leaf.
+- `variants:follow_up:writer-dangling-link-tolerance`: **settled** (the reader owns the verdict; every runtime's whole-store
+  `push_all` refuses a dangling link, as `push` does).
 
 ## Deferred doc findings this cut fixes
 

package-lock.json

@@ -1205,7 +1205,7 @@
       "license": "MIT",
       "dependencies": {
         "@gamecult/cultcache-ts": "^0.15.0",
-        "@gamecult/cultnet-ts": "^0.3.0"
+        "@gamecult/cultnet-ts": "^0.4.0"
       },
       "devDependencies": {
         "@gamecult/cultmesh-ts": "^0.2.0",
@@ -1222,7 +1222,7 @@
       "license": "MIT",
       "dependencies": {
         "@gamecult/cultcache-ts": "^0.15.0",
-        "@gamecult/cultnet-ts": "^0.3.0",
+        "@gamecult/cultnet-ts": "^0.4.0",
         "koffi": "3.3.0"
       },
       "devDependencies": {
@@ -1236,7 +1236,7 @@
     },
     "packages/cultnet-ts": {
       "name": "@gamecult/cultnet-ts",
-      "version": "0.3.0",
+      "version": "0.4.0",
       "license": "MIT",
       "dependencies": {
         "@gamecult/cultcache-ts": "^0.15.0",

package.json

@@ -10,7 +10,7 @@
   "scripts": {
     "build:ts": "node scripts/run-typescript-workspaces.mjs build",
     "test:ts": "node scripts/run-typescript-workspaces.mjs test",
-    "test:pack:ts": "node scripts/test-typescript-package-closure.mjs && node scripts/test-declared-dependency-ranges.mjs",
+    "test:pack:ts": "node --test scripts/test-declared-dependency-ranges.test.mjs && node scripts/test-typescript-package-closure.mjs && node scripts/test-declared-dependency-ranges.mjs",
     "test:eve-browser-network": "node scripts/verify-eve-browser-network.mjs"
   },
   "devDependencies": {

packages/cultcache-py/CHANGELOG.md

@@ -2,13 +2,28 @@
 
 ## Unreleased
 
+### Added
+
+- `read_payload_tree(type_name, payload, decoder=None)`: the exported owner of the one-value, depth-first payload read that `decode_payload` uses, for payloads read outside a definition (`cultnet-py`'s witness bundle decode needs it, so `cultnet-py` now requires `cultcache-py>=0.4.0`). The manifest version is 0.4.0, the minor these Unreleased breaking changes imply, set in this change so the workspace install resolves the new bound; the `## Unreleased` heading becomes `## [0.4.0]` when it is tagged.
+
 ### Changed
 
+- `store_write_lock` looks for a link at the store path again once the lock is held, so a link put at the path while a writer waited on the lock is refused with `StoreLinkedError` and the lock released, instead of being replaced. `JsonLinesBackingStore` takes no cross-process lock (only its thread lock, under which it already refuses a link), so it has no lock wait to re-check across. Pinned by a test that puts the link while a foreign process holds the lock.
+- `CultCache.is_writable` does not look at store paths: a link at a store path is not predicted, and the write refuses it with `StoreLinkedError`. Pinned by a test through a cache attached to a linked store.
+- `JsonLinesBackingStore` writes LF line endings on Windows. It wrote CRLF there, through `write_text` newline translation, before the commit_store_file change (#154, adbbb780).
 - `msgpack` is a hard dependency, as `pyproject.toml` declared it. The optional-import fallbacks and the `cultcache-py[msgpack]` extra they named (which never existed) are gone: a missing msgpack is an `ImportError` at import.
+- `JsonLinesBackingStore` writes through the same `commit_store_file` as the single-file store: a unique staged file, fsynced before the replace and removed when the replace fails, so a refused replace no longer leaves `<path>.tmp` behind. It staged a fixed `<path>.tmp` without an fsync.
 - The single-file store's `push`, `push_all` and `delete` take the cross-process lock on `<path>.lock` (flock; LockFileEx over the whole file on Windows) across the read and the replace, waiting up to `lock_timeout` seconds (30 by default, `TimeoutError` after), and exclude the C#, Rust and TypeScript runtimes' writers. The staged file is `<path>.tmp-<pid>-<uuid>`, fsynced before the replace, with a directory fsync after it off Windows. A fixed `<path>.tmp` is no longer used.
 
 ### Breaking
 
+- `push_all(envelopes, soft=False)` on the single-file and JSONL stores and on the `BackingStore` protocol takes the soft flag, as TypeScript, Rust and C# do: a soft push writes only where nothing is at the path; over a store the reader reads, empty included, it returns without writing, and over a file the reader cannot read it refuses (`StoreUnreadableError` for the single-file store). The `BackingStore` protocol has `pull_or_absent()`: the envelopes the reader reads, `None` when nothing is at the path, a raise when the path cannot be read; its default is `pull_all()`, which cannot say absent, so a store that inherits it is always read. The default `push_all` decides soft by it (writes where it says absent, skips over a store it read, refuses where it raises), and the single-file and JSONL stores expose their pull through it; an inheriting store that can tell nothing-at-the-path overrides `pull_or_absent`, not `push_all`. Before, a soft push through the default always skipped. A store kind that overrides `push_all(envelopes)` without the keyword fails when a caller passes `soft`.
+- A write at a store path that is a link, live or dangling, is refused with the new `StoreLinkedError` (an `OSError`, exported from `cultcache_py`; `.path` names the path) before the lock and the replace, for the single-file store and for `JsonLinesBackingStore` (`push`, `push_all`, `delete`), and nothing is written. Before, a write at a live link replaced the link with a regular file, and at a dangling link both stores raised `FileNotFoundError`. A caller catching `FileNotFoundError` there now catches `StoreLinkedError` (`OSError`); configure the link's target as the store path. On Windows a junction or any reparse point counts as a link. Reads through a live link work.
+- A record whose payload carries a slot past its reader's declared slots, at any depth (the document, a nested record, a list element, a union arm, a unit arm), is read, held read-only, and every write or removal of its key (`put`, `put_global`, `update`, `put_envelope`, `put_envelopes`, `delete`, `delete_global`) is refused with `SchemaConflictError` before any store is touched (`cultlib-gaps:ruling:extra-trailing-slots`). Reading dropped those slots silently and the next write shed them. `SchemaConflictError.unread_slots` is an `UnreadSlots(type_name, slot_count, declared_count, occurrences, depth0_only)` and the message names the type and both counts, never a slot value. A depth-0 mark is consented, and the record writable, only when the record is stored under an id the document lists in `compatible_schema_ids` and that id's catalog entry has slots past the document's, covering the mark's slot count (`cultlib-gaps:ruling:slot-mark-consent`); a nested mark, or a mark under the document's own id, keeps the record read-only whatever is declared. Missing trailing slots keep their declared defaults. An untouched marked record keeps its stored bytes through every other write. Added `CultCache.is_writable(document, key)` (advisory; the write still decides: it also answers False for a foreign-carried key, for a key held as a type the document does not own, and for a global document at a non-global key; `delete` asks the same judges, so removing a key held as another type is refused with `SchemaConflictError` unless the document owns that record's schema id (its own or one it lists compatible), in which case the removal removes that record, its file row and its lookups, as a write of the key would replace it; it returned silently and removed nothing), `DocumentDefinition.decode_payload_marked`, and `UnreadSlots`. A document with a custom `decode` (no slot codec) never marks. A store holding a variant record is still unreadable here. Implies a minor bump while the version is 0.x (0.3.0 to 0.4.0): code that wrote back a record from a newer writer now gets `SchemaConflictError`.
+- A payload is one MessagePack value: `DocumentDefinition.decode_payload` refuses bytes after it, by count, with `ValueError` `<type> payload has N bytes after its first MessagePack value (refused on read).` (never the bytes, never the depth refusal; a payload that ends early stays the decoder's), as the C# reference does (`tests/vectors/union-parity/bytes-after-outcomes.msgpack`). It raised `msgpack.ExtraData` (a `ValueError`, so only a caller naming `msgpack.ExtraData` is affected); this is a minor-version bump while pre-1.0. The refused set is unchanged. Cache loads, `get` and every definition built on the MessagePack decoder go through it; a user `payload_decoder` that raises `ExtraData` is refused the same way. Depth is judged first, so a value nested past 256 with a tail is the depth refusal, as in C#.
+- A cache holds one record per key whatever its type (`variants:ruling:cache-refuses-retype`). A `put`, `put_envelope`, `put_envelopes` or `put_global` of a second type under a key the cache holds, or under a key a store carries foreign, is refused with `SchemaConflictError` naming the key, even with no store, and changes nothing; retype a key by deleting it, then putting the new type. A write may replace another registered type's record only when the written type owns its schema id (declares it or lists it compatible) and both types share one home store. A load that reads one key from two stores, whatever the types, is refused with `CultCacheError` naming the key and both types, and admits nothing. A store that holds a record no registered type claims now loads and is carried: the cache does not serve it, the store keeps its bytes through every write, `delete` or `put` at its key is refused with `SchemaConflictError`, and registering a type that declares its schema id claims it at the next load. It raised `CultCacheError` "Unknown persisted document type". Two global types share the key `__global__`, so a second global type in one cache is now refused, and a store that already holds two global types at `__global__` (a JSONL store written by caches that never pulled could produce one) no longer loads: the pull raises `CultCacheError` and admits nothing. C# refuses a second persisted global on pull the same way (`cultcache-store-composition.md`, "Globals never invented"); repair such a file by deleting one of the two records with the runtime that wrote it.
+- Added `foreign_records()` and the frozen `ForeignRecord(key, schema_id, schema_name, stored_at)`, sorted by key in UTF-16 code-unit order. `stores.retyped` and `stores.written_owns` lose their underscore: the cache judge and the single-file store's commit guard ask one predicate.
+
 - A single-file store holding two records under one key is unreadable: the v1 reader and the legacy envelope-array reader refuse it with `StoreUnreadableError` (a key is compared by its exact code points, no case folding or normalisation). A catalog slot whose canonical schema is not a string is refused the same way. A store that loaded before can now be refused: repair it with the runtime that wrote the duplicate.
 - A `put` or `push_all` that would land a second type under a key the store holds is refused with `SchemaConflictError`, and the file is left as it was. Retype a key by deleting it, then putting the new type. A write replaces the record at a key only when the written type owns it: its catalog entry declares the stored schema id (its own, or one it lists compatible), so a renamed type that lists the old id compatible may replace the record, or it has the stored record's schema name. This runtime does not compare shapes, so a same-name type is never refused for dropping persisted slots as C# refuses it.
 - Writes of the same type replace by key: the last record wins, in a batch as in the file.

packages/cultcache-py/README.md

@@ -19,7 +19,12 @@ discovery, sessions, local server) build on it, mirroring `cultcache-rs` /
   `[format, schemaCatalog, records]`
 - records store raw MessagePack payload bytes under schema-catalog identity
 - payloads decode only through the registered document definition for that type
-- unknown persisted types fail closed
+- a payload is exactly one MessagePack value: bytes after it are refused on read, by count
+- a cache holds one record per key whatever its type: a write of a second type at a held key is refused with
+  `SchemaConflictError` (in memory too), and two stores holding one key refuse the load
+- a store record no registered type claims loads and is carried as foreign: `cache.foreign_records()` lists it, the store
+  keeps its bytes through every write, a write or removal at its key is refused, and registering a type that declares its
+  schema id claims it at the next load
 - global documents are singleton-style per type
 - one home store per document type: a store added with `add_backing_store`
   owns its types, otherwise the generic store is the home; a type claimed by a
@@ -93,6 +98,7 @@ store.
 - `update_global(...)`
 - `delete(...)`
 - `delete_global(...)`
+- `is_writable(document, key)` (advisory: would a write or removal of the key be refused; see below)
 - `snapshot()`
 
 ## Indexes And Roles
@@ -176,6 +182,16 @@ The payload is a MessagePack array. Field keys are durable slot indexes:
 - newly added fields should use new keys
 - fields with defaults tolerate missing or nil slots when older payloads are read
 
+A payload carrying a slot past the slots a reader declares, at any depth (the document, a nested record, a list element, a
+union arm, a unit arm), was written by a newer build. It is read, and the record is held read-only: `put`, `update`,
+`put_envelope(s)`, `delete` and their global forms refuse its key with `SchemaConflictError` before any store is touched, and
+`SchemaConflictError.unread_slots` is an `UnreadSlots(type_name, slot_count, declared_count, occurrences, depth0_only)` naming the
+first type read with extra slots (never a slot value). `CultCache.is_writable(document, key)` answers the same question before
+the write: False for such a record, for a key a store carries foreign, and for a key held as another type's record; the write
+still decides. `DocumentDefinition.decode_payload_marked(payload)` returns the value and its `UnreadSlots` (or None). Declaring the
+stored id in `compatible_schema_ids` consents to the loss of depth-0 slots that id's catalog entry reports; a nested mark never is.
+A store keeps a read-only record's bytes through every other write. A document with a custom `decode` never marks.
+
 That matches the Rust `#[derive(DatabaseEntry)]` formatter shape and the C#
 `[Key(n)]` intent: schema evolution comes from stable field slots, not source
 member order.

packages/cultcache-py/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "cultcache-py"
-version = "0.3.0"
+version = "0.4.0"
 description = "Python CultCache runtime for GameCult typed state."
 readme = "README.md"
 requires-python = ">=3.10"

packages/cultcache-py/src/cultcache_py/__init__.py

@@ -1,7 +1,7 @@
 from .backing_store import BackingStore, CultCacheEnvelope
 from .backing_store import CultCacheSchemaCatalogEntry, CultCacheSchemaCatalogMember
 from . import leaves
-from .cache import CultCache, CultCacheBuilder
+from .cache import CultCache, CultCacheBuilder, ForeignRecord
 from .documents import (
     MAX_PAYLOAD_DEPTH,
     MAX_SLOT_KEY,
@@ -9,15 +9,17 @@ from .documents import (
     DatabaseEntryField,
     DocumentDefinition,
     UnionArm,
+    UnreadSlots,
     database_entry_field,
     define_database_entry_type,
     define_document_registry,
     define_document_type,
     define_record_codec,
     define_union,
+    read_payload_tree,
 )
 from .leaves import SlotCodec
-from .stores import JsonLinesBackingStore, SchemaConflictError, SingleFileMessagePackBackingStore, StoreUnreadableError
+from .stores import JsonLinesBackingStore, SchemaConflictError, SingleFileMessagePackBackingStore, StoreLinkedError, StoreUnreadableError
 
 __all__ = [
     "BackingStore",
@@ -29,14 +31,18 @@ __all__ = [
     "CultCacheSchemaCatalogMember",
     "DatabaseEntryField",
     "DocumentDefinition",
+    "ForeignRecord",
     "JsonLinesBackingStore",
     "MAX_PAYLOAD_DEPTH",
     "MAX_SLOT_KEY",
     "SchemaConflictError",
     "SingleFileMessagePackBackingStore",
     "SlotCodec",
+    "StoreLinkedError",
     "StoreUnreadableError",
     "UnionArm",
+    "UnreadSlots",
+    "read_payload_tree",
     "leaves",
     "database_entry_field",
     "define_database_entry_type",

packages/cultcache-py/src/cultcache_py/backing_store.py

@@ -67,10 +67,20 @@ class BackingStore(Protocol):
     def delete(self, type: str, key: str) -> None:
         ...
 
-    def push_all(self, envelopes: list[CultCacheEnvelope]) -> None:
-        existing = {
-            (envelope.type, envelope.key): envelope for envelope in self.pull_all()
-        }
+    def pull_or_absent(self) -> list[CultCacheEnvelope] | None:
+        """The envelopes the reader reads (empty included), None when nothing is at the path; raises when the path cannot be read.
+
+        The default is pull_all, which cannot say absent: a store that inherits it is always a store the reader read. A store kind
+        that can tell nothing-at-the-path overrides this, and the default push_all then writes where nothing is on a soft push."""
+        return self.pull_all()
+
+    def push_all(self, envelopes: list[CultCacheEnvelope], soft: bool = False) -> None:
+        # Soft: write only where pull_or_absent says nothing is; skip over a store it read, empty included; its raise refuses.
+        pulled = self.pull_or_absent()
+        if soft and pulled is not None:
+            return
+        pulled = pulled or []
+        existing = {(envelope.type, envelope.key): envelope for envelope in pulled}
         for envelope in envelopes:
             existing[(envelope.type, envelope.key)] = envelope
         self._replace_all(list(existing.values()))

packages/cultcache-py/src/cultcache_py/cache.py

@@ -8,8 +8,8 @@ from dataclasses import dataclass, field, replace
 from typing import Any, Callable, Generic, Iterable, TypeVar
 
 from .backing_store import BackingStore, CultCacheEnvelope
-from .documents import DocumentDefinition, extract_value
-from .stores import SchemaConflictError
+from .documents import DocumentDefinition, UnreadSlots, extract_value
+from .stores import SchemaConflictError, retyped, written_owns
 
 T = TypeVar("T")
 F = TypeVar("F", bound=Callable[..., Any])
@@ -120,6 +120,24 @@ class _State:
     # of that global removes it from the home store. Remove once no store holds a global under a key
     # other than GLOBAL_KEY.
     legacy_global_keys: dict[str, str] = field(default_factory=dict)
+    # The records the last pull read that no registered type claims, sorted by key. Derived from the pull and swapped with the
+    # rest of the state, written nowhere else; it decides only refusals at its keys. A store keeps their bytes.
+    foreign: list["ForeignRecord"] = field(default_factory=list)
+    # The records held read-only, by key (a key holds one record) with the type that holds it: the payload carried slots past the
+    # declared ones and nothing consents to the loss. Derived from the load or the write that admitted the record and swapped with
+    # the rest of the state; it decides only refusals at its keys, and any other key is absent.
+    unread: dict[str, tuple[str, UnreadSlots]] = field(default_factory=dict)
+
+
+@dataclass(frozen=True)
+class ForeignRecord:
+    """A record a store holds that no registered type claims: the cache does not serve it, refuses a write or a removal at its
+    key, and a store keeps its bytes. Registering a type that declares its schema id claims it at the next load."""
+
+    key: str
+    schema_id: str
+    schema_name: str
+    stored_at: str
 
 
 @dataclass(frozen=True)
@@ -322,15 +340,24 @@ class CultCache:
         loaded_legacy_global_keys: dict[str, str] = {}
         routes, generic = self._state.stores_by_type, self._state.generic_store
         seen_globals: set[str] = set()
+        foreign: list[ForeignRecord] = []
+        loaded_unread: dict[str, tuple[str, UnreadSlots]] = {}
+        type_at_key: dict[str, tuple[str, int]] = {}  # one record per key across every store: its type (or schema name) and store
         stores: list[BackingStore] = []
         for candidate in [*self._state.stores_by_type.values(), self._state.generic_store]:
             if candidate is not None and all(candidate is not store for store in stores):
                 stores.append(candidate)
-        for store in stores:
+        for position, store in enumerate(stores):
             for envelope in store.pull_all():
                 document = self._resolve_document_for_envelope(envelope)
                 if document is None:
-                    raise CultCacheError(f"Unknown persisted document type: {envelope.type}")
+                    entry = envelope.catalog_entry
+                    held_name = entry.schema_name if entry is not None else envelope.type
+                    self._claim_key(type_at_key, envelope.key, held_name, position)
+                    foreign.append(
+                        ForeignRecord(envelope.key, envelope.schema_id or envelope.type, held_name, envelope.stored_at)
+                    )
+                    continue
                 if envelope.type != document.type:
                     envelope = CultCacheEnvelope(
                         key=envelope.key,
@@ -353,8 +380,11 @@ class CultCache:
                     if envelope.key != GLOBAL_KEY:
                         loaded_legacy_global_keys[envelope.type] = envelope.key
                         envelope = replace(envelope, key=GLOBAL_KEY)
-                envelope = self._stamped(document, envelope)
-                value = document.decode_payload(envelope.payload)
+                self._claim_key(type_at_key, envelope.key, envelope.type, position)
+                arrived, envelope = envelope, self._stamped(document, envelope)
+                value, unread = self._decode_marked(document, arrived)
+                if unread is not None:
+                    loaded_unread[envelope.key] = (envelope.type, unread)
                 loaded_values.setdefault(envelope.type, {})[envelope.key] = value
                 read_values[(envelope.type, envelope.key)] = value
                 loaded_envelopes.setdefault(envelope.type, {})[envelope.key] = envelope
@@ -369,7 +399,30 @@ class CultCache:
             self._state.indexes,
             self._state.lookup_keys,
             self._state.legacy_global_keys,
-        ) = (loaded_values, loaded_envelopes, loaded_names, loaded_indexes, loaded_lookup_keys, loaded_legacy_global_keys)
+            self._state.foreign,
+            self._state.unread,
+        ) = (
+            loaded_values,
+            loaded_envelopes,
+            loaded_names,
+            loaded_indexes,
+            loaded_lookup_keys,
+            loaded_legacy_global_keys,
+            sorted(foreign, key=lambda record: _utf16_order(record.key)),
+            loaded_unread,
+        )
+
+    @staticmethod
+    def _claim_key(type_at_key: dict[str, tuple[str, int]], key: str, type: str, store: int) -> None:
+        """A key holds one record whatever its type, across every store a load reads. The refusal names the key and both types,
+        never a payload."""
+        held, held_store = type_at_key.setdefault(key, (type, store))
+        if held != type or held_store != store:
+            raise CultCacheError(f"Record {key!r} is held by both {held} and {type}: a key holds one record; the load admitted nothing.")
+
+    def foreign_records(self) -> list[ForeignRecord]:
+        """The records the last load read that no registered type claims, sorted by key (UTF-16 code-unit order)."""
+        return list(self._state.foreign)
 
     def get(self, document: DocumentDefinition[T], key: str) -> T | None:
         self._assert_registered(document)
@@ -447,9 +500,9 @@ class CultCache:
     def put_envelope(self, document: DocumentDefinition[T], envelope: CultCacheEnvelope) -> T:
         self._assert_registered(document)
         self._check_envelope(document, envelope)
-        envelope = self._stamped(document, envelope)
-        value = document.decode_payload(envelope.payload)
-        self._write(document, [(envelope, value)], batch=False)
+        arrived, envelope = envelope, self._stamped(document, envelope)
+        value, unread = self._decode_marked(document, envelope)
+        self._write(document, [(envelope, value)], batch=False, unread={envelope.key: unread})
         return value
 
     @_mutating
@@ -457,13 +510,33 @@ class CultCache:
         self._assert_registered(document)
         values: list[T] = []
         stamped: list[CultCacheEnvelope] = []
+        unread: dict[str, UnreadSlots | None] = {}
         for envelope in envelopes:
             self._check_envelope(document, envelope)
             stamped.append(self._stamped(document, envelope))
-            values.append(document.decode_payload(envelope.payload))
-        self._write(document, list(zip(stamped, values)), batch=True)
+            value, unread[envelope.key] = self._decode_marked(document, stamped[-1])
+            values.append(value)
+        self._write(document, list(zip(stamped, values)), batch=True, unread=unread)
         return values
 
+    @staticmethod
+    def _decode_marked(document: DocumentDefinition[Any], held_as: CultCacheEnvelope) -> tuple[Any, UnreadSlots | None]:
+        """The payload decoded under the document, with the mark of any slot it carried past the declared ones, or no mark when the
+        loss is consented. `held_as` is the envelope under the id the record is stored under: a load's arrival, a write's stamped
+        envelope, so a key is writable in memory exactly when it is after a reload. A depth-0 mark is consented only when that id is
+        one the document lists compatible and its catalog entry has slots past the document's that cover the mark's slot count (the
+        loss a compatible-id declaration consents to, cultlib-gaps:ruling:slot-mark-consent). Any other mark keeps the record read-only."""
+        value, slots = document.decode_payload_marked(held_as.payload)
+        if slots is None:
+            return value, None
+        entry, stored = document.catalog_entry(), held_as.catalog_entry
+        if slots.depth0_only and stored is not None and held_as.schema_id in entry.compatible_schema_ids and held_as.schema_id != entry.schema_id:
+            declared = {member.slot for member in entry.members}
+            reported = [member.slot for member in stored.members if member.slot not in declared]
+            if reported and slots.slot_count <= max(reported) + 1:
+                return value, None
+        return value, slots
+
     @staticmethod
     def _stamped(document: DocumentDefinition[Any], envelope: CultCacheEnvelope) -> CultCacheEnvelope:
         """The record under its registered schema's id, whatever id the envelope arrived under, so the catalog entry a store
@@ -483,7 +556,12 @@ class CultCache:
             raise CultCacheError(f"Global document {document.type} must use key {GLOBAL_KEY}")
 
     def _write(
-        self, document: DocumentDefinition[Any], records: list[tuple[CultCacheEnvelope, Any]], *, batch: bool
+        self,
+        document: DocumentDefinition[Any],
+        records: list[tuple[CultCacheEnvelope, Any]],
+        *,
+        batch: bool,
+        unread: dict[str, UnreadSlots | None] | None = None,
     ) -> None:
         """Validates every record (home and name and index extractors included) before the store is
         touched; once the store accepts, applying to the cache has no fallible step."""
@@ -491,12 +569,14 @@ class CultCache:
         # A batch naming a key twice lands the last record for it, as C# CultCacheBatch stages one operation per key. The
         # judge, the store and the apply all read this one list.
         records = list({envelope.key: (envelope, value) for envelope, value in records}.values())
+        self._refuse_unread([envelope.key for envelope, _ in records])
         name_extractor = self._state.name_extractors.get(type)
         index_extractors = self._state.index_extractors.get(type, {})
         admitted = [
             (envelope, value, self._lookup_keys_for(value, name_extractor, index_extractors))
             for envelope, value in records
         ]
+        displaced = self._refuse_retype(document, [envelope for envelope, _ in records])
         self._refuse_index_sharing(
             [(type, envelope.key, keys) for envelope, _, keys in admitted],
             self._state.indexes,
@@ -515,16 +595,100 @@ class CultCache:
         values = self._state.values.setdefault(type, {})
         envelopes = self._state.envelopes.setdefault(type, {})
         lookup_keys = self._state.lookup_keys.setdefault(type, {})
+        for other, key in displaced:
+            self._drop(other, key)
         for envelope, value, keys in admitted:
             self._remove_lookups(type, envelope.key)
             values[envelope.key] = value
             envelopes[envelope.key] = envelope
+            # A held mark refused this write above, so a key reaching here carries none to clear.
+            if (mark := (unread or {}).get(envelope.key)) is not None:
+                self._state.unread[envelope.key] = (type, mark)
             lookup_keys[envelope.key] = keys
             if keys.name is not None:
                 self._state.names[(type, keys.name)] = envelope.key
             for index, index_value in keys.indexes.items():
                 self._state.indexes[(type, index, index_value)] = envelope.key
 
+    def _refuse_retype(self, document: DocumentDefinition[Any], written: list[CultCacheEnvelope]) -> list[tuple[str, str]]:
+        """The one key-identity judge (variants:ruling:cache-refuses-retype): a key holds one record whatever its type, so a write
+        may not land at a key this cache holds another type's record at, unless the written type owns that record's schema id
+        (the single-file store's commit guard asks the same question of the file), and may not land at a key a store carries
+        foreign. Returns the (type, key) records an owning write replaces; refuses, changing nothing, otherwise."""
+        replaced: list[tuple[str, str]] = []
+        foreign = {record.key: record for record in self._state.foreign}
+        for envelope in written:
+            carried = foreign.get(envelope.key)
+            if carried is not None:
+                raise self._foreign_refusal(carried)
+            for other, held_envelopes in self._state.envelopes.items():
+                held = held_envelopes.get(envelope.key)
+                if other == document.type or held is None:
+                    continue
+                if not written_owns(held, envelope) or self._store_for_type(other) is not self._store_for_type(document.type):
+                    raise retyped(held, envelope)
+                replaced.append((other, envelope.key))
+        return replaced
+
+    @_locked
+    def is_writable(self, document: DocumentDefinition[Any], key: str) -> bool:
+        """Whether a write or removal of the key by this document would pass the judges that run before any store is touched: False for
+        a record held read-only (its payload carried slots past the declared ones, at any depth, and nothing consents to the loss, so
+        writing it would drop data a newer writer stored), for a key a store carries foreign, and for a key held as another type's
+        record this document does not own. Advisory (the write still decides): it answers at call time, and a key nothing holds is
+        writable. It does not look at store paths: a link at a store path is not predicted, and the write refuses it with
+        `StoreLinkedError`."""
+        self._assert_registered(document)
+        try:
+            self._refuse_at(document, key)
+        except (SchemaConflictError, CultCacheError):
+            return False
+        return True
+
+    def _refuse_at(self, document: DocumentDefinition[Any], key: str) -> list[tuple[str, str]]:
+        """The judges a write or removal of the key by this document passes before any store is touched, asked by `is_writable` and
+        by `delete`: a global document writes only its global key, a record held read-only is never replaced, and a key held as
+        another type's record or carried foreign is refused (`_refuse_retype`)."""
+        if document.global_document and key != GLOBAL_KEY:
+            raise CultCacheError(f"Global document {document.type} must use key {GLOBAL_KEY}")
+        self._refuse_unread([key])
+        entry = document.catalog_entry()
+        probe = CultCacheEnvelope.create(key=key, type=document.type, payload=b"", schema_id=entry.schema_id, catalog_entry=entry)
+        return self._refuse_retype(document, [probe])
+
+    def _refuse_unread(self, keys: list[str]) -> None:
+        """The one check every write and removal asks before any store is touched."""
+        for key in keys:
+            held = self._state.unread.get(key)
+            if held is None:
+                continue
+            type, slots = held
+            raise SchemaConflictError(
+                self._state.envelopes[type][key].schema_id or type,
+                [self._state.documents[type].catalog_entry().schema_name],
+                key,
+                message=(
+                    f"{self._state.documents[type].catalog_entry().schema_name} record {key} is read-only: {slots.type_name} was read with "
+                    f"{slots.slot_count} slots where this build declares {slots.declared_count} ({slots.occurrences} object(s) in the "
+                    "record). Writing it would drop data a newer writer stored; read it with types that declare those slots, or "
+                    "write it from that build."
+                ),
+                unread_slots=slots,
+            )
+
+    @staticmethod
+    def _foreign_refusal(record: ForeignRecord) -> SchemaConflictError:
+        return SchemaConflictError(
+            record.schema_id,
+            [record.schema_name],
+            record.key,
+            message=(
+                f"Record {record.key!r} is held by the store as a {record.schema_name} (schema id {record.schema_id!r}) that no "
+                "registered type claims; a write or removal there would replace what this cache cannot read. Register the type "
+                "that owns the schema id, or remove the record with the runtime that wrote it."
+            ),
+        )
+
     @staticmethod
     def _retire_legacy_global(store: BackingStore, type: str, legacy_key: str) -> None:
         """The first write of a global loaded from a legacy key removes that record in the same write. If
@@ -564,19 +728,29 @@ class CultCache:
 
     def _delete(self, document: DocumentDefinition[Any], key: str) -> None:
         self._assert_registered(document)
+        # A key held as another type's record this document owns is removed, as a write of the key would replace it (C# Remove is by key).
+        owned = self._refuse_at(document, key)
         store = self._store_for_type(document.type)
         legacy_key = self._state.legacy_global_keys.get(document.type) if key == GLOBAL_KEY else None
         if store is not None:
-            store.delete(document.type, key if legacy_key is None else legacy_key)
+            # One record per key: the owned record when this document does not hold the key, else its own, in one store call.
+            holder = owned[0][0] if owned else document.type
+            store.delete(holder, key if legacy_key is None else legacy_key)
         if legacy_key is not None:
             del self._state.legacy_global_keys[document.type]
-        self._remove_lookups(document.type, key)
+        for other, _ in owned:
+            self._drop(other, key)
+        self._drop(document.type, key)
+
+    def _drop(self, type: str, key: str) -> None:
+        """Removes the held record and its lookups from the cache's maps; the store is the caller's."""
+        self._remove_lookups(type, key)
         for by_type in (self._state.values, self._state.envelopes, self._state.lookup_keys):
-            held = by_type.get(document.type)
+            held = by_type.get(type)
             if held is not None:
                 held.pop(key, None)
                 if not held:
-                    by_type.pop(document.type, None)
+                    by_type.pop(type, None)
 
     @_mutating
     def delete_global(self, document: DocumentDefinition[Any]) -> None:

packages/cultcache-py/src/cultcache_py/documents.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import json
+import threading
 from dataclasses import MISSING, dataclass, field
 from collections.abc import Mapping, Sequence, Set
 from itertools import chain
@@ -30,6 +31,49 @@ MAX_SLOT_KEY = 65535
 _STACK_FAULTS: tuple[type[BaseException], ...] = (_MsgpackStackError,)
 
 
+@dataclass(frozen=True)
+class UnreadSlots:
+    """What a payload decode found past the slots this runtime declares, at any depth: the first type read with extra slots, how
+    many slots it carried against how many it declares, and how many objects in the payload did. It holds no slot value, so a
+    refusal can name it. `depth0_only` is True when every mark sat in the document's own record (the half of consent the payload
+    decides). A record carrying it is read-only unless the schema comparison explains every mark (see `CultCache.is_writable`)."""
+
+    type_name: str
+    slot_count: int
+    declared_count: int
+    occurrences: int
+    depth0_only: bool
+
+
+class _SlotScope:
+    """Opened by `DocumentDefinition.decode_payload_marked`; the record codec and the union codec note into it. It is thread-local,
+    so no codec signature carries it, and a codec decoded outside a payload decode notes nothing."""
+
+    def __init__(self) -> None:
+        self.depth = 0  # records entered: 0 while the document's own record is read
+        self.first: tuple[str, int, int] | None = None
+        self.occurrences = 0
+        self.depth0_only = True
+
+    def note(self, type_name: str, slot_count: int, declared_count: int, depth0: bool) -> None:
+        if self.first is None:
+            self.first = (type_name, slot_count, declared_count)
+        self.occurrences += 1
+        self.depth0_only = self.depth0_only and depth0
+
+    def result(self) -> UnreadSlots | None:
+        if self.first is None:
+            return None
+        return UnreadSlots(*self.first, self.occurrences, self.depth0_only)
+
+
+_scope = threading.local()
+
+
+def _current_scope() -> _SlotScope | None:
+    return getattr(_scope, "open", None)
+
+
 _CONTAINERS = (Mapping, Sequence, Set)
 _SCALAR_SEQUENCES = (str, bytes, bytearray, memoryview)
 
@@ -114,6 +158,26 @@ def _messagepack_payload_decoder(payload: bytes) -> Any:
     return msgpack.unpackb(payload, raw=False)
 
 
+def read_payload_tree(type_name: str, payload: bytes, decoder: Callable[[bytes], Any] | None = None) -> Any:
+    """The one read of a payload's tree: exactly one MessagePack value, within the nesting limit. Depth is judged first,
+    on the value read so far, so a tail never pre-empts it (C# throws at container 257 before it reaches the tail); then a
+    tail is refused by count and never echoed. Raised outside the handler so no `__context__` keeps the tail."""
+    after = -1
+    unpacked: Any = None
+    try:
+        tree = (decoder or _messagepack_payload_decoder)(payload)
+    except _STACK_FAULTS:
+        raise CultCachePayloadDepthError(type_name, "read") from None
+    except msgpack.ExtraData as error:
+        after = len(error.extra)
+        unpacked = error.unpacked
+    if after >= 0:
+        _refuse_past_depth_limit(unpacked, type_name, "read")
+        raise ValueError(f"{type_name} payload has {after} bytes after its first MessagePack value (refused on read).")
+    _refuse_past_depth_limit(tree, type_name, "read")
+    return tree
+
+
 @dataclass(frozen=True)
 class DatabaseEntryField:
     name: str
@@ -185,15 +249,21 @@ class DocumentDefinition(Generic[T]):
         return self.payload_encoder(tree)
 
     def decode_payload(self, payload: bytes) -> T:
+        return self.decode_payload_marked(payload)[0]
+
+    def decode_payload_marked(self, payload: bytes) -> tuple[T, UnreadSlots | None]:
+        """The value and what the decode found past the declared slots, at any depth. The payload depth check runs first: a
+        payload past the limit is refused, never marked."""
+        tree = read_payload_tree(self.type, payload, self.payload_decoder)
+        outer, opened = _current_scope(), _SlotScope()
+        _scope.open = opened
         try:
-            tree = self.payload_decoder(payload)
-        except _STACK_FAULTS:
-            raise CultCachePayloadDepthError(self.type, "read") from None
-        _refuse_past_depth_limit(tree, self.type, "read")
-        value = self.decode(tree)
+            value = self.decode(tree)
+        finally:
+            _scope.open = outer
         if self.validate:
             self.validate(value)
-        return value
+        return value, opened.result()
 
     def __post_init__(self) -> None:
         # Judged here so every constructor passes it: the factories, the dataclass constructor and dataclasses.replace.
@@ -418,6 +488,9 @@ def define_union(
             raise ValueError(f"Union {name!r} value is malformed: expected [armKey, [armSlots]]")
         arm_name, codec = by_key[key]
         if codec is None:
+            scope = _current_scope()
+            if scope is not None and raw[1]:
+                scope.note(arm_name, len(raw[1]), 0, False)
             return UnionArm(arm_name, None)
         try:
             return UnionArm(arm_name, codec.decode(raw[1]))
@@ -479,17 +552,26 @@ def _record_codec(
     def decode(raw: Any) -> Any:
         if not isinstance(raw, list):
             raise ValueError(f"DatabaseEntry document type {type!r} expected a MessagePack array")
+        scope = _current_scope()
+        if scope is not None and len(raw) > max_key + 1:
+            scope.note(type, len(raw), max_key + 1, scope.depth == 0)
         values: dict[str, Any] = {}
-        for field in normalized:
-            if field.key < len(raw):
-                try:
-                    values[field.name] = field.codec.decode(raw[field.key])
-                except ValueError as error:
-                    raise ValueError(f"{type} slot {field.key} ({field.name}): {error}") from None
-            elif field.default is MISSING:
-                values[field.name] = None
-            else:
-                values[field.name] = field.default() if callable(field.default) else field.default
+        if scope is not None:
+            scope.depth += 1
+        try:
+            for field in normalized:
+                if field.key < len(raw):
+                    try:
+                        values[field.name] = field.codec.decode(raw[field.key])
+                    except ValueError as error:
+                        raise ValueError(f"{type} slot {field.key} ({field.name}): {error}") from None
+                elif field.default is MISSING:
+                    values[field.name] = None
+                else:
+                    values[field.name] = field.default() if callable(field.default) else field.default
+        finally:
+            if scope is not None:
+                scope.depth -= 1
         if cls is None:
             return values
         return cls(**values)

packages/cultcache-py/src/cultcache_py/stores.py

@@ -13,6 +13,7 @@ from typing import Any, Callable, Iterator, TypeVar
 
 import msgpack
 
+from .documents import UnreadSlots
 from .backing_store import (
     CultCacheEnvelope,
     CultCacheSchemaCatalogEntry,
@@ -46,9 +47,19 @@ class SchemaConflictError(ValueError):
     """A write the catalog cannot describe: records of different types under one schema id, two arrived schemas that share an id
     and disagree on the schema name, or a record no chosen entry publishes. Nothing is written. It names the id, the names
     involved (`schema_names`) and a record key (`record_key`). A cache raises it too, with an empty record key, when a
-    document registers a schema id another registered document already carries."""
+    document registers a schema id another registered document already carries. `unread_slots` is None except for the refusal to
+    write or remove a record held read-only because its payload carries slots past the declared ones; its message names the type
+    and both slot counts and never holds a slot value."""
 
-    def __init__(self, schema_id: str, schema_names: list[str], record_key: str, *, message: str | None = None) -> None:
+    def __init__(
+        self,
+        schema_id: str,
+        schema_names: list[str],
+        record_key: str,
+        *,
+        message: str | None = None,
+        unread_slots: UnreadSlots | None = None,
+    ) -> None:
         super().__init__(
             message
             or f"Schema id {schema_id!r} cannot describe record {record_key!r}: {', '.join(repr(name) for name in schema_names)}"
@@ -56,6 +67,7 @@ class SchemaConflictError(ValueError):
         self.schema_id = schema_id
         self.schema_names = schema_names
         self.record_key = record_key
+        self.unread_slots = unread_slots
 
 
 class JsonLinesBackingStore:
@@ -64,10 +76,17 @@ class JsonLinesBackingStore:
         self._lock = threading.RLock()
 
     def pull_all(self) -> list[CultCacheEnvelope]:
+        return self._pull() or []
+
+    def pull_or_absent(self) -> list[CultCacheEnvelope] | None:
+        return self._pull()
+
+    def _pull(self) -> list[CultCacheEnvelope] | None:
+        """The envelopes the reader reads, or None when nothing is at the path."""
         with self._lock:
             text = _read_store(self.path, lambda path: path.read_text(encoding="utf-8"))
             if text is None:
-                return []
+                return None
             envelopes: list[CultCacheEnvelope] = []
             for line_number, line in enumerate(text.splitlines(), start=1):
                 if not line.strip():
@@ -89,26 +108,31 @@ class JsonLinesBackingStore:
             return envelopes
 
     def push(self, envelope: CultCacheEnvelope) -> None:
-        with self._lock:
-            existing = {(item.type, item.key): item for item in self.pull_all()}
-            existing[(envelope.type, envelope.key)] = envelope
-            self._replace_all(list(existing.values()))
+        self.push_all([envelope])
 
-    def push_all(self, envelopes: list[CultCacheEnvelope]) -> None:
-        with self._lock:
-            existing = {(item.type, item.key): item for item in self.pull_all()}
+    def push_all(self, envelopes: list[CultCacheEnvelope], soft: bool = False) -> None:
+        def merge(existing: dict[tuple[str, str], CultCacheEnvelope]) -> None:
             for envelope in envelopes:
                 existing[(envelope.type, envelope.key)] = envelope
-            self._replace_all(list(existing.values()))
+        self._rewrite(merge, soft)
 
     def delete(self, type: str, key: str) -> None:
+        self._rewrite(lambda existing: existing.pop((type, key), None))
+
+    def _rewrite(self, change: Callable[[dict[tuple[str, str], CultCacheEnvelope]], object], soft: bool = False) -> None:
+        """The one entry of every write: refuses a link at the path, then reads the file (a soft write stops here when the
+        reader read it), applies the change and replaces it."""
         with self._lock:
-            existing = [item for item in self.pull_all() if not (item.type == type and item.key == key)]
-            self._replace_all(existing)
+            _refuse_linked(self.path)
+            arrived = self._pull()
+            if soft and arrived is not None:
+                return
+            existing = {(item.type, item.key): item for item in arrived or []}
+            change(existing)
+            self._replace_all(list(existing.values()))
 
     def _replace_all(self, envelopes: list[CultCacheEnvelope]) -> None:
         self.path.parent.mkdir(parents=True, exist_ok=True)
-        temp = self.path.with_suffix(self.path.suffix + ".tmp")
         lines = []
         for envelope in sorted(envelopes, key=lambda item: (item.type, item.key)):
             lines.append(json.dumps({
@@ -117,8 +141,7 @@ class JsonLinesBackingStore:
                 "payload": base64.b64encode(envelope.payload).decode("ascii"),
                 "stored_at": envelope.stored_at,
             }, ensure_ascii=False, sort_keys=True))
-        temp.write_text("\n".join(lines) + ("\n" if lines else ""), encoding="utf-8")
-        temp.replace(self.path)
+        commit_store_file(self.path, ("\n".join(lines) + ("\n" if lines else "")).encode("utf-8"))
 
 
 class SingleFileMessagePackBackingStore:
@@ -130,13 +153,20 @@ class SingleFileMessagePackBackingStore:
         self._format = STORE_FORMAT_VERSION
 
     def pull_all(self) -> list[CultCacheEnvelope]:
+        return self._pull() or []
+
+    def pull_or_absent(self) -> list[CultCacheEnvelope] | None:
+        return self._pull()
+
+    def _pull(self) -> list[CultCacheEnvelope] | None:
+        """The envelopes the reader reads, or None when nothing is at the path."""
         with self._lock:
             # An empty file is not a store (no writer leaves one), so it is decoded and refused.
             # The disk decides the header: a file that is gone is not marked.
             self._format = STORE_FORMAT_VERSION
             data = _read_store(self.path, Path.read_bytes)
             if data is None:
-                return []
+                return None
             try:
                 decoded = msgpack.unpackb(data, raw=False)
                 snapshot = _decode_snapshot(decoded)
@@ -151,9 +181,14 @@ class SingleFileMessagePackBackingStore:
         with self._write_transaction():
             self._replace_all([envelope], self.pull_all())
 
-    def push_all(self, envelopes: list[CultCacheEnvelope]) -> None:
+    def push_all(self, envelopes: list[CultCacheEnvelope], soft: bool = False) -> None:
+        """A soft push writes only where nothing is at the path: a store the reader reads is left byte for byte, and a file it
+        cannot read is refused by the same read, as in TS and Rust."""
         with self._write_transaction():
-            self._replace_all(list(envelopes), self.pull_all())
+            arrived = self._pull()
+            if soft and arrived is not None:
+                return
+            self._replace_all(list(envelopes), arrived or [])
 
     def delete(self, type: str, key: str) -> None:
         with self._write_transaction():
@@ -245,7 +280,7 @@ def _derive_catalog(records: list[tuple[CultCacheEnvelope, bool]]) -> list[CultC
     return [entry for entry, _ in chosen.values()]
 
 
-def _retyped(held: CultCacheEnvelope, written: CultCacheEnvelope) -> SchemaConflictError:
+def retyped(held: CultCacheEnvelope, written: CultCacheEnvelope) -> SchemaConflictError:
     """The refusal of a write that would put a second type under a key the store already holds (C# CacheBackingStore.Retyped)."""
     return SchemaConflictError(
         _schema_id_for(held),
@@ -258,7 +293,7 @@ def _retyped(held: CultCacheEnvelope, written: CultCacheEnvelope) -> SchemaConfl
     )
 
 
-def _written_owns(held: CultCacheEnvelope, written: CultCacheEnvelope) -> bool:
+def written_owns(held: CultCacheEnvelope, written: CultCacheEnvelope) -> bool:
     """Whether a write of `written` may replace `held` at its key (C# WrittenOwns): the written type's entry declares the held
     record's schema id (its own id or one it lists compatible), or it is the type of the same schema name. The same-name half
     stands in for C#'s "reads the published entry whole": this runtime does not compare shapes, so it never refuses a
@@ -277,8 +312,8 @@ def _encode_snapshot(
     landing: dict[str, CultCacheEnvelope] = {}
     for envelope in supplied:
         for held in (landing.get(envelope.key), held_by_key.get(envelope.key)):
-            if held is not None and not _written_owns(held, envelope):
-                raise _retyped(held, envelope)
+            if held is not None and not written_owns(held, envelope):
+                raise retyped(held, envelope)
         landing[envelope.key] = envelope
     supplied = list(landing.values())
     replaced = set(landing)
@@ -311,7 +346,7 @@ def commit_store_file(path: Path, data: bytes) -> None:
             os.fsync(fd)
         finally:
             os.close(fd)
-        os.replace(staged, path)
+        _replace_store(staged, path)
     except BaseException:
         try:
             os.unlink(staged)
@@ -326,11 +361,136 @@ def commit_store_file(path: Path, data: bytes) -> None:
             os.close(directory)
 
 
+REPLACE_ATTEMPTS = 25
+REPLACE_RETRY_SECONDS = 0.02
+_ERROR_ACCESS_DENIED = 5
+_ERROR_SHARING_VIOLATION = 32
+_ERROR_LOCK_VIOLATION = 33
+_POSIX_UNSUPPORTED = (1, 50, 87)  # incorrect function, not supported, invalid parameter: FAT, exFAT, before Windows 10 1607
+MOVEFILE_REPLACE_WRITE_THROUGH = 0x9  # MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH
+
+
+class ReplaceKernel:
+    """The kernel32 calls a Windows store replace needs, each answering 0 or a Win32 error code."""
+
+    def rename_posix(self, staged: str, destination: str) -> int:
+        """CreateFileW(staged, DELETE|SYNCHRONIZE), then FileRenameInfoEx with REPLACE_IF_EXISTS|POSIX_SEMANTICS, then CloseHandle."""
+        raise NotImplementedError
+
+    def move_file_ex(self, staged: str, destination: str, flags: int) -> int:
+        raise NotImplementedError
+
+    def sleep(self, seconds: float) -> None:
+        time.sleep(seconds)
+
+
+def _replace_store(staged: str | os.PathLike[str], destination: str | os.PathLike[str]) -> None:
+    """Replaces `destination` with `staged`: POSIX-semantics rename first on Windows (so a reader holding the store open
+    keeps it and rarely sees it absent; a stalled rename can still leave it absent for 5-47 ms on NTFS,
+    variants:ruling:posix-rename-absent-window-document), os.replace elsewhere."""
+    if sys.platform == "win32":
+        replace_store_windows(os.fspath(staged), os.fspath(destination), WindowsReplaceKernel())
+    else:
+        os.replace(staged, destination)
+
+
+def replace_store_windows(staged: str, destination: str, kernel: ReplaceKernel) -> None:
+    """POSIX-semantics rename, falling back for the rest of the call to write-through MoveFileExW where POSIX semantics are
+    unsupported; errors 5, 32 and 33 retry up to 25 times 20 ms apart, any other code raises at once. The TypeScript and C#
+    runtimes take the same decision table."""
+    posix = True
+    last = 0
+    for _ in range(REPLACE_ATTEMPTS):
+        code = kernel.rename_posix(staged, destination) if posix else kernel.move_file_ex(staged, destination, MOVEFILE_REPLACE_WRITE_THROUGH)
+        if posix and code in _POSIX_UNSUPPORTED:
+            posix = False
+            code = kernel.move_file_ex(staged, destination, MOVEFILE_REPLACE_WRITE_THROUGH)
+        if code == 0:
+            return
+        if code not in (_ERROR_ACCESS_DENIED, _ERROR_SHARING_VIOLATION, _ERROR_LOCK_VIOLATION):
+            raise _replace_error(f"CultCache could not replace the store: Win32 error {code}.", code)
+        last = code
+        kernel.sleep(REPLACE_RETRY_SECONDS)
+    raise _replace_error(f"CultCache could not replace the store after {REPLACE_ATTEMPTS} attempts: last Win32 error {last}.", last)
+
+
+def _replace_error(message: str, code: int) -> OSError:
+    error = OSError(message)
+    error.winerror = code  # type: ignore[attr-defined]
+    return error
+
+
+class WindowsReplaceKernel(ReplaceKernel):
+    """kernel32 bound by ctypes, as _try_lock_windows binds it. Windows only."""
+
+    def __init__(self) -> None:
+        import ctypes
+        from ctypes import wintypes
+
+        self._ctypes = ctypes
+        k = self._k = ctypes.WinDLL("kernel32", use_last_error=True)
+        k.CreateFileW.restype = wintypes.HANDLE
+        k.CreateFileW.argtypes = [wintypes.LPCWSTR, wintypes.DWORD, wintypes.DWORD, ctypes.c_void_p, wintypes.DWORD, wintypes.DWORD, wintypes.HANDLE]
+        k.SetFileInformationByHandle.restype = wintypes.BOOL
+        k.SetFileInformationByHandle.argtypes = [wintypes.HANDLE, ctypes.c_int, ctypes.c_void_p, wintypes.DWORD]
+        k.CloseHandle.restype = wintypes.BOOL
+        k.CloseHandle.argtypes = [wintypes.HANDLE]
+        k.MoveFileExW.restype = wintypes.BOOL
+        k.MoveFileExW.argtypes = [wintypes.LPCWSTR, wintypes.LPCWSTR, wintypes.DWORD]
+
+    def rename_posix(self, staged: str, destination: str) -> int:
+        ctypes, k = self._ctypes, self._k
+        delete_synchronize, share_all, open_existing, normal = 0x00110000, 0x7, 3, 0x80
+        handle = k.CreateFileW(staged, delete_synchronize, share_all, None, open_existing, normal, None)
+        if handle is None or ctypes.c_void_p(handle).value in (None, ctypes.c_void_p(-1).value):
+            return ctypes.get_last_error()
+        try:
+            # FILE_RENAME_INFO: Flags (DWORD), RootDirectory (pointer-aligned HANDLE), FileNameLength (DWORD), FileName (WCHAR[]).
+            name = os.path.abspath(destination).encode("utf-16-le")
+            pointer = ctypes.sizeof(ctypes.c_void_p)
+            length_at = pointer + pointer
+            info = ctypes.create_string_buffer(length_at + 4 + len(name) + 2)
+            info[0:4] = (0x3).to_bytes(4, "little")  # FILE_RENAME_FLAG_REPLACE_IF_EXISTS | FILE_RENAME_FLAG_POSIX_SEMANTICS
+            info[length_at:length_at + 4] = len(name).to_bytes(4, "little")
+            info[length_at + 4:length_at + 4 + len(name)] = name
+            file_rename_info_ex = 22
+            if k.SetFileInformationByHandle(handle, file_rename_info_ex, info, len(info)):
+                return 0
+            return ctypes.get_last_error()
+        finally:
+            k.CloseHandle(handle)
+
+    def move_file_ex(self, staged: str, destination: str, flags: int) -> int:
+        return 0 if self._k.MoveFileExW(staged, destination, flags) else self._ctypes.get_last_error()
+
+
+class StoreLinkedError(OSError):
+    """A write was asked of a store path that is a link: a replace there would swap the link for a regular file."""
+
+    def __init__(self, path: Path) -> None:
+        super().__init__(f"CultCache store {path} is a link, and a write at it would replace the link; configure the link's target as the store path.")
+        self.path = path
+
+
+def _refuse_linked(path: Path) -> None:
+    """Refuses a link at the store path: a file or directory link, and on Windows a junction or any reparse point (islink misses
+    junctions before Python 3.12). Absent is not a link."""
+    linked = os.path.islink(path)
+    if not linked and sys.platform == "win32":
+        try:
+            linked = bool(os.lstat(path).st_file_attributes & 0x400)  # FILE_ATTRIBUTE_REPARSE_POINT
+        except FileNotFoundError:
+            pass
+    if linked:
+        raise StoreLinkedError(path)
+
+
 @contextmanager
 def store_write_lock(path: Path, timeout: float = LOCK_TIMEOUT_SECONDS) -> Iterator[None]:
     """Holds the exclusive store lock on `<path>.lock`, the lock the C#, Rust and TypeScript runtimes take: flock on Unix,
     LockFileEx over the whole file on Windows, polled every 10 ms with no handle held between polls. The lock file is
     created if absent and never written or deleted."""
+    _refuse_linked(path)
     lock_path = path.with_name(path.name + ".lock")
     deadline = time.monotonic() + timeout
     while True:
@@ -341,6 +501,8 @@ def store_write_lock(path: Path, timeout: float = LOCK_TIMEOUT_SECONDS) -> Itera
             raise TimeoutError(f"CultCache timed out after {timeout} s waiting for the store lock {lock_path}.")
         time.sleep(_LOCK_POLL_SECONDS)
     try:
+        # A link may have been put at the path while the lock was awaited; the look above only saw the path before.
+        _refuse_linked(path)
         yield
     finally:
         release()

packages/cultcache-py/tests/test_cultcache.py

@@ -12,6 +12,7 @@ from cultcache_py import (
     CultCache,
     JsonLinesBackingStore,
     SingleFileMessagePackBackingStore,
+    StoreLinkedError,
     StoreUnreadableError,
     define_database_entry_type,
     define_document_type,
@@ -1431,10 +1432,10 @@ class CultCacheTests(unittest.TestCase):
                 self.assertNotIn("SECRET", str(caught.exception))
                 self.assertIn("not a valid store", str(caught.exception))
 
-    # What a write does through a symbolic link today. R3 decides whether a write resolves
-    # the link or refuses it; this pins the current behaviour so that change is deliberate.
+    # A write at a store path that is a link is refused: a replace there would swap the link for a regular file and
+    # detach the store from its target. Reads through a live link keep working.
     @unittest.skipIf(os.name != "posix", "symbolic links need POSIX here")
-    def test_r3_decides_resolve_or_refuse_a_push_through_a_live_link_replaces_the_link(self) -> None:
+    def test_a_write_at_a_live_link_is_refused_and_nothing_changes_while_a_read_through_it_works(self) -> None:
         with tempfile.TemporaryDirectory() as tmp:
             volume = Path(tmp) / "volume"
             volume.mkdir()
@@ -1442,12 +1443,91 @@ class CultCacheTests(unittest.TestCase):
             envelope = CultCacheEnvelope(key="a", type="t", payload=b"\x90", stored_at="2026-09-30T00:00:00Z")
             SingleFileMessagePackBackingStore(target).push(envelope)
             before = target.read_bytes()
-            link = Path(tmp) / "store.cc"
+            volume_before = sorted(p.name for p in volume.iterdir())
+            link = Path(tmp) / "link.cc"
             link.symlink_to(target)
-            SingleFileMessagePackBackingStore(link).push(replace(envelope, key="b"))
-            self.assertFalse(link.is_symlink())
-            self.assertTrue(link.is_file())
+            store = SingleFileMessagePackBackingStore(link)
+            for write in (
+                lambda: store.push(replace(envelope, key="b")),
+                lambda: store.push_all([replace(envelope, key="b")]),
+                lambda: store.delete("t", "a"),
+            ):
+                with self.assertRaises(StoreLinkedError) as caught:
+                    write()
+                self.assertIn(str(link), str(caught.exception))
+            self.assertTrue(link.is_symlink())
             self.assertEqual(target.read_bytes(), before)
+            self.assertEqual(sorted(p.name for p in Path(tmp).iterdir()), ["link.cc", "volume"])
+            self.assertEqual(sorted(p.name for p in volume.iterdir()), volume_before)
+            self.assertEqual([item.key for item in store.pull_all()], ["a"])
+
+    @unittest.skipIf(os.name != "posix", "symbolic links need POSIX here")
+    def test_a_json_lines_write_at_a_live_link_is_refused_and_the_link_survives(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            volume = Path(tmp) / "volume"
+            volume.mkdir()
+            target = volume / "store.jsonl"
+            envelope = CultCacheEnvelope(key="a", type="t", payload=b"\x90", stored_at="2026-09-30T00:00:00Z")
+            JsonLinesBackingStore(target).push(envelope)
+            before = target.read_bytes()
+            link = Path(tmp) / "link.jsonl"
+            link.symlink_to(target)
+            store = JsonLinesBackingStore(link)
+            for write in (
+                lambda: store.push(replace(envelope, key="b")),
+                lambda: store.push_all([replace(envelope, key="b")]),
+                lambda: store.delete("t", "a"),
+            ):
+                with self.assertRaises(StoreLinkedError):
+                    write()
+            self.assertTrue(link.is_symlink())
+            self.assertEqual(target.read_bytes(), before)
+            self.assertEqual(sorted(p.name for p in Path(tmp).iterdir()), ["link.jsonl", "volume"])
+            self.assertEqual(sorted(p.name for p in volume.iterdir()), ["store.jsonl"])
+
+    # The advisory query answers for the held record and the cache's judges; a link at the store path is the write's to refuse.
+    @unittest.skipIf(os.name != "posix", "symbolic links need POSIX here")
+    def test_is_writable_over_a_store_at_a_live_link_answers_true_while_the_cache_write_is_refused(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            volume = Path(tmp) / "volume"
+            volume.mkdir()
+            target = volume / "store.cc"
+            document = item_doc()
+            seed = CultCache.builder().register_document_type(document).add_generic_store(SingleFileMessagePackBackingStore(target)).build()
+            seed.put(document, "held", Item(name="Held", category="c", value=1))
+            before = target.read_bytes()
+            link = Path(tmp) / "link.cc"
+            link.symlink_to(target)
+            cache = CultCache.builder().register_document_type(document).add_generic_store(SingleFileMessagePackBackingStore(link)).build()
+            cache.pull_all_backing_stores()
+            names_before = (sorted(p.name for p in Path(tmp).iterdir()), sorted(p.name for p in volume.iterdir()))
+
+            self.assertTrue(cache.is_writable(document, "held"))
+            self.assertTrue(cache.is_writable(document, "fresh"))
+            with self.assertRaises(StoreLinkedError) as caught:
+                cache.put(document, "fresh", Item(name="Fresh", category="d", value=2))
+            self.assertEqual(Path(caught.exception.path), link)
+            self.assertTrue(link.is_symlink())
+            self.assertEqual(target.read_bytes(), before)
+            self.assertEqual((sorted(p.name for p in Path(tmp).iterdir()), sorted(p.name for p in volume.iterdir())), names_before)
+
+    def test_store_linked_error_is_an_os_error_carrying_the_path(self) -> None:
+        error = StoreLinkedError(Path("some/store.cc"))
+        self.assertIsInstance(error, OSError)
+        self.assertEqual(error.path, Path("some/store.cc"))
+
+    @unittest.skipIf(os.name != "posix", "symbolic links need POSIX here")
+    def test_a_write_at_a_live_directory_link_is_refused_as_a_link(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            real = Path(tmp) / "real"
+            real.mkdir()
+            link = Path(tmp) / "dirlink"
+            link.symlink_to(real, target_is_directory=True)
+            with self.assertRaises(StoreLinkedError):
+                SingleFileMessagePackBackingStore(link).push(
+                    CultCacheEnvelope(key="a", type="t", payload=b"\x90", stored_at="2026-09-30T00:00:00Z"))
+            self.assertTrue(link.is_symlink())
+            self.assertEqual(list(real.iterdir()), [])
 
     @unittest.skipIf(os.name != "posix", "symbolic links need POSIX here")
     def test_a_dangling_symlink_at_a_store_path_is_an_os_error_and_nothing_is_written(self) -> None:
@@ -1460,7 +1540,7 @@ class CultCacheTests(unittest.TestCase):
                 store = store_type(path)
                 with self.assertRaises(FileNotFoundError):
                     store.pull_all()
-                with self.assertRaises(FileNotFoundError):
+                with self.assertRaises(StoreLinkedError):
                     store.push(CultCacheEnvelope(key="k", type="t", payload=b"\x90", stored_at="2026-09-30T00:00:00Z"))
                 self.assertTrue(path.is_symlink())
                 self.assertEqual(list(volume.iterdir()), [])

packages/cultcache-py/tests/test_key_identity_vector.py

@@ -0,0 +1,316 @@
+from __future__ import annotations
+
+import re
+import shutil
+import tempfile
+import unittest
+from pathlib import Path
+
+import msgpack
+
+from cultcache_py.cache import CultCacheError
+from cultcache_py import (
+    CultCache,
+
+    JsonLinesBackingStore,
+    SchemaConflictError,
+    SingleFileMessagePackBackingStore,
+    database_entry_field,
+    define_database_entry_type,
+    leaves as t,
+)
+
+# variants:ruling:cache-refuses-retype, write-ownership-by-written-type, unheld-removal-refused-at-commit. The vector in
+# tests/vectors/key-identity is written only by the C# reference; this walks every row against the Python cache.
+VECTORS = Path(__file__).resolve().parents[3] / "tests" / "vectors" / "key-identity"
+
+IDS = {
+    "alpha": "sha256:b20703a98f49c253898404ab50ba2c630720f0b8a5e1a41614d5650be22799fe",
+    "beta": "sha256:dee4b727cf2ee04e61ab635ff0c5f3dca7345a411dc5f1018e583ab16009cf94",
+    "gamma": "sha256:fbc26e351e00c9e7185e8de171c7486aba707c229c949f0aae6b889288af5f6d",
+}
+DOCUMENTS = {
+    label: define_database_entry_type(
+        f"tests.ki_{label}",
+        [database_entry_field("text", 0, codec=t.string)],
+        schema_id=schema_id,
+        schema_name=f"tests.ki_{label}",
+    )
+    for label, schema_id in IDS.items()
+}
+LABEL_OF = {document.type: label for label, document in DOCUMENTS.items()}
+
+def file_records(path: Path) -> list[list[str]]:
+    return sorted([envelope.key, envelope.type] for envelope in SingleFileMessagePackBackingStore(path).pull_all())
+
+def stored(path: Path, key: str):
+    for envelope in SingleFileMessagePackBackingStore(path).pull_all():
+        if envelope.key == key:
+            return envelope.schema_id, envelope.stored_at, envelope.payload
+    return None
+
+class KeyIdentityVectorTests(unittest.TestCase):
+    def test_rows(self) -> None:
+        rows = msgpack.unpackb((VECTORS / "rows.msgpack").read_bytes(), raw=False)
+        walked = 0
+        for label, registered, ops, expect in rows:
+            with self.subTest(row=label), tempfile.TemporaryDirectory() as tmp:
+                self.walk(Path(tmp), registered, ops, expect)
+                walked += 1
+        self.assertEqual(walked, 12)
+
+    def walk(self, tmp: Path, registered: list[str], ops: list, expect: list) -> None:
+        refusal, held, file, foreign, kept = expect
+        state: dict = {"cache": None, "path": None, "before": None, "attached": []}
+
+        def builder() -> CultCache.builder:
+            made = CultCache.builder()
+            for name in registered:
+                made.register_document_type(DOCUMENTS[name])
+            return made
+
+        def open_cache(target) -> None:
+            if target == "memory":
+                state["cache"], state["path"] = builder().build(), None
+                return
+            path = tmp / "store.cc"
+            if target is not None and target != path:
+                shutil.copyfile(VECTORS / target, path)
+                state["before"] = path.read_bytes()
+            state["path"] = path
+            made = builder().add_generic_store(SingleFileMessagePackBackingStore(path))
+            state["cache"] = made.build()
+            state["cache"].pull_all_backing_stores()
+
+        def perform(op: list) -> None:
+            cache = state["cache"]
+            if op[0] == "open":
+                open_cache(op[1])
+            elif op[0] == "attach":
+                path = tmp / f"attached-{len(state['attached'])}.cc"
+                shutil.copyfile(VECTORS / op[1], path)
+                state["attached"].append((path, path.read_bytes()))
+                cache.add_backing_store(
+                    SingleFileMessagePackBackingStore(path), [DOCUMENTS[name].type for name in op[2]]
+                )
+                cache.pull_all_backing_stores()
+            elif op[0] == "reopen":
+                open_cache(state["path"])  # the same file, no fresh copy
+            elif op[0] == "put":
+                cache.put(DOCUMENTS[op[1]], op[2], {"text": op[3]})
+            elif op[0] == "delete":
+                cache.delete(DOCUMENTS[op[1]], op[2])
+            else:
+                self.fail(f"unknown op {op[0]}")
+
+        for op in ops[:-1]:
+            perform(op)
+        if refusal is None:
+            perform(ops[-1])
+        else:
+            key = refusal[0]
+            with self.assertRaises((SchemaConflictError, ValueError, RuntimeError)) as caught:
+                perform(ops[-1])
+            if ops[-1][0] == "attach":
+                # The key is read out of the refusal's own text (it opens "Record 'key' is held by") and occurs only as a
+                # delimited token, never inside a schema name or other word.
+                message = str(caught.exception)
+                named = re.match(r"Record '([^']*)' is held by", message)
+                self.assertIsNotNone(named, message)
+                self.assertEqual(named.group(1), key)
+                self.assertEqual(len(re.findall(rf"(?<![A-Za-z0-9_]){re.escape(key)}(?![A-Za-z0-9_])", message)), 1)
+                self.assertEqual(message.count(key), 1)
+                for path, before in state["attached"]:
+                    self.assertEqual(path.read_bytes(), before)
+            else:
+                self.assertIsInstance(caught.exception, SchemaConflictError)
+                self.assertEqual(caught.exception.record_key, key)
+                self.assertIn(key, str(caught.exception))
+        cache = state["cache"]
+        got_held = sorted(
+            [LABEL_OF[type], key, value["text"]]
+            for type, values in cache.snapshot().items()
+            for key, value in values.items()
+        )
+        self.assertEqual(got_held, held)
+        path = state["path"]
+        if file is None:
+            self.assertIsNone(path)
+        else:
+            self.assertEqual(file_records(path), file)
+        self.assertEqual([record.key for record in cache.foreign_records()], foreign)
+        if kept:
+            vector = tmp / "vector-before.cc"
+            vector.write_bytes(state["before"])
+            for key in kept:
+                self.assertIsNotNone(stored(vector, key))
+                self.assertEqual(stored(path, key), stored(vector, key))
+
+def alpha_beta(*names: str, store=None) -> CultCache:
+    made = CultCache.builder()
+    for name in names:
+        made.register_document_type(DOCUMENTS[name])
+    if store is not None:
+        made.add_generic_store(store)
+    return made.build()
+
+class KeyIdentityTests(unittest.TestCase):
+    def test_two_global_types_are_refused_in_one_cache_and_a_store_holding_both_does_not_load(self) -> None:
+        # C# refuses a second persisted global on pull (cultcache-store-composition.md, "Globals never invented"); the Python
+        # JSONL store and a cache with no store used to let two global types share __global__, so such a file can exist.
+        ga = define_database_entry_type(
+            "tests.ki_ga", [database_entry_field("text", 0, codec=t.string)], schema_id="sha256:" + "1" * 64, global_document=True
+        )
+        gb = define_database_entry_type(
+            "tests.ki_gb", [database_entry_field("text", 0, codec=t.string)], schema_id="sha256:" + "2" * 64, global_document=True
+        )
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "store.jsonl"
+            for document in (ga, gb):  # one cache per type that never pulled: how a file got two globals
+                writer = CultCache.builder().register_document_type(document).add_generic_store(JsonLinesBackingStore(path)).build()
+                writer.put_global(document, {"text": document.type})
+            both = CultCache.builder().register_document_type(ga).register_document_type(gb).add_generic_store(JsonLinesBackingStore(path)).build()
+            with self.assertRaises(CultCacheError) as caught:
+                both.pull_all_backing_stores()
+            self.assertIn("'__global__' is held by both", str(caught.exception))
+            self.assertEqual(both.snapshot(), {})
+            memory = CultCache.builder().register_document_type(ga).register_document_type(gb).build()
+            memory.put_global(ga, {"text": "a"})
+            with self.assertRaises(SchemaConflictError):
+                memory.put_global(gb, {"text": "b"})
+            self.assertEqual(memory.get_required_global(ga), {"text": "a"})
+
+    def test_every_write_path_refuses_a_second_type_and_never_echoes_the_payload(self) -> None:
+        alpha, beta = DOCUMENTS["alpha"], DOCUMENTS["beta"]
+        for name in ("put", "put_envelope", "put_envelopes"):
+            with self.subTest(path=name):
+                cache = alpha_beta("alpha", "beta")
+                cache.put(alpha, "k", {"text": "held"})
+                envelope = cache.get_envelope(alpha, "k")
+                other = type(envelope).create(
+                    key="k", type=beta.type, payload=beta.encode_payload({"text": "CANARY"}), schema_id=IDS["beta"]
+                )
+                writes = {
+                    "put": lambda: cache.put(beta, "k", {"text": "CANARY"}),
+                    "put_envelope": lambda: cache.put_envelope(beta, other),
+                    "put_envelopes": lambda: cache.put_envelopes(beta, [other]),
+                }
+                with self.assertRaises(SchemaConflictError) as caught:
+                    writes[name]()
+                self.assertEqual(caught.exception.record_key, "k")
+                self.assertNotIn("CANARY", str(caught.exception))
+                self.assertEqual(cache.get(alpha, "k"), {"text": "held"})
+                self.assertIsNone(cache.get(beta, "k"))
+
+    def test_two_routed_stores_holding_one_key_refuse_the_pull_and_keep_the_earlier_state(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            one, two = Path(tmp) / "one.cc", Path(tmp) / "two.cc"
+            shutil.copyfile(VECTORS / "catalog-store.cc", one)
+            shutil.copyfile(VECTORS / "run-store.cc", two)
+            cache = alpha_beta("alpha", "beta")
+            cache.add_backing_store(SingleFileMessagePackBackingStore(one), [DOCUMENTS["alpha"].type])
+            cache.pull_all_backing_stores()
+            cache.add_backing_store(SingleFileMessagePackBackingStore(two), [DOCUMENTS["beta"].type])
+            with self.assertRaises(Exception) as caught:
+                cache.pull_all_backing_stores()
+            self.assertIn("'qx'", str(caught.exception))
+            self.assertEqual(cache.get(DOCUMENTS["alpha"], "qx"), {"text": "a"})
+            self.assertIsNone(cache.get(DOCUMENTS["beta"], "qx"))
+
+    def test_a_foreign_record_is_listed_and_its_bytes_survive_writes_and_removals_elsewhere(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "store.cc"
+            shutil.copyfile(VECTORS / "foreign-store.cc", path)
+            before = stored(path, "k")
+            cache = alpha_beta("alpha", store=SingleFileMessagePackBackingStore(path))
+            cache.pull_all_backing_stores()
+            [record] = cache.foreign_records()
+            self.assertEqual((record.key, record.schema_id, record.schema_name), ("k", IDS["gamma"], "tests.ki_gamma"))
+            self.assertEqual(record.stored_at, before[1])
+            cache.put(DOCUMENTS["alpha"], "m", {"text": "m"})
+            cache.delete(DOCUMENTS["alpha"], "j")
+            self.assertEqual(stored(path, "k"), before)
+            self.assertEqual(file_records(path), [["k", "tests.ki_gamma"], ["m", "tests.ki_alpha"]])
+            claimed = alpha_beta("alpha", "gamma", store=SingleFileMessagePackBackingStore(path))
+            claimed.pull_all_backing_stores()
+            self.assertEqual(claimed.foreign_records(), [])
+            self.assertEqual(claimed.get(DOCUMENTS["gamma"], "k"), {"text": "g"})
+
+    def test_the_foreign_list_is_sorted_by_utf16_code_unit_and_replaced_by_the_next_pull(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "store.cc"
+            store = SingleFileMessagePackBackingStore(path)
+            gamma = DOCUMENTS["gamma"]
+            writer = alpha_beta("gamma", store=store)
+            for key in ("\U00010400", "Ａ", "b", "B"):
+                writer.put(gamma, key, {"text": "x"})
+            cache = alpha_beta("alpha", store=SingleFileMessagePackBackingStore(path))
+            cache.pull_all_backing_stores()
+            self.assertEqual([record.key for record in cache.foreign_records()], ["B", "b", "\U00010400", "Ａ"])
+            for key in ("B", "b", "\U00010400", "Ａ"):
+                writer.delete(gamma, key)
+            cache.pull_all_backing_stores()
+            self.assertEqual(cache.foreign_records(), [])
+
+class OwnershipAndStoreKindTests(unittest.TestCase):
+    """The cache judge answers on its own where the store has no commit guard (JSONL) or the records live in two stores."""
+
+    def test_a_jsonl_store_gets_no_help_from_a_disk_judge(self) -> None:
+        from cultcache_py import JsonLinesBackingStore
+
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "store.jsonl"
+            gamma = DOCUMENTS["gamma"]
+            alpha_beta("gamma", store=JsonLinesBackingStore(path)).put(gamma, "k", {"text": "g"})
+            before = path.read_bytes()
+            cache = alpha_beta("alpha", store=JsonLinesBackingStore(path))
+            cache.pull_all_backing_stores()
+            self.assertEqual([record.key for record in cache.foreign_records()], ["k"])
+            with self.assertRaises(SchemaConflictError):
+                cache.put(DOCUMENTS["alpha"], "k", {"text": "x"})
+            with self.assertRaises(SchemaConflictError):
+                cache.delete(DOCUMENTS["alpha"], "k")
+            self.assertEqual(path.read_bytes(), before)
+            cache.put(DOCUMENTS["alpha"], "j", {"text": "a"})  # the foreign line is carried through a write elsewhere
+            self.assertIn(b"tests.ki_gamma", path.read_bytes())
+
+    def test_a_foreign_key_in_two_stores_refuses_the_pull(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            one, two = Path(tmp) / "one.cc", Path(tmp) / "two.cc"
+            for path in (one, two):
+                alpha_beta("gamma", store=SingleFileMessagePackBackingStore(path)).put(DOCUMENTS["gamma"], "k", {"text": "g"})
+            cache = alpha_beta("alpha")
+            cache.add_backing_store(SingleFileMessagePackBackingStore(one), [DOCUMENTS["alpha"].type])
+            cache.add_backing_store(SingleFileMessagePackBackingStore(two), [DOCUMENTS["beta"].type])
+            with self.assertRaises(Exception) as caught:
+                cache.pull_all_backing_stores()
+            self.assertIn("'k'", str(caught.exception))
+
+    def test_a_type_that_owns_the_held_schema_id_replaces_the_record_and_the_key_keeps_one_type(self) -> None:
+        successor = define_database_entry_type(
+            "tests.ki_alpha2",
+            [database_entry_field("text", 0, codec=t.string)],
+            schema_id="sha256:" + "a" * 64,
+            schema_name="tests.ki_alpha2",
+            compatible_schema_ids=[IDS["alpha"]],
+        )
+        for routed in (False, True):
+            with self.subTest(routed=routed), tempfile.TemporaryDirectory() as tmp:
+                one, two = Path(tmp) / "one.cc", Path(tmp) / "two.cc"
+                made = CultCache.builder().register_document_type(DOCUMENTS["alpha"]).register_document_type(successor)
+                if routed:
+                    made.add_backing_store(SingleFileMessagePackBackingStore(one), [DOCUMENTS["alpha"].type])
+                    made.add_backing_store(SingleFileMessagePackBackingStore(two), [successor.type])
+                else:
+                    made.add_generic_store(SingleFileMessagePackBackingStore(one))
+                cache = made.build()
+                cache.put(DOCUMENTS["alpha"], "k", {"text": "old"})
+                if routed:
+                    with self.assertRaises(SchemaConflictError):  # one key would live in two stores
+                        cache.put(successor, "k", {"text": "new"})
+                    self.assertEqual(cache.get(DOCUMENTS["alpha"], "k"), {"text": "old"})
+                else:
+                    cache.put(successor, "k", {"text": "new"})
+                    self.assertIsNone(cache.get(DOCUMENTS["alpha"], "k"))
+                    self.assertEqual(cache.get(successor, "k"), {"text": "new"})
+                    self.assertEqual(file_records(one), [["k", "tests.ki_alpha2"]])

packages/cultcache-py/tests/test_slot_readonly.py

@@ -0,0 +1,509 @@
+from __future__ import annotations
+
+import dataclasses
+import shutil
+import threading
+import tempfile
+import unittest
+from pathlib import Path
+
+import msgpack
+from cultcache_py.cache import CultCacheError
+
+from cultcache_py import (
+    CultCache,
+    CultCachePayloadDepthError,
+    SlotCodec,
+    SchemaConflictError,
+    SingleFileMessagePackBackingStore,
+    StoreUnreadableError,
+    UnionArm,
+    UnreadSlots,
+    database_entry_field,
+    define_database_entry_type,
+    define_record_codec,
+    leaves as t,
+)
+import test_union_parity as _parity
+from test_union_parity import (
+    VECTORS,
+    _surface_value,
+    _vector,
+    surface_document,
+    unit_outcome,
+)
+
+SLOT = "extra-slot"  # the canary: the value of every extra slot in the vectors; no refusal may carry it
+
+# The vectors name the C# types; this runtime names a type by its codec's name, a document by its document type.
+_NAMES = {"UnionSurface": surface_document.type, "SurfaceDeclaring": surface_document.type, "Denied2": "Denied"}
+
+slot_unit_document = define_database_entry_type(
+    "tests.slot_unit",
+    [database_entry_field("name", 0, codec=t.string), database_entry_field("outcome", 1, codec=unit_outcome)],
+    name="name",
+)
+# The reader of extra-slot-consent.cc: the surface document's slots under a new schema id that lists the old one compatible.
+declaring_document = define_database_entry_type(
+    "tests.union_surface",
+    [
+        database_entry_field("id", 0, codec=t.string),
+        database_entry_field("version", 1, codec=t.int32),
+        database_entry_field("root", 2, codec=_parity._node),
+        database_entry_field("outcomes", 3, codec=t.list(_parity.outcome)),
+        database_entry_field("part", 4, codec=t.nullable(_parity.item)),
+        database_entry_field("crafted", 5, codec=t.nullable(_parity.crafted)),
+        database_entry_field("missing", 6, codec=_parity._node),
+    ],
+    name="id",
+    schema_id="tests.union_surface.v2",
+    schema_name="tests.union_surface",
+    compatible_schema_ids=("tests.union_surface.wide",),
+)
+
+# file -> (type, slots carried, slots declared, every mark at depth 0): the README table.
+_PAYLOADS = {
+    "extra-slot-record.msgpack": ("UnionSurface", 8, 7, True),
+    "extra-slot-nested-record.msgpack": ("Composition", 3, 2, False),
+    "extra-slot-arm.msgpack": ("Box", 3, 2, False),
+    "extra-slot-list-element.msgpack": ("Text", 3, 2, False),
+    "depth-skipped-at-limit.msgpack": ("UnionSurface", 8, 7, True),
+}
+
+
+def _copy_store_without_variants(source: Path, target: Path) -> None:
+    """This runtime holds no variant records (a five-slot record makes a store unreadable here), so the store vector is
+    walked with its variant row removed; every other byte is the C# writer's."""
+    [snapshot] = list(msgpack.Unpacker(open(source, "rb"), raw=False))
+    snapshot[2] = [record for record in snapshot[2] if len(record) <= 4]
+    target.write_bytes(msgpack.packb(snapshot, use_bin_type=True))
+
+
+def _open(path: Path, *documents) -> CultCache:
+    builder = CultCache.builder()
+    for document in documents:
+        builder.register_document_type(document)
+    cache = builder.add_generic_store(SingleFileMessagePackBackingStore(path)).build()
+    cache.pull_all_backing_stores()
+    return cache
+
+
+def _rows():
+    return msgpack.unpackb(_vector("slot-outcomes.msgpack"), raw=False)
+
+
+class PayloadMarkTests(unittest.TestCase):
+    def test_every_read_only_payload_decodes_and_names_its_mark(self) -> None:
+        for file, (type_name, carried, declared, depth0) in _PAYLOADS.items():
+            with self.subTest(file=file):
+                value, mark = surface_document.decode_payload_marked(_vector(file))
+                self.assertEqual(value, _surface_value())
+                self.assertEqual(mark, UnreadSlots(_NAMES.get(type_name, type_name), carried, declared, 1, depth0))
+                self.assertEqual(surface_document.decode_payload(_vector(file)), _surface_value())
+
+    def test_the_outcomes_manifest_still_counts_nine_rows_and_four_read_only(self) -> None:
+        rows = msgpack.unpackb(_vector("outcomes.msgpack"), raw=False)
+        self.assertEqual(len(rows), 9)
+        self.assertEqual([row[0] for row in rows if row[1] == "read-only"], [f for f in _PAYLOADS if f != "depth-skipped-at-limit.msgpack"])
+
+    def test_a_clean_payload_and_a_short_one_carry_no_mark(self) -> None:
+        self.assertEqual(surface_document.decode_payload_marked(_vector("union-surface.msgpack")), (_surface_value(), None))
+        slots = msgpack.unpackb(_vector("union-surface.msgpack"), raw=False)
+        slots[2] = [1, ["only-id"]]  # a Text arm with a missing trailing slot: defaults, no mark
+        _, mark = surface_document.decode_payload_marked(msgpack.packb(slots, use_bin_type=True))
+        self.assertIsNone(mark)
+
+    def test_a_retired_slot_below_the_highest_key_does_not_mark(self) -> None:
+        slots = msgpack.unpackb(_vector("union-surface.msgpack"), raw=False)
+        # Image's declared slots are 0, 1, 3 (2 retired): four carried, four declared.
+        image = slots[2][1][1][2]
+        self.assertEqual(image[0], 5)
+        image[1][2] = "retired-slot-value"
+        _, mark = surface_document.decode_payload_marked(msgpack.packb(slots, use_bin_type=True))
+        self.assertIsNone(mark)
+
+    def test_the_depth_check_runs_before_the_mark(self) -> None:
+        with self.assertRaises(CultCachePayloadDepthError):
+            surface_document.decode_payload_marked(_vector("depth-skipped-past-limit.msgpack"))
+
+    def test_the_unit_arm_with_extra_slots_is_read_past_and_marked(self) -> None:
+        payload = msgpack.packb(["unit-arm", [2, [SLOT]]], use_bin_type=True)
+        value, mark = slot_unit_document.decode_payload_marked(payload)
+        self.assertEqual(value, {"name": "unit-arm", "outcome": UnionArm("Denied")})
+        self.assertEqual(mark, UnreadSlots("Denied", 1, 0, 1, False))
+        self.assertEqual(slot_unit_document.decode_payload_marked(msgpack.packb(["ok", [2, []]]))[1], None)
+
+    def test_a_codec_decoded_outside_a_payload_decode_notes_nothing(self) -> None:
+        self.assertEqual(unit_outcome.decode([2, [SLOT]]), UnionArm("Denied"))
+
+    def test_the_scope_belongs_to_its_thread(self) -> None:
+        def decode_elsewhere(raw):
+            thread = threading.Thread(target=lambda: unit_outcome.decode([2, [SLOT]]))
+            thread.start()
+            thread.join()
+            return raw
+
+        outer = define_database_entry_type("tests.threaded", [database_entry_field("a", 0, codec=SlotCodec(lambda v: v, decode_elsewhere))])
+        self.assertIsNone(outer.decode_payload_marked(msgpack.packb(["x"]))[1])
+
+    def test_a_nested_payload_decode_restores_the_outer_scope(self) -> None:
+        def decode_clean_inside(raw):
+            surface_document.decode_payload_marked(_vector("union-surface.msgpack"))
+            return raw
+
+        inner = define_record_codec("Inner", [database_entry_field("x", 0, codec=t.string)])
+        outer = define_database_entry_type(
+            "tests.nested",
+            [
+                database_entry_field("a", 0, codec=SlotCodec(lambda v: v, decode_clean_inside)),
+                database_entry_field("b", 1, codec=inner),
+            ],
+        )
+        _, mark = outer.decode_payload_marked(msgpack.packb(["x", ["v", SLOT]]))
+        self.assertEqual(mark, UnreadSlots("Inner", 2, 1, 1, False))
+
+
+class StoreRowTests(unittest.TestCase):
+    def setUp(self) -> None:
+        self.tmp = Path(tempfile.mkdtemp())
+        self.addCleanup(shutil.rmtree, self.tmp, True)
+
+    def _store(self, name: str) -> tuple[Path, CultCache]:
+        path = self.tmp / name
+        _copy_store_without_variants(VECTORS / name, path)
+        documents = (declaring_document,) if name == "extra-slot-consent.cc" else (surface_document, slot_unit_document)
+        return path, _open(path, *documents)
+
+    def _document(self, store: str, key: str):
+        if key == "unit-arm":
+            return slot_unit_document
+        return declaring_document if store == "extra-slot-consent.cc" else surface_document
+
+    def test_the_variant_row_is_refused_as_a_store_not_walked_and_the_rest_of_the_store_reads_without_it(self) -> None:
+        # This runtime holds no variant records (ruling: refuse, not carry; the reference's marked-variant row, the one
+        # row with a flattenRefusedBy, is the C# reader's). A five-slot persisted record makes the whole store
+        # unreadable, the file is left as it was, and the store without exactly that row reads.
+        variants = [row for row in _rows() if row[8] is not None]
+        self.assertEqual([(row[0], row[1], row[8]) for row in variants], [("extra-slot-store.cc", "marked-variant", "marked")])
+        path = self.tmp / "extra-slot-store.cc"
+        shutil.copyfile(VECTORS / "extra-slot-store.cc", path)
+        before = path.read_bytes()
+        with self.assertRaises(StoreUnreadableError):
+            _open(path, surface_document, slot_unit_document)
+        self.assertEqual(path.read_bytes(), before)
+        _, cache = self._store("extra-slot-store.cc")
+        self.assertIsNone(cache.get(surface_document, "marked-variant"))
+        self.assertIsNotNone(cache.get(surface_document, "marked"))
+
+    def test_every_row_is_writable_exactly_where_the_vector_says_and_refuses_with_its_mark(self) -> None:
+        walked = 0
+        for store, key, writable, explained, type_name, carried, declared, occurrences, flatten in _rows():
+            if flatten is not None:
+                continue  # a variant: this runtime holds none (deviation)
+            walked += 1
+            with self.subTest(store=store, key=key):
+                path, cache = self._store(store)
+                document = self._document(store, key)
+                before = path.read_bytes()
+                self.assertEqual(cache.is_writable(document, key), writable)
+                held = cache.get(document, key)
+                self.assertIsNotNone(held)
+                if writable:
+                    continue
+                self.assertEqual(explained, False)
+                for attempt in (
+                    lambda: cache.put(document, key, held),
+                    lambda: cache.delete(document, key),
+                    lambda: cache.put_envelope(document, cache.get_required_envelope(document, key)),
+                    lambda: cache.put_envelopes(document, [cache.get_required_envelope(document, key)]),
+                    lambda: cache.update(document, key, lambda value: value),
+                ):
+                    with self.assertRaises(SchemaConflictError) as caught:
+                        attempt()
+                    refusal = caught.exception
+                    self.assertEqual(
+                        refusal.unread_slots,
+                        UnreadSlots(_NAMES.get(type_name, type_name), carried, declared, occurrences, refusal.unread_slots.depth0_only),
+                    )
+                    self.assertEqual(refusal.record_key, key)
+                    message = str(refusal)
+                    self.assertNotIn(SLOT, message)
+                    self.assertIn(refusal.unread_slots.type_name, message)
+                    self.assertIn(f"{carried} slots", message)
+                    self.assertIn(f"declares {declared}", message)
+                    self.assertEqual(path.read_bytes(), before)
+                self.assertTrue(cache.get(document, key) is held)
+        self.assertEqual(walked, 7)  # eight rows, the variant not walked
+
+    def test_a_key_no_store_holds_and_another_key_are_writable_while_a_marked_one_is_held(self) -> None:
+        path, cache = self._store("extra-slot-store.cc")
+        self.assertFalse(cache.is_writable(surface_document, "marked"))
+        self.assertTrue(cache.is_writable(surface_document, "nothing-here"))
+        cache.put(surface_document, "other", cache.get_required(surface_document, "clean"))
+        self.assertEqual(cache.get(surface_document, "other"), _surface_value())
+
+    def test_consent_lands_an_explained_mark_and_refuses_the_others(self) -> None:
+        path, cache = self._store("extra-slot-consent.cc")
+        self.assertTrue(cache.is_writable(declaring_document, "consented"))
+        cache.put(declaring_document, "consented", cache.get_required(declaring_document, "consented"))
+        [stored] = [e for e in SingleFileMessagePackBackingStore(path).pull_all() if e.key == "consented"]
+        self.assertEqual(stored.schema_id, "tests.union_surface.v2")
+        self.assertEqual(len(msgpack.unpackb(stored.payload, raw=False)), 7)  # the consented slot is gone
+        self.assertTrue(cache.is_writable(declaring_document, "consented"))
+        for key in ("over-consent", "nested"):
+            self.assertFalse(cache.is_writable(declaring_document, key), key)
+            with self.assertRaises(SchemaConflictError):
+                cache.put(declaring_document, key, cache.get_required(declaring_document, key))
+
+    def test_a_reload_marks_again_and_a_write_of_a_clean_envelope_over_a_marked_key_is_refused(self) -> None:
+        path, cache = self._store("extra-slot-store.cc")
+        envelope = cache.get_required_envelope(surface_document, "clean")
+        with self.assertRaises(SchemaConflictError):
+            cache.put_envelope(surface_document, type(envelope)(**{**envelope.__dict__, "key": "marked"}))
+        cache.pull_all_backing_stores()
+        self.assertFalse(cache.is_writable(surface_document, "marked"))
+
+    def test_a_written_envelope_that_carries_extra_slots_is_held_read_only(self) -> None:
+        path, cache = self._store("extra-slot-store.cc")
+        envelope = cache.get_required_envelope(surface_document, "clean")
+        carrying = type(envelope)(**{**envelope.__dict__, "key": "arrived", "payload": _vector("extra-slot-arm.msgpack")})
+        cache.put_envelope(surface_document, carrying)
+        self.assertFalse(cache.is_writable(surface_document, "arrived"))
+        with self.assertRaises(SchemaConflictError):
+            cache.delete(surface_document, "arrived")
+        cache.pull_all_backing_stores()
+        self.assertFalse(cache.is_writable(surface_document, "arrived"))
+
+    def test_a_batch_of_envelopes_that_carry_extra_slots_is_held_read_only(self) -> None:
+        path, cache = self._store("extra-slot-store.cc")
+        envelope = cache.get_required_envelope(surface_document, "clean")
+        batch = [
+            type(envelope)(**{**envelope.__dict__, "key": key, "payload": _vector(file)})
+            for key, file in (("b1", "extra-slot-arm.msgpack"), ("b2", "union-surface.msgpack"))
+        ]
+        cache.put_envelopes(surface_document, batch)
+        self.assertEqual([cache.is_writable(surface_document, key) for key in ("b1", "b2")], [False, True])
+
+    def test_a_mark_under_an_id_the_reader_does_not_list_compatible_is_not_consented(self) -> None:
+        unlisted = define_database_entry_type(
+            "tests.union_surface",
+            [database_entry_field("id", 0, codec=t.string)] + [database_entry_field(n, i, codec=c) for n, i, c in (
+                ("version", 1, t.int32), ("root", 2, _parity._node), ("outcomes", 3, t.list(_parity.outcome)),
+                ("part", 4, t.nullable(_parity.item)), ("crafted", 5, t.nullable(_parity.crafted)), ("missing", 6, _parity._node))],
+            name="id",
+            schema_id="tests.union_surface.v2",
+            schema_name="tests.union_surface",
+        )
+        path = self.tmp / "unlisted.cc"
+        _copy_store_without_variants(VECTORS / "extra-slot-consent.cc", path)
+        cache = _open(path, unlisted)
+        self.assertFalse(cache.is_writable(unlisted, "consented"))
+
+    def test_a_written_envelope_is_judged_on_the_id_it_is_stored_under_so_a_reload_agrees(self) -> None:
+        path, cache = self._store("extra-slot-consent.cc")
+        arrived = next(e for e in SingleFileMessagePackBackingStore(path).pull_all() if e.key == "consented")
+        self.assertEqual(arrived.schema_id, "tests.union_surface.wide")
+        cache.put_envelope(declaring_document, dataclasses.replace(arrived, key="via-envelope"))
+        cache.put_envelopes(declaring_document, [dataclasses.replace(arrived, key="via-batch")])
+        in_memory = [cache.is_writable(declaring_document, k) for k in ("via-envelope", "via-batch")]
+        cache.pull_all_backing_stores()
+        self.assertEqual([cache.is_writable(declaring_document, k) for k in ("via-envelope", "via-batch")], in_memory)
+        self.assertEqual(in_memory, [False, False])
+
+    def test_is_writable_agrees_with_the_write_for_a_key_a_store_carries_foreign(self) -> None:
+        path = self.tmp / "foreign.cc"
+        _copy_store_without_variants(VECTORS / "extra-slot-store.cc", path)
+        cache = _open(path, surface_document)  # tests.slot_unit is not registered: its record is carried foreign
+        self.assertEqual([r.key for r in cache.foreign_records()], ["unit-arm"])
+        self.assertFalse(cache.is_writable(surface_document, "unit-arm"))
+        with self.assertRaises(SchemaConflictError):
+            cache.put(surface_document, "unit-arm", _surface_value())
+        with self.assertRaises(SchemaConflictError):
+            cache.delete(surface_document, "unit-arm")
+
+    def test_every_key_of_a_batch_is_checked_wherever_the_marked_one_stands(self) -> None:
+        path, cache = self._store("extra-slot-store.cc")
+        before = path.read_bytes()
+        envelope = cache.get_required_envelope(surface_document, "clean")
+        fresh = dataclasses.replace(envelope, key="fresh")
+        marked = dataclasses.replace(envelope, key="marked")
+        for batch in ([fresh, marked], [marked, fresh], [fresh, dataclasses.replace(envelope, key="f2"), marked]):
+            with self.assertRaises(SchemaConflictError) as caught:
+                cache.put_envelopes(surface_document, batch)
+            self.assertEqual(caught.exception.record_key, "marked")
+            self.assertEqual(path.read_bytes(), before)
+            self.assertIsNone(cache.get(surface_document, "fresh"))
+
+    def test_only_the_marks_that_hold_a_record_read_only_are_kept_by_key(self) -> None:
+        _, store = self._store("extra-slot-store.cc")
+        self.assertEqual({k: v[0] for k, v in store._state.unread.items()}, {"marked": surface_document.type, "unit-arm": "tests.slot_unit"})
+        _, consent = self._store("extra-slot-consent.cc")
+        self.assertEqual(sorted(consent._state.unread), ["nested", "over-consent"])  # the consented mark is no state
+
+    def test_an_arrival_with_no_catalog_entry_under_a_listed_id_is_not_consented(self) -> None:
+        wide = next(e for e in SingleFileMessagePackBackingStore(VECTORS / "extra-slot-consent.cc").pull_all() if e.key == "consented")
+        bare = dataclasses.replace(wide, catalog_entry=None)
+
+        class Held:
+            def pull_all(self):
+                return [bare]
+
+            def push(self, envelope): ...
+
+            def push_all(self, envelopes): ...
+
+            def delete(self, type, key): ...
+
+        cache = CultCache.builder().register_document_type(declaring_document).add_generic_store(Held()).build()
+        cache.pull_all_backing_stores()
+        self.assertFalse(cache.is_writable(declaring_document, "consented"))
+
+    def test_a_removal_is_refused_where_is_writable_says_no(self) -> None:
+        path, cache = self._store("extra-slot-store.cc")
+        before = path.read_bytes()
+        other = define_database_entry_type("tests.other", [database_entry_field("a", 0, codec=t.string)], name="a")
+        cache2 = _open(self.tmp / "extra-slot-store.cc", surface_document, slot_unit_document, other)
+        self.assertFalse(cache2.is_writable(other, "clean"))
+        with self.assertRaises(SchemaConflictError):
+            cache2.delete(other, "clean")
+        self.assertEqual(path.read_bytes(), before)
+        self.assertIsNotNone(cache2.get(surface_document, "clean"))
+        self.assertTrue(cache2.is_writable(other, "nothing-here"))
+
+    def test_a_global_document_is_not_writable_at_a_key_other_than_the_global_one(self) -> None:
+        solo = define_database_entry_type("tests.solo", [database_entry_field("a", 0, codec=t.string)], global_document=True)
+        cache = CultCache.builder().register_document_type(solo).build()
+        self.assertFalse(cache.is_writable(solo, "elsewhere"))
+        with self.assertRaises(CultCacheError):
+            cache.put(solo, "elsewhere", {"a": "x"})
+        with self.assertRaises(CultCacheError):
+            cache.delete(solo, "elsewhere")
+        self.assertTrue(cache.is_writable(solo, CultCache.GLOBAL_KEY))
+
+    def test_a_reload_replaces_the_marks_wholesale(self) -> None:
+        path, cache = self._store("extra-slot-store.cc")
+        self.assertFalse(cache.is_writable(surface_document, "marked"))
+        # The store is repaired by its owner: the marked record is rewritten clean. The reload must forget the old mark.
+        [snapshot] = list(msgpack.Unpacker(open(path, "rb"), raw=False))
+        clean = next(r for r in snapshot[2] if r[0] == "clean")
+        for record in snapshot[2]:
+            if record[0] in ("marked", "unit-arm"):
+                record[3] = clean[3] if record[0] == "marked" else record[3]
+        snapshot[2] = [r for r in snapshot[2] if r[0] != "unit-arm"]
+        path.write_bytes(msgpack.packb(snapshot, use_bin_type=True))
+        cache.pull_all_backing_stores()
+        self.assertTrue(cache.is_writable(surface_document, "marked"))
+        self.assertEqual(cache._state.unread, {})
+
+    def test_a_listed_id_whose_catalog_reports_no_extra_slot_does_not_consent(self) -> None:
+        wide = next(e for e in SingleFileMessagePackBackingStore(VECTORS / "extra-slot-consent.cc").pull_all() if e.key == "consented")
+        same = dataclasses.replace(wide, catalog_entry=declaring_document.catalog_entry())  # the stored entry has no slot past the reader's
+
+        class Held:
+            def pull_all(self):
+                return [same]
+
+            def push(self, envelope): ...
+
+            def push_all(self, envelopes): ...
+
+            def delete(self, type, key): ...
+
+        cache = CultCache.builder().register_document_type(declaring_document).add_generic_store(Held()).build()
+        cache.pull_all_backing_stores()
+        self.assertFalse(cache.is_writable(declaring_document, "consented"))
+
+    def test_a_record_stored_under_the_readers_own_id_is_never_consented(self) -> None:
+        own = dataclasses.replace(
+            next(e for e in SingleFileMessagePackBackingStore(VECTORS / "extra-slot-consent.cc").pull_all() if e.key == "consented"),
+            schema_id="tests.union_surface.v2",
+        )
+        wider = dataclasses.replace(own.catalog_entry, schema_id="tests.union_surface.v2", compatible_schema_ids=("tests.union_surface.v2",))
+        listing = dataclasses.replace(
+            declaring_document, schema_id="tests.union_surface.v2", compatible_schema_ids=("tests.union_surface.wide", "tests.union_surface.v2")
+        )
+
+        class Held:
+            def pull_all(self):
+                return [dataclasses.replace(own, catalog_entry=wider)]
+
+            def push(self, envelope): ...
+
+            def push_all(self, envelopes): ...
+
+            def delete(self, type, key): ...
+
+        cache = CultCache.builder().register_document_type(listing).add_generic_store(Held()).build()
+        cache.pull_all_backing_stores()
+        self.assertFalse(cache.is_writable(listing, "consented"))
+
+    def test_a_removal_by_the_owner_of_a_key_held_as_another_type_removes_it_as_a_write_would_replace_it(self) -> None:
+        a = define_database_entry_type(
+            "tests.owned_a", [database_entry_field("a", 0, codec=t.string)], name="a", indexes={"by_a": "a"}
+        )
+        b = define_database_entry_type(
+            "tests.owned_b",
+            [database_entry_field("a", 0, codec=t.string)],
+            compatible_schema_ids=(a.catalog_entry().schema_id,),
+        )
+        path = self.tmp / "owned.cc"
+        writer = _open(path, a)
+        writer.put(a, "k", {"a": "x"})
+        writer.put(a, "other", {"a": "y"})
+        cache = _open(path, a, b)
+        self.assertTrue(cache.is_writable(b, "k"))
+        cache.delete(b, "k")
+        self.assertIsNone(cache.get(a, "k"))
+        self.assertIsNone(cache.get_by_index(a, "by_a", "x"))
+        self.assertEqual([e.key for e in SingleFileMessagePackBackingStore(path).pull_all()], ["other"])
+        self.assertTrue(cache.is_writable(b, "k"))
+
+    def test_an_owners_removal_is_one_store_call_so_the_cache_and_the_store_agree_when_it_fails(self) -> None:
+        a = define_database_entry_type("tests.one_a", [database_entry_field("a", 0, codec=t.string)], name="a")
+        b = define_database_entry_type(
+            "tests.one_b", [database_entry_field("a", 0, codec=t.string)], compatible_schema_ids=(a.catalog_entry().schema_id,)
+        )
+        path = self.tmp / "one.cc"
+        _open(path, a).put(a, "k", {"a": "x"})
+
+        class SecondDeleteFails(SingleFileMessagePackBackingStore):
+            calls = 0
+
+            def delete(self, type, key):
+                self.calls += 1
+                if self.calls > 1:
+                    raise OSError("second delete")
+                super().delete(type, key)
+
+        store = SecondDeleteFails(path)
+        cache = CultCache.builder().register_document_type(a).register_document_type(b).add_generic_store(store).build()
+        cache.pull_all_backing_stores()
+        cache.delete(b, "k")
+        self.assertEqual(store.calls, 1)
+        self.assertIsNone(cache.get(a, "k"))
+        self.assertEqual(SingleFileMessagePackBackingStore(path).pull_all(), [])
+
+    def test_writing_another_record_and_flushing_carries_the_marked_one_unchanged(self) -> None:
+        path, cache = self._store("extra-slot-store.cc")
+        original = {e.key: e for e in SingleFileMessagePackBackingStore(path).pull_all()}
+        cache.put(surface_document, "clean", {**_surface_value(), "version": 9})
+        after = {e.key: e for e in SingleFileMessagePackBackingStore(path).pull_all()}
+        for key in ("marked", "unit-arm"):
+            self.assertEqual(after[key].payload, original[key].payload, key)
+            self.assertEqual(after[key].schema_id, original[key].schema_id, key)
+            self.assertEqual(after[key].stored_at, original[key].stored_at, key)
+        self.assertNotEqual(after["clean"].payload, original["clean"].payload)
+        self.assertEqual(after["marked"].catalog_entry, original["marked"].catalog_entry)
+
+    def test_the_vector_store_loads_under_the_reference_documents_and_marks_nothing_else(self) -> None:
+        path, cache = self._store("extra-slot-store.cc")
+        self.assertTrue(cache.is_writable(surface_document, "clean"))
+        self.assertFalse(cache.is_writable(surface_document, "marked"))
+        self.assertFalse(cache.is_writable(slot_unit_document, "unit-arm"))
+        self.assertEqual(
+            cache.get(slot_unit_document, "unit-arm"), {"name": "unit-arm", "outcome": UnionArm("Denied")}
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()

packages/cultcache-py/tests/test_soft_push_all.py

@@ -0,0 +1,140 @@
+from __future__ import annotations
+
+import shutil
+import tempfile
+import unittest
+from pathlib import Path
+
+from cultcache_py import JsonLinesBackingStore, SingleFileMessagePackBackingStore, StoreUnreadableError
+from cultcache_py.backing_store import BackingStore, CultCacheEnvelope
+
+
+def envelope(key: str) -> CultCacheEnvelope:
+    return CultCacheEnvelope(key=key, type="t", payload=b"\x01", stored_at="2026-11-06T00:00:00Z")
+
+
+class SoftPushAllTests(unittest.TestCase):
+    """A soft push writes where nothing is, skips a store it reads, and refuses one it cannot read (TS and Rust parity)."""
+
+    def setUp(self) -> None:
+        self.dir = Path(tempfile.mkdtemp())
+        self.addCleanup(shutil.rmtree, self.dir, ignore_errors=True)
+        self.path = self.dir / "state.cc"
+
+    def test_over_a_readable_store_it_leaves_the_file_byte_for_byte(self) -> None:
+        for make in (SingleFileMessagePackBackingStore, JsonLinesBackingStore):
+            with self.subTest(make.__name__):
+                path = self.dir / make.__name__
+                store = make(path)
+                store.push_all([envelope("a")])
+                before = path.read_bytes()
+                store.push_all([envelope("b")], soft=True)
+                self.assertEqual(before, path.read_bytes())
+                self.assertEqual(["a"], [item.key for item in make(path).pull_all()])
+                store.push_all([envelope("b")])  # a plain push still lands what the caller holds
+                self.assertEqual(["a", "b"], sorted(item.key for item in make(path).pull_all()))
+
+    def test_over_a_readable_store_holding_no_records_it_leaves_the_file_byte_for_byte(self) -> None:
+        for make in (SingleFileMessagePackBackingStore, JsonLinesBackingStore):
+            with self.subTest(make.__name__):
+                path = self.dir / make.__name__
+                store = make(path)
+                store.push_all([envelope("a")])
+                store.delete("t", "a")
+                self.assertTrue(path.exists())
+                self.assertEqual([], make(path).pull_all())
+                before = path.read_bytes()
+                store.push_all([envelope("b")], soft=True)
+                self.assertEqual(before, path.read_bytes())
+                self.assertEqual([], make(path).pull_all())
+
+    def test_over_an_absent_path_it_writes(self) -> None:
+        for make in (SingleFileMessagePackBackingStore, JsonLinesBackingStore):
+            with self.subTest(make.__name__):
+                path = self.dir / make.__name__
+                make(path).push_all([envelope("a")], soft=True)
+                self.assertEqual(["a"], [item.key for item in make(path).pull_all()])
+
+    def test_over_an_unreadable_file_it_refuses_and_leaves_it(self) -> None:
+        junk = b"\xc1\x01\x02\x03"
+        self.path.write_bytes(junk)
+        with self.assertRaises(StoreUnreadableError):
+            SingleFileMessagePackBackingStore(self.path).push_all([envelope("a")], soft=True)
+        self.assertEqual(junk, self.path.read_bytes())
+
+    def test_over_an_unreadable_jsonl_file_it_refuses_and_leaves_it(self) -> None:
+        junk = b"this is not json\n"
+        self.path.write_bytes(junk)
+        with self.assertRaises(ValueError):
+            JsonLinesBackingStore(self.path).push_all([envelope("a")], soft=True)
+        self.assertEqual(junk, self.path.read_bytes())
+
+    def test_the_protocol_default_push_all_decides_soft_by_what_pull_or_absent_says(self) -> None:
+        class Memory(BackingStore):
+            def __init__(self) -> None:
+                self.items: list[CultCacheEnvelope] | None = None  # None: nothing at the path
+
+            def pull_all(self) -> list[CultCacheEnvelope]:
+                return list(self.items or [])
+
+            def pull_or_absent(self) -> list[CultCacheEnvelope] | None:
+                return None if self.items is None else list(self.items)
+
+            def _replace_all(self, envelopes: list[CultCacheEnvelope]) -> None:
+                self.items = list(envelopes)
+
+        store = Memory()
+        store.push_all([envelope("a")], soft=True)  # nothing at the path: writes
+        self.assertEqual(["a"], [item.key for item in store.items or []])
+        store.push_all([envelope("b")], soft=True)  # a store with records: skips
+        self.assertEqual(["a"], [item.key for item in store.items or []])
+        store.items = []
+        store.push_all([envelope("b")], soft=True)  # a store the reader read, empty: skips
+        self.assertEqual([], store.items)
+        store.push_all([envelope("b")])  # plain: lands
+        self.assertEqual(["b"], [item.key for item in store.items])
+
+    def test_a_store_that_only_pulls_all_is_read_so_a_soft_push_skips_it(self) -> None:
+        class PullOnly(BackingStore):
+            def __init__(self) -> None:
+                self.items: list[CultCacheEnvelope] = []
+
+            def pull_all(self) -> list[CultCacheEnvelope]:
+                return list(self.items)
+
+            def _replace_all(self, envelopes: list[CultCacheEnvelope]) -> None:
+                self.items = list(envelopes)
+
+        store = PullOnly()
+        store.push_all([envelope("a")], soft=True)
+        self.assertEqual([], store.items)
+
+    def test_the_single_file_and_jsonl_stores_say_absent_and_read_through_pull_or_absent(self) -> None:
+        for make in (SingleFileMessagePackBackingStore, JsonLinesBackingStore):
+            with self.subTest(make.__name__):
+                path = self.dir / make.__name__
+                store = make(path)
+                self.assertIsNone(store.pull_or_absent())
+                store.push_all([envelope("a")])
+                self.assertEqual(["a"], [item.key for item in store.pull_or_absent() or []])
+
+    def test_the_protocol_default_push_all_refuses_where_its_pull_refuses(self) -> None:
+        class Unreadable(BackingStore):
+            replaced = False
+
+            def pull_all(self) -> list[CultCacheEnvelope]:
+                raise StoreUnreadableError(Path("x"), ValueError("junk"))
+
+            def pull_or_absent(self) -> list[CultCacheEnvelope] | None:
+                raise StoreUnreadableError(Path("x"), ValueError("junk"))
+
+            def _replace_all(self, envelopes: list[CultCacheEnvelope]) -> None:
+                Unreadable.replaced = True
+
+        with self.assertRaises(StoreUnreadableError):
+            Unreadable().push_all([envelope("a")], soft=True)
+        self.assertFalse(Unreadable.replaced)
+
+
+if __name__ == "__main__":
+    unittest.main()

packages/cultcache-py/tests/test_store_lock.py

@@ -1,21 +1,25 @@
 from __future__ import annotations
 
 import os
+import select
 import shutil
 import subprocess
 import sys
 import tempfile
+import threading
 import time
 import unittest
 from pathlib import Path
 from unittest import mock
 
 from cultcache_py import SingleFileMessagePackBackingStore, stores
+from cultcache_py.stores import StoreLinkedError, store_write_lock
 from cultcache_py.backing_store import CultCacheEnvelope
 
 REPO = Path(__file__).resolve().parents[3]
 TS_STORE_FILE = REPO / "packages" / "cultcache-ts" / "dist" / "store-file.js"
 HOLD_SECONDS = 1.5
+HELD_WAIT_SECONDS = 3
 
 # A holder that takes the lock the way the Rust runtime does (an exclusive file lock), not through this package.
 PY_HOLDER = """
@@ -41,7 +45,14 @@ def envelope(key: str) -> CultCacheEnvelope:
 
 def start_holder(argv: list[str]) -> subprocess.Popen[str]:
     holder = subprocess.Popen(argv, stdout=subprocess.PIPE, text=True)
-    assert holder.stdout is not None and holder.stdout.readline().strip() == "HELD"
+    assert holder.stdout is not None
+    ready, _, _ = select.select([holder.stdout], [], [], HELD_WAIT_SECONDS)  # a holder blocked on a leaked lock never prints
+    if not ready:
+        holder.kill()
+        holder.wait()
+        holder.stdout.close()
+        raise AssertionError(f"the holder never took {argv[-2]}.lock within {HELD_WAIT_SECONDS} s: an earlier writer leaked the lock")
+    assert holder.stdout.readline().strip() == "HELD"
     holder.held_at = time.monotonic()  # type: ignore[attr-defined]
     return holder
 
@@ -73,6 +84,48 @@ class StoreLockTests(unittest.TestCase):
         holder = start_holder(["node", "-e", TS_HOLDER, str(TS_STORE_FILE), str(self.path), str(HOLD_SECONDS)])
         self.assert_write_waits_for(holder)
 
+    def test_a_link_put_while_a_writer_waits_on_the_lock_is_refused_once_it_holds_it(self) -> None:
+        target = self.dir / "volume" / "store.cc"
+        target.parent.mkdir()
+        SingleFileMessagePackBackingStore(target).push(envelope("a"))
+        before = target.read_bytes()
+        writes = {
+            "push": lambda store: store.push(envelope("b")),
+            "push_all": lambda store: store.push_all([envelope("b")]),
+            "delete": lambda store: store.delete("t", "a"),
+        }
+        missing = self.dir / "volume" / "missing.cc"
+        for (name, write), link_to in [(item, to) for item in writes.items() for to in (target, missing)]:
+            with self.subTest(name, dangling=link_to == missing):
+                if os.path.lexists(self.path):
+                    os.unlink(self.path)
+                holder = start_holder([sys.executable, "-c", PY_HOLDER, str(self.path), str(HOLD_SECONDS)])
+                self.addCleanup(holder.wait)
+                self.addCleanup(holder.stdout.close)  # type: ignore[union-attr]
+                outcome: list[BaseException | None] = []
+
+                def run() -> None:
+                    try:
+                        write(SingleFileMessagePackBackingStore(self.path, lock_timeout=10))
+                        outcome.append(None)
+                    except BaseException as exc:  # noqa: BLE001 - the thread hands the outcome to the test
+                        outcome.append(exc)
+
+                writer = threading.Thread(target=run)
+                writer.start()
+                time.sleep(0.3)
+                os.symlink(link_to, self.path)  # after the writer's pre-lock look, while it waits
+                writer.join()
+                holder.wait()
+                self.assertEqual(1, len(outcome))
+                self.assertIsInstance(outcome[0], StoreLinkedError)
+                self.assertTrue(os.path.islink(self.path), "the link was replaced")
+                self.assertEqual(before, target.read_bytes())
+                self.assertFalse(missing.exists(), "the dangling target was created")
+                os.unlink(self.path)  # a link is refused before the lock, so remove it to probe the writer's own lock file
+                with store_write_lock(self.path, timeout=0.2):  # the lock is free
+                    pass
+
     def test_the_lock_is_released_after_each_write(self) -> None:
         store = SingleFileMessagePackBackingStore(self.path, lock_timeout=0.2)
         for key in "abc":

packages/cultcache-py/tests/test_store_replace.py

@@ -0,0 +1,137 @@
+from __future__ import annotations
+
+import os
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+from unittest import mock
+
+from cultcache_py import SingleFileMessagePackBackingStore, stores
+from cultcache_py.backing_store import CultCacheEnvelope
+from cultcache_py.stores import MOVEFILE_REPLACE_WRITE_THROUGH, ReplaceKernel, replace_store_windows
+
+
+class FakeKernel(ReplaceKernel):
+    def __init__(self, posix: list[int], move_ex: list[int]) -> None:
+        self.posix, self.move_ex = list(posix), list(move_ex)
+        self.log: list[str] = []
+        self.sleeps: list[float] = []
+
+    def rename_posix(self, staged, destination):
+        self.log.append("posix")
+        return self.posix.pop(0) if self.posix else 0
+
+    def move_file_ex(self, staged, destination, flags):
+        self.log.append(f"moveex:{flags}")
+        return self.move_ex.pop(0) if self.move_ex else 0
+
+    def sleep(self, seconds):
+        self.sleeps.append(seconds)
+
+
+def run(posix, move_ex):
+    kernel = FakeKernel(posix, move_ex)
+    return kernel, lambda: replace_store_windows("a", "b", kernel)
+
+
+class WindowsReplaceTable(unittest.TestCase):
+    def test_falls_back_to_write_through_move_where_posix_rename_is_unsupported(self):
+        self.assertEqual(MOVEFILE_REPLACE_WRITE_THROUGH, 0x9)
+        for unsupported in (1, 50, 87):
+            kernel, go = run([unsupported], [0])
+            go()
+            self.assertEqual(kernel.log, ["posix", "moveex:9"])
+
+    def test_once_on_move_the_rest_of_the_call_stays_there(self):
+        kernel, go = run([87], [32, 0])
+        go()
+        self.assertEqual(kernel.log, ["posix", "moveex:9", "moveex:9"])
+
+    def test_transient_codes_retry_the_same_primitive(self):
+        for transient in (5, 32, 33):
+            kernel, go = run([transient, transient, 0], [])
+            go()
+            self.assertEqual(kernel.log, ["posix", "posix", "posix"])
+            self.assertEqual(kernel.sleeps, [0.02, 0.02])
+
+    def test_a_working_posix_rename_is_the_whole_replace(self):
+        kernel, go = run([0], [])
+        go()
+        self.assertEqual(kernel.log, ["posix"])
+        self.assertEqual(kernel.sleeps, [])
+
+    def test_unsupported_after_the_fallback_is_an_error_not_another_fallback(self):
+        kernel, go = run([87], [32, 87])
+        with self.assertRaisesRegex(OSError, "Win32 error 87") as caught:
+            go()
+        self.assertEqual(caught.exception.winerror, 87)
+        self.assertEqual(kernel.log, ["posix", "moveex:9", "moveex:9"])
+        for unsupported in (1, 50, 87):
+            kernel, go = run([87], [unsupported])
+            with self.assertRaisesRegex(OSError, f"Win32 error {unsupported}"):
+                go()
+            self.assertEqual(kernel.log, ["posix", "moveex:9"])
+
+    def test_gives_up_after_25_attempts_naming_the_last_code(self):
+        kernel, go = run([32] * 30, [])
+        with self.assertRaisesRegex(OSError, "after 25 attempts: last Win32 error 32\\."):
+            go()
+        self.assertEqual(len(kernel.log), 25)
+
+    def test_other_codes_fail_at_once(self):
+        kernel, go = run([2], [])
+        with self.assertRaisesRegex(OSError, "Win32 error 2"):
+            go()
+        self.assertEqual(len(kernel.log), 1)
+        kernel, go = run([87], [3])
+        with self.assertRaisesRegex(OSError, "Win32 error 3"):
+            go()
+
+
+class StoreWritesRouteThroughTheReplace(unittest.TestCase):
+    def test_both_stores_replace_through_replace_store(self):
+        seen: list[tuple[Path, Path]] = []
+        real = stores._replace_store
+
+        def spy(staged, destination):
+            seen.append((Path(staged), Path(destination)))
+            real(staged, destination)
+
+        with tempfile.TemporaryDirectory() as directory, mock.patch.object(stores, "_replace_store", spy):
+            envelope = CultCacheEnvelope(key="k", type="t", payload=b"\x01", stored_at="2026-11-06T00:00:00Z")
+            binary = Path(directory) / "s.cc"
+            SingleFileMessagePackBackingStore(binary).push_all([envelope])
+            lines = Path(directory) / "s.jsonl"
+            stores.JsonLinesBackingStore(lines).push_all([envelope])
+            self.assertEqual([destination for _, destination in seen], [binary, lines])
+            self.assertTrue(binary.read_bytes() and lines.read_text())
+
+    def test_a_failed_jsonl_replace_leaves_no_staged_file_and_the_old_store(self):
+        envelope = CultCacheEnvelope(key="k", type="t", payload=b"\x01", stored_at="2026-11-06T00:00:00Z")
+        with tempfile.TemporaryDirectory() as directory:
+            lines = Path(directory) / "s.jsonl"
+            store = stores.JsonLinesBackingStore(lines)
+            store.push_all([envelope])
+            before = lines.read_bytes()
+            with mock.patch.object(stores, "_replace_store", side_effect=OSError("replace refused")):
+                with self.assertRaises(OSError):
+                    store.push_all([CultCacheEnvelope(key="k2", type="t", payload=b"\x02", stored_at="2026-11-06T00:00:00Z")])
+            self.assertEqual(lines.read_bytes(), before)
+            self.assertEqual([p.name for p in Path(directory).iterdir() if ".tmp" in p.name], [])
+
+    @unittest.skipUnless(sys.platform == "win32", "needs a real Windows")
+    def test_real_kernel_replaces_through_both_primitives(self):
+        kernel = stores.WindowsReplaceKernel()
+        with tempfile.TemporaryDirectory() as directory:
+            for name, replace in (("posix", kernel.rename_posix), ("moveex", lambda s, d: kernel.move_file_ex(s, d, MOVEFILE_REPLACE_WRITE_THROUGH))):
+                staged, store = Path(directory, name + ".tmp"), Path(directory, name)
+                store.write_bytes(b"old")
+                staged.write_bytes(b"new")
+                self.assertEqual(replace(str(staged), str(store)), 0)
+                self.assertEqual(store.read_bytes(), b"new")
+            self.assertEqual(kernel.rename_posix(str(Path(directory, "missing")), str(Path(directory, "x"))), 2)
+
+
+if __name__ == "__main__":
+    unittest.main()

packages/cultcache-py/tests/test_union_parity.py

@@ -261,7 +261,9 @@ class UnionSurfaceVectorTests(unittest.TestCase):
             else:
                 read_only += 1
                 self.assertEqual(outcome_kind, "read-only", file)
-                self.assertEqual(surface_document.decode_payload(payload), _surface_value(), file)
+                value, mark = surface_document.decode_payload_marked(payload)
+                self.assertEqual(value, _surface_value(), file)
+                self.assertIsNotNone(mark, file)  # read past and marked: tests/test_slot_readonly.py pins what the mark holds
         self.assertEqual((refused, read_only), (5, 4))
 
 
@@ -526,7 +528,9 @@ class BoundsVectorTests(unittest.TestCase):
                     surface_document.encode_payload(surface_document.decode_payload(payload)), _vector(detail), file
                 )
             elif outcome_kind == "read-only":
-                self.assertEqual(surface_document.decode_payload(payload), _surface_value(), file)
+                value, mark = surface_document.decode_payload_marked(payload)
+                self.assertEqual(value, _surface_value(), file)
+                self.assertIsNotNone(mark, file)
             else:
                 with self.assertRaises(ValueError, msg=file) as caught:
                     surface_document.decode_payload(payload)
@@ -657,6 +661,78 @@ def _as_tuple(tree: object) -> object:
     return tuple(_as_tuple(child) for child in tree) if isinstance(tree, list) else tree
 
 
+
+class BytesAfterVectorTests(unittest.TestCase):
+    CLAUSE = "bytes after its first MessagePack value (refused on read)"
+
+    def _assert_chain_clean(self, error: BaseException, file: str) -> None:
+        link: BaseException | None = error
+        while link is not None:
+            self.assertNotIn(CANARY, str(link), file)
+            self.assertNotIsInstance(link, msgpack.ExtraData, file)
+            link = link.__cause__ or link.__context__
+
+    def test_every_bytes_after_vector_is_refused(self) -> None:
+        base = _vector("union-surface.msgpack")
+        entries = msgpack.unpackb(_vector("bytes-after-outcomes.msgpack"), raw=False)
+        self.assertEqual(len(entries), 4)
+        for file, outcome_kind, union, key, detail in entries:
+            self.assertEqual((outcome_kind, union, key, detail), ("refused", "UnionSurface", None, "bytes-after"), file)
+            payload = _vector(file)
+            self.assertTrue(payload.startswith(base), file)
+            count = len(payload) - len(base)
+            with self.assertRaises(ValueError, msg=file) as caught:
+                surface_document.decode_payload(payload)
+            error = caught.exception
+            self.assertIs(type(error), ValueError, file)
+            self.assertNotIsInstance(error, CultCachePayloadDepthError, file)
+            self.assertEqual(
+                str(error), f"{surface_document.type} payload has {count} {self.CLAUSE}.", file
+            )
+            self.assertNotIn("the limit is", str(error), file)
+            self._assert_chain_clean(error, file)
+
+    def test_a_single_file_store_holding_a_tail_as_a_record_payload_refuses_on_load(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "tail.cc"
+            shutil.copyfile(VECTORS / "union-surface.cc", path)
+            store = SingleFileMessagePackBackingStore(path)
+            [envelope] = store.pull_all()
+            store.push(dataclasses.replace(envelope, payload=_vector("bytes-after-nil.msgpack")))
+            cache = (
+                CultCache.builder()
+                .register_document_type(surface_document)
+                .add_generic_store(SingleFileMessagePackBackingStore(path))
+                .build()
+            )
+            with self.assertRaises(ValueError) as caught:
+                cache.pull_all_backing_stores()
+            self.assertIn(f"1 {self.CLAUSE}", str(caught.exception))
+            self.assertIn(surface_document.type, str(caught.exception))
+            self.assertIsNone(cache.get(surface_document, "surface"))
+
+    def test_depth_wins_over_a_tail_whatever_the_unpackers_own_stack_limit(self) -> None:
+        # Vector-independent: a value nested past 256 is the depth refusal even with a tail, as C# throws at container 257
+        # before it reaches the tail; 2000 is past msgpack's own stack, so the winner is not a library constant.
+        for depth in (257, 300, 900, 2000, 100000):
+            for tail in (b"\xc0", b"\xc1\xc1"):
+                with self.subTest(depth=depth, tail=len(tail)):
+                    with self.assertRaises(CultCachePayloadDepthError) as caught:
+                        surface_document.decode_payload(b"\x91" * depth + b"\xc0" + tail)
+                    self.assertIn("refused on read", str(caught.exception))
+        for depth in (1, 255, 256):
+            with self.subTest(at=depth):
+                with self.assertRaises(ValueError) as caught:
+                    surface_document.decode_payload(b"\x91" * depth + b"\xc0\xc0")
+                self.assertNotIsInstance(caught.exception, CultCachePayloadDepthError)
+                self.assertIn(f"1 {self.CLAUSE}", str(caught.exception))
+
+    def test_a_payload_that_ends_early_is_the_decoders_not_bytes_after(self) -> None:
+        truncated = _vector("union-surface.msgpack")[:-1]
+        with self.assertRaises(Exception) as caught:
+            surface_document.decode_payload(truncated)
+        self.assertNotIn("bytes after", str(caught.exception))
+
 class PayloadDepthRuleTests(unittest.TestCase):
     """The nesting rule at its seam, on definitions that are not unions: the same routine serves any payload codec."""
 

packages/cultcache-rs/.gitignore

@@ -1,2 +1 @@
 /target
-Cargo.lock

packages/cultcache-rs/CHANGELOG.md

@@ -6,8 +6,25 @@ only in git history.
 
 ## Unreleased
 
+### Changed
+
+- The single-file store re-checks for a link once the store lock is held (every write and the try-exchange), so a link put at the path while a writer waited on the lock is refused with `StoreLinkedError` and the lock released, as C# does, instead of being replaced. Pinned by a test that puts the link while a second holder owns the lock.
+- `CultCache::is_writable` does not look at store paths: a link at a store path is not predicted, and the write refuses it with `StoreLinkedError`. Pinned by a test through a cache attached to a linked store.
+
 ### Breaking
 
+Semver: this is a breaking change in the 0.x line (0.3.x to 0.4.0).
+
+- A write at a store path that is a symbolic link, live or dangling, is refused with the new public `StoreLinkedError` (`error.downcast_ref::<StoreLinkedError>()`) before the lock and the replace, and writes nothing: `push`, `push_all`, `delete`, the exchanges, and a soft `push_all`, which used to skip a link and now refuses. Before, a write at a live link replaced the link with a regular file and a dangling link failed with `io::ErrorKind::NotFound`. The redb stores (`RedbMessagePackBackingStore`, `OwnedRedbMessagePackBackingStore`) are exempt: they are ruled migrated and deleted (`paged-store-redb-migrate-and-delete`) and still open a live link's target. Configure the link's target as the store path. Reads through a live link work.
+- A record whose payload carries unread slots is read-only. A payload with a slot past its type's declared slots, at any depth (record, nested record, list element, union arm, unit arm), still decodes, and every write or removal of its key is now refused before any store is touched: `put`, `put_envelope`, `put_raw_envelope`, `put_prepared_batch` (the whole batch) and `delete`, so `update` too. The refusal is `SchemaConflictError` with the new `unread_slots`; its message names the type and both slot counts and never a slot value. Holders of such a record used to overwrite it and drop the extra slots silently. The payload nesting refusal still runs first. A held payload this build cannot read at all (an arm it lacks from a newer writer, or a corrupt record) is read-only too: every write or removal is refused with an error naming the type and key (a newer writer's record is read with that build; a corrupt one is restored from a backup or removed at the store itself, as no cache call removes it), and `is_writable` answers false. `load_soa` is a write of every held key it omits or changes, so it refuses to drop or replace a read-only record. `is_writable` also answers false for a key a store carries as a foreign record and for a type other than the one holding the key, as the writes do. Each write over a held key decodes the held payload once to ask (about 40% of a `put` of a 200,000-element record, measured in release); keys nothing holds pay nothing.
+- cultmesh-rs `pull_rudp_catalog_snapshot` applies a snapshot as one cache commit (`put_prepared_batch`), as C# does: a snapshot document for a key the node holds read-only, or any other refusal, applies nothing. It used to apply document by document, so a refusal ended the pull with the earlier documents kept. A snapshot whose types route to different backing stores is now refused whole, as a batch cannot span stores. C# `CultCache.Commit` refuses a cross-store commit the same way (`The batch spans A and B; a commit lands in one home store`), so the two agree; a test pins it.
+- `SchemaConflictError` gains the public field `unread_slots: Option<UnreadSlots>`; code that builds it with a struct literal must set it (`None`).
+- A unit arm with slots (`[N, [extra...]]`) decodes as the unit arm and marks the record, where the derive refused it.
+- The registration map's value changes from the schema name to a private struct holding the schema name and the unread-slots check.
+- A cache whose last `pull_all_backing_stores` was refused (a tail, a payload past the nesting bound, a duplicate unique-index value, a retype conflict, a record from the wrong store) refuses every `put`, `put_envelope`, `put_raw_envelope`, `put_prepared_batch`, `update` and `delete` with `CultCacheLoadRefused` until a pull succeeds. Before, it stayed writable over an empty image, and the next batch write replaced the store with only the new records.
+- `CacheBackingStore::push_all` writes the given entries onto the store as it is when the write lands, under the store's lock or transaction: a record under the same identity is replaced and no other record is removed. It used to replace everything the store held, so a cache whose image was stale (another writer had added a record since its pull) wiped that record with `put_prepared_batch`. `put_prepared_batch` now hands the store its staged records alone, as C# `CommitBatch` and Python `push_all` do; the lay-back of foreign records is gone because they are never rewritten. A custom `CacheBackingStore` must give `push_all` merge semantics. `push_all` reads the store, so through a dangling link it is refused like `push` and no longer replaces the link; a soft flush is unchanged.
+- A cache with a backing store also refuses every write and removal, with `CultCacheLoadRefused`, until it has pulled: a cache that never pulled, or that gained a store since its last pull, holds no image of its stores, and a batch from it replaced a populated store with only the new records. `is_writable` answers false meanwhile. A cache with no store needs no pull. Callers that attach a store and write (cultmesh nodes created with `pull_on_start: false`) must call `pull_all_backing_stores` first.
+- `decode_payload`, `put_raw_envelope` and prepared batches refuse a payload with bytes after its first MessagePack value (`payload has {n} bytes after its first MessagePack value`), by count; the tail is never walked or quoted. They used to read the first value and keep or drop the tail, so a record with a stray tail was served and rewritten without it. A store holding such a record (single-file, redb, `load_soa`) is refused at load, naming the type, the key and the count, and stays unreadable until the record is repaired; the same check now runs on every record at load, as the C# and Python runtimes do at open. The nesting bound is part of that check, so a stored payload nested past it is refused at load too, where it used to load and refuse on read.
 - A single-file store written as `cultcache.store.v3` is read and written: a store the C# runtime marked v3 (it holds a record with an element id: an owned list element with a `[CultElementId]` member) keeps its header here, and is carried through every rewrite with its ids; this runtime never drops the mark. A runtime from before this change refuses a v3 store by name. Rolling back to an older release after a store has been written as v3 is one-way: there is no carry-back, so restore from a copy taken before upgrading.
 - A write over a file the reader refuses (a zero-byte file, a truncated store, a stamp this runtime does not read) refuses with `CultCacheStoreUnreadable` and leaves the file as it is. A whole-store write used to replace such a file. This reverses 0.3.1, where `push_all` replaced a file with no readable stamp (healing it); the stamp rule now has one owner, the reader every write asks under the lock, and it accepts v1 and v3 (0.3.1 refused v3).
 - `#[cultcache(index)]` means unique, as in C# `RefuseIndexSharing`: within one type and one alias no two records hold one non-blank value. A put, batch, push or load that would make two records hold a value is refused, naming both keys and the alias, and a store that already holds a duplicate does not open. A grouping index is no longer expressible; a consumer that relied on shared values must drop the `index` and look up by another way.
@@ -17,10 +34,13 @@ only in git history.
 - A single-file store holds one record per key. The v1 and legacy readers refuse a store with two records under one key (`CultCacheStoreUnreadable`, the record `Undecodable`): the store does not open, and a write over it refuses and leaves the file. A consumer that holds such a file must repair it with the runtime that wrote it before opening it here.
 - Every single-file writer (`push`, `push_all`, `insert_entry_if_absent`, the compare-exchange and snapshot-append family, and the cache's puts and batches) refuses to put a second type under a key the store holds, with `SchemaConflictError` naming the key and both types, writing nothing. Retyping a key is a delete, then an add (one batch may hold both). A write owns the held record when its schema id equals the id the held record is stored under, as C# `WrittenOwns` asks; a type renamed under a stable id therefore replaces its own record, and a write of another type name under another id is refused (`push` of the same type name under another id still replaces the record, as before; `compare_and_swap_entry`, and a `push_all` batch holding one type under two ids, refuse it). Registered types here declare no compatible ids, so equality is the whole test. Writers used to leave two records under the key.
 - `compare_and_swap_entry` over a single file refuses an in-place retype (expected `A/k`, replacement `B/k` under another schema id) with the same `SchemaConflictError`, as `compare_exchange` does, where it used to retype the record and return `true`. A lost race still returns `false` first.
+- A cache holds one record per key. `put`, `put_envelope`, `put_raw_envelope` and a batch of a second type under a key the cache holds, or a key a store carries foreign, are refused with `SchemaConflictError` even with no store (a memory-only cache used to hold both), whatever schema id the envelope claims: another registered type's record is never owned. `put_envelope`, `put_raw_envelope`, `put_prepared_batch` and `load_soa` also refuse, at any key, an envelope whose schema id names another type registered in this cache (the id a pull would resolve the record by). An id this cache does not register is trusted as the envelope claims it: at a key this cache does not hold, the single-file store decides ownership by that id, so such an envelope can replace another writer's record stored under it, and a reader registering the type the id names serves the record as that type. Store-level writers called directly (`push`, `insert_entry_if_absent`, compare-and-swap) still trust the claimed id. A refused write or pull changes nothing. Two stores holding one key refuse the pull, naming the key and both types, and so does one store holding two records at a key that resolve to one type. A store holding a record no registered type claims now loads (it used to refuse with "No schema is registered for persisted entry type") and the record is carried, through `put_prepared_batch` too, which lays foreign records back byte for byte; `delete` at a foreign key is refused. `load_soa` refuses a second type at a key or a record at a foreign key, and still refuses an unregistered type. The redb stores still key by `(type, key)`, and their own writers (`push`, `insert_entry_if_absent`, compare-and-swap) still put a second type at a held key: a cache now refuses to pull such a redb store with `SchemaConflictError`, where it used to load both records.
 - A write of the same type under a held key replaces the record by key, and in one `push_all` the last given of several entries under a key and a schema id is the record, whatever their type names. The redb stores are unchanged and still key by type and key.
 
 ### Added
 
+- `UnreadSlots { type_name, slot_count, declared_count, occurrences }`, `decode_payload_marked` (the decode that returns the mark) and `CultCache::is_writable(type, key)`. The derives' slot visitors note into a thread-local scope the decode entry opens (`__enter_slots`, `__note_unread_slots`, `__UnitArmSlots`, doc-hidden); a decode outside that entry notes nothing.
+- `CultCache::foreign_records()` and `ForeignRecord { key, schema_id, schema_name, stored_at }`: the records the last pull found that no registered type claims, sorted by key.
 - Lookups, matching the C# `GetByName`, `GetByIndex` and `GetGlobal`. `#[cultcache(name)]` and `#[cultcache(index)]` / `#[cultcache(index = "alias")]` on `DatabaseEntry` fields and `#[cultcache(global)]` on the struct give `CultCache::get_by_name`, `get_by_index` and `get_global`. An empty name and a blank index value are not found; records of one type sharing a name find the one with the smallest key (an index value is unique, below). A second record of a global type under another key is refused on every write path and on load with `CultCacheSecondGlobal`. Two `name` members, or two members with one index alias, are refused at compile time. A member's text comes from `CultLookupValue` (`String`, `Option` of one, integers, `bool`, `char`).
 - `SchemaConflictError`, the typed refusal of a write the catalog cannot describe: records of different types under one schema id, or an arrived schema and a registered one that share an id and disagree on the schema name. A whole-store write (`push_all`) refuses with it, names the schema id, the names involved and a record key, writes nothing and leaves the file as it is. A caller tells it apart with `error.downcast_ref::<SchemaConflictError>()`.
 

packages/cultcache-rs/Cargo.lock

@@ -0,0 +1,730 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "android_system_properties"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae221649c9976a6f6c56ae1facf410f3ddb33cc661c4b7b61020a912d4237fbc"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "anyhow"
+version = "1.0.104"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "330a5ed07fa54e4702c9d6c4174f74427fc0ef6e214bbd677ae50a5099946470"
+
+[[package]]
+name = "ar_archive_writer"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "523e5e187fff36fcb8d1d19ccf0ca4ca43ec3d158316057f66dc6f72716bc5ec"
+dependencies = [
+ "object",
+]
+
+[[package]]
+name = "autocfg"
+version = "1.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2032f911046de80f0a198e0901378627c33f59ea0ac00e363d481118bd70a53"
+
+[[package]]
+name = "bitflags"
+version = "2.13.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3ded4057c258ba199e2d26386d3af3780957ecaee6c4ef4041c6b4b8b97c0b06"
+
+[[package]]
+name = "bumpalo"
+version = "3.20.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72f5acc6cb2ba439de613abc23857ec3d78374d8ed5ac84e9d11336e87da8649"
+
+[[package]]
+name = "cc"
+version = "1.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4ff2a8126fff0f8c839080d619675a585e61720bb12d2baceae45769fd66f155"
+dependencies = [
+ "find-msvc-tools",
+ "shlex",
+]
+
+[[package]]
+name = "cfg-if"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e7648175b45a9a48536d676f68d918270699102aa8dab5496df06904c914600"
+
+[[package]]
+name = "chrono"
+version = "0.4.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1aa79e62e7697b8e29b513a68abacf485adcd1fe8284a4316c5ae868e6633327"
+dependencies = [
+ "iana-time-zone",
+ "js-sys",
+ "num-traits",
+ "serde",
+ "wasm-bindgen",
+ "windows-link",
+]
+
+[[package]]
+name = "core-foundation-sys"
+version = "0.8.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "773648b94d0e5d620f64f280777445740e61fe701025087ec8b57f45c791888b"
+
+[[package]]
+name = "cultcache-rs"
+version = "0.3.1"
+dependencies = [
+ "anyhow",
+ "chrono",
+ "cultcache-rs-derive",
+ "fs2",
+ "pretty_assertions",
+ "redb",
+ "rmp-serde",
+ "serde",
+ "serde_bytes",
+ "serde_json",
+ "serde_stacker",
+ "stacker",
+ "tempfile",
+ "uuid",
+ "windows-sys 0.59.0",
+]
+
+[[package]]
+name = "cultcache-rs-derive"
+version = "0.2.0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.119",
+]
+
+[[package]]
+name = "diff"
+version = "0.1.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56254986775e3233ffa9c4d7d3faaf6d36a2c09d30b20687e9f88bc8bafc16c8"
+
+[[package]]
+name = "errno"
+version = "0.3.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e35d6e78f4cebb90e51d543db8fe41528851d6deeef6ef21ebd4bfdc1e784776"
+dependencies = [
+ "libc",
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "fastrand"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da7c62ceae207dd37ea5b845da6a0696c799f85e97da1ab5b7910be3c1c80223"
+
+[[package]]
+name = "find-msvc-tools"
+version = "0.1.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1c66915cc5391097de7a2b0b972e8505aa33c0df401fd3a6811dbdb32881ba48"
+
+[[package]]
+name = "fs2"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9564fc758e15025b46aa6643b1b77d047d1a56a1aea6e01002ac0c7026876213"
+dependencies = [
+ "libc",
+ "winapi",
+]
+
+[[package]]
+name = "futures-core"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "92d699e522242e69e3003b94ecc1f960f3a5e015aa7c5d7486e65ad01dd94f5e"
+
+[[package]]
+name = "futures-task"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cd417de3d1d015fc3bfd2b1ea46dfc7bab72ef86f1cc7cc9c78e728b34a6d1fd"
+
+[[package]]
+name = "futures-util"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d50a92467f8ba5dd6e3ee5d4bd04d73ab2e4e1c44474a0674821dfce14b79bc"
+dependencies = [
+ "futures-core",
+ "futures-task",
+ "pin-project-lite",
+ "slab",
+]
+
+[[package]]
+name = "getrandom"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "300e883d756b2e4ec94e02791f39b04b522276138852cfc41d9fb7e904106099"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "r-efi",
+]
+
+[[package]]
+name = "iana-time-zone"
+version = "0.1.65"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e31bc9ad994ba00e440a8aa5c9ef0ec67d5cb5e5cb0cc7f8b744a35b389cc470"
+dependencies = [
+ "android_system_properties",
+ "core-foundation-sys",
+ "iana-time-zone-haiku",
+ "js-sys",
+ "log",
+ "wasm-bindgen",
+ "windows-core",
+]
+
+[[package]]
+name = "iana-time-zone-haiku"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f31827a206f56af32e590ba56d5d2d085f558508192593743f16b2306495269f"
+dependencies = [
+ "cc",
+]
+
+[[package]]
+name = "itoa"
+version = "1.0.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3bd1574e617a9a6c1f8f8181bd7e841e1f20e4277607ef28945765188d6284d4"
+
+[[package]]
+name = "js-sys"
+version = "0.3.107"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8dc09d2154098bbf4ef54eab6b117a3c24cbbffe94046b16ee6d6d4510584d3a"
+dependencies = [
+ "cfg-if",
+ "futures-util",
+ "wasm-bindgen",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.191"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "65cd87c9a6d60536580b316ad985726104730a5151c99845f2490428ef91240a"
+
+[[package]]
+name = "linux-raw-sys"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32a66949e030da00e8c7d4434b251670a91556f4144941d37452769c25d58a53"
+
+[[package]]
+name = "log"
+version = "0.4.35"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5d15f86d12da44cd8d4ec3c73984537eb7f4cadcb9776a575a0a8a05ca11005c"
+
+[[package]]
+name = "memchr"
+version = "2.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98"
+
+[[package]]
+name = "num-traits"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "object"
+version = "0.39.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2e5a6c098c7a3b6547378093f5cc30bc54fd361ce711e05293a5cc589562739b"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "once_cell"
+version = "1.21.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
+
+[[package]]
+name = "pin-project-lite"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
+
+[[package]]
+name = "pretty_assertions"
+version = "1.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3ae130e2f271fbc2ac3a40fb1d07180839cdbbe443c7a27e1e3c13c5cac0116d"
+dependencies = [
+ "diff",
+ "yansi",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.107"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "985e7ec9bb745e6ce6535b544d84d6cd6f7ad8bd711c398938ae983b91a766d9"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "psm"
+version = "0.1.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4dcd034599e63b970727f70d79e02d62390a4a84f7c6b827c27c46d5ac3fa622"
+dependencies = [
+ "ar_archive_writer",
+ "cc",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.47"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fbf4db142a473a8d80c26bbf18454ed458bf8d26c8219c331daecfdbd079001"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "r-efi"
+version = "6.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8dcc9c7d52a811697d2151c701e0d08956f92b0e24136cf4cf27b57a6a0d9bf"
+
+[[package]]
+name = "redb"
+version = "4.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b317ef681e18f6091efbfab532eaf924a135c492d9d0299d0fbfae07e92a39b"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "rmp"
+version = "0.8.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4ba8be72d372b2c9b35542551678538b562e7cf86c3315773cae48dfbfe7790c"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "rmp-serde"
+version = "1.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72f81bee8c8ef9b577d1681a70ebbc962c232461e397b22c208c43c04b67a155"
+dependencies = [
+ "rmp",
+ "serde",
+]
+
+[[package]]
+name = "rustix"
+version = "1.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5e76742e5294153d4dde1207dbec5bdd81eef6fabdc0d2118babadabfd858aa"
+dependencies = [
+ "bitflags",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "rustversion"
+version = "1.0.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf54715a573b99ac80df0bc206da022bcd442c974952c7b9720069370852e21f"
+
+[[package]]
+name = "serde"
+version = "1.0.229"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4148590afebada386688f18773da617792bf2ef03ffc1e4cbd2b1d45b023e0ba"
+dependencies = [
+ "serde_core",
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_bytes"
+version = "0.11.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a5d440709e79d88e51ac01c4b72fc6cb7314017bb7da9eeff678aa94c10e3ea8"
+dependencies = [
+ "serde",
+ "serde_core",
+]
+
+[[package]]
+name = "serde_core"
+version = "1.0.229"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "67dca2c9c51e58a4791a4b1ed58308b39c64224d349a935ab5039aa360942a48"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.229"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7a5d71263a5a7d47b41f6b3f06ba276f10cc18b0931f1799f710578e2309348"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 3.0.10",
+]
+
+[[package]]
+name = "serde_json"
+version = "1.0.154"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7e9cc8b1b85264074fbcc02a88680c4096b1e47df8f739dceb03bf482f04bd6"
+dependencies = [
+ "itoa",
+ "memchr",
+ "serde",
+ "serde_core",
+ "zmij",
+]
+
+[[package]]
+name = "serde_stacker"
+version = "0.1.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d4936375d50c4be7eff22293a9344f8e46f323ed2b3c243e52f89138d9bb0f4a"
+dependencies = [
+ "serde",
+ "serde_core",
+ "stacker",
+]
+
+[[package]]
+name = "shlex"
+version = "2.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8fadd59c855ef2080decdef8ff161eb6661b86933c9d82e5ba29dc602a55aba"
+
+[[package]]
+name = "slab"
+version = "0.4.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c790de23124f9ab44544d7ac05d60440adc586479ce501c1d6d7da3cd8c9cf5"
+
+[[package]]
+name = "stacker"
+version = "0.1.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "707f49d46706bacf8a2b00d51dace3f9de527c13eec3778f570c411f89e69967"
+dependencies = [
+ "cc",
+ "cfg-if",
+ "libc",
+ "psm",
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.119"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "872831b642d1a07999a962a351ed35b955ea2cfc8f3862091e2a240a84f17297"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "syn"
+version = "3.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4ae9ccbea3a7b0b09443036490c8f34a8b1b760fd345e5c0dae0aac718faea79"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "tempfile"
+version = "3.27.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32497e9a4c7b38532efcdebeef879707aa9f794296a4f0244f6f69e9bc8574bd"
+dependencies = [
+ "fastrand",
+ "getrandom",
+ "once_cell",
+ "rustix",
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2c754d6c33795a1c324727428e5a7dedb5b06195f9890bdbcba760d3e246563"
+
+[[package]]
+name = "uuid"
+version = "1.29.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bed99139f7dac9b5cfe5f17be4d66dc7079a34dee1d74bcc77217119240e267c"
+dependencies = [
+ "getrandom",
+ "js-sys",
+ "wasm-bindgen",
+]
+
+[[package]]
+name = "wasm-bindgen"
+version = "0.2.130"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a0181c14ddd6c7b8b0b0132a5f1ea2f32be0d893cd3ea97b6e3b28886b8a3d1c"
+dependencies = [
+ "cfg-if",
+ "rustversion",
+ "wasm-bindgen-macro",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.130"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e931a02a39abdbf66966fc35902b5ed58344750a70885bed4ebb3d8eaf28ed9"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.130"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2ca4b54280e455bd831e33a6b8e734baf432fe63fbc35c42ac14ce67a043a53a"
+dependencies = [
+ "bumpalo",
+ "proc-macro2",
+ "quote",
+ "syn 3.0.10",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.130"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3b1f9c3798725016c6ee5f2f57869ec0831e8bbc0ab0310a86e787e97f41389e"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
+
+[[package]]
+name = "windows-core"
+version = "0.62.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8e83a14d34d0623b51dce9581199302a221863196a1dde71a7663a4c2be9deb"
+dependencies = [
+ "windows-implement",
+ "windows-interface",
+ "windows-link",
+ "windows-result",
+ "windows-strings",
+]
+
+[[package]]
+name = "windows-implement"
+version = "0.60.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "053e2e040ab57b9dc951b72c264860db7eb3b0200ba345b4e4c3b14f67855ddf"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.119",
+]
+
+[[package]]
+name = "windows-interface"
+version = "0.59.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f316c4a2570ba26bbec722032c4099d8c8bc095efccdc15688708623367e358"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.119",
+]
+
+[[package]]
+name = "windows-link"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"
+
+[[package]]
+name = "windows-result"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7781fa89eaf60850ac3d2da7af8e5242a5ea78d1a11c49bf2910bb5a73853eb5"
+dependencies = [
+ "windows-link",
+]
+
+[[package]]
+name = "windows-strings"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7837d08f69c77cf6b07689544538e017c1bfcf57e34b4c0ff58e6c2cd3b37091"
+dependencies = [
+ "windows-link",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.59.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
+dependencies = [
+ "windows-targets",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.61.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae137229bcbd6cdf0f7b80a31df61766145077ddf49416a728b02cb3921ff3fc"
+dependencies = [
+ "windows-link",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
+
+[[package]]
+name = "yansi"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cfe53a6657fd280eaa890a3bc59152892ffa3e30101319d168b781ed6529b049"
+
+[[package]]
+name = "zmij"
+version = "1.0.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "29666d0abbfad1e3dc4dcf6144730dd3a3ab225bbbdac83319345b1b44ccfc1b"

packages/cultcache-rs/Cargo.toml

@@ -31,4 +31,4 @@ pretty_assertions = "1.4"
 tempfile = "3"
 
 [target.'cfg(windows)'.dependencies]
-windows-sys = { version = "0.59", features = ["Win32_Foundation", "Win32_Storage_FileSystem"] }
+windows-sys = { version = "0.59", features = ["Win32_Foundation", "Win32_Storage_FileSystem", "Win32_Security", "Win32_System_WindowsProgramming"] }

packages/cultcache-rs/README.md

@@ -21,8 +21,14 @@ CultCache is a domain cache with persistence adapters.
 
 - `CultCache` is the query and mutation surface.
 - Domain structs implement `DatabaseEntry`.
-- Entries are stored behind a `type::key` identity, so multiple entry types
-  can share a logical key without colliding.
+- A cache holds one record per key whatever its type. Records are held per
+  `(type, key)`, but a write of a second type under a key the cache holds, or a
+  key a store carries foreign, is refused with `SchemaConflictError` naming the
+  key (no store needed); retyping a key is a delete, then an add. A store
+  record no registered type claims loads: the cache does not serve it, lists it
+  in `foreign_records()`, lays it back byte for byte through every write
+  including `put_prepared_batch`, and refuses a write or delete at its key.
+  Registering a type that claims its schema id picks it up at the next pull.
 - Each payload is encoded directly from the known `DatabaseEntry` type into
   MessagePack bytes.
 - Backing stores are adapters, not the public data model.
@@ -33,8 +39,8 @@ CultCache is a domain cache with persistence adapters.
   file access with a sidecar lock file.
 
 This is not an ORM, not a database, and not distributed consensus in a novelty
-hat. If multiple processes write the same backing file, use an external lock or
-a coordinator.
+hat. Several processes may write the same single-file store, one at a time under
+its sidecar lock; write ordering across keys or stores needs a coordinator.
 
 ## Current API
 
@@ -230,6 +236,17 @@ assert_eq!(rmp_serde::from_slice::<Node>(&bytes)?, tree);
 # Ok::<(), Box<dyn std::error::Error>>(())
 ```
 
+## Records written by a newer build
+
+A payload that carries a slot past the slots its type declares, in a record, a nested record, a list element or a union
+arm (a unit arm declares none), still decodes: the extra slots are skipped. The cache then holds that record read-only,
+because writing it would drop what the newer writer stored. `put`, `put_envelope`, `put_raw_envelope`,
+`put_prepared_batch` and `delete` of its key are refused with `SchemaConflictError`, whose `unread_slots` names the type
+and the slot counts and never a value; `CultCache::is_writable(type, key)` answers the same check. An untouched
+read-only record keeps its bytes through every other write. A short payload (missing trailing slots) is not marked, and
+a payload nested past `MAX_PAYLOAD_DEPTH` is refused before anything is read. `decode_payload_marked` is the decode that
+returns the `UnreadSlots` mark. This runtime has no compatible schema ids, so no mark is consented.
+
 ## Structure Of Arrays
 
 The C# CultCache hot path exposes CPU-local SoA scans as:
@@ -367,10 +384,10 @@ an empty store. Any other failure to reach it, such as a symlink loop, a file
 where a parent directory should be, or a missing permission, is an I/O error.
 A store file that exists and holds zero bytes is `Undecodable`: no CultCache
 writer leaves one. A symbolic link whose target is gone is not a missing store:
-reading it is an I/O error, so a read-then-write (`push`, `delete`, the exchanges)
-fails before writing. Writes do not yet follow links: a write through a live link,
-and a `push_all` through a dangling one, replace the link with a regular file and
-leave its target alone. A refusal names no
+reading it is an I/O error. A write at a store path that is a link, live or dangling, is
+refused with `StoreLinkedError` (`error.downcast_ref::<StoreLinkedError>()`) before the
+lock and the replace, so no write swaps a link for a regular file; configure the link's
+target as the store path. Reads through a live link work. A refusal names no
 value read from the file; it names a record only by its key and schema id, and
 a header only when it has the shape `cultcache.store.v<digits>`.
 
@@ -458,7 +475,7 @@ That is the Rust version of the original trick:
 
 - C# refuses to store objects outside the `DatabaseEntry` root type.
 - Runtime-visible `DatabaseEntry` subclasses get dedicated formatters.
-- Unknown or unregistered types are rejected.
+- A write of an unregistered type is rejected; a stored record of an unregistered type is carried as foreign, not decoded.
 - MessagePack payload bytes deserialize through known concrete formatters, not
   an open-world type loader or generic structured-value bridge.
 

packages/cultcache-rs/cultcache-rs-derive/src/lib.rs

@@ -381,6 +381,7 @@ fn slot_codec(ident: &syn::Ident, slots: &[CultCacheSlot]) -> proc_macro2::Token
                     where
                         __A: ::serde::de::SeqAccess<'de>,
                     {
+                        let __ticket = ::cultcache_rs::__enter_slots();
                         #(#option_declarations)*
                         let mut index = 0usize;
                         while index <= #max_slot {
@@ -390,7 +391,15 @@ fn slot_codec(ident: &syn::Ident, slots: &[CultCacheSlot]) -> proc_macro2::Token
                             }
                             index += 1;
                         }
-                        while let ::std::option::Option::Some(_) = seq.next_element::<::serde::de::IgnoredAny>()? {}
+                        // The slots past the declared ones are skipped and counted: the decode entry marks the record
+                        // that carried them read-only.
+                        let mut __extra = 0usize;
+                        while seq.next_element::<::serde::de::IgnoredAny>()?.is_some() {
+                            __extra += 1;
+                        }
+                        if __extra > 0 {
+                            ::cultcache_rs::__note_unread_slots(__ticket, stringify!(#ident), #max_slot + 1 + __extra, #max_slot + 1);
+                        }
                         Ok(#ident {
                             #(#build_fields),*
                         })
@@ -567,10 +576,13 @@ fn union_codec(input: DeriveInput) -> syn::Result<proc_macro2::TokenStream> {
             quote! {
                 #key => {
                     match seq
-                        .next_element::<::std::option::Option<[(); 0]>>()
+                        .next_element::<::std::option::Option<::cultcache_rs::__UnitArmSlots>>()
                         .map_err(|_| ::serde::de::Error::custom(#arity_message))?
                     {
-                        ::std::option::Option::Some(::std::option::Option::Some(_)) => #ident::#variant,
+                        ::std::option::Option::Some(::std::option::Option::Some(slots)) => {
+                            slots.note(stringify!(#variant));
+                            #ident::#variant
+                        }
                         ::std::option::Option::Some(::std::option::Option::None) => {
                             return ::std::result::Result::Err(::serde::de::Error::custom(
                                 format!(#nil_slots_message, #key),

packages/cultcache-rs/examples/cultcache_interop.rs

@@ -1,6 +1,8 @@
 use anyhow::Result;
 use anyhow::anyhow;
 use cultcache_rs::CultCache;
+use cultcache_rs::CultSlots;
+use cultcache_rs::CultUnion;
 use cultcache_rs::DatabaseEntry;
 use cultcache_rs::SingleFileMessagePackBackingStore;
 use serde_json::json;
@@ -39,6 +41,100 @@ struct CultCacheInteropDeck {
     marks: Vec<CultCacheInteropMark>,
 }
 
+// A union field and nested bytes: the shapes a Bifrost-style store holds beyond plain strings.
+#[derive(Clone, Debug, PartialEq, Eq, CultUnion)]
+enum InteropArm {
+    #[cultcache(key = 0)]
+    Text(InteropTextArm),
+    #[cultcache(key = 1)]
+    Pack(InteropPackArm),
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, CultSlots)]
+struct InteropTextArm {
+    #[cultcache(key = 0)]
+    text: String,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, CultSlots)]
+struct InteropPackArm {
+    #[cultcache(key = 0)]
+    label: String,
+    #[cultcache(key = 1)]
+    chunks: Vec<serde_bytes::ByteBuf>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, DatabaseEntry)]
+#[cultcache(type = "cultcache.interop-shape", schema = "CultCacheInteropShape")]
+struct CultCacheInteropShape {
+    #[cultcache(key = 0)]
+    document_id: String,
+    #[cultcache(key = 1)]
+    arm: InteropArm,
+    #[cultcache(key = 2)]
+    raw: serde_bytes::ByteBuf,
+}
+
+fn shapes() -> Vec<CultCacheInteropShape> {
+    vec![
+        CultCacheInteropShape {
+            document_id: "shape:text".into(),
+            arm: InteropArm::Text(InteropTextArm { text: "union arm 0".into() }),
+            raw: (0..=255u8).collect::<Vec<_>>().into(),
+        },
+        CultCacheInteropShape {
+            document_id: "shape:pack".into(),
+            arm: InteropArm::Pack(InteropPackArm {
+                label: "union arm 1".into(),
+                chunks: vec![vec![0xc0, 0xc1, 0x00].into(), vec![].into(), vec![0x92, 0x01, 0x02].into()],
+            }),
+            raw: vec![0xde, 0xad, 0xbe, 0xef].into(),
+        },
+    ]
+}
+
+fn write_shapes(file: &str) -> Result<()> {
+    let mut cache = CultCache::new();
+    cache.register_entry_type::<CultCacheInteropShape>()?;
+    cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(file))?;
+    cache.pull_all_backing_stores()?;
+    for shape in shapes() {
+        cache.put(&shape.document_id, &shape)?;
+    }
+    print_shapes(shapes())
+}
+
+/// Opens the store through the read-only snapshot door: no lock file, no staging file, no rewrite.
+fn read_shapes(file: &str) -> Result<()> {
+    let envelopes = SingleFileMessagePackBackingStore::new(file).pull_all_read_only_snapshot()?;
+    let mut found = Vec::new();
+    for envelope in envelopes.iter().filter(|envelope| envelope.r#type == CultCacheInteropShape::TYPE) {
+        found.push(cultcache_rs::decode_payload::<CultCacheInteropShape>(&envelope.payload)?);
+    }
+    print_shapes(found)
+}
+
+fn print_shapes(mut found: Vec<CultCacheInteropShape>) -> Result<()> {
+    let hex = |bytes: &[u8]| bytes.iter().map(|byte| format!("{byte:02X}")).collect::<String>();
+    found.sort_by(|a, b| a.document_id.cmp(&b.document_id));
+    let rows: Vec<_> = found
+        .iter()
+        .map(|shape| {
+            let arm = match &shape.arm {
+                InteropArm::Text(text) => json!({ "kind": "text", "text": text.text }),
+                InteropArm::Pack(pack) => json!({
+                    "kind": "pack",
+                    "label": pack.label,
+                    "chunks": pack.chunks.iter().map(|chunk| hex(chunk)).collect::<Vec<_>>(),
+                }),
+            };
+            json!({ "documentId": shape.document_id, "arm": arm, "raw": hex(&shape.raw) })
+        })
+        .collect();
+    println!("{}", serde_json::to_string(&rows)?);
+    Ok(())
+}
+
 fn read_deck(file: &str) -> Result<()> {
     let mut cache = CultCache::new();
     cache.register_entry_type::<CultCacheInteropDeck>()?;
@@ -70,6 +166,8 @@ fn main() -> Result<()> {
         "write" => write_note(file, require_arg(&options, "runtime-id")?)?,
         "read" => read_note(file)?,
         "read-deck" => read_deck(file)?,
+        "write-shapes" => write_shapes(file)?,
+        "read-shapes" => read_shapes(file)?,
         "hold-lock" => hold_lock(file, require_arg(&options, "ms")?.parse()?)?,
         _ => return Err(anyhow!("unknown mode {mode}")),
     }

packages/cultcache-rs/tests/common/mod.rs

@@ -0,0 +1,235 @@
+//! The union-parity vectors' types and constructed value, shared by the test files that walk them.
+#![allow(dead_code)]
+
+use std::path::PathBuf;
+
+use cultcache_rs::CultSlots;
+use cultcache_rs::CultUnion;
+use cultcache_rs::DatabaseEntry;
+
+
+#[derive(Clone, Debug, PartialEq, CultUnion)]
+pub enum Node {
+    #[cultcache(key = 0)]
+    Box(BoxArm),
+    #[cultcache(key = 1)]
+    Text(TextArm),
+    #[cultcache(key = 2)]
+    Use(UseArm),
+    #[cultcache(key = 5)]
+    Image(ImageArm),
+    #[cultcache(key = 6)]
+    Wrap(WrapArm),
+}
+
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct WrapArm {
+    #[cultcache(key = 0)]
+    pub inner: Option<std::boxed::Box<Node>>,
+    #[cultcache(key = 1)]
+    pub id: String,
+}
+
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct BoxArm {
+    #[cultcache(key = 0)]
+    pub id: String,
+    #[cultcache(key = 1)]
+    pub children: Vec<Node>,
+}
+
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct TextArm {
+    #[cultcache(key = 0)]
+    pub id: String,
+    #[cultcache(key = 1)]
+    pub content: String,
+}
+
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct UseArm {
+    #[cultcache(key = 0)]
+    pub id: String,
+    #[cultcache(key = 1)]
+    pub composition: Composition,
+    #[cultcache(key = 2)]
+    pub slots: Vec<Option<Node>>,
+}
+
+// Slot 2 is retired: a gap written nil.
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct ImageArm {
+    #[cultcache(key = 0)]
+    pub id: String,
+    #[cultcache(key = 1)]
+    pub uri: String,
+    #[cultcache(key = 3)]
+    pub alt: String,
+}
+
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct Composition {
+    #[cultcache(key = 0)]
+    pub name: String,
+    #[cultcache(key = 1)]
+    pub body: Option<std::boxed::Box<Node>>,
+}
+
+#[derive(Clone, Debug, PartialEq, CultUnion)]
+pub enum Outcome {
+    #[cultcache(key = 0)]
+    Pending(PendingArm),
+    #[cultcache(key = 1)]
+    Completed(CompletedArm),
+    #[cultcache(key = 2)]
+    Denied(IdArm),
+    #[cultcache(key = -2147483648)]
+    Floor(IdArm),
+    #[cultcache(key = 2147483647)]
+    Ceiling(IdArm),
+}
+
+// The codec's unit arm (no members, written [key, []]), kept apart from the golden: a document list's arms carry ids.
+#[derive(Clone, Debug, PartialEq, CultUnion)]
+pub enum UnitOutcome {
+    #[cultcache(key = 2)]
+    Denied,
+    #[cultcache(key = -2147483648)]
+    Floor,
+    #[cultcache(key = 2147483647)]
+    Ceiling,
+}
+
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct PendingArm {
+    #[cultcache(key = 0)]
+    pub message: String,
+    #[cultcache(key = 1)]
+    pub id: String,
+}
+
+// An arm with no members of its own: just its element id.
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct IdArm {
+    #[cultcache(key = 0)]
+    pub id: String,
+}
+
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct CompletedArm {
+    #[cultcache(key = 0)]
+    pub source_version: i32,
+    #[cultcache(key = 1)]
+    pub id: String,
+}
+
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct NamedArm {
+    #[cultcache(key = 0)]
+    pub name: String,
+}
+
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct UsesArm {
+    #[cultcache(key = 0)]
+    pub name: String,
+    #[cultcache(key = 1)]
+    pub uses: i32,
+}
+
+#[derive(Clone, Debug, PartialEq, CultSlots)]
+pub struct CountArm {
+    #[cultcache(key = 0)]
+    pub name: String,
+    #[cultcache(key = 1)]
+    pub count: i32,
+}
+
+#[derive(Clone, Debug, PartialEq, CultUnion)]
+pub enum Item {
+    #[cultcache(key = 0)]
+    Gem(NamedArm),
+    #[cultcache(key = 1)]
+    Tool(UsesArm),
+    #[cultcache(key = 2)]
+    Part(CountArm),
+}
+
+// The same arms as Item under its own keys: key 2 is unknown to it.
+#[derive(Clone, Debug, PartialEq, CultUnion)]
+pub enum CraftedItem {
+    #[cultcache(key = 0)]
+    Tool(UsesArm),
+    #[cultcache(key = 1)]
+    Part(CountArm),
+}
+
+#[derive(Clone, Debug, PartialEq, DatabaseEntry)]
+#[cultcache(type = "tests.union_surface", schema = "tests.union_surface.v1")]
+pub struct UnionSurface {
+    #[cultcache(key = 0)]
+    pub id: String,
+    #[cultcache(key = 1)]
+    pub version: i32,
+    #[cultcache(key = 2)]
+    pub root: Option<Node>,
+    #[cultcache(key = 3)]
+    pub outcomes: Vec<Outcome>,
+    #[cultcache(key = 4)]
+    pub part: Option<Item>,
+    #[cultcache(key = 5)]
+    pub crafted: Option<CraftedItem>,
+    #[cultcache(key = 6)]
+    pub missing: Option<Node>,
+}
+
+pub fn text(id: &str, content: &str) -> Node {
+    Node::Text(TextArm { id: id.into(), content: content.into() })
+}
+
+pub fn image(id: &str, uri: &str, alt: &str) -> Node {
+    Node::Image(ImageArm { id: id.into(), uri: uri.into(), alt: alt.into() })
+}
+
+pub fn boxed(id: &str, children: Vec<Node>) -> Node {
+    Node::Box(BoxArm { id: id.into(), children })
+}
+
+pub fn constructed() -> UnionSurface {
+    let inner = boxed("0000000000d0", vec![text("0000000000d1", "x"), image("0000000000d2", "uri://a", "alt")]);
+    UnionSurface {
+        id: "surface".into(),
+        version: 3,
+        root: Some(boxed(
+            "0000000000c0",
+            vec![
+                text("0000000000c1", "hello"),
+                Node::Use(UseArm {
+                    id: "0000000000c2".into(),
+                    composition: Composition { name: "comp".into(), body: Some(std::boxed::Box::new(inner)) },
+                    slots: vec![Some(text("0000000000e1", "slot")), None, Some(boxed("0000000000e2", vec![]))],
+                }),
+                image("0000000000c3", "uri://b", ""),
+            ],
+        )),
+        outcomes: vec![
+            Outcome::Pending(PendingArm { message: "wait".into(), id: "0000000000a1".into() }),
+            Outcome::Completed(CompletedArm { source_version: 7, id: "0000000000a2".into() }),
+            Outcome::Denied(id_arm("0000000000a3")),
+        ],
+        part: Some(Item::Tool(UsesArm { name: "hammer".into(), uses: 12 })),
+        crafted: Some(CraftedItem::Part(CountArm { name: "gear".into(), count: 4 })),
+        missing: None,
+    }
+}
+
+pub fn id_arm(id: &str) -> IdArm {
+    IdArm { id: id.into() }
+}
+
+pub fn vector(name: &str) -> Vec<u8> {
+    let path = PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+        .join("../../tests/vectors/union-parity")
+        .join(name);
+    std::fs::read(&path).unwrap_or_else(|error| panic!("{}: {error}", path.display()))
+}

packages/cultcache-rs/tests/key_identity_vector.rs

@@ -0,0 +1,283 @@
+//! `tests/vectors/key-identity`, written only by the C# reference: a cache holds one record per key whatever its type, and a
+//! store holding a record no registered type claims loads, lists it as foreign and keeps its bytes
+//! (`variants:ruling:cache-refuses-retype`, `write-ownership-by-written-type`, `unheld-removal-refused-at-commit`).
+//! Every row is walked against this cache: each put row twice, once as `put` and once as a one-entry `put_prepared_batch`.
+
+use std::path::{Path, PathBuf};
+
+use cultcache_rs::{
+    CacheBackingStore, CultCache, DatabaseEntry, SchemaConflictError, SingleFileMessagePackBackingStore,
+};
+use serde_json::Value;
+
+// The ids C# writes in the store catalogs and on every record (the vector's README).
+#[derive(Clone, Debug, PartialEq, Eq, DatabaseEntry)]
+#[cultcache(type = "sha256:b20703a98f49c253898404ab50ba2c630720f0b8a5e1a41614d5650be22799fe", schema = "tests.ki_alpha")]
+struct Alpha {
+    #[cultcache(key = 0)]
+    text: String,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, DatabaseEntry)]
+#[cultcache(type = "sha256:dee4b727cf2ee04e61ab635ff0c5f3dca7345a411dc5f1018e583ab16009cf94", schema = "tests.ki_beta")]
+struct Beta {
+    #[cultcache(key = 0)]
+    text: String,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, DatabaseEntry)]
+#[cultcache(type = "sha256:fbc26e351e00c9e7185e8de171c7486aba707c229c949f0aae6b889288af5f6d", schema = "tests.ki_gamma")]
+struct Gamma {
+    #[cultcache(key = 0)]
+    text: String,
+}
+
+fn vectors() -> PathBuf {
+    PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("../../tests/vectors/key-identity")
+}
+
+/// `[refusal key or nil, held [type, key, text], file [key, schema name] or nil, foreign keys, kept foreign keys]`.
+type Expect = (Option<Vec<String>>, Vec<(String, String, String)>, Option<Vec<(String, String)>>, Vec<String>, Vec<String>);
+type Row = (String, Vec<String>, Vec<Vec<Value>>, Expect);
+
+fn text(value: &Value) -> &str {
+    value.as_str().unwrap()
+}
+
+fn register(cache: &mut CultCache, names: &[String]) {
+    for name in names {
+        match name.as_str() {
+            "alpha" => drop(cache.register_entry_type::<Alpha>().unwrap()),
+            "beta" => drop(cache.register_entry_type::<Beta>().unwrap()),
+            "gamma" => drop(cache.register_entry_type::<Gamma>().unwrap()),
+            other => panic!("unknown type {other}"),
+        }
+    }
+}
+
+fn short(entry_type: &str) -> &'static str {
+    match entry_type {
+        t if t == Alpha::TYPE => "alpha",
+        t if t == Beta::TYPE => "beta",
+        t if t == Gamma::TYPE => "gamma",
+        other => panic!("unknown entry type {other}"),
+    }
+}
+
+fn put(cache: &mut CultCache, as_batch: bool, kind: &str, key: &str, body: &str) -> anyhow::Result<()> {
+    macro_rules! write {
+        ($t:ident) => {{
+            let value = $t { text: body.to_string() };
+            if as_batch {
+                let (entry, _) = cache.prepare_entry(key, &value)?;
+                cache.put_prepared_batch(vec![entry])
+            } else {
+                cache.put(key, &value).map(drop)
+            }
+        }};
+    }
+    match kind {
+        "alpha" => write!(Alpha),
+        "beta" => write!(Beta),
+        "gamma" => write!(Gamma),
+        other => panic!("unknown type {other}"),
+    }
+}
+
+fn delete(cache: &mut CultCache, kind: &str, key: &str) -> anyhow::Result<bool> {
+    match kind {
+        "alpha" => cache.delete::<Alpha>(key),
+        "beta" => cache.delete::<Beta>(key),
+        "gamma" => cache.delete::<Gamma>(key),
+        other => panic!("unknown type {other}"),
+    }
+}
+
+fn open_cache(registered: &[String], path: Option<&Path>) -> anyhow::Result<CultCache> {
+    let mut cache = CultCache::new();
+    register(&mut cache, registered);
+    if let Some(path) = path {
+        cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(path))?;
+        cache.pull_all_backing_stores()?;
+    }
+    Ok(cache)
+}
+
+/// The records a store file holds, read by a fresh store: (key, schema name, schema id, stored-at, payload).
+fn file_records(path: &Path) -> Vec<(String, String, Option<String>, String, Vec<u8>)> {
+    let mut records: Vec<_> = SingleFileMessagePackBackingStore::new(path)
+        .pull_all()
+        .unwrap()
+        .into_iter()
+        .map(|entry| (entry.key, entry.r#type, entry.schema_id, entry.stored_at, entry.payload))
+        .collect();
+    records.sort_by(|left, right| left.0.encode_utf16().cmp(right.0.encode_utf16()));
+    records
+}
+
+fn walk(row: &Row, as_batch: bool) -> Result<(), String> {
+    let (label, registered, ops, expect) = row;
+    let dir = tempfile::tempdir().unwrap();
+    let mut path: Option<PathBuf> = None;
+    let mut before = Vec::new();
+    let mut cache: Option<CultCache> = None;
+    let mut refused: Option<anyhow::Error> = None;
+    let mut refused_key: Option<String> = None;
+    let mut shared_key: Option<String> = None;
+    let mut wrote = false;
+    for (index, op) in ops.iter().enumerate() {
+        let last = index == ops.len() - 1;
+        let result: anyhow::Result<()> = match text(&op[0]) {
+            "open" => {
+                drop(cache.take());
+                match &op[1] {
+                    Value::String(file) if file == "memory" => open_cache(registered, None).map(|opened| cache = Some(opened)),
+                    file => {
+                        let fresh = dir.path().join("store.cc");
+                        if let Value::String(file) = file {
+                            std::fs::copy(vectors().join(file), &fresh).unwrap();
+                        }
+                        before = if fresh.exists() { file_records(&fresh) } else { Vec::new() };
+                        let opened = open_cache(registered, Some(&fresh));
+                        path = Some(fresh);
+                        opened.map(|opened| cache = Some(opened))
+                    }
+                }
+            }
+            "reopen" => {
+                drop(cache.take());
+                open_cache(registered, path.as_deref()).map(|opened| cache = Some(opened))
+            }
+            "attach" => {
+                let file = text(&op[1]);
+                let attached = dir.path().join(file);
+                std::fs::copy(vectors().join(file), &attached).unwrap();
+                let held: Vec<String> = cache.as_ref().unwrap().snapshot().into_iter().map(|entry| entry.key).collect();
+                let shared: Vec<String> = file_records(&attached).into_iter().map(|record| record.0).filter(|key| held.contains(key)).collect();
+                let home: Vec<String> = op[2].as_array().unwrap().iter().map(|name| short_to_type(text(name)).to_string()).collect();
+                let cache = cache.as_mut().unwrap();
+                let attach = cache
+                    .add_backing_store(SingleFileMessagePackBackingStore::new(&attached), home)
+                    .and_then(|()| cache.pull_all_backing_stores());
+                if attach.is_err() && last && shared.len() == 1 {
+                    refused_key = Some(shared[0].clone());
+                    shared_key = refused_key.clone();
+                    assert_eq!(std::fs::read(&attached).unwrap(), std::fs::read(vectors().join(file)).unwrap(), "{label}: a refused attach leaves the store as it was");
+                }
+                attach
+            }
+            "put" => {
+                wrote = true;
+                put(cache.as_mut().unwrap(), as_batch, text(&op[1]), text(&op[2]), text(&op[3]))
+            }
+            "delete" => delete(cache.as_mut().unwrap(), text(&op[1]), text(&op[2])).map(drop),
+            other => panic!("{label}: unknown op {other}"),
+        };
+        match result {
+            Ok(()) => {}
+            Err(error) if last => refused = Some(error),
+            Err(error) => return Err(format!("{label}: op {index} failed: {error:#}")),
+        }
+    }
+    if !wrote && as_batch {
+        return Ok(()); // not a write row: the batch variant is the same walk
+    }
+    let Some(cache) = cache.as_ref() else {
+        return Err(format!("{label} (batch {as_batch}): the cache did not open: {:#}", refused.unwrap()));
+    };
+    let last = ops.last().unwrap();
+    if let Some(error) = &refused {
+        if let Some(conflict) = error.downcast_ref::<SchemaConflictError>() {
+            refused_key = Some(conflict.record_key.clone());
+            let named = if text(&last[0]) == "attach" { shared_key.clone().unwrap() } else { text(&last[2]).to_string() };
+            assert_eq!(named, conflict.record_key, "{label}: the refusal names the key written, removed or shared");
+        }
+        let key = refused_key.clone().unwrap_or_default();
+        let message = format!("{error:#}");
+        let (all, delimited) = occurrences(&message, &key);
+        assert!(!key.is_empty() && delimited > 0, "{label}: the refusal names the key as a token: {message}");
+        if text(&last[0]) == "attach" {
+            assert_eq!(all, delimited, "{label}: the key occurs in the refusal only as a delimited token: {message}");
+        }
+    }
+    let mut held: Vec<(String, String, String)> = cache
+        .snapshot()
+        .into_iter()
+        .map(|entry| {
+            let body = match short(&entry.r#type) {
+                "alpha" => cache.get::<Alpha>(&entry.key).unwrap().unwrap().text,
+                "beta" => cache.get::<Beta>(&entry.key).unwrap().unwrap().text,
+                _ => cache.get::<Gamma>(&entry.key).unwrap().unwrap().text,
+            };
+            (short(&entry.r#type).to_string(), entry.key, body)
+        })
+        .collect();
+    held.sort_by(|a, b| (a.0.as_str(), a.1.encode_utf16().collect::<Vec<_>>()).cmp(&(b.0.as_str(), b.1.encode_utf16().collect::<Vec<_>>())));
+    let foreign: Vec<String> = cache.foreign_records().into_iter().map(|record| record.key).collect();
+    let (file, kept) = match &path {
+        None => (None, Vec::new()),
+        Some(path) => {
+            let after = file_records(path);
+            let kept = foreign
+                .iter()
+                .filter(|key| {
+                    let original = before.iter().find(|record| &record.0 == *key);
+                    let now = after.iter().find(|record| &record.0 == *key);
+                    original.is_some() && original.map(|r| (&r.2, &r.3, &r.4)) == now.map(|r| (&r.2, &r.3, &r.4))
+                })
+                .cloned()
+                .collect();
+            // This writer names a catalog entry by the record's type, which for these types is the id; C# names it by the
+            // schema name. Which type the record at a key is, is the verdict, so the id reads as its schema name.
+            let name = |described: String| match described.as_str() {
+                t if t == Alpha::TYPE => Alpha::SCHEMA_NAME.to_string(),
+                t if t == Beta::TYPE => Beta::SCHEMA_NAME.to_string(),
+                t if t == Gamma::TYPE => Gamma::SCHEMA_NAME.to_string(),
+                _ => described,
+            };
+            (Some(after.into_iter().map(|record| (record.0, name(record.1))).collect::<Vec<_>>()), kept)
+        }
+    };
+    let observed: Expect = (refused_key.map(|key| vec![key]), held, file, foreign, kept);
+    if &observed == expect { Ok(()) } else { Err(format!("{label} (batch {as_batch}): committed {expect:?} but this cache answers {observed:?}")) }
+}
+
+/// How often `key` occurs in `message`, and how often as a delimited token (not a piece of a longer word, schema name or id).
+fn occurrences(message: &str, key: &str) -> (usize, usize) {
+    let word = |c: Option<char>| c.is_some_and(|c| c.is_ascii_alphanumeric() || c == '_');
+    let found: Vec<usize> = message.match_indices(key).map(|(at, _)| at).collect();
+    let delimited = found
+        .iter()
+        .filter(|at| !word(message[..**at].chars().next_back()) && !word(message[**at + key.len()..].chars().next()))
+        .count();
+    (found.len(), delimited)
+}
+
+fn short_to_type(name: &str) -> &'static str {
+    match name {
+        "alpha" => Alpha::TYPE,
+        "beta" => Beta::TYPE,
+        "gamma" => Gamma::TYPE,
+        other => panic!("unknown type {other}"),
+    }
+}
+
+#[test]
+fn key_identity_rows_hold_their_verdicts() {
+    let bytes = std::fs::read(vectors().join("rows.msgpack")).unwrap();
+    let rows: Vec<Row> = rmp_serde::from_slice(&bytes).unwrap();
+    let mut walked = 0;
+    let mut failed = Vec::new();
+    for row in &rows {
+        let mut ok = true;
+        for as_batch in [false, true] {
+            if let Err(message) = walk(row, as_batch) {
+                failed.push(message);
+                ok = false;
+            }
+        }
+        walked += usize::from(ok);
+    }
+    assert!(failed.is_empty(), "{}", failed.join("\n"));
+    assert_eq!(walked, 12, "rows walked");
+}

packages/cultcache-rs/tests/slot_readonly.rs

@@ -0,0 +1,541 @@
+//! A record whose payload carries unread slots at any depth is read-only: the C# reference's union-parity vectors
+//! (README "Extra trailing slot" and "Slot stores") walked through the cache. This runtime has no compatible schema
+//! ids, so every mark is unconsented and no `explained` outcome can arise.
+
+mod common;
+
+use std::path::Path;
+
+use common::*;
+use cultcache_rs::CultCache;
+use cultcache_rs::CultCacheEnvelope;
+use cultcache_rs::DatabaseEntry;
+use cultcache_rs::SchemaConflictError;
+use cultcache_rs::SingleFileMessagePackBackingStore;
+use cultcache_rs::UnreadSlots;
+use cultcache_rs::decode_payload_marked;
+
+/// A row of `slot-outcomes.msgpack`: store, key, writable, explained, type, slots, declared, occurrences, flattenRefusedBy.
+type SlotRow = (String, String, bool, Option<bool>, Option<String>, Option<usize>, Option<usize>, Option<usize>, Option<String>);
+
+const SLOT_VALUE: &str = "extra-slot";
+
+/// `tests.slot_unit`, a document `[Name, Outcome: UnitOutcome]`.
+#[derive(Clone, Debug, PartialEq, DatabaseEntry)]
+#[cultcache(type = "tests.slot_unit", schema = "tests.slot_unit.v1")]
+struct SlotUnit {
+    #[cultcache(key = 0)]
+    name: String,
+    #[cultcache(key = 1)]
+    outcome: UnitOutcome,
+}
+
+/// Two declared slots, the second defaulted: a payload of one slot is short, not marked.
+#[derive(Clone, Debug, PartialEq, DatabaseEntry)]
+#[cultcache(type = "tests.shortened", schema = "tests.shortened.v1")]
+struct Shortened {
+    #[cultcache(key = 0)]
+    id: String,
+    #[cultcache(key = 1, default)]
+    note: String,
+}
+
+fn registered() -> CultCache {
+    let mut cache = CultCache::new();
+    cache.register_entry_type::<UnionSurface>().unwrap();
+    cache.register_entry_type::<SlotUnit>().unwrap();
+    cache
+}
+
+/// Any MessagePack value a store holds, enough to drop one record from a store and write the rest back.
+#[derive(serde::Serialize, serde::Deserialize)]
+#[serde(untagged)]
+enum Packed {
+    Nil(()),
+    Bool(bool),
+    Int(i64),
+    Text(String),
+    Bin(#[serde(with = "serde_bytes")] Vec<u8>),
+    Array(Vec<Packed>),
+}
+
+/// The committed store without its `marked-variant` record. A variant is a five-slot record, which this runtime's
+/// store reader refuses whole (`the_variant_row_...`), so the other rows are walked from a copy without it.
+fn without_variant_row(store: &[u8]) -> Vec<u8> {
+    let Packed::Array(mut parts) = rmp_serde::from_slice(store).unwrap() else { panic!("a store is an array") };
+    let Packed::Array(records) = parts.last_mut().unwrap() else { panic!("a store ends in its records") };
+    let before = records.len();
+    records.retain(|record| !matches!(record, Packed::Array(fields) if matches!(fields.first(), Some(Packed::Text(key)) if key == "marked-variant")));
+    assert_eq!(records.len(), before - 1);
+    rmp_serde::to_vec(&parts).unwrap()
+}
+
+/// A copy of a committed store, opened with both types registered; the vector itself is never written. The slot store
+/// is read without its variant row.
+fn open_copy(file: &str, dir: &Path) -> (CultCache, std::path::PathBuf) {
+    let path = dir.join(file);
+    let bytes = if file == "extra-slot-store.cc" { without_variant_row(&vector(file)) } else { vector(file) };
+    std::fs::write(&path, bytes).unwrap();
+    let mut cache = registered();
+    cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+    cache.pull_all_backing_stores().unwrap();
+    (cache, path)
+}
+
+fn envelope(key: &str, payload: Vec<u8>) -> CultCacheEnvelope {
+    CultCacheEnvelope {
+        key: key.into(),
+        r#type: UnionSurface::TYPE.into(),
+        payload,
+        stored_at: "2026-01-01T00:00:00Z".into(),
+        schema_id: None,
+    }
+}
+
+fn conflict(error: &anyhow::Error) -> &SchemaConflictError {
+    error.downcast_ref::<SchemaConflictError>().unwrap_or_else(|| panic!("not a schema conflict: {error:#}"))
+}
+
+fn mark(type_name: &str, slot_count: usize, declared_count: usize, occurrences: usize) -> UnreadSlots {
+    UnreadSlots { type_name: type_name.into(), slot_count, declared_count, occurrences }
+}
+
+/// The marks the README table pins, by `detail`. The reference names an arm by its class; here an arm is the
+/// `...Arm` struct the union wraps.
+fn expected_mark(detail: &str) -> UnreadSlots {
+    match detail {
+        "record" | "depth" => mark("UnionSurface", 8, 7, 1),
+        "nested-record" => mark("Composition", 3, 2, 1),
+        "arm" => mark("BoxArm", 3, 2, 1),
+        "list-element" => mark("TextArm", 3, 2, 1),
+        other => panic!("unknown detail {other}"),
+    }
+}
+
+fn assert_refused_with(error: &anyhow::Error, key: &str, expected: &UnreadSlots) {
+    let refusal = conflict(error);
+    assert_eq!(refusal.unread_slots.as_ref(), Some(expected));
+    assert_eq!(refusal.record_key, key);
+    assert_eq!(refusal.schema_names.len(), 1);
+    let message = error.to_string();
+    assert!(message.contains(&expected.type_name), "{message}");
+    assert!(message.contains(&expected.slot_count.to_string()) && message.contains(&expected.declared_count.to_string()), "{message}");
+    assert!(!message.contains(SLOT_VALUE), "a refusal echoed the slot value: {message}");
+}
+
+#[test]
+fn every_read_only_vector_decodes_marked_and_is_not_writable() {
+    let rows: Vec<(String, String, String, Option<i64>, String)> = rmp_serde::from_slice(&vector("outcomes.msgpack")).unwrap();
+    assert_eq!(rows.len(), 9);
+    let bounds: Vec<serde_json::Value> = rmp_serde::from_slice(&vector("bounds-outcomes.msgpack")).unwrap();
+    let mut cases: Vec<(String, String)> = rows
+        .into_iter()
+        .filter(|(_, outcome, ..)| outcome == "read-only")
+        .map(|(file, _, _, _, detail)| (file, detail))
+        .collect();
+    for entry in &bounds[1..] {
+        let fields: Vec<&str> = entry.as_array().unwrap().iter().filter_map(|field| field.as_str()).collect();
+        if fields[1] == "read-only" {
+            cases.push((fields[0].to_string(), fields[3].to_string()));
+        }
+    }
+    assert_eq!(cases.len(), 5);
+    for (file, detail) in cases {
+        let payload = vector(&file);
+        let (value, found) = decode_payload_marked::<UnionSurface>(&payload).unwrap_or_else(|error| panic!("{file}: {error:#}"));
+        assert_eq!(value, constructed(), "{file}");
+        assert_eq!(found, Some(expected_mark(&detail)), "{file}");
+
+        let mut cache = registered();
+        let dir = tempfile::tempdir().unwrap();
+        cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(dir.path().join("s.cc"))).unwrap();
+        cache.pull_all_backing_stores().unwrap();
+        cache.put_raw_envelope(envelope("k", payload.clone())).unwrap();
+        assert_eq!(cache.get::<UnionSurface>("k").unwrap(), Some(constructed()), "{file}");
+        assert!(!cache.is_writable(UnionSurface::TYPE, "k").unwrap(), "{file}");
+        assert!(cache.is_writable(UnionSurface::TYPE, "unheld").unwrap(), "{file}");
+        let error = cache.put("k", &constructed()).unwrap_err();
+        assert_refused_with(&error, "k", &expected_mark(&detail));
+    }
+}
+
+#[test]
+fn clean_and_short_payloads_are_writable_and_unmarked() {
+    let (value, found) = decode_payload_marked::<UnionSurface>(&vector("union-surface.msgpack")).unwrap();
+    assert_eq!((value, found), (constructed(), None));
+    // A payload short of its declared slots keeps its defaults and does not mark.
+    let (value, found) = decode_payload_marked::<Shortened>(&rmp_serde::to_vec(&("only",)).unwrap()).unwrap();
+    assert_eq!((value.id.as_str(), value.note.as_str(), found), ("only", "", None));
+}
+
+#[test]
+fn a_payload_past_the_nesting_limit_is_refused_never_marked() {
+    for file in ["depth-skipped-past-limit.msgpack", "depth-past-limit.msgpack"] {
+        let error = decode_payload_marked::<UnionSurface>(&vector(file)).unwrap_err();
+        assert!(error.to_string().contains("the limit is 256"), "{file}: {error:#}");
+    }
+}
+
+#[test]
+fn a_plain_serde_decode_marks_nothing_and_does_not_leak_a_scope() {
+    // No scope is open: the visitors note into nothing.
+    let value: UnionSurface = rmp_serde::from_slice(&vector("extra-slot-record.msgpack")).unwrap();
+    assert_eq!(value, constructed());
+    // A marked decode followed by a clean one: the first mark does not survive into the second.
+    assert!(decode_payload_marked::<UnionSurface>(&vector("extra-slot-record.msgpack")).unwrap().1.is_some());
+    assert_eq!(decode_payload_marked::<UnionSurface>(&vector("union-surface.msgpack")).unwrap().1, None);
+}
+
+#[test]
+fn the_slot_store_rows_walk_through_the_cache() {
+    let rows: Vec<SlotRow> =
+        rmp_serde::from_slice(&vector("slot-outcomes.msgpack")).unwrap();
+    assert_eq!(rows.len(), 8);
+    let dir = tempfile::tempdir().unwrap();
+    let mut walked = 0;
+    for (store, key, writable, _explained, type_name, slots, declared, occurrences, flatten_refused_by) in rows {
+        // The variant row is a record this runtime cannot hold: see the variant test. The consent store's `writable` and
+        // `explained` answer the compatible-id declaration, which this runtime has none of; its marks are walked below.
+        if flatten_refused_by.is_some() || store == "extra-slot-consent.cc" {
+            continue;
+        }
+        let case = dir.path().join(&key);
+        std::fs::create_dir_all(&case).unwrap();
+        let (mut cache, _) = open_copy(&store, &case);
+        let type_id = if key == "unit-arm" { SlotUnit::TYPE } else { UnionSurface::TYPE };
+        assert_eq!(cache.is_writable(type_id, &key).unwrap(), writable, "{store} {key}");
+        let removal = if key == "unit-arm" { cache.delete::<SlotUnit>(&key) } else { cache.delete::<UnionSurface>(&key) };
+        match writable {
+            true => assert!(removal.unwrap()),
+            false => {
+                let found = conflict(&removal.unwrap_err()).unread_slots.clone().unwrap();
+                // The reference names the unit arm's class, Denied2; here the variant.
+                let expected_type = match type_name.as_deref().unwrap() {
+                    "Denied2" => "Denied",
+                    other => other,
+                };
+                assert_eq!((found.type_name.as_str(), Some(found.slot_count), Some(found.declared_count), Some(found.occurrences)), (expected_type, slots, declared, occurrences));
+                assert!(cache.snapshot_envelopes().iter().any(|held| held.key == key), "a refused removal removed {key}");
+            }
+        }
+        walked += 1;
+    }
+    assert_eq!(walked, 3);
+}
+
+#[test]
+fn the_consent_store_marks_are_unconsented_here() {
+    let rows: Vec<SlotRow> =
+        rmp_serde::from_slice(&vector("slot-outcomes.msgpack")).unwrap();
+    let dir = tempfile::tempdir().unwrap();
+    let mut found = 0;
+    for (store, key, _writable, _explained, _type_name, slots, declared, occurrences, _) in rows {
+        if store != "extra-slot-consent.cc" {
+            continue;
+        }
+        let (cache, _) = open_copy(&store, dir.path());
+        let held = cache.snapshot_envelopes().into_iter().find(|held| held.key == key).unwrap();
+        let (_, mark) = decode_payload_marked::<UnionSurface>(&held.payload).unwrap();
+        match slots {
+            // The reference's `consented` row is writable there (a listed compatible id covers it); here every mark refuses.
+            None => assert_eq!(mark, None, "{key}"),
+            Some(slots) => {
+                let mark = mark.unwrap_or_else(|| panic!("{key} carried no mark"));
+                // The first type read is the document, whose reference name is SurfaceDeclaring.
+                assert_eq!(mark.type_name, "UnionSurface", "{key}");
+                assert_eq!((Some(mark.slot_count), Some(mark.declared_count), Some(mark.occurrences)), (Some(slots), declared, occurrences), "{key}");
+                assert!(!cache.is_writable(UnionSurface::TYPE, &key).unwrap(), "{key}");
+            }
+        }
+        found += 1;
+    }
+    assert_eq!(found, 4);
+}
+
+#[test]
+fn every_write_entry_refuses_a_marked_key_before_any_store_is_touched() {
+    let dir = tempfile::tempdir().unwrap();
+    let (mut cache, path) = open_copy("extra-slot-store.cc", dir.path());
+    let expected = mark("Composition", 3, 2, 1);
+    let before = std::fs::read(&path).unwrap();
+    let held = cache.snapshot_envelopes().into_iter().find(|held| held.key == "marked").unwrap();
+    let clean = cache.snapshot_envelopes().into_iter().find(|held| held.key == "clean").unwrap();
+    assert!(!cache.is_writable(UnionSurface::TYPE, "marked").unwrap());
+    assert!(cache.is_writable(UnionSurface::TYPE, "clean").unwrap());
+
+    let replacing = envelope("marked", rmp_serde::to_vec(&constructed()).unwrap());
+    assert_refused_with(&cache.put("marked", &constructed()).unwrap_err(), "marked", &expected);
+    assert_refused_with(&cache.put_envelope::<UnionSurface>(replacing.clone()).unwrap_err(), "marked", &expected);
+    assert_refused_with(&cache.put_raw_envelope(replacing.clone()).unwrap_err(), "marked", &expected);
+    assert_refused_with(&cache.put_prepared_batch(vec![replacing]).unwrap_err(), "marked", &expected);
+    assert_refused_with(&cache.delete::<UnionSurface>("marked").unwrap_err(), "marked", &expected);
+    assert_refused_with(
+        &cache.update::<UnionSurface, _>("marked", |current| current.unwrap()).unwrap_err(),
+        "marked",
+        &expected,
+    );
+
+    // A batch with a marked key refuses whole: its clean member is not written either.
+    let mut rewritten = clean.clone();
+    rewritten.payload = rmp_serde::to_vec(&UnionSurface { version: 9, ..constructed() }).unwrap();
+    let batch = vec![rewritten, envelope("marked", rmp_serde::to_vec(&constructed()).unwrap())];
+    assert_refused_with(&cache.put_prepared_batch(batch).unwrap_err(), "marked", &expected);
+
+    assert_eq!(std::fs::read(&path).unwrap(), before, "a refused write touched the store");
+    assert_eq!(cache.snapshot_envelopes().into_iter().find(|entry| entry.key == "marked").unwrap(), held);
+    assert_eq!(cache.snapshot_envelopes().into_iter().find(|entry| entry.key == "clean").unwrap(), clean);
+
+    // A write to another key succeeds, and the marked record's bytes, schema id and stored-at are carried unchanged.
+    cache.put("clean", &UnionSurface { version: 9, ..constructed() }).unwrap();
+    cache.put("other", &constructed()).unwrap();
+    assert!(cache.delete::<UnionSurface>("other").unwrap());
+    let mut reopened = registered();
+    reopened.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+    reopened.pull_all_backing_stores().unwrap();
+    let carried = reopened.snapshot_envelopes().into_iter().find(|entry| entry.key == "marked").unwrap();
+    assert_eq!(carried, held);
+    assert_eq!(carried.payload, vector("extra-slot-nested-record.msgpack"));
+    assert_eq!(reopened.get::<UnionSurface>("clean").unwrap().unwrap().version, 9);
+}
+
+#[test]
+fn a_unit_arm_with_slots_decodes_as_the_unit_arm_and_marks() {
+    let (document, found) = decode_payload_marked::<SlotUnit>(&unit_arm_payload()).unwrap();
+    assert_eq!(document, SlotUnit { name: "unit-arm".into(), outcome: UnitOutcome::Denied });
+    assert_eq!(found, Some(mark("Denied", 1, 0, 1)));
+
+    let dir = tempfile::tempdir().unwrap();
+    let (mut cache, _) = open_copy("extra-slot-store.cc", dir.path());
+    assert_eq!(cache.get::<SlotUnit>("unit-arm").unwrap(), Some(document.clone()));
+    assert!(!cache.is_writable(SlotUnit::TYPE, "unit-arm").unwrap());
+    let error = cache.put("unit-arm", &document).unwrap_err();
+    assert_refused_with(&error, "unit-arm", &mark("Denied", 1, 0, 1));
+    assert_refused_with(&cache.delete::<SlotUnit>("unit-arm").unwrap_err(), "unit-arm", &mark("Denied", 1, 0, 1));
+
+    // Several elements are still one marked object, and a clean unit arm is unmarked.
+    let (_, found) = decode_payload_marked::<UnitOutcome>(&rmp_serde::to_vec(&(2u64, ("a", "b", "c"))).unwrap()).unwrap();
+    assert_eq!(found, Some(mark("Denied", 3, 0, 1)));
+    let (_, found) = decode_payload_marked::<UnitOutcome>(&vector("unit-arm-denied.msgpack")).unwrap();
+    assert_eq!(found, None);
+}
+
+fn unit_arm_payload() -> Vec<u8> {
+    let dir = tempfile::tempdir().unwrap();
+    let (cache, _) = open_copy("extra-slot-store.cc", dir.path());
+    cache.snapshot_envelopes().into_iter().find(|held| held.key == "unit-arm").unwrap().payload
+}
+
+#[test]
+fn the_variant_row_of_the_slot_store_is_refused_whole_by_the_store_reader() {
+    // `marked-variant` is a five-slot record (a variant): this runtime holds no variants, and its v1 snapshot reader
+    // refuses such a record, so the store as written cannot load here and the other rows are walked without it.
+    let dir = tempfile::tempdir().unwrap();
+    let path = dir.path().join("extra-slot-store.cc");
+    std::fs::write(&path, vector("extra-slot-store.cc")).unwrap();
+    let mut cache = registered();
+    cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+    let error = cache.pull_all_backing_stores().unwrap_err();
+    assert!(format!("{error:#}").contains("is not decodable"), "{error:#}");
+}
+
+fn slot_unit_envelope(key: &str, payload: Vec<u8>) -> CultCacheEnvelope {
+    CultCacheEnvelope { r#type: SlotUnit::TYPE.into(), ..envelope(key, payload) }
+}
+
+#[test]
+fn a_held_payload_the_type_cannot_read_is_read_only_and_refused_by_name() {
+    let mut cache = registered();
+    // A newer writer's record: an arm this build lacks and an extra root slot. get cannot read it, and it is the data
+    // read-only exists to protect.
+    let newer = rmp_serde::to_vec(&("CANARY-name", (99u64, ("x",)), "CANARY-extra")).unwrap();
+    cache.put_raw_envelope(slot_unit_envelope("n", newer)).unwrap();
+    assert!(cache.get::<SlotUnit>("n").is_err());
+    assert!(!cache.is_writable(SlotUnit::TYPE, "n").unwrap());
+    let replacement = SlotUnit { name: "n".into(), outcome: UnitOutcome::Denied };
+    let held = cache.snapshot_envelopes();
+    for error in [
+        cache.put("n", &replacement).unwrap_err(),
+        cache.put_raw_envelope(slot_unit_envelope("n", rmp_serde::to_vec(&replacement).unwrap())).unwrap_err(),
+        cache.delete::<SlotUnit>("n").unwrap_err(),
+    ] {
+        let message = format!("{error:#}");
+        assert!(message.contains("\"n\"") && message.contains("tests.slot_unit") && message.contains("read-only"), "{message}");
+        assert!(!message.contains("CANARY"), "{message}");
+    }
+    assert_eq!(cache.snapshot_envelopes(), held);
+}
+
+#[test]
+fn a_corrupt_held_payload_is_refused_naming_the_key_never_its_bytes() {
+    let mut cache = registered();
+    cache.put_raw_envelope(envelope("broken", rmp_serde::to_vec(&("CANARY-id", "CANARY-version")).unwrap())).unwrap();
+    assert!(!cache.is_writable(UnionSurface::TYPE, "broken").unwrap());
+    let error = cache.delete::<UnionSurface>("broken").unwrap_err();
+    let message = format!("{error:#}");
+    assert!(message.contains("\"broken\"") && message.contains("backup") && message.contains("store"), "{message}");
+    assert!(!message.contains("build that wrote it"), "{message}");
+    assert!(!message.contains("CANARY"), "{message}");
+    assert!(cache.is_writable("tests.unregistered", "broken").is_err());
+}
+
+fn held_marked_and_clean() -> (CultCache, tempfile::TempDir, std::path::PathBuf) {
+    let dir = tempfile::tempdir().unwrap();
+    let (cache, path) = open_copy("extra-slot-store.cc", dir.path());
+    (cache, dir, path)
+}
+
+#[test]
+fn load_soa_does_not_replace_or_drop_a_marked_record() {
+    use cultcache_rs::CultCacheSoaTable;
+    let (mut cache, _dir, path) = held_marked_and_clean();
+    let all = cache.snapshot_envelopes();
+    let held = all.iter().find(|held| held.key == "marked").unwrap().clone();
+    let without: Vec<_> = all.iter().filter(|held| held.key != "marked").cloned().collect();
+    let mut replaced = all.clone();
+    replaced.iter_mut().find(|held| held.key == "marked").unwrap().payload = rmp_serde::to_vec(&constructed()).unwrap();
+    for table in [without, replaced] {
+        let error = cache.load_soa(CultCacheSoaTable::from_envelopes(table)).unwrap_err();
+        assert_refused_with(&error, "marked", &mark("Composition", 3, 2, 1));
+        assert_eq!(cache.snapshot_envelopes(), all, "a refused load changed the image");
+    }
+    // The same record carried unchanged, with another key added, loads.
+    let mut kept = all.clone();
+    kept.push(envelope("added", rmp_serde::to_vec(&constructed()).unwrap()));
+    cache.load_soa(CultCacheSoaTable::from_envelopes(kept)).unwrap();
+    assert_eq!(cache.snapshot_envelopes().iter().find(|held| held.key == "marked"), Some(&held));
+    // A clean record may be dropped by a load.
+    let no_clean: Vec<_> = cache.snapshot_envelopes().into_iter().filter(|held| held.key != "clean").collect();
+    cache.load_soa(CultCacheSoaTable::from_envelopes(no_clean)).unwrap();
+    // The marked record is still on disk after the next batch.
+    let rewrite = envelope("added", rmp_serde::to_vec(&UnionSurface { version: 5, ..constructed() }).unwrap());
+    cache.put_prepared_batch(vec![rewrite]).unwrap();
+    let mut reopened = registered();
+    reopened.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+    reopened.pull_all_backing_stores().unwrap();
+    assert_eq!(reopened.snapshot_envelopes().iter().find(|held| held.key == "marked"), Some(&held));
+}
+
+#[test]
+fn is_writable_agrees_with_the_writes_for_foreign_keys_and_other_types() {
+    let dir = tempfile::tempdir().unwrap();
+    // Only UnionSurface registered: the store's unit-arm record is foreign here.
+    let path = dir.path().join("extra-slot-store.cc");
+    std::fs::write(&path, without_variant_row(&vector("extra-slot-store.cc"))).unwrap();
+    let mut cache = CultCache::new();
+    cache.register_entry_type::<UnionSurface>().unwrap();
+    cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+    cache.pull_all_backing_stores().unwrap();
+    assert!(cache.put("unit-arm", &constructed()).is_err());
+    assert!(!cache.is_writable(UnionSurface::TYPE, "unit-arm").unwrap());
+    assert!(cache.is_writable(UnionSurface::TYPE, "unheld").unwrap());
+
+    // Another registered type at a key a record of this one holds.
+    let (mut cache, _dir, _) = held_marked_and_clean();
+    let other = SlotUnit { name: "clean".into(), outcome: UnitOutcome::Denied };
+    assert!(cache.put("clean", &other).is_err());
+    assert!(!cache.is_writable(SlotUnit::TYPE, "clean").unwrap());
+    assert!(!cache.is_writable(SlotUnit::TYPE, "marked").unwrap());
+    assert!(cache.is_writable(UnionSurface::TYPE, "clean").unwrap());
+}
+
+#[test]
+fn a_marked_key_refuses_a_batch_wherever_it_sits() {
+    let (mut cache, _dir, path) = held_marked_and_clean();
+    let before = std::fs::read(&path).unwrap();
+    let marked = envelope("marked", rmp_serde::to_vec(&constructed()).unwrap());
+    let clean = |key: &str| envelope(key, rmp_serde::to_vec(&constructed()).unwrap());
+    for batch in [
+        vec![marked.clone(), clean("a"), clean("b")],
+        vec![clean("a"), marked.clone(), clean("b")],
+        vec![clean("a"), clean("b"), marked.clone()],
+    ] {
+        let error = cache.put_prepared_batch(batch).unwrap_err();
+        assert_refused_with(&error, "marked", &mark("Composition", 3, 2, 1));
+        assert_eq!(std::fs::read(&path).unwrap(), before);
+        assert!(cache.snapshot_envelopes().iter().all(|held| held.key != "a" && held.key != "b"));
+    }
+}
+
+#[test]
+fn a_marked_decode_leaves_no_scope_open() {
+    assert_eq!(cultcache_rs::__enter_slots(), 0);
+    decode_payload_marked::<UnionSurface>(&vector("extra-slot-record.msgpack")).unwrap();
+    assert_eq!(cultcache_rs::__enter_slots(), 0, "a marked decode left its scope open on this thread");
+    let _ = decode_payload_marked::<UnionSurface>(&vector("depth-skipped-past-limit.msgpack"));
+    assert_eq!(cultcache_rs::__enter_slots(), 0);
+}
+
+#[test]
+fn is_writable_is_false_for_a_type_with_no_home_store() {
+    let dir = tempfile::tempdir().unwrap();
+    let mut cache = registered();
+    // One store, routed to SlotUnit only: UnionSurface has no home.
+    cache.add_backing_store(SingleFileMessagePackBackingStore::new(dir.path().join("s.cc")), [SlotUnit::TYPE]).unwrap();
+    cache.pull_all_backing_stores().unwrap();
+    assert!(cache.put("k", &constructed()).is_err());
+    assert!(!cache.is_writable(UnionSurface::TYPE, "k").unwrap());
+    assert!(cache.is_writable(SlotUnit::TYPE, "k").unwrap());
+}
+
+#[test]
+fn load_soa_refuses_a_same_length_replacement_of_a_marked_record() {
+    use cultcache_rs::CultCacheSoaTable;
+    let (mut cache, _dir, _) = held_marked_and_clean();
+    let all = cache.snapshot_envelopes();
+    let marked = all.iter().find(|held| held.key == "marked").unwrap();
+    // One value (a bin16) of the marked record's length: same length, different bytes. A value followed by padding
+    // would be refused at admission as bytes after the value, before the read-only check is reached.
+    let length = marked.payload.len();
+    let mut same_length = vec![0u8; length];
+    same_length[..3].copy_from_slice(&[0xc5, ((length - 3) >> 8) as u8, (length - 3) as u8]);
+    assert_eq!(same_length.len(), marked.payload.len());
+    let mut replaced = all.clone();
+    replaced.iter_mut().find(|held| held.key == "marked").unwrap().payload = same_length;
+    let error = cache.load_soa(CultCacheSoaTable::from_envelopes(replaced)).unwrap_err();
+    assert_refused_with(&error, "marked", &mark("Composition", 3, 2, 1));
+    assert_eq!(cache.snapshot_envelopes(), all);
+}
+
+// The payload check runs before the mark scope opens: a tail on a slot-bearing payload is refused by count, never marked.
+#[test]
+fn a_tail_on_a_slot_payload_is_refused_before_any_mark() {
+    let mut tailed = vector("extra-slot-record.msgpack");
+    tailed.push(0xc0);
+    let error = decode_payload_marked::<UnionSurface>(&tailed).unwrap_err();
+    assert!(format!("{error:#}").contains("payload has 1 bytes after its first MessagePack value"), "{error:#}");
+    // Nothing leaked: the next marked decode finds exactly its own mark.
+    let found = decode_payload_marked::<UnionSurface>(&vector("extra-slot-record.msgpack")).unwrap().1.unwrap();
+    assert_eq!(found.occurrences, 1);
+}
+
+// A store holding marked records and one with a tail is refused at load; the cache then refuses every write with the load
+// refusal (not a per-key mark conflict), and the store file is untouched.
+#[test]
+fn a_store_with_marked_records_and_a_tail_is_refused_and_its_cache_writes_nothing() {
+    use cultcache_rs::CacheBackingStore;
+    use cultcache_rs::CultCacheLoadRefused;
+    let (mut held, _dir, path) = held_marked_and_clean();
+    let mut tailed = vector("union-surface.msgpack");
+    tailed.push(0xc0);
+    SingleFileMessagePackBackingStore::new(&path).push(&envelope("tailed", tailed)).unwrap();
+    let before = std::fs::read(&path).unwrap();
+    // The cache that held the store re-reads it and is refused.
+    assert!(format!("{:#}", held.pull_all_backing_stores().unwrap_err()).contains("bytes after"));
+    let fresh_value = constructed();
+    let mut fresh = registered();
+    fresh.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+    assert!(fresh.pull_all_backing_stores().is_err());
+    for cache in [&mut held, &mut fresh] {
+        let staged = cache.prepare_entry("new", &fresh_value).unwrap().0;
+        let errors = [
+            cache.put("new", &fresh_value).unwrap_err(),
+            cache.put_prepared_batch(vec![staged.clone()]).unwrap_err(),
+            cache.put_raw_envelope(staged).unwrap_err(),
+            cache.delete::<UnionSurface>("new").unwrap_err(),
+        ];
+        for error in errors {
+            assert!(error.downcast_ref::<CultCacheLoadRefused>().is_some(), "{error:#}");
+        }
+    }
+    assert_eq!(std::fs::read(&path).unwrap(), before);
+}

packages/cultcache-rs/tests/union_parity.rs

@@ -1,244 +1,21 @@
 //! The Rust runtime held to tests/vectors/union-parity, written by the C# reference.
 //! Bytes and outcomes are read from the committed files; only the constructed value is spelled here.
 
-use std::path::PathBuf;
-
 use cultcache_rs::CultCache;
 use cultcache_rs::CacheBackingStore;
 use cultcache_rs::CultCacheEnvelope;
+use cultcache_rs::CultCacheLoadRefused;
+use cultcache_rs::CultCacheSoaTable;
 use cultcache_rs::MAX_PAYLOAD_DEPTH;
 use cultcache_rs::PayloadTooDeep;
 use cultcache_rs::check_payload_depth;
-use cultcache_rs::CultSlots;
-use cultcache_rs::CultUnion;
+use cultcache_rs::decode_payload;
+use cultcache_rs::RedbMessagePackBackingStore;
 use cultcache_rs::DatabaseEntry;
 use cultcache_rs::SingleFileMessagePackBackingStore;
 
-#[derive(Clone, Debug, PartialEq, CultUnion)]
-enum Node {
-    #[cultcache(key = 0)]
-    Box(BoxArm),
-    #[cultcache(key = 1)]
-    Text(TextArm),
-    #[cultcache(key = 2)]
-    Use(UseArm),
-    #[cultcache(key = 5)]
-    Image(ImageArm),
-    #[cultcache(key = 6)]
-    Wrap(WrapArm),
-}
-
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct WrapArm {
-    #[cultcache(key = 0)]
-    inner: Option<std::boxed::Box<Node>>,
-    #[cultcache(key = 1)]
-    id: String,
-}
-
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct BoxArm {
-    #[cultcache(key = 0)]
-    id: String,
-    #[cultcache(key = 1)]
-    children: Vec<Node>,
-}
-
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct TextArm {
-    #[cultcache(key = 0)]
-    id: String,
-    #[cultcache(key = 1)]
-    content: String,
-}
-
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct UseArm {
-    #[cultcache(key = 0)]
-    id: String,
-    #[cultcache(key = 1)]
-    composition: Composition,
-    #[cultcache(key = 2)]
-    slots: Vec<Option<Node>>,
-}
-
-// Slot 2 is retired: a gap written nil.
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct ImageArm {
-    #[cultcache(key = 0)]
-    id: String,
-    #[cultcache(key = 1)]
-    uri: String,
-    #[cultcache(key = 3)]
-    alt: String,
-}
-
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct Composition {
-    #[cultcache(key = 0)]
-    name: String,
-    #[cultcache(key = 1)]
-    body: Option<std::boxed::Box<Node>>,
-}
-
-#[derive(Clone, Debug, PartialEq, CultUnion)]
-enum Outcome {
-    #[cultcache(key = 0)]
-    Pending(PendingArm),
-    #[cultcache(key = 1)]
-    Completed(CompletedArm),
-    #[cultcache(key = 2)]
-    Denied(IdArm),
-    #[cultcache(key = -2147483648)]
-    Floor(IdArm),
-    #[cultcache(key = 2147483647)]
-    Ceiling(IdArm),
-}
-
-// The codec's unit arm (no members, written [key, []]), kept apart from the golden: a document list's arms carry ids.
-#[derive(Clone, Debug, PartialEq, CultUnion)]
-enum UnitOutcome {
-    #[cultcache(key = 2)]
-    Denied,
-    #[cultcache(key = -2147483648)]
-    Floor,
-    #[cultcache(key = 2147483647)]
-    Ceiling,
-}
-
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct PendingArm {
-    #[cultcache(key = 0)]
-    message: String,
-    #[cultcache(key = 1)]
-    id: String,
-}
-
-// An arm with no members of its own: just its element id.
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct IdArm {
-    #[cultcache(key = 0)]
-    id: String,
-}
-
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct CompletedArm {
-    #[cultcache(key = 0)]
-    source_version: i32,
-    #[cultcache(key = 1)]
-    id: String,
-}
-
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct NamedArm {
-    #[cultcache(key = 0)]
-    name: String,
-}
-
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct UsesArm {
-    #[cultcache(key = 0)]
-    name: String,
-    #[cultcache(key = 1)]
-    uses: i32,
-}
-
-#[derive(Clone, Debug, PartialEq, CultSlots)]
-struct CountArm {
-    #[cultcache(key = 0)]
-    name: String,
-    #[cultcache(key = 1)]
-    count: i32,
-}
-
-#[derive(Clone, Debug, PartialEq, CultUnion)]
-enum Item {
-    #[cultcache(key = 0)]
-    Gem(NamedArm),
-    #[cultcache(key = 1)]
-    Tool(UsesArm),
-    #[cultcache(key = 2)]
-    Part(CountArm),
-}
-
-// The same arms as Item under its own keys: key 2 is unknown to it.
-#[derive(Clone, Debug, PartialEq, CultUnion)]
-enum CraftedItem {
-    #[cultcache(key = 0)]
-    Tool(UsesArm),
-    #[cultcache(key = 1)]
-    Part(CountArm),
-}
-
-#[derive(Clone, Debug, PartialEq, DatabaseEntry)]
-#[cultcache(type = "tests.union_surface", schema = "tests.union_surface.v1")]
-struct UnionSurface {
-    #[cultcache(key = 0)]
-    id: String,
-    #[cultcache(key = 1)]
-    version: i32,
-    #[cultcache(key = 2)]
-    root: Option<Node>,
-    #[cultcache(key = 3)]
-    outcomes: Vec<Outcome>,
-    #[cultcache(key = 4)]
-    part: Option<Item>,
-    #[cultcache(key = 5)]
-    crafted: Option<CraftedItem>,
-    #[cultcache(key = 6)]
-    missing: Option<Node>,
-}
-
-fn text(id: &str, content: &str) -> Node {
-    Node::Text(TextArm { id: id.into(), content: content.into() })
-}
-
-fn image(id: &str, uri: &str, alt: &str) -> Node {
-    Node::Image(ImageArm { id: id.into(), uri: uri.into(), alt: alt.into() })
-}
-
-fn boxed(id: &str, children: Vec<Node>) -> Node {
-    Node::Box(BoxArm { id: id.into(), children })
-}
-
-fn constructed() -> UnionSurface {
-    let inner = boxed("0000000000d0", vec![text("0000000000d1", "x"), image("0000000000d2", "uri://a", "alt")]);
-    UnionSurface {
-        id: "surface".into(),
-        version: 3,
-        root: Some(boxed(
-            "0000000000c0",
-            vec![
-                text("0000000000c1", "hello"),
-                Node::Use(UseArm {
-                    id: "0000000000c2".into(),
-                    composition: Composition { name: "comp".into(), body: Some(std::boxed::Box::new(inner)) },
-                    slots: vec![Some(text("0000000000e1", "slot")), None, Some(boxed("0000000000e2", vec![]))],
-                }),
-                image("0000000000c3", "uri://b", ""),
-            ],
-        )),
-        outcomes: vec![
-            Outcome::Pending(PendingArm { message: "wait".into(), id: "0000000000a1".into() }),
-            Outcome::Completed(CompletedArm { source_version: 7, id: "0000000000a2".into() }),
-            Outcome::Denied(id_arm("0000000000a3")),
-        ],
-        part: Some(Item::Tool(UsesArm { name: "hammer".into(), uses: 12 })),
-        crafted: Some(CraftedItem::Part(CountArm { name: "gear".into(), count: 4 })),
-        missing: None,
-    }
-}
-
-fn id_arm(id: &str) -> IdArm {
-    IdArm { id: id.into() }
-}
-
-fn vector(name: &str) -> Vec<u8> {
-    let path = PathBuf::from(env!("CARGO_MANIFEST_DIR"))
-        .join("../../tests/vectors/union-parity")
-        .join(name);
-    std::fs::read(&path).unwrap_or_else(|error| panic!("{}: {error}", path.display()))
-}
+mod common;
+use common::*;
 
 fn decode(bytes: &[u8]) -> Result<UnionSurface, String> {
     rmp_serde::from_slice(bytes).map_err(|error| error.to_string())
@@ -325,11 +102,10 @@ fn an_unknown_arm_lists_the_declared_keys_and_never_echoes_the_payload() {
 
 #[test]
 fn a_union_that_is_not_a_key_and_slots_pair_is_refused_naming_the_enum() {
-    let cases: [(&str, Vec<u8>); 4] = [
+    let cases: [(&str, Vec<u8>); 3] = [
         ("an empty array", vec![0x90]),
         ("a trailing element", rmp_serde::to_vec(&(1u64, (7u8,), 0u8)).unwrap()),
         ("a string key", rmp_serde::to_vec(&("CANARY-key", (7u8,))).unwrap()),
-        ("a unit arm with slots", rmp_serde::to_vec(&(2u64, ("CANARY-slot",))).unwrap()),
     ];
     for (label, bytes) in cases {
         let message = rmp_serde::from_slice::<UnitOutcome>(&bytes).unwrap_err().to_string();
@@ -692,7 +468,7 @@ fn envelope(key: &str, payload: &[u8]) -> CultCacheEnvelope {
 }
 
 // A payload past the bound cannot be admitted through the cache, so a store file written behind its
-// back stands in for one a peer or an older runtime left.
+// back stands in for one a peer or an older runtime left; load or read refuses it.
 fn through_cache(payload: &[u8]) -> Result<UnionSurface, String> {
     let temp = tempfile::tempdir().unwrap();
     let path = temp.path().join("foreign.cc");
@@ -700,7 +476,10 @@ fn through_cache(payload: &[u8]) -> Result<UnionSurface, String> {
     let mut cache = CultCache::new();
     cache.register_entry_type::<UnionSurface>().unwrap();
     cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
-    cache.pull_all_backing_stores().unwrap();
+    // The payload check runs at load, so a payload past the bound is refused there, before any read.
+    if let Err(error) = cache.pull_all_backing_stores() {
+        return Err(format!("{error:#}"));
+    }
     match cache.get::<UnionSurface>("k") {
         Ok(value) => Ok(value.expect("the envelope was stored")),
         Err(error) => Err(format!("{error:#}")),
@@ -757,6 +536,174 @@ fn bounds_vectors() {
     assert_eq!((accepted, refused, read_only), (4, 7, 1));
 }
 
+// A payload is one MessagePack value (bytes-after-outcomes.msgpack): every door refuses a tail by
+// its count, names the clause, never the depth limit (the tail is not walked) and never a value.
+#[test]
+fn bytes_after_vectors() {
+    let rows: Vec<serde_json::Value> = rmp_serde::from_slice(&vector("bytes-after-outcomes.msgpack")).unwrap();
+    assert_eq!(rows.len(), 4);
+    let surface = vector("union-surface.msgpack");
+    for row in &rows {
+        let fields = row.as_array().unwrap();
+        let (file, outcome, union, detail) = (fields[0].as_str().unwrap(), fields[1].as_str().unwrap(), fields[2].as_str().unwrap(), fields[4].as_str().unwrap());
+        assert_eq!((outcome, union, detail), ("refused", "UnionSurface", "bytes-after"), "{file}");
+        let bytes = vector(file);
+        assert_eq!(&bytes[..surface.len()], &surface[..], "{file}");
+        let clause = format!("payload has {} bytes after its first MessagePack value", bytes.len() - surface.len());
+        let check = |door: &str, message: &str| {
+            assert!(message.contains(&clause), "{file} {door}: {message}");
+            assert!(!message.contains("the limit is"), "{file} {door} walked the tail: {message}");
+            assert!(!message.contains("CANARY-bytes-after-7d1e"), "{file} {door} echoed the tail: {message}");
+            assert!(!message.contains(CANARY), "{file} {door} echoed a value: {message}");
+        };
+        let error = decode_payload::<UnionSurface>(&bytes).unwrap_err();
+        assert!(error.downcast_ref::<PayloadTooDeep>().is_none(), "{file}");
+        check("decode_payload", &format!("{error:#}"));
+        // A store written behind the cache's back is refused at load, naming the type, the key and the count.
+        let temp = tempfile::tempdir().unwrap();
+        let path = temp.path().join("foreign.cc");
+        SingleFileMessagePackBackingStore::new(&path).push(&envelope("k", &bytes)).unwrap();
+        let mut single = CultCache::new();
+        single.register_entry_type::<UnionSurface>().unwrap();
+        single.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+        let message = format!("{:#}", single.pull_all_backing_stores().unwrap_err());
+        check("single-file load", &message);
+        assert!(message.contains("\"k\"") && message.contains(UnionSurface::TYPE), "{file}: {message}");
+        let redb_path = temp.path().join("foreign.redb");
+        RedbMessagePackBackingStore::new(&redb_path).unwrap().push(&envelope("k", &bytes)).unwrap();
+        let mut redb = CultCache::new();
+        redb.register_entry_type::<UnionSurface>().unwrap();
+        redb.add_generic_backing_store(RedbMessagePackBackingStore::new(&redb_path).unwrap()).unwrap();
+        let message = format!("{:#}", redb.pull_all_backing_stores().unwrap_err());
+        check("redb load", &message);
+        assert!(message.contains("\"k\"") && message.contains(UnionSurface::TYPE), "{file}: {message}");
+        let mut soa = CultCache::new();
+        soa.register_entry_type::<UnionSurface>().unwrap();
+        let message = format!("{:#}", soa.load_soa(CultCacheSoaTable::from_envelopes(vec![envelope("k", &bytes)])).unwrap_err());
+        check("load_soa", &message);
+        assert!(message.contains("\"k\"") && message.contains(UnionSurface::TYPE), "{file}: {message}");
+        assert!(soa.snapshot().is_empty(), "{file}");
+        // Raw admission refuses and stages nothing.
+        let mut raw = CultCache::new();
+        raw.register_entry_type::<UnionSurface>().unwrap();
+        let message = format!("{:#}", raw.put_raw_envelope(envelope("k", &bytes)).unwrap_err());
+        check("put_raw_envelope", &message);
+        assert!(raw.snapshot().is_empty(), "{file}");
+    }
+}
+
+// Depth is found inside the first value, so a tail never hides it: a payload nested past the bound
+// with a tail after it is the depth refusal, not bytes after.
+#[test]
+fn depth_beats_a_tail() {
+    let mut deep = vec![0x91u8; MAX_PAYLOAD_DEPTH + 1];
+    deep.push(0xc0);
+    deep.push(0xc0);
+    let error = decode_payload::<UnionSurface>(&deep).unwrap_err();
+    assert_eq!(error.downcast_ref::<PayloadTooDeep>(), Some(&TOO_DEEP), "{error:#}");
+}
+
+// Depth is refused where the payload is loaded: a store holding one nested past the bound is not read.
+#[test]
+fn depth_is_refused_at_load() {
+    let mut deep = vec![0x91u8; MAX_PAYLOAD_DEPTH + 1];
+    deep.push(0xc0);
+    let temp = tempfile::tempdir().unwrap();
+    let path = temp.path().join("deep.cc");
+    SingleFileMessagePackBackingStore::new(&path).push(&envelope("k", &deep)).unwrap();
+    let mut cache = CultCache::new();
+    cache.register_entry_type::<UnionSurface>().unwrap();
+    cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+    let error = cache.pull_all_backing_stores().unwrap_err();
+    assert_eq!(error.downcast_ref::<PayloadTooDeep>(), Some(&TOO_DEEP), "{error:#}");
+    assert!(cache.snapshot().is_empty());
+}
+
+// load_soa is a load too: a table holding a payload nested past the bound is refused with the typed depth refusal, the
+// prior view is kept, and a tail behind the depth is still the depth refusal.
+#[test]
+fn load_soa_refuses_a_payload_nested_past_the_bound() {
+    let mut deep = vec![0x91u8; MAX_PAYLOAD_DEPTH + 1];
+    deep.push(0xc0);
+    let mut cache = CultCache::new();
+    cache.register_entry_type::<UnionSurface>().unwrap();
+    cache.load_soa(CultCacheSoaTable::from_envelopes(vec![envelope("kept", &vector("union-surface.msgpack"))])).unwrap();
+    let before = cache.snapshot();
+    for payload in [deep.clone(), [deep.clone(), vec![0xc0]].concat()] {
+        let error = cache.load_soa(CultCacheSoaTable::from_envelopes(vec![envelope("k", &payload)])).unwrap_err();
+        assert_eq!(error.downcast_ref::<PayloadTooDeep>(), Some(&TOO_DEEP), "{error:#}");
+        assert_eq!(cache.snapshot(), before, "a refused load keeps the prior view");
+    }
+}
+
+// A cache whose load was refused refuses every write and removal and leaves the store as it was: a
+// later write would otherwise persist the empty image over the records it never read.
+#[test]
+fn a_refused_load_refuses_every_write() {
+    let tail = {
+        let mut bytes = vector("union-surface.msgpack");
+        bytes.push(0xc0);
+        bytes
+    };
+    let good = envelope("good", &vector("union-surface.msgpack"));
+    let bad = envelope("bad", &tail);
+    for redb in [false, true] {
+        let temp = tempfile::tempdir().unwrap();
+        let path = temp.path().join(if redb { "seed.redb" } else { "seed.cc" });
+        let mut cache = CultCache::new();
+        cache.register_entry_type::<UnionSurface>().unwrap();
+        if redb {
+            let mut store = RedbMessagePackBackingStore::new(&path).unwrap();
+            store.push(&good).unwrap();
+            store.push(&bad).unwrap();
+            drop(store);
+            cache.add_generic_backing_store(RedbMessagePackBackingStore::new(&path).unwrap()).unwrap();
+        } else {
+            let mut store = SingleFileMessagePackBackingStore::new(&path);
+            store.push(&good).unwrap();
+            store.push(&bad).unwrap();
+            cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+        }
+        let load = cache.pull_all_backing_stores().unwrap_err();
+        assert!(format!("{load:#}").contains("bytes after"), "{load:#}");
+        let before = std::fs::read(&path).unwrap();
+        let value = constructed();
+        let staged = cache.prepare_entry("new", &value).unwrap().0;
+        let results: Vec<(&str, anyhow::Error)> = vec![
+            ("put", cache.put("new", &value).unwrap_err()),
+            ("put_prepared_batch", cache.put_prepared_batch(vec![staged.clone()]).unwrap_err()),
+            ("put_envelope", cache.put_envelope::<UnionSurface>(staged.clone()).unwrap_err()),
+            ("put_raw_envelope", cache.put_raw_envelope(staged.clone()).unwrap_err()),
+            ("update", cache.update::<UnionSurface, _>("good", |current| current.unwrap_or_else(constructed)).unwrap_err()),
+            ("delete", cache.delete::<UnionSurface>("good").unwrap_err()),
+            ("delete a key the image lacks", cache.delete::<UnionSurface>("absent").unwrap_err()),
+        ];
+        for (door, error) in results {
+            let refusal = error.downcast_ref::<CultCacheLoadRefused>().unwrap_or_else(|| panic!("{door} redb={redb}: {error:#}"));
+            assert!(refusal.to_string().contains("bytes after"), "{door}: {refusal}");
+        }
+        assert_eq!(std::fs::read(&path).unwrap(), before, "redb={redb}: the store changed");
+        assert!(cache.snapshot().is_empty());
+        // Repairing the store and loading again lifts it.
+        if redb {
+            RedbMessagePackBackingStore::new(&path).unwrap().delete(&bad).unwrap();
+        } else {
+            SingleFileMessagePackBackingStore::new(&path).delete(&bad).unwrap();
+        }
+        cache.pull_all_backing_stores().unwrap();
+        cache.put("new", &value).unwrap();
+    }
+}
+
+// A payload that ends early is not bytes after the value: the decoder refuses it, not the check.
+#[test]
+fn a_truncated_payload_is_the_decoders_not_bytes_after() {
+    let mut truncated = vec![0x91, 0xd9, 0x40];
+    truncated.extend_from_slice(b"short");
+    let message = format!("{:#}", decode_payload::<UnionSurface>(&truncated).unwrap_err());
+    assert!(!message.contains("bytes after"), "{message}");
+}
+
 fn wrap_chain(wraps: usize, leaf: Node) -> UnionSurface {
     let mut node = leaf;
     for _ in 0..wraps {
@@ -788,6 +735,7 @@ fn write_refused_past_limit() {
     let mut cache = CultCache::new();
     cache.register_entry_type::<UnionSurface>().unwrap();
     cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+    cache.pull_all_backing_stores().unwrap();
 
     let at_limit = wrap_chain(126, boxed("0000000000f0", vec![]));
     assert_eq!(cache.put("at", &at_limit).unwrap(), at_limit);
@@ -871,6 +819,7 @@ fn the_raw_doors_hold_the_bound_for_arms_maps_and_arrays() {
         cache.register_entry_type::<UnionSurface>().unwrap();
         cache.register_entry_type::<MapDoc>().unwrap();
         cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&path)).unwrap();
+        cache.pull_all_backing_stores().unwrap();
         cache.put_raw_envelope(raw(type_name, "at-raw", at.clone())).unwrap();
         cache.put_prepared_batch(vec![raw(type_name, "at-batch", at.clone())]).unwrap();
         let stored = cache.snapshot_envelopes();

packages/cultcache-rs/tests/unique_index.rs

@@ -6,7 +6,7 @@
 use std::path::{Path, PathBuf};
 
 use cultcache_rs::{
-    CultCache, CultCacheEnvelope, CultCacheSoaTable, DatabaseEntry, SingleFileMessagePackBackingStore,
+    CultCache, CultCacheEnvelope, CultCacheLoadRefused, CultCacheSoaTable, DatabaseEntry, SingleFileMessagePackBackingStore,
 };
 use serde::Deserialize;
 
@@ -245,9 +245,9 @@ fn delete_releases_a_value() {
 fn types_sharing_an_alias_and_a_value_do_not_conflict() {
     let mut cache = memory_cache();
     cache.put("a", &unique("S")).unwrap();
-    cache.put("a", &Other { sku: "S".into() }).unwrap();
-    cache.put("b", &Other { sku: "T".into() }).unwrap();
-    assert!(cache.put("b", &Other { sku: "S".into() }).is_err());
+    cache.put("oa", &Other { sku: "S".into() }).unwrap();
+    cache.put("ob", &Other { sku: "T".into() }).unwrap();
+    assert!(cache.put("ob", &Other { sku: "S".into() }).is_err());
     assert_eq!(cache.get_by_index::<Unique>("Sku", "S").unwrap().unwrap(), unique("S"));
     assert_eq!(cache.get_by_index::<Other>("Sku", "S").unwrap().unwrap(), Other { sku: "S".into() });
 }
@@ -419,6 +419,54 @@ fn a_load_of_a_duplicate_image_is_refused_and_keeps_the_prior_view() {
     soa.put("item:y", &unique("K")).unwrap();
 }
 
+// A pull refused for a duplicate unique-index value, or for one key held under two types in two stores, closes the same
+// write gate a payload refusal does: the cache holds no image of its stores, so a write would lay the empty image over them.
+#[test]
+fn a_pull_refused_for_a_duplicate_index_or_a_retype_closes_every_write() {
+    fn assert_gated(cache: &mut CultCache, path: &Path, door_label: &str) {
+        let before = std::fs::read(path).unwrap();
+        let errors = [
+            ("put", cache.put("item:new", &unique("N")).unwrap_err()),
+            ("put_raw_envelope", cache.put_raw_envelope(cache.prepare_entry("item:new", &unique("N")).unwrap().0).unwrap_err()),
+            ("delete", cache.delete::<Unique>("item:keep").unwrap_err()),
+        ];
+        for (door, error) in errors {
+            assert!(error.downcast_ref::<CultCacheLoadRefused>().is_some(), "{door_label} {door}: {error:#}");
+        }
+        assert_eq!(std::fs::read(path).unwrap(), before, "{door_label}: the store changed");
+    }
+
+    // Duplicate index value found in the stored image.
+    let dir = tempfile::tempdir().unwrap();
+    let path = dir.path().join("dup.cc");
+    let mut cache = cache_at(&path);
+    cache.put("item:keep", &unique("K")).unwrap();
+    let mut twin = twin_cache_at(&path);
+    twin.put("item:b", &Twin { sku: "S".into(), category: "c".into() }).unwrap();
+    twin.put("item:a", &Twin { sku: "S".into(), category: "c".into() }).unwrap();
+    assert!(error_text(cache.pull_all_backing_stores()).contains("both hold unique index 'Sku'"));
+    assert_gated(&mut cache, &path, "duplicate index");
+
+    // One key held under two types by two stores. The cache pulled cleanly first, so only the refused pull can close the gate.
+    let (first, second) = (dir.path().join("first.cc"), dir.path().join("second.cc"));
+    let mut cache = CultCache::new();
+    cache.register_entry_type::<Plain>().unwrap();
+    cache.register_entry_type::<Other>().unwrap();
+    cache.register_entry_type::<Unique>().unwrap();
+    cache.add_backing_store(SingleFileMessagePackBackingStore::new(&first), [Plain::TYPE]).unwrap();
+    cache.add_backing_store(SingleFileMessagePackBackingStore::new(&second), [Other::TYPE]).unwrap();
+    cache.pull_all_backing_stores().unwrap();
+    cache.put("k", &Plain { value: "p".into() }).unwrap();
+    let mut seed = CultCache::new();
+    seed.register_entry_type::<Other>().unwrap();
+    seed.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&second)).unwrap();
+    seed.pull_all_backing_stores().unwrap();
+    seed.put("k", &Other { sku: "o".into() }).unwrap();
+    assert!(error_text(cache.pull_all_backing_stores()).contains("\"k\""));
+    assert_gated(&mut cache, &first, "retype");
+    assert_eq!(cache.get::<Plain>("k").unwrap().unwrap().value, "p", "a refused pull keeps the prior view");
+}
+
 #[test]
 fn a_multi_index_store_with_a_duplicate_on_the_second_alias_refuses_to_open() {
     let dir = tempfile::tempdir().unwrap();

packages/cultcache-ts/CHANGELOG.md

@@ -5,8 +5,15 @@ All notable changes to `@gamecult/cultcache-ts` are recorded here, following
 
 ## [Unreleased]
 
+### Changed
+
+- `withStoreWriteLock` looks for a link at the store path again once the lock is held, so a link put at the path while a writer waited on the lock is refused with `StoreLinkedError` and the lock released, instead of being replaced. Pinned by a test that puts the link while another holder owns the lock.
+- `CultCache.isWritable` does not look at store paths: a link at a store path is not predicted, and the write refuses it with `StoreLinkedError`. Pinned by a test through a cache attached to a linked store.
+
 ### Breaking
 
+- A write at a single-file store path that is a symbolic link, live or dangling, is refused with the new `StoreLinkedError` (exported from the package entry; `error.path` names the path) before the lock and the replace, and writes nothing: `push`, `pushAll`, `delete` and a soft flush alike. Before, a write at a live link replaced the link with a regular file, a dangling link failed with `ENOENT` (or, for `pushAll`, was replaced), and a soft flush at a link skipped. A caller catching `ENOENT` around a write at a dangling link now catches `StoreLinkedError`; configure the link's target as the store path. Reads through a live link work. An `lstat` failure other than `ENOENT` (`ENOTDIR`, `EACCES`, `ELOOP`) is rethrown as it is.
+- `SingleFileMessagePackBackingStore.pushAll` writes the given entries onto the store as it is under the lock, as `push` does: a record under the same key is replaced and no other is removed. It used to replace the whole file with the entries, so `CultMesh.flush()` from a cache that held less than the store (a node created with `pullOnStart: false`, or one whose image was stale) wiped the records it never read. A caller that relied on `pushAll` to reset a store removes the file first. A soft flush is unchanged. `CultCache.storedSnapshot()` is the image as the stores hold it (a global loaded from a legacy key under that key) and is what `CultMesh.flush` persists, so a flush no longer leaves such a global under two keys; `snapshot()` is unchanged.
 - A single-file store marked `cultcache.store.v3` (it holds an element id, written by the C# runtime) is read, and a rewrite keeps the mark and the ids; this runtime does not decide when a document carries ids. A runtime from before this change refuses a v3 store by name, so rolling back to an older release after a store has been written as v3 is one-way: there is no carry-back, so restore from a copy taken before upgrading.
 - `indexes` are unique, as C# `[CultIndex]`: a write or a load that leaves two records of a type holding one non-blank
   value under one alias is refused naming both keys and the alias, and writes nothing. Index text is the C# canonical
@@ -18,9 +25,18 @@ All notable changes to `@gamecult/cultcache-ts` are recorded here, following
 - A `put`, `push` or `pushAll` that would land a second type under a held key (against the file, or within one batch) is refused with `SchemaConflictError`, and nothing is written. The written type may replace the record when its catalog entry carries the stored schema id as its own or lists it compatible (a type renamed under a stable id restamps the record, as C# does); otherwise retyping a key is a delete, then a put. The C# allowance for an undeclared older id of the same schema name that reads whole is not ported: a same-named type keeps passing, including one that drops persisted slots, which C# refuses.
 - Same-type writes replace by key; in one `pushAll` batch the last entry for a key wins.
 - A store whose canonical-schema catalog slot is not a string is refused as `StoreUnreadableError`.
+- The cache holds one record per key (variants:ruling:cache-refuses-retype). A `put` or `putEnvelope` that lands a second type under a key the cache holds, or under a key a store carries foreign, is refused with `SchemaConflictError` naming the key, even with no store (a memory-only cache used to hold both types at the key). A type that owns the held record's schema id (as for the store) replaces it, unless the held record is in a store other than the written type's home: that rename is refused with `SchemaConflictError` (remove the record first). Two stores holding one key, registered or foreign, refuse the load and admit nothing. A store's `delete` removes the record whose stored schema id the removal's type owns, whatever the arrived record's `type` string.
+- A store holding a record no registered type claims now loads (it used to throw "No schema is registered..."): the cache does not serve the record, lists it in `foreignRecords()`, keeps its bytes through every write, and refuses a `put` or a `delete` at its key with `SchemaConflictError` (variants:ruling:unheld-removal-refused-at-commit). Registering a type that claims its schema id serves it at the next `pullAllBackingStores`.
+- A record whose payload carries a slot past its reader's declared slots, at any depth (the record, a nested record, a list element, a union arm, a unit arm), is now held read-only: it loads and reads, and every `put`, `putEnvelope`, `update` or `delete` of its key is refused with `SchemaConflictError` before a store is touched (cultlib-gaps:ruling:extra-trailing-slots, as the C# reference). A load used to skip the extra slots silently and a later write shed them. The refusal names the schema, the key, the type that was read with extra slots and both slot counts, never a slot value, and carries them as `SchemaConflictError.unreadSlots`. An untouched record keeps its bytes through writes of other keys. Missing trailing slots keep their declared defaults and mark nothing. A `put` never marks (the value is encoded by this runtime); a `putEnvelope` of a payload carrying extra slots lands its bytes and holds the record read-only. A mark at depth 0 is consented to only when the record arrived under a schema id other than the reader's own that the reader lists compatible, and that id's catalog entry lists those slots (a writer that adds a slot and keeps the reader's id is never consented to) (`unreadSlots.explained`); every other mark refuses whatever is declared. New: `CultCache.isWritable(definition, key)` (live, advisory), `CultCache.unreadSlots(definition, key)` and the exported `CultCacheUnreadSlots`. Documents with no slot codec (a plain map, a user formatter) never mark. A `delete` is by key: a type that owns the schema id of the record held at the key as another type removes that one record (one store call, the cache dropped once the store has removed it), and a type that does not own it is refused with `SchemaConflictError`, as a `put` is; `isWritable` answers both. Implied semver: a minor bump (0.16.0) while the package is 0.x; a major one at 1.0 and after.
+
+### Added
+
+- `checkPayloadDepth` returns the offset where the first value ends, or `undefined` when the payload ends early (a header, a container or a str/bin/scalar body cut short; it was `void`); it still refuses only depth. The bytes-after refusal is internal (`checkPayloadIsOneValue`, not exported); no new public name.
+- `CultCache.foreignRecords()`: the `{key, schemaId, schemaName, storedAt}` of every record the last pull carried and no registered type claims, sorted by key ordinal.
 
 ### Changed
 
+- A document payload is exactly one MessagePack value (cultlib-gaps:ruling:trailing-bytes-refuse). `decodeDocumentPayload`, the one reader (store loads, `put`/`putEnvelope`, CultNet replication, the provider command), and the inspector refuse bytes after the first value with `document type "T" payload has N bytes after its first MessagePack value.`, counted from the walk's end and never walked or echoed; a payload that ends early stays the decoder's to refuse. The refused set is unchanged; only the text changed (it was `@msgpack`'s `RangeError` "Extra N of M byte(s)" for a plain document and the codec reader's "bytes after its value" for a codec document, and the inspector's preview no longer shows a tail), so code matching either text must match this one. `readWire` reads one value and no longer checks what follows. Stated limit: a definition with its own `formatter` is not walked, so whether its payload is one value is the formatter's. Implied bump: 0.16.0 (pre-1.0 minor, with the Breaking entries above).
 - Opening a legacy (pre-v1) store is a pure read: payloads that were not bytes are normalized in memory and the
   file is left as it was, so a codec that refuses the content cannot lose the old bytes. The next push, delete or
   flush rewrites the file as v1, merging what the open read.

packages/cultcache-ts/README.md

@@ -49,7 +49,9 @@ through `decodeDocumentPayload`, and when you need the bytes themselves (hashing
 write) take them with `documentPayloadBytes`, the sanctioned escape.
 
 - `decodeDocumentPayload(definition, payload)` reads a payload through the definition's formatter,
-  codec or plain map and then its schema. The definition is required.
+  codec or plain map and then its schema. The definition is required. A payload is exactly one
+  MessagePack value: bytes after the first are refused by count, naming the type, and never walked or
+  echoed (a payload that ends early is the decoder's to refuse).
 - `encodeDocumentPayload(definition, value)` is the writer: the schema first, then the formatter,
   codec or plain map.
 - `documentPayloadFromBytes(bytes)` is where bytes enter (a record you validated, a store read, a
@@ -172,7 +174,7 @@ const settings = cache.getRequiredGlobal(settingsDocument);
 - `updateGlobal(...)`
 - `delete(...)`
 - `deleteGlobal(...)`
-- `snapshot()`
+- `snapshot()` (the logical image) and `storedSnapshot()` (the image as the stores hold it, for a whole flush)
 - `getEnvelope(...)`
 - `getRequiredEnvelope(...)`
 - `getGlobalEnvelope(...)`
@@ -231,6 +233,16 @@ its exact decimal expansion; NaN and infinities have no value. `roles` name sele
 member's catalog `indexAlias`, so the catalog bytes are the same either way); they imply nothing about uniqueness and
 are never indexed for lookup, so `getByIndex` on a role answers `undefined`. An alias is declared in one of the two.
 
+### One record per key, and foreign records
+
+A cache holds one record per key whatever its type (variants:ruling:cache-refuses-retype). A write of a type that does not
+own the held record's schema id (it carries that id as its own or lists it compatible) is refused with
+`SchemaConflictError` naming the key, with or without a store; retyping a key is `delete` then `put`. A store that holds a
+record no registered type claims still loads: the cache does not serve it, `foreignRecords()` lists it (`key`,
+`schemaId`, `schemaName`, `storedAt`, by key ordinal), every write keeps its bytes, and a `put` or `delete` at its key is
+refused. Registering a type that claims its schema id serves it at the next `pullAllBackingStores`. Two stores that hold
+one key refuse the load and admit nothing.
+
 ### Migrating an existing `indexes` key
 
 Apply per key, and do it BEFORE the CultLib checkout your tools load is rebuilt or updated. A consumer that loads
@@ -317,7 +329,7 @@ If you do not supply one, `CultCacheTS` uses MessagePack plus Zod validation by
 
 The 256-container nesting bound (`MAX_PAYLOAD_DEPTH`, refused with `CultCachePayloadDepthError`) covers the MessagePack the
 library itself writes: the default format and a codec. A payload your formatter writes is opaque bytes in any format, so the
-library does not walk it as MessagePack; its format and its bounds are your formatter's.
+library does not walk it as MessagePack; its format, its bounds and whether it is one value are your formatter's.
 
 Zod is no longer mandatory. Any schema object with a `parse(...)` function will
 do, which means generated Ajv-backed JSON-schema contracts can feed the cache
@@ -361,8 +373,11 @@ const sceneDocument = defineDocumentType({
 });
 ```
 
-- A slot is `[name, codec, default?]`. A gap is written nil and skipped on read; an extra trailing slot is skipped; a
-  slot missing from the payload (or nil, when a default is declared) takes its default, and is refused without one.
+- A slot is `[name, codec, default?]`. A gap is written nil and skipped on read; an extra trailing slot is read past and
+  marks the record read-only (every write or removal of its key is refused with `SchemaConflictError`, `cache.isWritable`
+  asks first). The one writable case is a depth-0 extra slot of a record that arrived under a schema id other than the reader's own, which the
+  reader lists in `compatibleSchemaIds`, whose catalog entry lists those slots: declaring that id consents to the loss, and a write restamps
+  the record. A nested slot, or a writer that keeps the reader's own id, is never consented to. A slot missing from the payload (or nil, when a default is declared) takes its default, and is refused without one.
 - A union refuses an undeclared arm key on read, naming the union, the key and the declared keys. Nothing falls back
   to a default arm. An arm with no slots is `codecs.unit` and is written `[key, []]`.
 - A refusal names the union, the field and the slot; it never echoes the value it refused.

packages/cultcache-ts/src/browser.ts

@@ -2,7 +2,7 @@
 // (node:fs, koffi). Bring your own CacheBackingStore, or none.
 export * as codecs from "./codec";
 export type { Codec, SlotsCodec } from "./codec";
-export { CultCache, CultCacheBuilder } from "./cult-cache";
+export { CultCache, CultCacheBuilder, type CultCacheForeignRecord } from "./cult-cache";
 export { inspectCultCacheBytes } from "./cult-cache-inspector";
 export {
   decodeDocumentPayload,
@@ -34,6 +34,7 @@ export type {
   CultCacheIndexScalar,
   InferCultCacheSchemaValue,
   CultCacheStoreRegistration,
+  CultCacheUnreadSlots,
   PushAllOptions,
 } from "./types";
 export type {

packages/cultcache-ts/src/codec.ts

@@ -198,6 +198,66 @@ type SlotSpec<TValue, TName extends string = string> =
 
 type SlotsSpec<TValue> = Readonly<Record<number, { [K in keyof TValue & string]: SlotSpec<TValue[K], K> }[keyof TValue & string]>>;
 
+// The slots a payload decode read past, noted by `slots` and the unit arm while the one decode entry (decodeNoting) has a scope
+// open, and read out by that entry. Module-scoped as the reference's is thread-bound: a decode is synchronous, and a decode
+// outside the entry (a codec called directly, a CultMesh read) notes nothing. No codec signature carries it.
+export interface NotedSlots {
+  /** The first type read with extra slots, outermost first. */
+  readonly typeName: string;
+  readonly slotCount: number;
+  readonly declaredCount: number;
+  readonly occurrences: number;
+  /** True when every noted object was the document's own: a union adds no depth, each record or arm inside a field adds one. */
+  readonly depth0Only: boolean;
+}
+
+interface SlotScope {
+  depth: number;
+  found?: { typeName: string; slotCount: number; declaredCount: number; occurrences: number; depth0Only: boolean };
+}
+
+let scope: SlotScope | undefined;
+
+/** The one decode entry: runs the decode with a scope open and returns its value with what it noted. */
+export function decodeNoting<T>(decode: () => T): { value: T; unreadSlots?: NotedSlots } {
+  const outer = scope;
+  const mine: SlotScope = { depth: 0 };
+  scope = mine;
+  try {
+    const value = decode();
+    return mine.found ? { value, unreadSlots: mine.found } : { value };
+  } finally {
+    scope = outer;
+  }
+}
+
+function noteExtraSlots(typeName: string, slotCount: number, declaredCount: number): void {
+  if (!scope) return;
+  const found = scope.found;
+  if (found) {
+    found.occurrences += 1;
+    found.depth0Only &&= scope.depth === 0;
+  } else {
+    scope.found = { typeName, slotCount, declaredCount, occurrences: 1, depth0Only: scope.depth === 0 };
+  }
+}
+
+// What a record inside a field reads at: one deeper than the record holding the field.
+function nested<T>(read: () => T): T {
+  if (!scope) return read();
+  scope.depth += 1;
+  try {
+    return read();
+  } finally {
+    scope.depth -= 1;
+  }
+}
+
+// The reference's type name for a mark: the type, not its namespace or the type it is nested in.
+function simpleTypeName(typeName: string | undefined): string {
+  return typeName === undefined ? "record" : typeName.slice(Math.max(typeName.lastIndexOf("."), typeName.lastIndexOf("+")) + 1);
+}
+
 const INT32_MIN = -(2 ** 31);
 const INT32_MAX = 2 ** 31 - 1;
 
@@ -232,7 +292,7 @@ function pascalCase(name: string): string {
 }
 
 // A positional record: slot `key` holds field `name`. Gaps are written nil and skipped on read, extra trailing slots
-// are skipped, and a slot missing from the payload takes its declared default or is refused. A default fills only a
+// are read past and noted (decodeNoting): the record that carried them is read-only, never rewritten without them, and a slot missing from the payload takes its declared default or is refused. A default fills only a
 // missing trailing slot, never a nil: as in the reference, a nil in a reference slot (string, bytes, record, union,
 // list) reads as null and writes back as nil, so a record the reference wrote re-encodes byte-identical, and a nil in
 // a value slot (int, float, bool) is refused unless the slot is nullable.
@@ -281,6 +341,9 @@ export function slots<TValue extends object>(spec: SlotsSpec<TValue>, typeName?:
     decode(raw) {
       expect(raw, "an array of slots", Array.isArray(raw));
       const input = raw as unknown[];
+      if (input.length > length) {
+        noteExtraSlots(simpleTypeName(typeName), input.length, length);
+      }
       const out: Record<string, unknown> = {};
       for (const field of fields) {
         const present = field.key < input.length;
@@ -291,7 +354,7 @@ export function slots<TValue extends object>(spec: SlotsSpec<TValue>, typeName?:
           ? defaultOf(field)
           : input[field.key] === null && !field.codec.valueType
             ? null
-            : at(`${field.name} (slot ${field.key})`, () => field.codec.decode(input[field.key]));
+            : at(`${field.name} (slot ${field.key})`, () => nested(() => field.codec.decode(input[field.key])));
       }
       return out as TValue;
     },
@@ -363,6 +426,9 @@ export function union<TValue extends { kind: string }>(
       if (arm === undefined) {
         throw new Error(`Union ${name}: unknown arm key ${key} (declared keys: ${declared}).`);
       }
+      if (arm.body === unit && raw[1].length > 0) {
+        noteExtraSlots(arm.armName, raw[1].length, 0);
+      }
       const fields = arm.body === unit ? {} : at(`arm ${arm.armName}`, () => (arm.body as SlotsCodec<any>).decode(raw[1]));
       return { kind: arm.armName, ...fields } as unknown as TValue;
     },

packages/cultcache-ts/src/cult-cache-inspector.ts

@@ -1,6 +1,6 @@
 import { decode } from "@msgpack/msgpack";
 
-import { checkPayloadDepth } from "./payload-depth";
+import { checkPayloadDepth, checkPayloadIsOneValue } from "./payload-depth";
 import { type StoreFormat, isStoreSnapshot, refuseUnreadStoreBytes, requireStoreSlots, requireV1RecordSlots } from "./store-format";
 
 export interface CultCacheInspection {
@@ -235,12 +235,22 @@ function decodeLegacyEnvelope(value: unknown): InspectedRecord {
   };
 }
 
-// The inspector's one payload read: the depth walk first, so a payload past the limit is refused before any decoder sees it.
+// The inspector's one payload read: the depth walk first, so a payload past the limit is refused before any decoder sees it,
+// and bytes after the first value are refused with the shared clause (the tail is never decoded or shown).
 function decodeBoundedPayload(payload: Uint8Array): unknown {
-  checkPayloadDepth(payload);
+  checkPayloadIsOneValue(payload, "document payload");
   return decode(payload);
 }
 
+// Where the first value ends (the whole payload when it ends early or cannot be walked): a preview never shows a tail.
+function valueEnd(payload: Uint8Array): number {
+  try {
+    return checkPayloadDepth(payload) ?? payload.length;
+  } catch {
+    return payload.length;
+  }
+}
+
 function previewPayload(payload: Uint8Array): Pick<InspectedRecord, "payloadPreview" | "payloadDecodeError"> {
   try {
     return { payloadPreview: toJsonSafe(decodeBoundedPayload(payload)) };
@@ -248,7 +258,7 @@ function previewPayload(payload: Uint8Array): Pick<InspectedRecord, "payloadPrev
     return {
       payloadPreview: {
         bytes: payload.length,
-        hexPrefix: [...payload.slice(0, 32)]
+        hexPrefix: [...payload.slice(0, Math.min(32, valueEnd(payload)))]
           .map((value) => value.toString(16).padStart(2, "0"))
           .join(" "),
       },

packages/cultcache-ts/src/cult-cache.ts

@@ -1,6 +1,6 @@
 import {
   declaresRole,
-  decodeDocumentPayload,
+  decodeDocumentPayloadMarked,
   documentPayloadBytes,
   documentPayloadFromBytes,
   encodeDocumentPayload,
@@ -8,8 +8,9 @@ import {
   schemaIdentityOf,
 } from "./document";
 import { resolveDocumentFormatter } from "./document-formatter";
+import type { NotedSlots } from "./codec";
 import type { DocumentPayload } from "./document";
-import { SchemaConflictError } from "./store-format";
+import { SchemaConflictError, schemaIdForEnvelope, writtenOwns } from "./store-format";
 import type {
   AnyCultCacheDocumentDefinition,
   CacheBackingStore,
@@ -20,6 +21,7 @@ import type {
   CultCacheEnvelope,
   CultCacheSchemaCatalogEntry,
   CultCacheStoreRegistration,
+  CultCacheUnreadSlots,
 } from "./types";
 
 type Accessor = (value: unknown) => string | undefined;
@@ -27,7 +29,7 @@ type Accessor = (value: unknown) => string | undefined;
 // A registered definition reads and writes its documents through the owner, on payloads the cache has cloned.
 type RegisteredFormatter = {
   encode(value: unknown): DocumentPayload;
-  decode(payload: DocumentPayload): unknown;
+  decode(payload: DocumentPayload): { value: unknown; unreadSlots?: NotedSlots };
 };
 
 type RegisteredDefinition = {
@@ -50,6 +52,10 @@ type HydratedEntry = CultCacheEnvelope & {
   catalogEntry: NonNullable<CultCacheEnvelope["catalogEntry"]>;
   value: unknown;
   lookups: EntryLookups;
+  // What the payload decode read past: set when the record was admitted, and it makes the record read-only unless explained.
+  unreadSlots?: CultCacheUnreadSlots;
+  // The schema id the record arrived under, before it was admitted under its reader's: what an unread-slots refusal names.
+  storedSchemaId?: string;
 };
 
 // Everything a pull replaces. Built whole, then swapped in with one assignment.
@@ -64,6 +70,17 @@ type HydratedState = {
   // delete of that global removes it from the home store. Remove once no store holds a global under
   // a key other than GLOBAL_KEY.
   readonly legacyGlobals: Map<string, CultCacheEnvelope>;
+  // The records the last pull found that no registered type claims. Derived from the pull and replaced with the state; it
+  // decides nothing but the refusal of a write or a removal at its keys.
+  readonly foreign: CultCacheForeignRecord[];
+};
+
+/** A record a store carries that no registered type claims: the cache does not serve it, keeps its bytes, and refuses a write or a removal at its key. */
+export type CultCacheForeignRecord = {
+  readonly key: string;
+  readonly schemaId: string;
+  readonly schemaName: string;
+  readonly storedAt: string;
 };
 
 // Lookups for every held record of one type under candidate accessors, derived before anything is installed.
@@ -73,6 +90,20 @@ type DerivedTypeLookups = {
   readonly indexMaps: Map<string, Map<string, string>>;
 };
 
+// The consent a compatible-id declaration gives (cultlib-gaps:ruling:slot-mark-consent): a mark is explained only when the record
+// arrived under an id other than the reader's own that the reader lists compatible, it is at
+// depth 0 and the schema comparison of the catalog entry the record arrived with against the reader's own reported the slots it
+// carries as ignored, so its slot count is at most the highest ignored slot plus one. A record written or put through the cache
+// arrives under the reader's own entry, which ignores nothing, so no mark of it is explained.
+function explainedBy(noted: NotedSlots, reader: CultCacheSchemaCatalogEntry, arrivedId: string, arrived: CultCacheSchemaCatalogEntry | undefined): boolean {
+  if (arrivedId === reader.schemaId || !(reader.compatibleSchemaIds ?? []).includes(arrivedId)) {
+    return false;
+  }
+  const declared = new Set((reader.members ?? []).map((member) => member.slot));
+  const ignored = (arrived?.members ?? []).map((member) => member.slot).filter((slot) => !declared.has(slot));
+  return noted.depth0Only && noted.slotCount <= Math.max(-1, ...ignored) + 1;
+}
+
 function emptyHydratedState(): HydratedState {
   return {
     entries: new Map(),
@@ -81,6 +112,7 @@ function emptyHydratedState(): HydratedState {
     indexToKeyMaps: new Map(),
     globalKeys: new Map(),
     legacyGlobals: new Map(),
+    foreign: [],
   };
 }
 
@@ -280,11 +312,14 @@ export class CultCache {
         for (const entry of entries) {
           const registered = this.#resolveDefinitionForEnvelope(entry);
           if (!registered) {
-            throw new Error(
-              entry.schemaId
-                ? `No schema is registered for persisted schema id "${entry.schemaId}".`
-                : `No schema is registered for persisted document type "${entry.type}".`,
-            );
+            // A store may hold what this cache has no type for; it is carried, not served, and not a reason to refuse the load.
+            next.foreign.push({
+              key: entry.key,
+              schemaId: schemaIdForEnvelope(entry),
+              schemaName: entry.catalogEntry?.schemaName ?? entry.type,
+              storedAt: entry.storedAt,
+            });
+            continue;
           }
 
           const type = registered.definition.type;
@@ -297,7 +332,7 @@ export class CultCache {
           }
 
           const payload = this.#cloneBytes(entry.payload);
-          const value = registered.formatter.decode(payload);
+          const { value, unreadSlots } = registered.formatter.decode(payload);
           let admitted: CultCacheEnvelope = { ...entry, type, payload };
           if (registered.global) {
             const persistedKey = persistedGlobalKeys.get(type);
@@ -312,11 +347,28 @@ export class CultCache {
               admitted = { ...admitted, key: CultCache.GLOBAL_KEY };
             }
           }
-          const hydrated = this.#admitEntry(next, registered, admitted, value);
+          const hydrated = this.#admitEntry(next, registered, admitted, value, unreadSlots);
+          const other = this.#heldUnderOtherType(next, type, hydrated.key);
+          if (other !== undefined) {
+            throw new Error(`Record ${hydrated.key} is held by two stores, as type "${other.type}" and as type "${type}".`);
+          }
           this.#installEntry(next, registered, hydrated);
         }
       }
 
+      const foreignByKey = new Map<string, string>();
+      for (const record of next.foreign) {
+        const first = foreignByKey.get(record.key);
+        if (first !== undefined) {
+          throw new Error(`Record ${record.key} is held by two stores, as schema "${first}" and as schema "${record.schemaName}".`);
+        }
+        foreignByKey.set(record.key, record.schemaName);
+        const other = [...this.#definitions.keys()].map((type) => next.entries.get(this.#entryId(type, record.key))).find((held) => held !== undefined);
+        if (other !== undefined) {
+          throw new Error(`Record ${record.key} is held by two stores, as type "${other.type}" and as schema "${record.schemaName}".`);
+        }
+      }
+
       // Judged whole, once: the refusal names the least violation of the state this load would leave, whatever the
       // order of the stores and of the entries in them.
       refuseLeastIndexSharing(function* () {
@@ -486,10 +538,9 @@ export class CultCache {
       if (!envelope.storedAt || envelope.storedAt.trim().length === 0) {
         throw new Error(`CultCache envelope storedAt for type "${definition.type}" must be non-empty.`);
       }
-      this.#requireGlobalKey(registered, envelope.key);
 
       const payload = this.#cloneBytes(envelope.payload);
-      const parsed = registered.formatter.decode(payload) as CultCacheDocumentValue<TDefinition>;
+      const { value: parsed, unreadSlots } = registered.formatter.decode(payload) as { value: CultCacheDocumentValue<TDefinition>; unreadSlots?: NotedSlots };
       const entry: CultCacheEnvelope = {
         key: envelope.key,
         type: envelope.type,
@@ -500,7 +551,7 @@ export class CultCache {
         schemaId: registered.catalogEntry.schemaId,
         catalogEntry: registered.catalogEntry,
       };
-      await this.#writeNow(registered, entry, parsed);
+      await this.#writeNow(registered, entry, parsed, unreadSlots);
       return parsed;
     });
   }
@@ -553,10 +604,46 @@ export class CultCache {
     });
   }
 
+  /** What the record's payload carried past this build's declared slots, or undefined: the held record is read-only unless `explained`. */
+  unreadSlots(definition: AnyCultCacheDocumentDefinition, key: string): CultCacheUnreadSlots | undefined {
+    return this.#hydrated.entries.get(this.#entryId(this.#requireDefinition(definition).definition.type, key))?.unreadSlots;
+  }
+
+  /**
+   * Whether a write of the record's own type at the key would be let through: it asks the judge #writeNow asks, of the record the
+   * cache holds (a key a store carries foreign, a record of another type the write does not own or cannot replace, a global at
+   * another key, a record carrying unread slots nothing consents to). It answers the WRITE form. A removal asks the judge's
+   * removal form and differs in two states: an owner's `delete` of a record held in another store than its own home succeeds
+   * where this is false (a write would push to the wrong store), and `delete` of a global type at a key other than __global__ is
+   * the plain false of an unheld key where this is false. It does not look at store paths: a link at a store path is not predicted, and
+   * the write refuses it with `StoreLinkedError`. Live and advisory: the write or removal still decides.
+   */
+  isWritable(definition: AnyCultCacheDocumentDefinition, key: string): boolean {
+    const registered = this.#requireDefinition(definition);
+    try {
+      this.#judge(registered, key, this.#probe(registered, key));
+      return true;
+    } catch {
+      return false;
+    }
+  }
+
+  // What the last pull found that no registered type claims, by key ordinal. A later registration claims a record at the next pull.
+  foreignRecords(): readonly CultCacheForeignRecord[] {
+    return [...this.#hydrated.foreign].sort((left, right) => compareOrdinal(left.key, right.key));
+  }
+
   snapshot(): CultCacheEnvelope[] {
     return [...this.#hydrated.entries.values()].map((entry) => this.#toEnvelope(entry));
   }
 
+  // The image as the stores hold it, for persisting it whole (a flush): a global loaded from a legacy key is handed out under
+  // that key until its first write retires it, so a flush cannot leave the store holding it under two keys. `snapshot` is the
+  // logical image and always names a global by CultCache.GLOBAL_KEY.
+  storedSnapshot(): CultCacheEnvelope[] {
+    return [...this.#hydrated.entries.values()].map((entry) => this.#hydrated.legacyGlobals.get(entry.type) ?? this.#toEnvelope(entry));
+  }
+
   #registerNow(definition: AnyCultCacheDocumentDefinition): void {
     // Every registration refusal is a SchemaConflictError naming the new definition's schema id and both schema names.
     const refuse = (holder: RegisteredDefinition, claimed: CultCacheSchemaCatalogEntry, what: string) =>
@@ -643,9 +730,8 @@ export class CultCache {
     value: CultCacheDocumentValue<TDefinition>,
   ): Promise<CultCacheDocumentValue<TDefinition>> {
     const registered = this.#requireDefinition(definition);
-    this.#requireGlobalKey(registered, key);
     const payload = registered.formatter.encode(value);
-    const parsed = registered.formatter.decode(payload) as CultCacheDocumentValue<TDefinition>;
+    const { value: parsed, unreadSlots } = registered.formatter.decode(payload) as { value: CultCacheDocumentValue<TDefinition>; unreadSlots?: NotedSlots };
     const entry: CultCacheEnvelope = {
       key,
       type: definition.type,
@@ -654,15 +740,16 @@ export class CultCache {
       schemaId: registered.catalogEntry.schemaId,
       catalogEntry: registered.catalogEntry,
     };
-    await this.#writeNow(registered, entry, parsed);
+    await this.#writeNow(registered, entry, parsed, unreadSlots);
     return parsed;
   }
 
   // Validates the whole write (home, global singleton, name and index accessors) before the store
   // is touched; once the store accepts, applying to the cache has no fallible step.
-  async #writeNow(registered: RegisteredDefinition, entry: CultCacheEnvelope, value: unknown): Promise<void> {
+  async #writeNow(registered: RegisteredDefinition, entry: CultCacheEnvelope, value: unknown, unreadSlots?: NotedSlots): Promise<void> {
     const home = this.#homeStore(entry.type);
-    const hydrated = this.#admitEntry(this.#hydrated, registered, entry, value);
+    const retyped = this.#judge(registered, entry.key, entry);
+    const hydrated = this.#admitEntry(this.#hydrated, registered, entry, value, unreadSlots);
     this.#refuseIndexSharing(this.#hydrated, entry.type, registered.catalogEntry.schemaName, entry.key, hydrated.lookups);
     const legacy = this.#hydrated.legacyGlobals.get(entry.type);
     await home?.push(entry);
@@ -670,9 +757,133 @@ export class CultCache {
       await this.#retireLegacyGlobal(home, legacy, entry);
     }
     this.#hydrated.legacyGlobals.delete(entry.type);
+    if (retyped !== undefined) {
+      // The record the write restamped (it owns the held id) is the same record: one key, one held type.
+      this.#removeEntry(this.#hydrated, this.#definitions.get(retyped.type)!, retyped);
+    }
     this.#installEntry(this.#hydrated, registered, hydrated);
   }
 
+  // An envelope of the definition's type at the key, carrying nothing: what the judge asks about a write or a removal by that type.
+  #probe(registered: RegisteredDefinition, key: string): CultCacheEnvelope {
+    return {
+      key, type: registered.definition.type, payload: documentPayloadFromBytes(new Uint8Array(0)), storedAt: "",
+      schemaId: registered.catalogEntry.schemaId, catalogEntry: registered.catalogEntry,
+    };
+  }
+
+  // The one judge of whether a key may be written (a written envelope) or removed (none), before any store is touched: it throws the
+  // refusal, and #writeNow, #deleteNow and isWritable all ask it, so the query cannot disagree with the write. For a write it
+  // returns the held record of another type that the write owns and so restamps, if any. A refusal names keys and schemas,
+  // never a payload or a slot value.
+  #judge(registered: RegisteredDefinition, key: string, written?: CultCacheEnvelope): HydratedEntry | undefined {
+    const type = registered.definition.type;
+    const held = this.#hydrated.entries.get(this.#entryId(type, key));
+    if (written === undefined) {
+      // A removal is by key: the record it removes is the one held at the key, of this type or of another type whose schema id
+      // this type owns (the record a write of this type would replace). A held record of a type it does not own is refused.
+      this.#refuseForeignKey(key, type, "removed");
+      this.#refuseUnread(held);
+      if (held !== undefined) {
+        return undefined;
+      }
+      const other = this.#heldUnderOtherType(this.#hydrated, type, key);
+      if (other === undefined) {
+        return undefined;
+      }
+      if (!writtenOwns(this.#probe(registered, key), schemaIdForEnvelope(other))) {
+        throw new SchemaConflictError(
+          registered.catalogEntry.schemaId,
+          [other.type, type],
+          key,
+          `CultCache holds record "${key}" as type "${other.type}", so type "${type}" cannot remove it.`,
+        );
+      }
+      this.#refuseUnread(other);
+      return other;
+    }
+    this.#requireGlobalKey(registered, key);
+    const retyped = this.#refuseRetype(written);
+    this.#refuseUnread(held);
+    this.#refuseUnread(retyped);
+    if (retyped !== undefined && this.#homeStore(retyped.type) !== this.#homeStore(type)) {
+      // The write owns the held record's id and would replace it, but the held record is in another store; the push
+      // reaches only this type's home, so the old record would stay in its own file and load as a second holder.
+      throw new SchemaConflictError(
+        schemaIdForEnvelope(written),
+        [retyped.type, type],
+        key,
+        `CultCache holds record "${key}" as type "${retyped.type}" in another store than the home of type "${type}", so the rename cannot replace it; remove the record first.`,
+      );
+    }
+    return retyped;
+  }
+
+  // The one refusal of a record held read-only for the slots its payload carries past this build's: a write or a removal of
+  // its key. It names the type and the counts, never a slot value. A mark that is explained (see #admitEntry) is consented to.
+  #unreadRefusal(held: HydratedEntry | undefined): SchemaConflictError | undefined {
+    const unread = held?.unreadSlots;
+    if (held === undefined || unread === undefined || unread.explained) {
+      return undefined;
+    }
+    return new SchemaConflictError(
+      held.storedSchemaId ?? held.schemaId ?? held.type,
+      [held.catalogEntry.schemaName],
+      held.key,
+      `${held.catalogEntry.schemaName} record ${held.key} is read-only: ${unread.typeName} was read with ${unread.slotCount} slots where this build declares ${unread.declaredCount} ` +
+        `(${unread.occurrences} object(s) in the record). Writing it would drop data a newer writer stored; read it with types that declare those slots, or write it from that build.`,
+      unread,
+    );
+  }
+
+  #refuseUnread(held: HydratedEntry | undefined): void {
+    const refusal = this.#unreadRefusal(held);
+    if (refusal !== undefined) {
+      throw refusal;
+    }
+  }
+
+  // The one key-identity judge of the cache: may this write land at its key, given what the cache holds there under
+  // every registered type and the keys its stores carry foreign. The store judges the file with the same predicate
+  // (writtenOwns); this judges the cache, which a store-less cache has no other judge for. Returns the held record of
+  // another type the write owns and so replaces, if any. A refusal names the key and schemas, never a payload.
+  #refuseRetype(entry: CultCacheEnvelope): HydratedEntry | undefined {
+    this.#refuseForeignKey(entry.key, entry.type, "written");
+    const held = this.#heldUnderOtherType(this.#hydrated, entry.type, entry.key);
+    if (held === undefined || writtenOwns(entry, schemaIdForEnvelope(held))) {
+      return held;
+    }
+    throw new SchemaConflictError(
+      schemaIdForEnvelope(entry),
+      [held.type, entry.type],
+      entry.key,
+      `CultCache holds record "${entry.key}" as type "${held.type}", so type "${entry.type}" cannot be written under the same key; remove the record first.`,
+    );
+  }
+
+  #refuseForeignKey(key: string, type: string, what: "written" | "removed"): void {
+    const foreign = this.#hydrated.foreign.find((record) => record.key === key);
+    if (foreign !== undefined) {
+      throw new SchemaConflictError(
+        foreign.schemaId,
+        [foreign.schemaName],
+        key,
+        `CultCache store carries record "${key}" as schema "${foreign.schemaName}" (${foreign.schemaId}), which no registered type claims, so type "${type}" cannot be ${what} at that key.`,
+      );
+    }
+  }
+
+  // The record another registered type holds at the key, if any.
+  #heldUnderOtherType(state: HydratedState, type: string, key: string): HydratedEntry | undefined {
+    for (const other of this.#definitions.keys()) {
+      const held = other === type ? undefined : state.entries.get(this.#entryId(other, key));
+      if (held !== undefined) {
+        return held;
+      }
+    }
+    return undefined;
+  }
+
   // The first write of a global loaded from a legacy key removes that record in the same write. If the
   // removal fails, the new record is taken back out, so the store keeps only the legacy record.
   async #retireLegacyGlobal(home: CacheBackingStore, legacy: CultCacheEnvelope, written: CultCacheEnvelope): Promise<void> {
@@ -689,15 +900,20 @@ export class CultCache {
     key: string,
   ): Promise<boolean> {
     const registered = this.#requireDefinition(definition);
-    const entry = this.#hydrated.entries.get(this.#entryId(definition.type, key));
+    // variants:ruling:unheld-removal-refused-at-commit: a key a store carries foreign is refused, a key held by nobody is the
+    // existing false; a key held as another type is removed by an owner of its id and refused to any other type.
+    // Removal is by key, in one store call: the record held at the key of this type, else the one of another type this type owns.
+    const owned = this.#judge(registered, key);
+    const entry = this.#hydrated.entries.get(this.#entryId(definition.type, key)) ?? owned;
     if (!entry) {
       return false;
     }
 
-    const home = this.#homeStore(definition.type);
-    await home?.delete(this.#hydrated.legacyGlobals.get(definition.type) ?? this.#toEnvelope(entry));
-    this.#hydrated.legacyGlobals.delete(definition.type);
-    this.#removeEntry(this.#hydrated, registered, entry);
+    // The cache drops the record only once the store has removed it.
+    const home = this.#homeStore(entry.type);
+    await home?.delete(this.#hydrated.legacyGlobals.get(entry.type) ?? this.#toEnvelope(entry));
+    this.#hydrated.legacyGlobals.delete(entry.type);
+    this.#removeEntry(this.#hydrated, this.#definitions.get(entry.type)!, entry);
     return true;
   }
 
@@ -724,7 +940,7 @@ export class CultCache {
 
     return {
       encode: (value: unknown) => this.#cloneBytes(encodeDocumentPayload(definition, value)),
-      decode: (payload: DocumentPayload) => decodeDocumentPayload(definition, this.#cloneBytes(payload)),
+      decode: (payload: DocumentPayload) => decodeDocumentPayloadMarked(definition, this.#cloneBytes(payload)),
     };
   }
 
@@ -904,6 +1120,7 @@ export class CultCache {
     registered: RegisteredDefinition,
     entry: CultCacheEnvelope,
     value: unknown,
+    noted?: NotedSlots,
   ): HydratedEntry {
     if (registered.global) {
       const currentGlobalKey = state.globalKeys.get(entry.type);
@@ -924,6 +1141,8 @@ export class CultCache {
       catalogEntry: registered.catalogEntry,
       value,
       lookups,
+      storedSchemaId: entry.schemaId ?? entry.type,
+      ...(noted ? { unreadSlots: { ...noted, explained: explainedBy(noted, registered.catalogEntry, entry.schemaId ?? entry.type, entry.catalogEntry) } } : {}),
     };
   }
 

packages/cultcache-ts/src/document-formatter.ts

@@ -1,7 +1,7 @@
 import { decode, encode } from "@msgpack/msgpack";
 
 import { MAX_PAYLOAD_DEPTH } from "./payload-depth";
-import type { SlotsCodec } from "./codec";
+import { decodeNoting, type NotedSlots, type SlotsCodec } from "./codec";
 import type { AnyCultCacheDocumentDefinition, CultCacheDocumentFormatter } from "./types";
 import { readWire, writeWire } from "./wire";
 
@@ -16,6 +16,13 @@ export function resolveDocumentFormatter(definition: AnyCultCacheDocumentDefinit
   return definition.formatter ?? (definition.codec ? codecFormatter(definition.codec) : plainDocumentFormatter);
 }
 
+// The one decode of a document's bytes, with the slots it read past. A plain formatter or a user formatter has no slot codec
+// and carries everything, so it notes nothing.
+export function decodeMarked(definition: AnyCultCacheDocumentDefinition, bytes: Uint8Array): { value: unknown; unreadSlots?: NotedSlots } {
+  const formatter = resolveDocumentFormatter(definition);
+  return decodeNoting(() => formatter.decode(bytes));
+}
+
 const plainDocumentFormatter: CultCacheDocumentFormatter<unknown> = {
   // The encoder's own depth refusal (100 by default) is set above the limit, so the payload walk decides.
   encode: (value: unknown) => encode(value, { maxDepth: MAX_PAYLOAD_DEPTH * 2 }),

packages/cultcache-ts/src/document.ts

@@ -1,5 +1,6 @@
-import { resolveDocumentFormatter } from "./document-formatter";
-import { checkPayloadDepth } from "./payload-depth";
+import type { NotedSlots } from "./codec";
+import { decodeMarked, resolveDocumentFormatter } from "./document-formatter";
+import { checkPayloadDepth, checkPayloadIsOneValue } from "./payload-depth";
 import type {
   AnyCultCacheDocumentDefinition,
   CultCacheSchemaCatalogMember,
@@ -118,10 +119,24 @@ export function decodeDocumentPayload<TDefinition extends AnyCultCacheDocumentDe
   definition: TDefinition,
   payload: DocumentPayload,
 ): CultCacheDocumentValue<TDefinition> {
+  return decodeDocumentPayloadMarked(definition, payload).value;
+}
+
+// The same read with the slots it read past (cult-cache-ts slot-readonly). The depth check runs first: a payload past the
+// limit is refused, never marked.
+export function decodeDocumentPayloadMarked<TDefinition extends AnyCultCacheDocumentDefinition>(
+  definition: TDefinition,
+  payload: DocumentPayload,
+): { value: CultCacheDocumentValue<TDefinition>; unreadSlots?: NotedSlots } {
   const bytes = documentPayloadBytes(payload);
-  if (writesLibraryMessagePack(definition)) checkPayloadDepth(bytes, `document type "${definition.type}" payload`);
-  const decoded = resolveDocumentFormatter(definition).decode(bytes);
-  return definition.schema.parse(decoded) as CultCacheDocumentValue<TDefinition>;
+  if (writesLibraryMessagePack(definition)) {
+    // A payload is exactly one MessagePack value: bytes after the first are refused by count before any formatter reads,
+    // so a tail is refused before any slot is marked.
+    checkPayloadIsOneValue(bytes, `document type "${definition.type}" payload`);
+  }
+  const { value: decoded, unreadSlots } = decodeMarked(definition, bytes);
+  const value = definition.schema.parse(decoded) as CultCacheDocumentValue<TDefinition>;
+  return unreadSlots ? { value, unreadSlots } : { value };
 }
 
 // The one writer: the definition's schema first, then its formatter, codec or plain map.

packages/cultcache-ts/src/index.ts

@@ -1,2 +1,3 @@
 export * from "./browser";
 export { SingleFileMessagePackBackingStore, readSingleFileStore, type SingleFileStoreRead } from "./single-file-messagepack-backing-store";
+export { StoreLinkedError } from "./store-file";

packages/cultcache-ts/src/payload-depth.ts

@@ -12,8 +12,9 @@ export class CultCachePayloadDepthError extends Error {
 
 // Walks the headers of one MessagePack value iteratively (a count stack bounded by the limit, scalars skipped by length,
 // nothing read) and throws at the first container past the limit. The message names the subject, the depth and the limit,
-// never payload bytes. A payload that ends early is the reader's to refuse.
-export function checkPayloadDepth(bytes: Uint8Array, subject = "document payload"): void {
+// never payload bytes. Returns the offset where the first value ends, or undefined when the payload ends early (the
+// reader's to refuse); what follows that offset is never walked, and whether it may exist is the caller's rule.
+export function checkPayloadDepth(bytes: Uint8Array, subject = "document payload"): number | undefined {
   const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
   const remaining = new Float64Array(MAX_PAYLOAD_DEPTH);
   let depth = 0;
@@ -33,12 +34,12 @@ export function checkPayloadDepth(bytes: Uint8Array, subject = "document payload
     else if (code <= 0x8f) { container = true; header = 1; children = 2 * (code & 0x0f); }
     else if (code <= 0x9f) { container = true; header = 1; children = code & 0x0f; }
     else if (code <= 0xbf) skip = 1 + (code & 0x1f);
-    else if (code === 0xc4 || code === 0xd9) { const n = width(1); if (n === undefined) return; skip = 2 + n; }
-    else if (code === 0xc5 || code === 0xda) { const n = width(2); if (n === undefined) return; skip = 3 + n; }
-    else if (code === 0xc6 || code === 0xdb) { const n = width(4); if (n === undefined) return; skip = 5 + n; }
-    else if (code === 0xc7) { const n = width(1); if (n === undefined) return; skip = 3 + n; }
-    else if (code === 0xc8) { const n = width(2); if (n === undefined) return; skip = 4 + n; }
-    else if (code === 0xc9) { const n = width(4); if (n === undefined) return; skip = 6 + n; }
+    else if (code === 0xc4 || code === 0xd9) { const n = width(1); if (n === undefined) return undefined; skip = 2 + n; }
+    else if (code === 0xc5 || code === 0xda) { const n = width(2); if (n === undefined) return undefined; skip = 3 + n; }
+    else if (code === 0xc6 || code === 0xdb) { const n = width(4); if (n === undefined) return undefined; skip = 5 + n; }
+    else if (code === 0xc7) { const n = width(1); if (n === undefined) return undefined; skip = 3 + n; }
+    else if (code === 0xc8) { const n = width(2); if (n === undefined) return undefined; skip = 4 + n; }
+    else if (code === 0xc9) { const n = width(4); if (n === undefined) return undefined; skip = 6 + n; }
     else if (code === 0xca || code === 0xce || code === 0xd2) skip = 5;
     else if (code === 0xcb || code === 0xcf || code === 0xd3) skip = 9;
     else if (code === 0xcc || code === 0xd0) skip = 2;
@@ -47,10 +48,10 @@ export function checkPayloadDepth(bytes: Uint8Array, subject = "document payload
     else if (code === 0xd6) skip = 6;
     else if (code === 0xd7) skip = 10;
     else if (code === 0xd8) skip = 18;
-    else if (code === 0xdc) { const n = width(2); if (n === undefined) return; container = true; header = 3; children = n; }
-    else if (code === 0xdd) { const n = width(4); if (n === undefined) return; container = true; header = 5; children = n; }
-    else if (code === 0xde) { const n = width(2); if (n === undefined) return; container = true; header = 3; children = 2 * n; }
-    else { const n = width(4); if (n === undefined) return; container = true; header = 5; children = 2 * n; }
+    else if (code === 0xdc) { const n = width(2); if (n === undefined) return undefined; container = true; header = 3; children = n; }
+    else if (code === 0xdd) { const n = width(4); if (n === undefined) return undefined; container = true; header = 5; children = n; }
+    else if (code === 0xde) { const n = width(2); if (n === undefined) return undefined; container = true; header = 3; children = 2 * n; }
+    else { const n = width(4); if (n === undefined) return undefined; container = true; header = 5; children = 2 * n; }
 
     if (container) {
       if (depth === MAX_PAYLOAD_DEPTH) throw new CultCachePayloadDepthError(MAX_PAYLOAD_DEPTH + 1, MAX_PAYLOAD_DEPTH, subject);
@@ -63,8 +64,20 @@ export function checkPayloadDepth(bytes: Uint8Array, subject = "document payload
       position += skip;
     }
 
+    // A scalar whose declared length runs past the payload is an early end, not a value.
+    if (position > bytes.length) return undefined;
     // One element is complete; close every container it was the last element of.
     while (depth > 0 && --remaining[depth - 1] === 0) depth--;
-    if (depth === 0) return;
+    if (depth === 0) return position;
   }
+  return undefined;
+}
+
+// The one rule that a payload is exactly one MessagePack value: the depth walk, then a refusal of bytes after the first
+// value, by count, naming the subject, from the walk's end. The tail is never walked or echoed; a payload that ends early
+// stays the decoder's to refuse. decodeDocumentPayload and the inspector speak this clause and no other.
+export function checkPayloadIsOneValue(bytes: Uint8Array, subject: string): number | undefined {
+  const end = checkPayloadDepth(bytes, subject);
+  if (end !== undefined && end < bytes.length) throw new Error(`${subject} has ${bytes.length - end} bytes after its first MessagePack value.`);
+  return end;
 }

packages/cultcache-ts/src/single-file-messagepack-backing-store.ts

@@ -7,7 +7,7 @@ import { z } from "zod";
 
 import { documentPayloadBytes, documentPayloadFromBytes } from "./document";
 import { commitStoreFile, withStoreWriteLock } from "./store-file";
-import { STORE_FORMAT_VERSION, SchemaConflictError, type StoreFormat, StoreUnreadableError, isStoreSnapshot, refuseUnreadStoreBytes, requireStoreSlots, requireV1RecordSlots } from "./store-format";
+import { STORE_FORMAT_VERSION, SchemaConflictError, type StoreFormat, StoreUnreadableError, isStoreSnapshot, refuseUnreadStoreBytes, requireStoreSlots, requireV1RecordSlots, schemaIdForEnvelope, writtenOwns } from "./store-format";
 import type {
   CacheBackingStore,
   CultCacheEnvelope,
@@ -71,8 +71,10 @@ export class SingleFileMessagePackBackingStore implements CacheBackingStore {
       const disk = this.#readDisk();
       this.#format = disk.format;
       const existing = disk.envelopes;
+      // The record the file stores at the key is the one removed when the removal's schema owns its stored id: the
+      // arrived record's type is its schema's name, which a type of another name does not carry.
       const filtered = existing.filter(
-        (candidate) => !(candidate.type === entry.type && candidate.key === entry.key),
+        (candidate) => !(candidate.key === entry.key && (schemaIdForEnvelope(candidate) === schemaIdForEnvelope(entry) || writtenOwns(entry, schemaIdForEnvelope(candidate)))),
       );
       await this.#writeAll([], filtered);
     });
@@ -80,31 +82,24 @@ export class SingleFileMessagePackBackingStore implements CacheBackingStore {
 
   async pushAll(entries: CultCacheEnvelope[], options: PushAllOptions = {}): Promise<void> {
     await this.#enqueue(async () => {
-      // A flush of the whole store writes the header the file on disk carries, read now: a file marked for element ids
-      // stays marked, and one that is not (or is gone or legacy) is written unmarked. The file is read by the same
-      // reader as `pullAll`, so one it would refuse (not exactly one store, a variant, a body it cannot decode) is refused
-      // and left as it is. A soft flush asks that reader too: nothing at the path is written, a store is left alone.
-      try {
-        const disk = this.#readDisk();
-        if (options.soft && !disk.absent) {
-          return;
-        }
-
-        this.#format = disk.format;
-      } catch (error) {
-        // Only a dangling link reaches here with ENOENT: it holds no store, so a whole-store flush has no header to keep and
-        // replaces the link (R3 pins this). A soft flush does not replace what it cannot read, and every merging writer
-        // has already refused the link when it read the current entries.
-        if (options.soft || (error as NodeJS.ErrnoException).code !== "ENOENT") {
-          throw error;
-        }
-
-        this.#format = STORE_FORMAT_VERSION;
+      // A flush writes `entries` onto the store as it is under the lock, the way a push does: a record under the same key
+      // is replaced and no other is removed, so a cache whose image is stale (or empty, never pulled) cannot drop what
+      // another writer added. The store is read by the same reader as `pullAll`, so one it would refuse (not exactly one
+      // store, a variant, a body it cannot decode) is refused and left as it is. A soft flush asks that reader too: nothing
+      // at the path is written, a store is left alone.
+      // The reader owns the verdict on what is at the path: a dangling link is refused here as it is for open and push.
+      const disk = this.#readDisk();
+      if (options.soft && !disk.absent) {
+        return;
       }
 
-      requireOneTypePerKey(this.filePath, entries, []);
+      this.#format = disk.format;
+      const held = disk.envelopes;
+
       // A key is held once: of same-type entries sharing a key in one batch, the last is kept.
-      await this.#writeAll([...new Map(entries.map((entry) => [entry.key, entry])).values()], []);
+      const supplied = [...new Map(entries.map((entry) => [entry.key, entry])).values()];
+      requireOneTypePerKey(this.filePath, entries, held);
+      await this.#writeAll(supplied, held);
     });
   }
 
@@ -138,14 +133,6 @@ export class SingleFileMessagePackBackingStore implements CacheBackingStore {
   }
 }
 
-// As C# WrittenOwns' declared half: the written type owns the stored schema id when its catalog entry carries that id as its own
-// or lists it compatible, so a type renamed under a stable id restamps the record it already holds. (The C# half that lets an
-// undeclared older id of the same schema name through when it reads whole is not ported; a same-named type keeps passing.)
-function writtenOwns(written: CultCacheEnvelope, storedId: string): boolean {
-  const entry = written.catalogEntry;
-  return entry !== undefined && (entry.schemaId === storedId || (entry.compatibleSchemaIds ?? []).includes(storedId));
-}
-
 // A store holds a key once, and the reader refuses a file that holds it twice, so a write that would put a second type under a
 // key (against a record on disk, or within its own batch) is refused before anything is written. Retyping a record is a delete
 // of the old type followed by a put of the new one.
@@ -383,10 +370,6 @@ function defaultEntryFor(entry: CultCacheEnvelope): CultCacheSchemaCatalogEntry
   };
 }
 
-function schemaIdForEnvelope(entry: CultCacheEnvelope): string {
-  return entry.schemaId ?? entry.type;
-}
-
 function encodeCatalogEntry(entry: CultCacheSchemaCatalogEntry): unknown[] {
   return [
     entry.schemaId,

packages/cultcache-ts/src/store-file.ts

@@ -5,7 +5,7 @@
 // lazily inside `loadKernel`, so a consumer that never writes a store never loads it.
 
 import { closeSync, openSync, constants as fsConstants } from "node:fs";
-import { mkdir, open, rename, rm } from "node:fs/promises";
+import { lstat, mkdir, open, rename, rm } from "node:fs/promises";
 import type { FileHandle } from "node:fs/promises";
 import { dirname } from "node:path";
 
@@ -25,6 +25,30 @@ export class StoreReplacedNotDurableError extends Error {
   }
 }
 
+/** Thrown when a write is asked of a store path that is a link: a replace there would swap the link for a regular file. */
+export class StoreLinkedError extends Error {
+  constructor(readonly path: string) {
+    super(`CultCache store ${path} is a link, and a write at it would replace the link; configure the link's target as the store path.`);
+    this.name = "StoreLinkedError";
+  }
+}
+
+/** Refuses a link at the store path (file or directory link; libuv reports Windows junctions as links). Absent is not a link. */
+export async function refuseLinkedStore(storePath: string): Promise<void> {
+  let linked = false;
+  try {
+    linked = (await lstat(storePath)).isSymbolicLink();
+  } catch (error) {
+    if ((error as NodeJS.ErrnoException).code !== "ENOENT") {
+      throw error;
+    }
+  }
+
+  if (linked) {
+    throw new StoreLinkedError(storePath);
+  }
+}
+
 /** The file operations of one commit. Tests record or fail them; production uses `nodeStoreFileOps`. */
 export interface StoreFileOps {
   createExclusive(path: string): Promise<FileHandle>;
@@ -177,6 +201,7 @@ export async function withStoreWriteLock<T>(
 ): Promise<T> {
   const lockPath = `${storePath}.lock`;
   const timeoutMs = options.timeoutMs ?? LOCK_TIMEOUT_MS;
+  await refuseLinkedStore(storePath);
   await mkdir(dirname(lockPath), { recursive: true });
 
   const started = Date.now();
@@ -193,6 +218,8 @@ export async function withStoreWriteLock<T>(
   }
 
   try {
+    // A link may have been put at the path while the lock was awaited; the look above only saw the path before.
+    await refuseLinkedStore(storePath);
     return await operation();
   } finally {
     release();

packages/cultcache-ts/src/store-format.ts

@@ -1,5 +1,7 @@
 import { decode } from "@msgpack/msgpack";
 
+import type { CultCacheEnvelope, CultCacheUnreadSlots } from "./types";
+
 export const STORE_FORMAT_VERSION = "cultcache.store.v1";
 
 /**
@@ -81,13 +83,16 @@ export class SchemaConflictError extends Error {
   readonly schemaId: string;
   readonly schemaNames: string[];
   readonly recordKey: string;
+  /** Set when the refusal is for unread slots; undefined for every other refusal. */
+  readonly unreadSlots?: CultCacheUnreadSlots;
 
-  constructor(schemaId: string, schemaNames: string[], recordKey: string, message?: string) {
+  constructor(schemaId: string, schemaNames: string[], recordKey: string, message?: string, unreadSlots?: CultCacheUnreadSlots) {
     super(message ?? `Schema id "${schemaId}" cannot describe record "${recordKey}": ${schemaNames.map((name) => `"${name}"`).join(", ")}.`);
     this.name = "SchemaConflictError";
     this.schemaId = schemaId;
     this.schemaNames = schemaNames;
     this.recordKey = recordKey;
+    this.unreadSlots = unreadSlots;
   }
 }
 
@@ -151,3 +156,19 @@ export function requireStoreSlots(decoded: unknown[]): void {
     throw new Error(`CultCache store has ${decoded.length} top-level slots; this runtime reads ${STORE_SLOTS} (header, schema catalog, records).`);
   }
 }
+
+/** The schema id a record is stored under: the one it carries, else its type. */
+export function schemaIdForEnvelope(entry: CultCacheEnvelope): string {
+  return entry.schemaId ?? entry.type;
+}
+
+/**
+ * As C# WrittenOwns' declared half: the written type owns the stored schema id when its catalog entry carries that id as its own
+ * or lists it compatible, so a type renamed under a stable id restamps the record it already holds. (The C# half that lets an
+ * undeclared older id of the same schema name through when it reads whole is not ported; a same-named type keeps passing.)
+ * The one predicate of the key-identity rule: the store judges the file with it and the cache judges what it holds.
+ */
+export function writtenOwns(written: CultCacheEnvelope, storedId: string): boolean {
+  const entry = written.catalogEntry;
+  return entry !== undefined && (entry.schemaId === storedId || (entry.compatibleSchemaIds ?? []).includes(storedId));
+}

packages/cultcache-ts/src/types.ts

@@ -99,6 +99,26 @@ export interface CultCacheEnvelope {
   catalogEntry?: CultCacheSchemaCatalogEntry;
 }
 
+/**
+ * What a payload decode found past the slots this build declares, at any depth: the first type read with extra slots, how many
+ * slots it carried against how many it declares, and how many objects in the record did. It holds no slot value, so a refusal
+ * can name it. A record carrying it is read-only unless `explained`.
+ */
+export interface CultCacheUnreadSlots {
+  /** The first type read with extra slots (the unit arm's arm name for a unit arm). */
+  readonly typeName: string;
+  readonly slotCount: number;
+  readonly declaredCount: number;
+  readonly occurrences: number;
+  /** True when every mark sat in the document's own object. */
+  readonly depth0Only: boolean;
+  /**
+   * True only when every mark is at depth 0 and the schema comparison of the id the record was stored under reported every slot
+   * the mark carries (slotCount is at most the highest reported slot plus one): the loss a compatible-id declaration consents to.
+   */
+  readonly explained: boolean;
+}
+
 export interface PushAllOptions {
   soft?: boolean;
 }

packages/cultcache-ts/src/wire.ts

@@ -128,7 +128,6 @@ export function readWire(payload: Uint8Array): unknown {
     }
   }
 
-  const tree = next();
-  if (offset !== payload.length) throw new Error("the MessagePack payload has bytes after its value.");
-  return tree;
+  // One value is read; the caller owns what follows it (decodeDocumentPayload refuses a payload with a tail).
+  return next();
 }

packages/cultcache-ts/test/cult-cache.test.ts

@@ -15,6 +15,7 @@ import { CultCache } from "../src/cult-cache";
 import { inspectCultCacheBytes } from "../src/cult-cache-inspector";
 import { defineDocumentRegistry, defineDocumentType, documentPayloadBytes, documentPayloadFromBytes } from "../src/document";
 import { SingleFileMessagePackBackingStore, readSingleFileStore, readStoreBytes } from "../src/single-file-messagepack-backing-store";
+import { StoreLinkedError, withStoreWriteLock } from "../src/store-file";
 import { SchemaConflictError, StoreUnreadableError, refuseUnreadStoreBytes } from "../src/store-format";
 import type { AnyCultCacheDocumentDefinition, CacheBackingStore, CultCacheEnvelope, CultCacheSchema } from "../src/types";
 
@@ -33,8 +34,7 @@ const cultcacheRsRoot = existsSync(resolve(cultLibRoot, "packages", "cultcache-r
   ? resolve(cultLibRoot, "packages", "cultcache-rs")
   : resolve(cultCacheTsRoot, "..", "cultcache-rs");
 const rustInteropBinary = resolve(
-  cultcacheRsRoot,
-  "target",
+  process.env.CARGO_TARGET_DIR ?? resolve(cultcacheRsRoot, "target"),
   "debug",
   "examples",
   process.platform === "win32" ? "cultcache_interop.exe" : "cultcache_interop",
@@ -266,10 +266,10 @@ test("CultCache fails closed on unknown or illegal persisted polymorphic state",
     ]))
     .build();
 
-  await assert.rejects(
-    async () => cacheWithUnknownType.pullAllBackingStores(),
-    /No schema is registered for persisted document type "forbidden"\./,
-  );
+  // A record no registered type claims is carried, not a reason to refuse the load.
+  await cacheWithUnknownType.pullAllBackingStores();
+  assert.deepEqual(cacheWithUnknownType.snapshot(), []);
+  assert.deepEqual(cacheWithUnknownType.foreignRecords().map((record) => [record.key, record.schemaName]), [["mystery", "forbidden"]]);
 
   const cacheWithDuplicateGlobal = CultCache.builder()
     .withDocumentType(settingsDocument)
@@ -1019,6 +1019,7 @@ test("legacyKeyGlobalLoadsWithoutWritingAndFirstWriteLeavesOneGlobal", async ()
   assert.deepEqual(reloaded.getRequiredGlobal(settingsDocument), { t: "new" });
 
   // Deleting an adopted global removes the legacy record.
+  await rm(storePath);
   await new SingleFileMessagePackBackingStore(storePath).pushAll([legacy]);
   const deleting = build();
   await deleting.pullAllBackingStores();
@@ -1026,10 +1027,30 @@ test("legacyKeyGlobalLoadsWithoutWritingAndFirstWriteLeavesOneGlobal", async ()
   assert.deepEqual(await new SingleFileMessagePackBackingStore(storePath).pullAll(), []);
 
   // Two globals of one type on disk, under any keys, are refused.
+  await rm(storePath);
   await new SingleFileMessagePackBackingStore(storePath).pushAll([legacy, { ...legacy, key: CultCache.GLOBAL_KEY }]);
   await assert.rejects(build().pullAllBackingStores(), /has multiple persisted entries/u);
 });
 
+test("a flush of a cache that loaded a legacy-key global leaves the store reopenable", async () => {
+  const settingsDocument = defineDocumentType({ type: "settings", schema: z.object({ t: z.string() }), global: true });
+  const storePath = join(await mkdtemp(join(tmpdir(), "cultcache-legacy-flush-")), "generic.cc");
+  const store = new SingleFileMessagePackBackingStore(storePath);
+  const build = () => CultCache.builder().withRegistry(defineDocumentRegistry(settingsDocument)).withGenericStore(store).build();
+  const seed = CultCache.builder().withRegistry(defineDocumentRegistry(settingsDocument)).build();
+  await seed.putGlobal(settingsDocument, { t: "old" });
+  await store.push({ ...seed.getRequiredEnvelope(settingsDocument, CultCache.GLOBAL_KEY), key: "legacy" });
+
+  const cache = build();
+  await cache.pullAllBackingStores();
+  assert.equal(cache.snapshot()[0]!.key, CultCache.GLOBAL_KEY, "the logical image names the global by the global key");
+  await store.pushAll(cache.storedSnapshot());
+  assert.deepEqual((await store.pullAll()).map((entry) => entry.key), ["legacy"], "the flush wrote the record under the key the store holds it");
+  const reopened = build();
+  await reopened.pullAllBackingStores();
+  assert.deepEqual(reopened.getRequiredGlobal(settingsDocument), { t: "old" });
+});
+
 test("concurrentPutAndAttachCannotLandRecordInNonHomeStore", async () => {
   const settingsDocument = defineDocumentType({ type: "settings", schema: z.object({ t: z.string() }) });
   const tempDir = await mkdtemp(join(tmpdir(), "cultcache-put-attach-race-"));
@@ -1252,6 +1273,48 @@ test("CultCache v1 MessagePack stores are readable across TS, Rust, C#, and Pyth
   }
 });
 
+// A Bifrost-shaped store (a union field, nested bytes) written by one of C# and Rust is opened by the other: C# reads through
+// its store, Rust through the read-only snapshot door, which takes no lock and writes nothing. Leftover staging files from an
+// interrupted write of either runtime sit beside the store; a read neither deletes them nor lets them change what it reads, and
+// the store file's bytes are the same after every read.
+test("A store written by C# or Rust with a union and nested bytes is read back equal by the other, read-only, past leftover staging files", async () => {
+  await buildInteropPeers();
+  const tempDir = await mkdtemp(join(tmpdir(), "cultcache-shapes-"));
+  const rustRead = (file: string) => runJsonCommand("rust-read-shapes", rustInteropBinary, ["read-shapes", "--file", file], cultcacheRsRoot);
+  const csharpRead = (file: string) => runJsonCommand("csharp-read-shapes", dotnetCommand, [csharpInteropDll, "read-shapes", "--file", file], cultLibRoot);
+  const peers = [
+    {
+      writer: "csharp",
+      write: (file: string) => runJsonCommand("csharp-write-shapes", dotnetCommand, [csharpInteropDll, "write-shapes", "--file", file], cultLibRoot),
+      read: rustRead,
+    },
+    {
+      writer: "rust",
+      write: (file: string) => runJsonCommand("rust-write-shapes", rustInteropBinary, ["write-shapes", "--file", file], cultcacheRsRoot),
+      read: csharpRead,
+    },
+  ];
+  for (const { writer, write, read } of peers) {
+    const file = join(tempDir, `${writer}.cc`);
+    const written = await write(file);
+    assert.equal(written.length, 2);
+    // The leftovers an interrupted write leaves: C# stages as `.<name>.<guid N>.tmp`, Rust as `<name>.<guid>.tmp`; both hold partial bytes.
+    const leftovers = [
+      join(tempDir, `.${writer}.cc.0123456789abcdef0123456789abcdef.tmp`),
+      join(tempDir, `${writer}.cc.00000000-0000-4000-8000-000000000000.tmp`),
+    ];
+    for (const leftover of leftovers) {
+      await writeFile(leftover, Buffer.from([0x93, 0xb2]));
+    }
+    const before = await readFile(file);
+    assert.deepEqual(await read(file), written, `${writer}'s store did not read back equal`);
+    assert.deepEqual(await readFile(file), before, `reading ${writer}'s store changed its bytes`);
+    for (const leftover of leftovers) {
+      assert.ok(await exists(leftover), `reading ${writer}'s store removed ${leftover}`);
+    }
+  }
+});
+
 // Records and catalog entries a runtime does not own survive its writes. C# writes a store and each other runtime writes its own
 // note into it: C# reads its note back, and its record and catalog entry are as C# wrote them. C# then writes again, and the other
 // runtime's record and catalog entry are as that runtime wrote them. Identity is compared on the decoded MessagePack values, every
@@ -2043,7 +2106,7 @@ async function readTsInteropStore(file: string): Promise<InteropNote> {
 
 async function buildInteropPeers(): Promise<void> {
   if (!(await exists(rustInteropBinary))) {
-    await execAsync(`"${cargoCommand}" build --quiet --example cultcache_interop`, {
+    await execAsync(`"${cargoCommand}" build --locked --quiet --example cultcache_interop`, {
       cwd: cultcacheRsRoot,
     });
   }
@@ -2261,7 +2324,7 @@ test("a stamp this runtime reads, followed by bytes that are not UTF-8, gets the
   }
 });
 
-test("pushAll leaves a store it reads alone when soft, and replaces one it reads otherwise", async () => {
+test("pushAll leaves a store it reads alone when soft, and writes onto one it reads otherwise", async () => {
   const vector = await readFile(resolve(cultLibRoot, "tests", "vectors", "document-variants-c2a", "v3-base.msgpack"));
   const envelope = { key: "probe", type: "probe", payload: documentPayloadFromBytes(new Uint8Array([0x80])), storedAt: "2026-10-22T00:00:00Z" };
   const existing = join(await mkdtemp(join(tmpdir(), "cultcache-pushall-soft-")), "store.msgpack");
@@ -2273,7 +2336,7 @@ test("pushAll leaves a store it reads alone when soft, and replaces one it reads
   const store = new SingleFileMessagePackBackingStore(own);
   await store.pushAll([envelope]);
   await store.pushAll([{ ...envelope, key: "second" }]);
-  assert.deepEqual((await store.pullAll()).map((entry) => entry.key), ["second"]);
+  assert.deepEqual((await store.pullAll()).map((entry) => entry.key), ["probe", "second"]);
 });
 
 test("SingleFileMessagePackBackingStore reads only a missing store as empty", async () => {
@@ -2404,12 +2467,36 @@ test("SingleFileMessagePackBackingStore refuses a dangling symlink at its path a
     () => store.pullAll(),
     (error: NodeJS.ErrnoException) => error.code === "ENOENT" && error.message.includes("symbolic link") && error.message.includes(file),
   );
-  await assert.rejects(() => store.push(envelope), (error: NodeJS.ErrnoException) => error.code === "ENOENT");
-  await assert.rejects(() => store.pushAll([envelope], { soft: true }), (error: NodeJS.ErrnoException) => error.code === "ENOENT");
+  await assert.rejects(() => store.push(envelope), (error: unknown) => error instanceof StoreLinkedError);
+  await assert.rejects(() => store.pushAll([envelope], { soft: true }), (error: unknown) => error instanceof StoreLinkedError);
   assert.ok((await lstat(file)).isSymbolicLink());
   assert.deepEqual(await readdir(volume), []);
 });
 
+// The advisory query answers for the held record and the cache's judges; a link at the store path is the write's to refuse.
+test("isWritable over a store at a live link answers true while the cache write is refused", { skip: process.platform === "win32" }, async () => {
+  const dir = await mkdtemp(join(tmpdir(), "cultcache-writable-link-"));
+  const volume = join(dir, "volume");
+  await mkdir(volume);
+  const target = join(volume, "store.cc");
+  const link = join(dir, "link.cc");
+  const document = defineDocumentType({ type: "note", schema: z.object({ text: z.string() }) });
+  await CultCache.builder().withDocumentType(document).withGenericStore(new SingleFileMessagePackBackingStore(target)).build()
+    .put(document, "held", { text: "held" });
+  const before = await readFile(target);
+  await symlink(target, link);
+  const cache = CultCache.builder().withDocumentType(document).withGenericStore(new SingleFileMessagePackBackingStore(link)).build();
+  await cache.pullAllBackingStores();
+  const namesBefore = [(await readdir(dir)).sort(), (await readdir(volume)).sort()];
+
+  assert.equal(cache.isWritable(document, "held"), true);
+  assert.equal(cache.isWritable(document, "fresh"), true);
+  await assert.rejects(() => cache.put(document, "fresh", { text: "fresh" }), (error: unknown) => error instanceof StoreLinkedError && error.path === link);
+  assert.ok((await lstat(link)).isSymbolicLink());
+  assert.deepEqual(await readFile(target), before);
+  assert.deepEqual([(await readdir(dir)).sort(), (await readdir(volume)).sort()], namesBefore);
+});
+
 // The second look of the read, staged: nothing is at the path only when the read and the lstat both find nothing. A path
 // that changed between them (a link in a parent swapped for a file, a store that appeared) is never an empty store.
 test("readStoreBytes reports nothing at the path only when the lstat finds nothing too", async () => {
@@ -2446,9 +2533,9 @@ test("SingleFileMessagePackBackingStore record refusal names only a string key",
   }
 });
 
-// What a write does through a symbolic link today. R3 decides whether a write resolves the link
-// or refuses it; these pin the current behaviour so that change is deliberate.
-test("R3 decides resolve-or-refuse: a push through a live link replaces the link", { skip: process.platform === "win32" }, async () => {
+// A write at a store path that is a link is refused: a replace there would swap the link for a regular file and
+// detach the store from its target. Reads through a live link keep working.
+test("a write at a live link is refused and nothing changes, while a read through it still works", { skip: process.platform === "win32" }, async () => {
   const dir = await mkdtemp(join(tmpdir(), "cultcache-live-link-"));
   const volume = join(dir, "volume");
   await mkdir(volume);
@@ -2456,21 +2543,42 @@ test("R3 decides resolve-or-refuse: a push through a live link replaces the link
   const envelope = { key: "a", type: "t", payload: documentPayloadFromBytes(Uint8Array.of(0x90)), storedAt: "2026-09-30T00:00:00Z" };
   await new SingleFileMessagePackBackingStore(target).push(envelope);
   const before = await readFile(target);
-  const link = join(dir, "store.cc");
+  const volumeBefore = (await readdir(volume)).sort();
+  const link = join(dir, "link.cc");
   await symlink(target, link);
-  await new SingleFileMessagePackBackingStore(link).push({ ...envelope, key: "b" });
-  assert.ok((await lstat(link)).isFile());
+  const store = new SingleFileMessagePackBackingStore(link);
+  const refused = (error: unknown) => error instanceof StoreLinkedError && error.path === link && error.message.includes(link);
+  await assert.rejects(() => store.push({ ...envelope, key: "b" }), refused);
+  await assert.rejects(() => store.pushAll([{ ...envelope, key: "b" }]), refused);
+  await assert.rejects(() => store.delete(envelope), refused);
+  assert.ok((await lstat(link)).isSymbolicLink());
   assert.deepEqual(await readFile(target), before);
+  assert.deepEqual((await readdir(dir)).sort(), ["link.cc", "volume"]);
+  assert.deepEqual((await readdir(volume)).sort(), volumeBefore);
+  assert.deepEqual((await store.pullAll()).map((e) => e.key), ["a"]);
 });
 
-test("R3 decides resolve-or-refuse: a pushAll through a dangling link replaces the link", { skip: process.platform === "win32" }, async () => {
+test("a write at a live directory link is refused as a link", { skip: process.platform === "win32" }, async () => {
+  const dir = await mkdtemp(join(tmpdir(), "cultcache-dir-link-"));
+  const realDir = join(dir, "real");
+  await mkdir(realDir);
+  const link = join(dir, "dirlink");
+  await symlink(realDir, link);
+  const envelope = { key: "a", type: "t", payload: documentPayloadFromBytes(Uint8Array.of(0x90)), storedAt: "2026-09-30T00:00:00Z" };
+  await assert.rejects(() => new SingleFileMessagePackBackingStore(link).push(envelope), (error: unknown) => error instanceof StoreLinkedError);
+  assert.ok((await lstat(link)).isSymbolicLink());
+  assert.deepEqual(await readdir(realDir), []);
+});
+
+test("a pushAll through a dangling link is refused like push, and the link and its volume are left as they were", { skip: process.platform === "win32" }, async () => {
   const dir = await mkdtemp(join(tmpdir(), "cultcache-dangling-push-all-"));
   const volume = join(dir, "volume");
   await mkdir(volume);
   const link = join(dir, "store.cc");
   await symlink(join(volume, "store.cc"), link);
-  await new SingleFileMessagePackBackingStore(link).pushAll([{ key: "a", type: "t", payload: documentPayloadFromBytes(Uint8Array.of(0x90)), storedAt: "2026-09-30T00:00:00Z" }]);
-  assert.ok((await lstat(link)).isFile());
+  const envelope = { key: "a", type: "t", payload: documentPayloadFromBytes(Uint8Array.of(0x90)), storedAt: "2026-09-30T00:00:00Z" };
+  await assert.rejects(() => new SingleFileMessagePackBackingStore(link).pushAll([envelope]), (error: unknown) => error instanceof StoreLinkedError);
+  assert.ok((await lstat(link)).isSymbolicLink());
   assert.deepEqual(await readdir(volume), []);
 });
 
@@ -2575,7 +2683,7 @@ test("SingleFileMessagePackBackingStore pushAll refuses a store whose header it
 
 // A file is replaced by a rewrite exactly when this runtime's own reader opens it: one verdict per file, asked by pullAll,
 // pushAll, soft pushAll, push and delete alike; a soft flush leaves the files that read as they are. The bytes and every runtime's verdict: tests/vectors/document-variants-c2a/readability.
-test("SingleFileMessagePackBackingStore replaces a file exactly when it reads", async () => {
+test("SingleFileMessagePackBackingStore rewrites a file exactly when it reads", async () => {
   const root = join(c2aVectors, "readability");
   const rows = (await readFile(join(root, "manifest.txt"), "utf8"))
     .split(/\r?\n/u)
@@ -2612,6 +2720,7 @@ test("SingleFileMessagePackBackingStore replaces a file exactly when it reads",
                 ? store.push(envelopes[0]!)
                 : store.delete(envelopes[0]!);
       if (reads) {
+        const heldBefore = operation === "pushAll" ? (await new SingleFileMessagePackBackingStore(file).pullAll()).map((entry) => entry.key) : [];
         await run();
         if (operation === "pullAll") {
           continue;
@@ -2628,14 +2737,15 @@ test("SingleFileMessagePackBackingStore replaces a file exactly when it reads",
         assert.equal((decode(await readFile(file)) as unknown[])[0], vector.includes("v3") ? "cultcache.store.v3" : "cultcache.store.v1", `${vector} ${operation}`);
         const keys = (await new SingleFileMessagePackBackingStore(file).pullAll()).map((entry) => entry.key);
         if (operation === "pushAll") {
-          assert.deepEqual(keys, envelopes.map((entry) => entry.key).sort(), `${vector} ${operation}`);
+          assert.deepEqual(envelopes.map((entry) => entry.key).filter((key) => !keys.includes(key)), [], `${vector} ${operation}: every written key is held`);
+          assert.deepEqual(heldBefore.filter((key) => !keys.includes(key)), [], `${vector} ${operation}: nothing else is removed`);
         } else if (operation === "push") {
           assert.ok(keys.includes(envelopes[0]!.key), `${vector} ${operation}`);
         } else {
           assert.ok(!keys.includes(envelopes[0]!.key), `${vector} ${operation}`);
         }
       } else if (isDirectory) {
-        await assert.rejects(run, `${vector} ${operation}`);
+        await assert.rejects(run, (error) => !(error instanceof StoreUnreadableError), `${vector} ${operation}: an I/O failure, not a typed refusal`);
         assert.ok((await lstat(file)).isDirectory(), `${vector} ${operation} replaced the directory`);
         assert.deepEqual(await readdir(file), [], `${vector} ${operation} wrote into the directory`);
       } else {
@@ -2653,19 +2763,21 @@ test("SingleFileMessagePackBackingStore replaces a file exactly when it reads",
 // One key is held once: a push whose type does not own the stored schema id is refused, so the writer cannot emit a store its own
 // reader refuses; one whose type owns it (its own id, or one it lists compatible, as C# WrittenOwns) restamps the record in place.
 test("SingleFileMessagePackBackingStore push asks whether the written type owns the stored id, not what the types are called", async () => {
-  const seed = CultCache.builder().withDocumentType(ownsId).withDocumentType(listsId).build();
-  await seed.put(ownsId, "k", { name: "owner" });
-  await seed.put(listsId, "k", { name: "lister" });
+  // One cache holds one record per key, so each envelope is made in a cache of its own.
+  const owner = CultCache.builder().withDocumentType(ownsId).build();
+  const lister = CultCache.builder().withDocumentType(listsId).build();
+  await owner.put(ownsId, "k", { name: "owner" });
+  await lister.put(listsId, "k", { name: "lister" });
   const file = join(await mkdtemp(join(tmpdir(), "cultcache-push-key-")), "store.msgpack");
   const store = new SingleFileMessagePackBackingStore(file);
   const idsOf = async () => ((decode(await readFile(file)) as unknown[][])[2] as unknown[][]).map((record) => [record[0], record[1]]);
 
-  await store.push(seed.getRequiredEnvelope(listsId, "k"));
-  await assert.rejects(() => store.push(seed.getRequiredEnvelope(ownsId, "k")), SchemaConflictError);
+  await store.push(lister.getRequiredEnvelope(listsId, "k"));
+  await assert.rejects(() => store.push(owner.getRequiredEnvelope(ownsId, "k")), SchemaConflictError);
   assert.deepEqual(await idsOf(), [["k", "id.lister"]]);
 
-  await store.pushAll([seed.getRequiredEnvelope(listsId, "k")]);
-  await store.push(seed.getRequiredEnvelope(listsId, "k"));
+  await store.pushAll([lister.getRequiredEnvelope(listsId, "k")]);
+  await store.push(lister.getRequiredEnvelope(listsId, "k"));
   assert.equal((await store.pullAll()).length, 1);
 });
 
@@ -2760,7 +2872,6 @@ test("every registration refusal is a SchemaConflictError naming the id and both
 // Cross-runtime store lock: each runtime's writer excludes the others on `<file>.lock`.
 
 import { spawn } from "node:child_process";
-import { withStoreWriteLock } from "../src/store-file";
 
 type LockHolder = { exited: Promise<number | null>; stderr: () => string };
 

packages/cultcache-ts/test/key-identity-vector.test.ts

@@ -0,0 +1,377 @@
+import assert from "node:assert/strict";
+import { existsSync } from "node:fs";
+import { copyFile, mkdtemp, readFile, rm } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join, resolve } from "node:path";
+import { test } from "node:test";
+
+import { decode, encode } from "@msgpack/msgpack";
+import { z } from "zod";
+
+import { CultCache } from "../src/cult-cache";
+import { defineDocumentType, documentPayloadBytes, documentPayloadFromBytes } from "../src/document";
+import { SingleFileMessagePackBackingStore, readSingleFileStore } from "../src/single-file-messagepack-backing-store";
+import { SchemaConflictError } from "../src/store-format";
+import type { AnyCultCacheDocumentDefinition, CultCacheEnvelope } from "../src/types";
+
+// variants:ruling:cache-refuses-retype, write-ownership-by-written-type, unheld-removal-refused-at-commit. The vectors in
+// tests/vectors/key-identity are written by the C# reference (see its README for the rule and the row shapes); this walks
+// every row against the TS cache. A leaf keeps no verdict of its own.
+
+function findVectors(from: string): string {
+  for (let dir = from; ; dir = resolve(dir, "..")) {
+    if (existsSync(join(dir, "tests", "vectors", "key-identity"))) return join(dir, "tests", "vectors", "key-identity");
+    if (resolve(dir, "..") === dir) throw new Error("tests/vectors/key-identity not found above the test.");
+  }
+}
+const vectors = findVectors(__dirname);
+
+// One string slot [0: Text]; the schema ids are the ones C# wrote (README). The type is the schema name, the name a record
+// read back from a store carries as its type (the store's delete matches on it).
+function kiType(type: string, id: string) {
+  const schemaName = `tests.ki_${type}`;
+  return defineDocumentType({
+    type: schemaName,
+    schemaId: `sha256:${id}`,
+    schemaName,
+    schemaVersion: `${schemaName}.v1`,
+    schema: z.object({ text: z.string() }),
+    formatter: {
+      encode: (value: { text: string }) => encode([value.text]),
+      decode: (payload: Uint8Array) => ({ text: (decode(payload) as [string])[0] }),
+    },
+  });
+}
+const types: Record<string, AnyCultCacheDocumentDefinition> = {
+  alpha: kiType("alpha", "b20703a98f49c253898404ab50ba2c630720f0b8a5e1a41614d5650be22799fe"),
+  beta: kiType("beta", "dee4b727cf2ee04e61ab635ff0c5f3dca7345a411dc5f1018e583ab16009cf94"),
+  gamma: kiType("gamma", "fbc26e351e00c9e7185e8de171c7486aba707c229c949f0aae6b889288af5f6d"),
+};
+
+type Op = [string, ...unknown[]];
+type Row = [string, string[], Op[], [[string] | null, [string, string, string][], [string, string][] | null, string[], string[]]];
+
+const compare = (left: string, right: string) => (left < right ? -1 : left > right ? 1 : 0);
+const textOf = (envelope: CultCacheEnvelope) => (decode(documentPayloadBytes(envelope.payload)) as [string])[0];
+const stored = (path: string) => new Map(readSingleFileStore(path).envelopes.map((e) => [e.key, e]));
+const sameRecord = (left: CultCacheEnvelope | undefined, right: CultCacheEnvelope | undefined) =>
+  left !== undefined && right !== undefined && left.schemaId === right.schemaId && left.storedAt === right.storedAt &&
+  Buffer.compare(Buffer.from(documentPayloadBytes(left.payload)), Buffer.from(documentPayloadBytes(right.payload))) === 0;
+
+test("vectors rows.msgpack: every row's refusal, held records, file, foreign list and kept bytes", async () => {
+  const rows = decode(await readFile(join(vectors, "rows.msgpack"))) as Row[];
+  assert.equal(rows.length, 12);
+  let walked = 0;
+  const failures: string[] = [];
+  for (const [label, registered, ops, expect] of rows) {
+    const dir = await mkdtemp(join(tmpdir(), "ki-"));
+    try {
+      const [refusal, held, file, foreign, kept] = expect;
+      let counter = 0;
+      let path: string | undefined;
+      let cache!: CultCache;
+      let before: Map<string, CultCacheEnvelope> | undefined;
+      const attached: string[] = [];
+      const build = (store: string | undefined) => {
+        let builder = CultCache.builder();
+        for (const name of registered) builder = builder.withDocumentType(types[name]!);
+        if (store !== undefined) builder = builder.withGenericStore(new SingleFileMessagePackBackingStore(store));
+        return builder.build();
+      };
+      const fresh = async (name: string) => {
+        const copy = join(dir, `${counter++}-${name}`);
+        await copyFile(join(vectors, name), copy);
+        return copy;
+      };
+
+      let refused: unknown;
+      let failed = false;
+      let beforeBytes: Buffer | undefined;
+      let beforeCache: CultCacheEnvelope[] = [];
+      let beforeAttached: Buffer[] = [];
+      for (const [index, op] of ops.entries()) {
+        const last = index === ops.length - 1;
+        if (last) {
+          beforeCache = cache?.snapshot() ?? [];
+          beforeAttached = await Promise.all(attached.map((copy) => readFile(copy)));
+          beforeBytes = path !== undefined ? await readFile(path) : undefined;
+        }
+        try {
+          switch (op[0]) {
+            case "open": {
+              const arg = op[1] as string | null;
+              path = arg === "memory" ? undefined : arg === null ? join(dir, "fresh.cc") : await fresh(arg);
+              if (path !== undefined && arg !== null) before = stored(path);
+              cache = build(path);
+              await cache.pullAllBackingStores();
+              break;
+            }
+            case "attach": {
+              const copy = await fresh(op[1] as string);
+              attached.push(copy);
+              await cache.addBackingStore(new SingleFileMessagePackBackingStore(copy), ...(op[2] as string[]).map((name) => types[name]!));
+              await cache.pullAllBackingStores();
+              break;
+            }
+            case "reopen":
+              cache = build(path);
+              await cache.pullAllBackingStores();
+              break;
+            case "put":
+              await cache.put(types[op[1] as string]!, op[2] as string, { text: op[3] as string } as never);
+              break;
+            case "delete":
+              await cache.delete(types[op[1] as string]!, op[2] as string);
+              break;
+            default:
+              assert.fail(`${label}: unknown op ${op[0]}`);
+          }
+        } catch (error) {
+          if (!last) throw error;
+          refused = error;
+          failed = true;
+        }
+      }
+
+      if (refusal === null) {
+        assert.equal(failed, false, `${label}: the last op lands (${String(refused)})`);
+      } else {
+        assert.equal(failed, true, `${label}: the last op is refused`);
+        const [key] = refusal;
+        if (label === "key-in-two-stores-refused") {
+          // The key is read out of the refusal as a delimited token: the message opens "Record <key> is held by" and the key
+          // occurs nowhere else in it (not inside a schema name).
+          const message = (refused as Error).message;
+          const named = /^Record (\S+) is held by/u.exec(message);
+          assert.equal(named?.[1], key, `${label}: the refusal opens with the key`);
+          assert.equal(message.split(/[^A-Za-z0-9_.]+/u).filter((token) => token === key).length, 1, `${label}: the key occurs only as a delimited token`);
+          assert.deepEqual(cache.snapshot(), beforeCache, `${label}: the earlier pulled state survives`);
+          assert.deepEqual(await Promise.all(attached.slice(0, beforeAttached.length).map((copy) => readFile(copy))), beforeAttached, `${label}: the attached files are byte-identical`);
+        } else {
+          assert.ok(refused instanceof SchemaConflictError, `${label}: a typed schema conflict, got ${String(refused)}`);
+          assert.equal((refused as SchemaConflictError).recordKey, key, `${label}: names the key`);
+          assert.deepEqual(cache.snapshot(), beforeCache, `${label}: the cache is unchanged`);
+          if (path !== undefined) assert.deepEqual(await readFile(path), beforeBytes, `${label}: the store is byte-identical`);
+        }
+      }
+
+      assert.deepEqual(
+        cache.snapshot()
+          .map((e) => [e.type.replace("tests.ki_", ""), e.key, textOf(e)] as [string, string, string])
+          .sort((l, r) => compare(l[0], r[0]) || compare(l[1], r[1])),
+        held,
+        `${label}: held`,
+      );
+      if (path === undefined) {
+        assert.equal(file, null, `${label}: no store`);
+      } else {
+        assert.deepEqual(
+          [...stored(path).values()]
+            .map((e) => [e.key, e.catalogEntry?.schemaName ?? e.type] as [string, string])
+            .sort((l, r) => compare(l[0], r[0])),
+          file,
+          `${label}: file`,
+        );
+        if (before !== undefined) {
+          const after = stored(path);
+          assert.deepEqual(foreign.filter((key) => sameRecord(before!.get(key), after.get(key))), kept, `${label}: kept`);
+        }
+      }
+      assert.deepEqual(cache.foreignRecords().map((record: { key: string }) => record.key), foreign, `${label}: foreign`);
+      walked++;
+    } catch (error) {
+      failures.push(`${label}: ${error instanceof Error ? error.message.split("\n")[0] : String(error)}`);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  }
+  assert.deepEqual(failures, [], "every row holds its verdict");
+  assert.equal(walked, 12);
+});
+
+// Beyond the vector: what the walker's string-typed rows cannot say.
+const CANARY = "CANARY-ki-77c1";
+const plain = (type: string, schemaId: string, compatibleSchemaIds?: string[]) =>
+  defineDocumentType({ type, schemaId, schemaName: type, schemaVersion: `${type}.v1`, schema: z.object({ v: z.string() }), ...(compatibleSchemaIds ? { compatibleSchemaIds } : {}) });
+
+test("a refusal names the key and schemas and never echoes the written value", async () => {
+  const alpha = plain("cn.alpha", "cn.alpha.v1");
+  const beta = plain("cn.beta", "cn.beta.v1");
+  const cache = CultCache.builder().withDocumentType(alpha).withDocumentType(beta).build();
+  await cache.put(alpha, "k", { v: "first" });
+  await assert.rejects(cache.put(beta, "k", { v: CANARY }), (error: Error) => {
+    assert.ok(error instanceof SchemaConflictError && error.recordKey === "k");
+    assert.ok(!error.message.includes(CANARY));
+    return true;
+  });
+  assert.deepEqual(cache.get(alpha, "k"), { v: "first" });
+  assert.equal(cache.get(beta, "k"), undefined);
+  await assert.rejects(cache.putEnvelope(beta, { key: "k", type: "cn.beta", payload: documentPayloadFromBytes(encode({ v: CANARY })), storedAt: "2026-01-01T00:00:00Z" }), SchemaConflictError);
+  assert.equal(cache.snapshot().length, 1);
+});
+
+test("a type that owns the held record's id replaces it: one record at the key, no second type held", async () => {
+  const old = plain("cn.old", "cn.id.v1");
+  const renamed = plain("cn.new", "cn.id.v2", ["cn.id.v2", "cn.id.v1"]);
+  const cache = CultCache.builder().withDocumentType(old).withDocumentType(renamed).build();
+  await cache.put(old, "k", { v: "a" });
+  await cache.put(renamed, "k", { v: "b" });
+  assert.deepEqual(cache.snapshot().map((e) => [e.type, e.key]), [["cn.new", "k"]]);
+  assert.equal(cache.get(old, "k"), undefined);
+});
+
+test("a store carrying an unregistered record loads, lists it sorted, keeps it through writes of other keys, and a later registration claims it", async () => {
+  const dir = await mkdtemp(join(tmpdir(), "ki-"));
+  try {
+    const path = join(dir, "s.cc");
+    await copyFile(join(vectors, "foreign-store.cc"), path);
+    const open = (...names: string[]) => {
+      let builder = CultCache.builder();
+      for (const name of names) builder = builder.withDocumentType(types[name]!);
+      return builder.withGenericStore(new SingleFileMessagePackBackingStore(path)).build();
+    };
+    const cache = open("alpha");
+    await cache.pullAllBackingStores();
+    const record = stored(path).get("k")!;
+    assert.deepEqual(cache.foreignRecords(), [
+      { key: "k", schemaId: "sha256:fbc26e351e00c9e7185e8de171c7486aba707c229c949f0aae6b889288af5f6d", schemaName: "tests.ki_gamma", storedAt: record.storedAt },
+    ]);
+    await cache.put(types.alpha!, "z", { text: "z" } as never);
+    await cache.delete(types.alpha!, "j");
+    assert.ok(sameRecord(stored(path).get("k"), record), "the foreign record's stored bytes survive");
+    assert.equal(await cache.delete(types.alpha!, "nobody"), false);
+
+    const claimed = open("alpha", "gamma");
+    await claimed.pullAllBackingStores();
+    assert.deepEqual(claimed.foreignRecords(), []);
+    assert.equal(claimed.snapshot().length, 2);
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+test("a foreign key one store carries and another holds under a registered type refuses the load and admits nothing", async () => {
+  const dir = await mkdtemp(join(tmpdir(), "ki-"));
+  try {
+    const foreign = join(dir, "foreign.cc");
+    const catalog = join(dir, "catalog.cc");
+    await copyFile(join(vectors, "catalog-store.cc"), catalog);
+    const writer = CultCache.builder().withDocumentType(types.gamma!).withGenericStore(new SingleFileMessagePackBackingStore(foreign)).build();
+    await writer.put(types.gamma!, "qx", { text: "g" } as never);
+    const cache = CultCache.builder().withDocumentType(types.alpha!).build();
+    await cache.addBackingStore(new SingleFileMessagePackBackingStore(catalog), types.alpha!);
+    await cache.pullAllBackingStores();
+    await cache.addBackingStore(new SingleFileMessagePackBackingStore(foreign));
+    await assert.rejects(cache.pullAllBackingStores(), /held by two stores/u);
+    assert.deepEqual(cache.snapshot().map((e) => e.key), ["qx"], "the earlier pulled state survives");
+    assert.deepEqual(cache.foreignRecords(), []);
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+// The cache judge answers for what the cache holds whatever the store is: a store that never judges (it only records
+// what it is asked) is asked nothing at a foreign key, and foreign records list by key ordinal.
+test("a foreign key is refused by the cache before any store is asked, and foreign records list sorted", async () => {
+  const calls: string[] = [];
+  const record = (key: string, schemaId: string): CultCacheEnvelope => ({
+    key,
+    type: "unclaimed",
+    schemaId,
+    storedAt: "2026-01-01T00:00:00Z",
+    payload: documentPayloadFromBytes(encode(["x"])),
+  });
+  const store = {
+    pullAll: async () => [record("m", "unclaimed.m.v1"), record("b", "unclaimed.b.v1")],
+    push: async (entry: CultCacheEnvelope) => void calls.push(`push ${entry.key}`),
+    delete: async (entry: CultCacheEnvelope) => void calls.push(`delete ${entry.key}`),
+  };
+  const cache = CultCache.builder().withDocumentType(types.alpha!).withGenericStore(store).build();
+  await cache.pullAllBackingStores();
+  assert.deepEqual(cache.foreignRecords().map((r) => [r.key, r.schemaId, r.schemaName]), [["b", "unclaimed.b.v1", "unclaimed"], ["m", "unclaimed.m.v1", "unclaimed"]]);
+  await assert.rejects(cache.put(types.alpha!, "m", { text: CANARY } as never), (error: Error) => {
+    assert.ok(error instanceof SchemaConflictError && error.recordKey === "m");
+    assert.ok(!error.message.includes(CANARY));
+    return true;
+  });
+  await assert.rejects(cache.delete(types.alpha!, "b"), (error: Error) => error instanceof SchemaConflictError && error.recordKey === "b");
+  assert.equal(await cache.delete(types.alpha!, "nobody"), false);
+  assert.deepEqual(calls, []);
+});
+
+// The store's delete matches the record the file stores by its schema id, not by the type string: a record read back is
+// typed by its schema's name, which a type of another name does not carry.
+test("a delete removes the record the file stores although the type differs from the schema name, and the key retypes across a reload", async () => {
+  const dir = await mkdtemp(join(tmpdir(), "ki-"));
+  try {
+    const path = join(dir, "s.cc");
+    const named = (type: string, schemaName: string, schemaId: string) =>
+      defineDocumentType({ type, schemaId, schemaName, schemaVersion: `${schemaName}.v1`, schema: z.object({ v: z.string() }) });
+    const first = named("app.first", "wire.first", "wire.first.v1");
+    const second = named("app.second", "wire.second", "wire.second.v1");
+    const open = () => CultCache.builder().withDocumentType(first).withDocumentType(second).withGenericStore(new SingleFileMessagePackBackingStore(path)).build();
+    const writer = open();
+    await writer.put(first, "k", { v: "a" });
+    const reader = open();
+    await reader.pullAllBackingStores();
+    assert.equal(await reader.delete(first, "k"), true);
+    assert.deepEqual([...stored(path).keys()], [], "the record is gone from the file");
+    await reader.put(second, "k", { v: "b" });
+    assert.deepEqual([...stored(path).values()].map((e) => [e.key, e.catalogEntry?.schemaName]), [["k", "wire.second"]]);
+    const again = open();
+    await again.pullAllBackingStores();
+    assert.deepEqual(again.snapshot().map((e) => [e.type, e.key]), [["app.second", "k"]]);
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+test("an owned rename whose two types home in different stores is refused, and neither store changes", async () => {
+  const dir = await mkdtemp(join(tmpdir(), "ki-"));
+  try {
+    const oldPath = join(dir, "old.cc");
+    const newPath = join(dir, "new.cc");
+    const old = plain("rn.old", "rn.id.v1");
+    const renamed = plain("rn.new", "rn.id.v2", ["rn.id.v2", "rn.id.v1"]);
+    const cache = CultCache.builder().withDocumentType(old).withDocumentType(renamed).build();
+    await cache.addBackingStore(new SingleFileMessagePackBackingStore(oldPath), old);
+    await cache.addBackingStore(new SingleFileMessagePackBackingStore(newPath), renamed);
+    await cache.put(old, "k", { v: "a" });
+    const before = await readFile(oldPath);
+    await assert.rejects(cache.put(renamed, "k", { v: CANARY }), (error: Error) => {
+      assert.ok(error instanceof SchemaConflictError && error.recordKey === "k");
+      assert.ok(!error.message.includes(CANARY));
+      return true;
+    });
+    assert.deepEqual(await readFile(oldPath), before);
+    assert.equal(existsSync(newPath), false, "the new home was never written");
+    assert.deepEqual(cache.snapshot().map((e) => [e.type, e.key]), [["rn.old", "k"]]);
+    // Same home: the rename replaces.
+    const together = CultCache.builder().withDocumentType(old).withDocumentType(renamed).withGenericStore(new SingleFileMessagePackBackingStore(join(dir, "one.cc"))).build();
+    await together.put(old, "k", { v: "a" });
+    await together.put(renamed, "k", { v: "b" });
+    assert.deepEqual(together.snapshot().map((e) => [e.type, e.key]), [["rn.new", "k"]]);
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+test("two stores each carrying an unregistered record at one key refuse the load and admit nothing", async () => {
+  const dir = await mkdtemp(join(tmpdir(), "ki-"));
+  try {
+    const paths = [join(dir, "a.cc"), join(dir, "b.cc")];
+    for (const path of paths) {
+      const writer = CultCache.builder().withDocumentType(types.gamma!).withGenericStore(new SingleFileMessagePackBackingStore(path)).build();
+      await writer.put(types.gamma!, "k", { text: "g" } as never);
+    }
+    // Neither store's records are claimed: gamma is not registered here.
+    const cache = CultCache.builder().withDocumentType(types.alpha!).withDocumentType(types.beta!).build();
+    await cache.addBackingStore(new SingleFileMessagePackBackingStore(paths[0]!), types.alpha!);
+    await cache.addBackingStore(new SingleFileMessagePackBackingStore(paths[1]!), types.beta!);
+    await assert.rejects(cache.pullAllBackingStores(), /^Error: Record k is held by two stores/u);
+    assert.deepEqual(cache.foreignRecords(), []);
+    assert.deepEqual(cache.snapshot(), []);
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});

packages/cultcache-ts/test/payload-depth.test.ts

@@ -119,6 +119,19 @@ test("a payload that ends early, is empty or carries trailing bytes is the reade
   assert.doesNotThrow(() => checkPayloadDepth(bytes(0xc0)));
 });
 
+test("the walk returns where the first value ends, and undefined when the payload ends early", () => {
+  assert.equal(checkPayloadDepth(bytes(0xc0)), 1);
+  assert.equal(checkPayloadDepth(bytes(0xc0, 0xc1, 0xc1)), 1, "a top-level scalar ends at its own length; the tail is not judged");
+  assert.equal(checkPayloadDepth(bytes(0x92, 0x01, 0xa1, 0x61, 0xc0)), 5 - 1, "a container ends when its last child completes");
+  assert.equal(checkPayloadDepth(cat(bytes(0x90), arrays(L + 50))), 1, "the tail is never walked");
+  assert.equal(checkPayloadDepth(bytes()), undefined);
+  assert.equal(checkPayloadDepth(bytes(0x92, 0x01)), undefined);
+  assert.equal(checkPayloadDepth(bytes(0xd9)), undefined);
+  for (const cut of [[0xcc], [0xcb, 0x3f, 0xf8], [0xa5, 0x61, 0x62, 0x63], [0xc4, 0x02, 0x01], [0xd7, 0x01]]) {
+    assert.equal(checkPayloadDepth(bytes(...cut)), undefined, `a scalar cut short: ${cut.map((value) => value.toString(16)).join(" ")}`);
+  }
+});
+
 test("the walk is iterative: 100000 nested arrays are refused with the depth error, not a RangeError", () => {
   refused(arrays(100_000), "100000 nested arrays");
   refused(chain(bytes(0x81, 0x00), 100_000), "100000 nested maps");
@@ -198,6 +211,13 @@ test("the inspector previews a payload at the limit and reports one past it, or
   }
 });
 
+test("the inspector refuses bytes after a payload's first value with the shared clause and previews no tail", async () => {
+  const file = await storeWith(bytes(0xc0, 0xc1, 0xc1));
+  const record = inspectCultCacheBytes(file, await readFile(file)).records[0]!;
+  assert.equal(record.payloadDecodeError, "document payload has 2 bytes after its first MessagePack value.");
+  assert.deepEqual(record.payloadPreview, { bytes: 3, hexPrefix: "c0" });
+});
+
 // A header whose length or count needs all four bytes: the low sixteen bits of the length are small, the whole is not.
 const be32 = (n: number) => bytes((n >>> 24) & 0xff, (n >>> 16) & 0xff, (n >>> 8) & 0xff, n & 0xff);
 

packages/cultcache-ts/test/slot-readonly.test.ts

@@ -0,0 +1,461 @@
+import assert from "node:assert/strict";
+import { copyFile, mkdtemp, readFile, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { test } from "node:test";
+
+import { decode, encode } from "@msgpack/msgpack";
+import { z } from "zod";
+
+import { codecs } from "../src";
+import { CultCache } from "../src/cult-cache";
+import { defineDocumentType, documentPayloadBytes, documentPayloadFromBytes } from "../src/document";
+import { SingleFileMessagePackBackingStore, readSingleFileStore } from "../src/single-file-messagepack-backing-store";
+import { SchemaConflictError, StoreUnreadableError } from "../src/store-format";
+import type { CacheBackingStore, CultCacheEnvelope, CultCacheUnreadSlots } from "../src/types";
+import {
+  type Surface, envelopeOf, golden, hex, memoryStore, read, slotUnitDocument, surfaceCodec, surfaceDeclaringDocument, surfaceDocument, surfaceSchema, vectors,
+} from "./union-surface-fixture";
+
+// cultlib-gaps:cut:slot-readonly-ts. A payload carrying a slot past its reader's declared slots, at any depth, is read, held
+// read-only, and every write or removal of its key is refused before a store is touched. The vectors are written by the C#
+// reference: tests/vectors/union-parity/README.md, "Extra trailing slot" and "Slot stores".
+
+const { slots, string } = codecs;
+const SLOT_VALUE = "extra-slot";
+
+function mark(typeName: string, slotCount: number, declaredCount: number, depth0Only: boolean, explained = false, occurrences = 1): CultCacheUnreadSlots {
+  return { typeName, slotCount, declaredCount, occurrences, depth0Only, explained };
+}
+
+// File, then the mark the README table gives for it.
+const PAYLOAD_ROWS: [string, CultCacheUnreadSlots][] = [
+  ["extra-slot-record.msgpack", mark("UnionSurface", 8, 7, true)],
+  ["extra-slot-nested-record.msgpack", mark("Composition", 3, 2, false)],
+  ["extra-slot-arm.msgpack", mark("Box", 3, 2, false)],
+  ["extra-slot-list-element.msgpack", mark("Text", 3, 2, false)],
+  ["depth-skipped-at-limit.msgpack", mark("UnionSurface", 8, 7, true)],
+];
+
+async function readOnlyFiles(name: string): Promise<string[]> {
+  const rows = decode(await read(name)) as unknown[][];
+  return rows.filter((row) => row[1] === "read-only").map((row) => row[0] as string);
+}
+
+test("the read-only payload vectors are exactly the ones this walker names: four in outcomes, one in bounds", async () => {
+  const listed = [...(await readOnlyFiles("outcomes.msgpack")), ...(await readOnlyFiles("bounds-outcomes.msgpack"))];
+  assert.deepEqual(listed.sort(), PAYLOAD_ROWS.map(([file]) => file).sort());
+});
+
+for (const [file, expected] of PAYLOAD_ROWS) {
+  test(`${file}: read past the extra slot, held read-only with the mark, every write and removal of the key refused`, async () => {
+    const document = surfaceDocument();
+    const entries = [envelopeOf(await read(file))];
+    const before = hex(documentPayloadBytes(entries[0]!.payload));
+    const cache = CultCache.builder().withDocumentType(document).withGenericStore(memoryStore(entries)).build();
+    await cache.pullAllBackingStores();
+
+    assert.deepEqual(cache.get(document, "surface"), golden, "the extra slot is read past");
+    assert.deepEqual(cache.unreadSlots(document, "surface"), expected);
+    assert.equal(cache.isWritable(document, "surface"), false);
+    assert.equal(cache.isWritable(document, "another"), true);
+
+    const refused = (error: unknown) => {
+      assert.ok(error instanceof SchemaConflictError, "a SchemaConflictError");
+      assert.deepEqual(error.unreadSlots, expected);
+      assert.equal(error.recordKey, "surface");
+      assert.ok(error.message.includes(expected.typeName), error.message);
+      assert.ok(error.message.includes(`read with ${expected.slotCount} slots where this build declares ${expected.declaredCount} (${expected.occurrences} object(s)`), error.message);
+      assert.ok(!error.message.includes(SLOT_VALUE), "the refusal never holds a slot value");
+      return true;
+    };
+    await assert.rejects(() => cache.put(document, "surface", golden), refused);
+    await assert.rejects(() => cache.update(document, "surface", (value) => ({ ...value!, version: 4 })), refused);
+    const replacement = envelopeOf(await read("union-surface.msgpack"));
+    await assert.rejects(() => cache.putEnvelope(document, replacement), refused);
+    await assert.rejects(() => cache.delete(document, "surface"), refused);
+    assert.equal(entries.length, 1, "nothing reached the store");
+    assert.equal(hex(documentPayloadBytes(entries[0]!.payload)), before, "the held bytes are untouched");
+    assert.deepEqual(cache.get(document, "surface"), golden, "the record is still held");
+
+    await cache.put(document, "another", golden);
+    assert.equal(entries.length, 2, "another key of the same store writes");
+  });
+}
+
+test("a clean payload and a short one are writable: missing trailing slots keep the defaults and mark nothing", async () => {
+  const document = surfaceDocument();
+  const short = encode([...(decode(await read("union-surface.msgpack")) as unknown[]).slice(0, 6)]);
+  const entries = [envelopeOf(await read("union-surface.msgpack")), { ...envelopeOf(short), key: "short" }];
+  const cache = CultCache.builder().withDocumentType(document).withGenericStore(memoryStore(entries)).build();
+  await cache.pullAllBackingStores();
+  for (const key of ["surface", "short"]) {
+    assert.equal(cache.unreadSlots(document, key), undefined);
+    assert.equal(cache.isWritable(document, key), true);
+  }
+  await cache.put(document, "short", golden);
+});
+
+test("a payload past the nesting limit is refused, never marked", async () => {
+  const entries = [envelopeOf(await read("depth-skipped-past-limit.msgpack"))];
+  const cache = CultCache.builder().withDocumentType(surfaceDocument()).withGenericStore(memoryStore(entries)).build();
+  await assert.rejects(() => cache.pullAllBackingStores(), /nesting|depth/iu);
+});
+
+test("putEnvelope of a payload carrying extra slots lands the bytes and holds the record read-only", async () => {
+  const document = surfaceDocument();
+  const entries: ReturnType<typeof envelopeOf>[] = [];
+  const cache = CultCache.builder().withDocumentType(document).withGenericStore(memoryStore(entries)).build();
+  const marked = envelopeOf(await read("extra-slot-nested-record.msgpack"));
+  await cache.putEnvelope(document, marked);
+  assert.equal(hex(documentPayloadBytes(entries[0]!.payload)), hex(await read("extra-slot-nested-record.msgpack")), "the bytes are carried");
+  assert.deepEqual(cache.unreadSlots(document, "surface"), mark("Composition", 3, 2, false));
+  assert.equal(cache.isWritable(document, "surface"), false);
+  await assert.rejects(() => cache.put(document, "surface", golden), SchemaConflictError);
+});
+
+test("a key a store carries foreign is not writable", async () => {
+  const document = surfaceDocument();
+  const foreign = { ...envelopeOf(await read("union-surface.msgpack")), key: "stranger", type: "tests.unknown", schemaId: "tests.unknown.v1" };
+  const cache = CultCache.builder().withDocumentType(document).withGenericStore(memoryStore([foreign])).build();
+  await cache.pullAllBackingStores();
+  assert.equal(cache.isWritable(document, "stranger"), false);
+  assert.equal(cache.isWritable(document, "other"), true);
+});
+
+test("a write by a type that owns the held record's id restamps it, and is refused when that record carries unread slots", async () => {
+  const typed = (type: string, schemaId: string, compatibleSchemaIds: string[] = []) =>
+    defineDocumentType({ type, schemaId, schemaName: type, schemaVersion: `${type}.v1`, compatibleSchemaIds, schema: surfaceSchema, codec: surfaceCodec, name: "id" });
+  const older = typed("tests.surface_older", "tests.surface_older.v1");
+  const newer = typed("tests.surface_newer", "tests.surface_newer.v1", ["tests.surface_older.v1"]);
+  for (const [file, lands] of [["union-surface.msgpack", true], ["extra-slot-record.msgpack", false]] as const) {
+    const held = { ...envelopeOf(await read(file)), type: older.type, schemaId: "tests.surface_older.v1" };
+    const cache = CultCache.builder().withDocumentType(older).withDocumentType(newer).withGenericStore(memoryStore([held])).build();
+    await cache.pullAllBackingStores();
+    assert.equal(cache.isWritable(newer, "surface"), lands, `${file}: isWritable agrees with the write by the type that owns the id`);
+    const write = cache.put(newer, "surface", golden);
+    if (lands) {
+      await write;
+    } else {
+      await assert.rejects(() => write, (error: unknown) => error instanceof SchemaConflictError && error.unreadSlots?.typeName === "UnionSurface");
+    }
+  }
+});
+
+// The store vectors. TS has no variant records: extra-slot-store.cc carries one (marked-variant), so the whole file is refused
+// by name, and the walk runs over the file without that record.
+async function copyOf(name: string): Promise<string> {
+  const path = join(await mkdtemp(join(tmpdir(), "slot-readonly-")), name);
+  await copyFile(join(vectors, name), path);
+  return path;
+}
+
+async function withoutVariant(path: string): Promise<void> {
+  const [format, catalog, records] = decode(await readFile(path)) as [unknown, unknown[], unknown[][]];
+  await writeFile(path, encode([format, catalog, records.filter((record) => record[0] !== "marked-variant")]));
+}
+
+type SlotRow = [string, string, boolean, boolean | null, string | null, number | null, number | null, number | null, string | null];
+
+async function slotRows(): Promise<SlotRow[]> {
+  return decode(await read("slot-outcomes.msgpack")) as SlotRow[];
+}
+
+// The catalog entry the file publishes for a schema: its id and the reference's content hash, which a store rewrites with the
+// definition's own.
+async function catalogOf(file: string, schemaName: string): Promise<[string, string]> {
+  const [, catalog] = decode(await read(file)) as [unknown, string[][]];
+  const entry = catalog.find((candidate) => candidate[1] === schemaName)!;
+  return [entry[0]!, entry[3]!];
+}
+
+async function openStore(file: string, consent: boolean) {
+  const path = await copyOf(file);
+  if (file === "extra-slot-store.cc") await withoutVariant(path);
+  const surface = consent ? surfaceDeclaringDocument() : surfaceDocument(...(await catalogOf(file, "tests.union_surface")));
+  const slotUnit = consent ? undefined : slotUnitDocument(...(await catalogOf(file, "tests.slot_unit")));
+  const builder = CultCache.builder().withDocumentType(surface).withGenericStore(new SingleFileMessagePackBackingStore(path));
+  const cache = (slotUnit ? builder.withDocumentType(slotUnit) : builder).build();
+  await cache.pullAllBackingStores();
+  return { path, cache, surface, slotUnit };
+}
+
+test("extra-slot-store.cc carries a variant, which this runtime refuses by name; the rest of the file is walked", async () => {
+  const path = await copyOf("extra-slot-store.cc");
+  assert.throws(() => readSingleFileStore(path), StoreUnreadableError);
+});
+
+test("every slot-outcomes row holds: the mark, IsWritable, and the removal refused exactly where the record is not writable", async () => {
+  const rows = await slotRows();
+  assert.equal(rows.length, 8);
+  let walked = 0;
+  for (const [file, key, writable, explained, typeName, slots, declared, occurrences, flattenRefusedBy] of rows) {
+    if (flattenRefusedBy !== null) continue; // a variant: this runtime holds none
+    walked += 1;
+    const { path, cache, surface, slotUnit } = await openStore(file!, file === "extra-slot-consent.cc");
+    const document = key === "unit-arm" ? slotUnit! : surface;
+    const label = `${file} ${key}`;
+    const found = cache.unreadSlots(document, key!);
+    if (typeName === null) {
+      assert.equal(found, undefined, label);
+    } else {
+      assert.ok(found, label);
+      assert.deepEqual([found.explained, found.typeName, found.slotCount, found.declaredCount, found.occurrences], [explained, typeName, slots, declared, occurrences], label);
+    }
+    assert.equal(cache.isWritable(document, key!), writable, label);
+
+    const original = await readFile(path);
+    if (writable) {
+      assert.equal(await cache.delete(document, key!), true, label);
+    } else {
+      await assert.rejects(
+        () => cache.delete(document, key!),
+        (error: unknown) => error instanceof SchemaConflictError && error.unreadSlots?.typeName === typeName && !error.message.includes(SLOT_VALUE),
+        label,
+      );
+      assert.equal(Buffer.compare(original, await readFile(path)), 0, `${label}: the file is unchanged`);
+    }
+  }
+  assert.equal(walked, 7);
+});
+
+test("consent: a write of the explained record lands; the over-consent write is refused; the nested mark is refused", async () => {
+  const consented = await openStore("extra-slot-consent.cc", true);
+  const value = consented.cache.get(consented.surface, "consented") as Surface;
+  assert.deepEqual(value, golden);
+  await consented.cache.put(consented.surface, "consented", value);
+  assert.equal(consented.cache.unreadSlots(consented.surface, "consented"), undefined, "the write dropped the explained slot and the mark with it");
+  assert.equal(readSingleFileStore(consented.path).envelopes.find((e) => e.key === "consented")!.schemaId, "tests.union_surface.v2");
+
+  for (const key of ["over-consent", "nested"]) {
+    const refused = await openStore("extra-slot-consent.cc", true);
+    await assert.rejects(
+      () => refused.cache.put(refused.surface, key, golden),
+      (error: unknown) => error instanceof SchemaConflictError && error.schemaId === "tests.union_surface.wide",
+      `${key}: the refusal names the id the record was stored under`,
+    );
+  }
+});
+
+test("carried: after writing another record, the marked record's bytes, schema id, stored-at and every catalog entry are the originals", async () => {
+  const { path, cache, surface } = await openStore("extra-slot-store.cc", false);
+  const originals = readSingleFileStore(path);
+  await cache.put(surface, "clean", golden);
+  const after = readSingleFileStore(path);
+  for (const key of ["marked", "unit-arm"]) {
+    const was = originals.envelopes.find((e) => e.key === key)!;
+    const now = after.envelopes.find((e) => e.key === key)!;
+    assert.equal(hex(documentPayloadBytes(now.payload)), hex(documentPayloadBytes(was.payload)), key);
+    assert.equal(now.schemaId, was.schemaId, key);
+    assert.equal(now.storedAt, was.storedAt, key);
+    assert.deepEqual(now.catalogEntry, was.catalogEntry, key);
+  }
+});
+
+// A writer that adds a slot and keeps its schema id (TS ids are hand-written; C# ids hash the members): the reader of that
+// same id has declared nothing, so it consents to nothing.
+test("a wider writer under the reader's own schema id is read-only, and a real round trip does not shed the slot", async () => {
+  const doc = (columns: 1 | 2, compatibleSchemaIds: string[] = []) => defineDocumentType({
+    type: "tests.own_id",
+    schemaId: "tests.own_id.v1",
+    schemaName: "tests.own_id",
+    compatibleSchemaIds,
+    schema: z.object({ n: z.string(), extra: z.string().optional() }),
+    codec: columns === 2
+      ? slots<{ n: string; extra: string }>({ 0: ["n", string], 1: ["extra", string] }, "Own")
+      : slots<{ n: string }>({ 0: ["n", string] }, "Own"),
+    name: "n",
+  });
+  const path = join(await mkdtemp(join(tmpdir(), "slot-readonly-")), "own.cc");
+  const wide = doc(2);
+  const writer = CultCache.builder().withDocumentType(wide).withGenericStore(new SingleFileMessagePackBackingStore(path)).build();
+  await writer.put(wide, "k", { n: "n1", extra: "kept" });
+  const bytes = await readFile(path);
+
+  for (const compatible of [[], ["tests.own_id.v1"]]) {
+    const reader = doc(1, compatible);
+    const cache = CultCache.builder().withDocumentType(reader).withGenericStore(new SingleFileMessagePackBackingStore(path)).build();
+    await cache.pullAllBackingStores();
+    assert.deepEqual(cache.unreadSlots(reader, "k"), mark("Own", 2, 1, true), "unexplained: the arrived id is the reader's own");
+    assert.equal(cache.isWritable(reader, "k"), false);
+    await assert.rejects(() => cache.put(reader, "k", { n: "n2" }), SchemaConflictError);
+    await assert.rejects(() => cache.delete(reader, "k"), SchemaConflictError);
+    assert.equal(Buffer.compare(bytes, await readFile(path)), 0, "the file still holds the slot");
+  }
+});
+
+test("a record that arrived under an id the reader does not list compatible is never consented to", async () => {
+  const path = await copyOf("extra-slot-consent.cc");
+  const reader = surfaceDocument("tests.union_surface.v2"); // resolves by type name; lists nothing
+  const cache = CultCache.builder().withDocumentType(reader).withGenericStore(new SingleFileMessagePackBackingStore(path)).build();
+  await cache.pullAllBackingStores();
+  assert.equal(cache.unreadSlots(reader, "consented")?.explained, false);
+  assert.equal(cache.isWritable(reader, "consented"), false);
+});
+
+// isWritable is the write's own judge, not a second one: for every key state it answers what put does.
+test("isWritable equals the outcome of put for every key state the write judges", async () => {
+  const typed = (type: string, schemaId: string, extra: Record<string, unknown> = {}) =>
+    defineDocumentType({ type, schemaId, schemaName: type, schemaVersion: `${type}.v1`, schema: surfaceSchema, codec: surfaceCodec, name: "id", ...extra });
+  const older = typed("tests.surface_older", "tests.surface_older.v1");
+  const newer = typed("tests.surface_newer", "tests.surface_newer.v1", { compatibleSchemaIds: ["tests.surface_older.v1"] });
+  const stranger = typed("tests.surface_stranger", "tests.surface_stranger.v1");
+  const global = typed("tests.surface_global", "tests.surface_global.v1", { global: true });
+  const clean = (key: string, type: string, schemaId: string) => ({ ...envelopeOf(new Uint8Array()), key, type, schemaId });
+  const held = async (key: string, file: string, type: string, schemaId: string) =>
+    ({ ...envelopeOf(await read(file)), key, type, schemaId });
+
+  type Row = { name: string; build: () => Promise<{ cache: CultCache; target: typeof older; key: string }> };
+  const rows: Row[] = [
+    { name: "owned clean record in the writer's own store", build: async () => {
+      const cache = CultCache.builder().withDocumentType(older).withDocumentType(newer)
+        .withGenericStore(memoryStore([await held("k", "union-surface.msgpack", older.type, older.schemaId!)])).build();
+      return { cache, target: newer, key: "k" };
+    } },
+    { name: "owned record held in a store other than the writer's home", build: async () => {
+      const cache = CultCache.builder().withDocumentType(older).withDocumentType(newer)
+        .withBackingStore(memoryStore([await held("k", "union-surface.msgpack", older.type, older.schemaId!)]), older)
+        .withBackingStore(memoryStore([]), newer).build();
+      return { cache, target: newer, key: "k" };
+    } },
+    { name: "a record of a type that does not own the writer's id", build: async () => {
+      const cache = CultCache.builder().withDocumentType(older).withDocumentType(stranger)
+        .withGenericStore(memoryStore([await held("k", "union-surface.msgpack", older.type, older.schemaId!)])).build();
+      return { cache, target: stranger, key: "k" };
+    } },
+    { name: "a global type at a key other than the global key", build: async () => {
+      const cache = CultCache.builder().withDocumentType(global).withGenericStore(memoryStore([])).build();
+      return { cache, target: global, key: "x" };
+    } },
+    { name: "a key a store carries foreign", build: async () => {
+      const cache = CultCache.builder().withDocumentType(older)
+        .withGenericStore(memoryStore([{ ...clean("k", "tests.unknown", "tests.unknown.v1"), payload: documentPayloadFromBytes(await read("union-surface.msgpack")) }])).build();
+      return { cache, target: older, key: "k" };
+    } },
+    { name: "a marked record of the writer's own type", build: async () => {
+      const cache = CultCache.builder().withDocumentType(older)
+        .withGenericStore(memoryStore([await held("k", "extra-slot-record.msgpack", older.type, older.schemaId!)])).build();
+      return { cache, target: older, key: "k" };
+    } },
+    { name: "an unheld key", build: async () => ({ cache: CultCache.builder().withDocumentType(older).withGenericStore(memoryStore([])).build(), target: older, key: "k" }) },
+  ];
+  const outcomes: [string, boolean, boolean][] = [];
+  for (const row of rows) {
+    const { cache, target, key } = await row.build();
+    await cache.pullAllBackingStores();
+    const predicted = cache.isWritable(target, key);
+    const landed = await cache.put(target, key === "x" ? "x" : key, golden).then(() => true, () => false);
+    assert.equal(predicted, landed, row.name);
+    outcomes.push([row.name, predicted, landed]);
+  }
+  assert.deepEqual(outcomes.map(([, writable]) => writable), [true, false, false, false, false, false, true]);
+  // The same judge refuses a removal of a key held read-only or carried foreign.
+  const removals = CultCache.builder().withDocumentType(older)
+    .withGenericStore(memoryStore([await held("k", "extra-slot-record.msgpack", older.type, older.schemaId!)])).build();
+  await removals.pullAllBackingStores();
+  await assert.rejects(() => removals.delete(older, "k"), SchemaConflictError);
+  const stranger2 = CultCache.builder().withDocumentType(older)
+    .withGenericStore(memoryStore([{ ...envelopeOf(await read("union-surface.msgpack")), key: "f", type: "tests.unknown", schemaId: "tests.unknown.v1" }])).build();
+  await stranger2.pullAllBackingStores();
+  await assert.rejects(() => stranger2.delete(older, "f"), SchemaConflictError);
+});
+
+// A removal is by key (C# Remove): the owner of a held record's id removes the one record that exists, in one store call and
+// with the cache dropped only once the store has; a type that does not own it is refused like put, and isWritable agrees.
+test("delete of a key held as another type: the owner removes it once, a stranger is refused, a failing store leaves cache and store agreeing", async () => {
+  const typed = (type: string, schemaId: string, extra: Record<string, unknown> = {}) =>
+    defineDocumentType({ type, schemaId, schemaName: type, schemaVersion: `${type}.v1`, schema: surfaceSchema, codec: surfaceCodec, name: "id", ...extra });
+  const older = typed("tests.surface_older", "tests.surface_older.v1");
+  const newer = typed("tests.surface_newer", "tests.surface_newer.v1", { compatibleSchemaIds: ["tests.surface_older.v1"] });
+  const stranger = typed("tests.surface_stranger", "tests.surface_stranger.v1");
+  const heldRecord = async (): Promise<CultCacheEnvelope> => ({ ...envelopeOf(await read("union-surface.msgpack")), key: "k", type: older.type, schemaId: older.schemaId });
+  const open = async (failing = false) => {
+    const rows = [await heldRecord()];
+    const calls: string[] = [];
+    const store: CacheBackingStore = {
+      async pullAll() { return rows.map((row) => ({ ...row })); },
+      async push(entry) { rows.push(entry); },
+      async delete(entry) {
+        calls.push(entry.key);
+        if (failing) throw new Error("store refused the removal");
+        rows.splice(rows.findIndex((row) => row.key === entry.key), 1);
+      },
+    };
+    const cache = CultCache.builder().withDocumentType(older).withDocumentType(newer).withDocumentType(stranger).withGenericStore(store).build();
+    await cache.pullAllBackingStores();
+    return { cache, rows, calls };
+  };
+
+  const owner = await open();
+  assert.equal(owner.cache.isWritable(newer, "k"), true);
+  assert.equal(await owner.cache.delete(newer, "k"), true, "the owner's removal removes the one record");
+  assert.deepEqual([owner.rows.length, owner.calls.length, owner.cache.get(older, "k")], [0, 1, undefined], "one store call, record gone from store and cache");
+
+  const refused = await open();
+  assert.equal(refused.cache.isWritable(stranger, "k"), false);
+  await assert.rejects(() => refused.cache.delete(stranger, "k"), SchemaConflictError);
+  assert.deepEqual([refused.rows.length, refused.calls.length, refused.cache.get(older, "k") !== undefined], [1, 0, true]);
+
+  const failing = await open(true);
+  await assert.rejects(() => failing.cache.delete(newer, "k"), /store refused/u);
+  assert.deepEqual([failing.rows.length, failing.calls.length, failing.cache.get(older, "k") !== undefined], [1, 1, true], "the store failed: neither side dropped it");
+
+  const same = await open();
+  assert.equal(await same.cache.delete(older, "k"), true);
+  assert.equal(await same.cache.delete(older, "k"), false, "an unheld key is still the plain false");
+});
+
+// The removal form's three finer behaviours (cultlib-gaps:finding:cut-slot-readonly-ts.s4.removal-form-unpinned).
+test("an owner's delete: refused for a marked record, taken from the held record's store, and clears the held type's lookups", async () => {
+  const typed = (type: string, schemaId: string, extra: Record<string, unknown> = {}) =>
+    defineDocumentType({ type, schemaId, schemaName: type, schemaVersion: `${type}.v1`, schema: surfaceSchema, codec: surfaceCodec, name: "id", ...extra });
+  const older = typed("tests.surface_older", "tests.surface_older.v1", { indexes: { byVersion: (value: Surface) => String(value.version) } });
+  const newer = typed("tests.surface_newer", "tests.surface_newer.v1", { compatibleSchemaIds: ["tests.surface_older.v1"] });
+  const heldIn = async (file: string): Promise<CultCacheEnvelope> =>
+    ({ ...envelopeOf(await read(file)), key: "k", type: older.type, schemaId: older.schemaId });
+  const recording = (rows: CultCacheEnvelope[]) => {
+    const removed: string[] = [];
+    const store: CacheBackingStore = {
+      async pullAll() { return rows.map((row) => ({ ...row })); },
+      async push(entry) { rows.push(entry); },
+      async delete(entry) { removed.push(entry.key); rows.splice(rows.findIndex((row) => row.key === entry.key), 1); },
+    };
+    return { store, removed, rows };
+  };
+
+  // 1. The owner may not remove a record carrying unread slots nothing consents to.
+  const marked = recording([await heldIn("extra-slot-record.msgpack")]);
+  const markedCache = CultCache.builder().withDocumentType(older).withDocumentType(newer).withGenericStore(marked.store).build();
+  await markedCache.pullAllBackingStores();
+  await assert.rejects(() => markedCache.delete(newer, "k"), (error: unknown) => error instanceof SchemaConflictError && error.unreadSlots?.typeName === "UnionSurface");
+  assert.deepEqual([marked.rows.length, marked.removed.length, markedCache.get(older, "k") !== undefined], [1, 0, true]);
+
+  // 2. The removal goes to the store of the record that exists, not the deleting type's; there the write form is false (it would
+  //    push to the wrong store) while the removal succeeds.
+  const olderStore = recording([await heldIn("union-surface.msgpack")]);
+  const newerStore = recording([]);
+  const split = CultCache.builder().withDocumentType(older).withDocumentType(newer)
+    .withBackingStore(olderStore.store, older).withBackingStore(newerStore.store, newer).build();
+  await split.pullAllBackingStores();
+  assert.equal(split.isWritable(newer, "k"), false, "isWritable answers the write form: the rename cannot replace a record in another store");
+  assert.equal(await split.delete(newer, "k"), true);
+  assert.deepEqual([olderStore.removed, newerStore.removed, split.get(older, "k")], [["k"], [], undefined]);
+
+  // 3. The held type's name and index lookups are cleared with the record.
+  const single = recording([await heldIn("union-surface.msgpack")]);
+  const cache = CultCache.builder().withDocumentType(older).withDocumentType(newer).withGenericStore(single.store).build();
+  await cache.pullAllBackingStores();
+  assert.equal(cache.getKeyByName(older, "surface"), "k");
+  assert.equal(cache.getKeyByIndex(older, "byVersion", "3"), "k");
+  await cache.delete(newer, "k");
+  assert.equal(cache.getKeyByName(older, "surface"), undefined);
+  assert.equal(cache.getKeyByIndex(older, "byVersion", "3"), undefined);
+  assert.equal(cache.getAll(older).length, 0);
+});
+
+test("a global type at a key other than the global key: isWritable is false and delete is the plain false of an unheld key", async () => {
+  const global = defineDocumentType({ type: "tests.surface_global", schemaId: "tests.surface_global.v1", schemaName: "tests.surface_global", schemaVersion: "tests.surface_global.v1", schema: surfaceSchema, codec: surfaceCodec, name: "id", global: true });
+  const cache = CultCache.builder().withDocumentType(global).withGenericStore(memoryStore([])).build();
+  assert.equal(cache.isWritable(global, "x"), false);
+  assert.equal(await cache.delete(global, "x"), false);
+});

packages/cultcache-ts/test/store-file.test.ts

@@ -10,6 +10,7 @@ import { promisify } from "node:util";
 
 import { decode, encode } from "@msgpack/msgpack";
 
+import { StoreLinkedError as PackageStoreLinkedError } from "../src/index";
 import { documentPayloadBytes, documentPayloadFromBytes } from "../src/document";
 import { SingleFileMessagePackBackingStore } from "../src/single-file-messagepack-backing-store";
 import { SchemaConflictError, StoreUnreadableError } from "../src/store-format";
@@ -23,6 +24,7 @@ import {
   replaceStoreFile,
   replaceStoreFileWindows,
   windowsKernel,
+  refuseLinkedStore,
   withStoreWriteLock,
 } from "../src/store-file";
 import type { ReplaceKernel, StoreFileOps } from "../src/store-file";
@@ -415,6 +417,43 @@ test("a second writer in this process waits for the store lock and runs after re
   }
 });
 
+test("a link put while a writer waits on the store lock is refused once it holds the lock", { skip: process.platform === "win32" }, async () => {
+  const directory = await scratch();
+  try {
+    const target = join(directory, "target.cc");
+    await new SingleFileMessagePackBackingStore(target).push(noteEnvelope("a"));
+    const before = await readFile(target);
+    const writes: Array<[string, (store: SingleFileMessagePackBackingStore) => Promise<void>]> = [
+      ["push", (store) => store.push(noteEnvelope("b"))],
+      ["pushAll", (store) => store.pushAll([noteEnvelope("b")])],
+      ["delete", (store) => store.delete(noteEnvelope("a"))],
+    ];
+    const missing = join(directory, "missing.cc");
+    for (const [name, write, linkTo] of writes.flatMap(([n, w]) => [[n, w, target], [`${n} (dangling)`, w, missing]] as const)) {
+      const link = join(directory, `${name.replace(/\W+/g, "-")}.cc`);
+      let writer: Promise<void> | undefined;
+      await withStoreWriteLock(link, async () => {
+        writer = write(new SingleFileMessagePackBackingStore(link));
+        writer.catch(() => undefined);
+        await sleepFor(150);
+        await fsp.symlink(linkTo, link); // after the writer's pre-lock look, while it waits
+      });
+      await assert.rejects(writer!, (error: unknown) => error instanceof PackageStoreLinkedError, name);
+      assert.ok((await fsp.lstat(link)).isSymbolicLink(), `${name}: the link was replaced`);
+      assert.deepEqual(await readFile(target), before, `${name}: the target changed`);
+      await assert.rejects(fsp.lstat(missing), { code: "ENOENT" }, `${name}: the dangling target was created`);
+      await rm(link); // the link is refused before the lock, so remove it to probe the lock
+      assert.equal(await withStoreWriteLock(link, async () => "free", { timeoutMs: 200 }), "free", `${name}: the lock is held`);
+    }
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+});
+
+function noteEnvelope(key: string): CultCacheEnvelope {
+  return { key, type: "note", payload: documentPayloadFromBytes(Uint8Array.of(0x91, 1)), storedAt: "2026-10-20T00:00:00Z" };
+}
+
 test("the store lock gives up after its wait bound and names the lock path", async () => {
   const directory = await scratch();
   try {
@@ -670,7 +709,7 @@ test("delete removes only the record at that type and key", async () => {
   }
 });
 
-test("pushAll replaces the whole store, and a soft pushAll leaves an existing store alone", async () => {
+test("pushAll writes onto the store as it is: it replaces by key and removes nothing, and a soft pushAll leaves an existing store alone", async () => {
   const directory = await scratch();
   try {
     const path = join(directory, "store.cc");
@@ -681,7 +720,14 @@ test("pushAll replaces the whole store, and a soft pushAll leaves an existing st
     await store.pushAll([entryOf("b", "t", 2)], { soft: true });
     assert.deepEqual([...(await readFile(path))], [...before], "soft leaves an existing store byte for byte");
     await store.pushAll([entryOf("b", "t", 2)]);
-    assert.deepEqual(await snapshotOf(store), ["t/b:2"]);
+    assert.deepEqual(await snapshotOf(store), ["t/a:1", "t/b:2"], "a record the batch does not name stays");
+    await store.pushAll([entryOf("a", "t", 7)]);
+    assert.deepEqual(await snapshotOf(store), ["t/a:7", "t/b:2"], "a record the batch names is replaced");
+    await store.pushAll([]);
+    assert.deepEqual(await snapshotOf(store), ["t/a:7", "t/b:2"], "an empty flush from a cache that holds nothing wipes nothing");
+    const before2 = [...(await readFile(path))];
+    await assert.rejects(() => store.pushAll([entryOf("a", "u", 1)]), SchemaConflictError);
+    assert.deepEqual([...(await readFile(path))], before2, "a batch that retypes a held key is refused and the file is unchanged");
   } finally {
     await rm(directory, { recursive: true, force: true });
   }
@@ -811,3 +857,35 @@ test("opening writes nothing: a missing store leaves no lock file, a legacy stor
     await rm(directory, { recursive: true, force: true });
   }
 });
+
+test("StoreLinkedError is importable from the package entry and is what a write at a link throws", { skip: process.platform === "win32" }, async () => {
+  const directory = await scratch();
+  try {
+    const target = join(directory, "target.cc");
+    await writeFile(target, "x");
+    const link = join(directory, "link.cc");
+    await fsp.symlink(target, link);
+    await assert.rejects(
+      () => refuseLinkedStore(link),
+      (error: unknown) => error instanceof PackageStoreLinkedError && error.path === link && error.name === "StoreLinkedError",
+    );
+    await assert.rejects(() => new SingleFileMessagePackBackingStore(link).pushAll([]), (error: unknown) => error instanceof PackageStoreLinkedError);
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+});
+
+test("refuseLinkedStore lets a path that is absent pass and rethrows any other lstat failure", { skip: process.platform === "win32" }, async () => {
+  const directory = await scratch();
+  try {
+    await refuseLinkedStore(join(directory, "absent.cc"));
+    const file = join(directory, "file");
+    await writeFile(file, "x");
+    await assert.rejects(
+      () => refuseLinkedStore(join(file, "child.cc")),
+      (error: unknown) => (error as NodeJS.ErrnoException).code === "ENOTDIR",
+    );
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+});

packages/cultcache-ts/test/union-parity.test.ts

@@ -1,8 +1,7 @@
 import assert from "node:assert/strict";
-import { existsSync } from "node:fs";
 import { mkdtemp, readFile, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
-import { join, resolve } from "node:path";
+import { join } from "node:path";
 import { test } from "node:test";
 
 import { decode, encode } from "@msgpack/msgpack";
@@ -22,190 +21,14 @@ import {
   encodeDocumentPayload,
 } from "../src/document";
 import { SingleFileMessagePackBackingStore } from "../src/single-file-messagepack-backing-store";
-import type { AnyCultCacheDocumentDefinition, CacheBackingStore, CultCacheEnvelope } from "../src/types";
+import type { AnyCultCacheDocumentDefinition, CultCacheEnvelope } from "../src/types";
+
+import {
+  CANARY, type Node, type Surface, golden, hex, node, outcome, read, surfaceCodec, surfaceDocument, surfaceSchema, vectors, envelopeOf, memoryStore,
+} from "./union-surface-fixture";
 
 const { array, boolean, bytes, float32, float64, int32, int64, lazy, list, nullable, slots, string, union, unit } = codecs;
 
-// The names the C# reference gives the fixture's types (CultSchemaTypeNames.FromType), as union-surface.cc carries them.
-const CS = "GameCult.Caching.Tests.UnionParityVectorTests+";
-
-// The golden is tests/vectors/union-parity, written by the C# reference. Everything below that is bytes or an expected
-// outcome is read from those committed files; only the value the payload must decode to is spelled here.
-function findVectors(from: string): string {
-  for (let dir = from; ; dir = resolve(dir, "..")) {
-    if (existsSync(join(dir, "tests", "vectors", "union-parity"))) return join(dir, "tests", "vectors", "union-parity");
-    if (resolve(dir, "..") === dir) throw new Error("tests/vectors/union-parity not found above the test.");
-  }
-}
-const vectors = findVectors(__dirname);
-const read = async (name: string) => new Uint8Array(await readFile(join(vectors, name)));
-
-// The string the C# writer put inside every refusal payload, to prove a refusal never echoes the payload.
-const CANARY = "CANARY-union-golden-4c2a";
-
-type Node =
-  | { kind: "Box"; id: string; children: (Node | null)[] }
-  | { kind: "Text"; id: string; content: string }
-  | { kind: "Use"; id: string; composition: Composition; slots: (Node | null)[] }
-  | { kind: "Image"; id: string; uri: string; alt: string }
-  | { kind: "Wrap"; inner: Node | null; id: string };
-interface Composition { name: string; body: Node | null }
-type Outcome = { kind: "Pending"; message: string } | { kind: "Completed"; sourceVersion: number } | { kind: "Denied" } | { kind: "Floor" } | { kind: "Ceiling" };
-// The golden's Outcome: the arms of a list carry an element id, so Denied, Floor and Ceiling are one-slot records.
-type GoldenOutcome =
-  | { kind: "Pending"; message: string; id: string }
-  | { kind: "Completed"; sourceVersion: number; id: string }
-  | { kind: "Denied"; id: string }
-  | { kind: "Floor"; id: string }
-  | { kind: "Ceiling"; id: string };
-type Item = { kind: "Gem"; name: string } | { kind: "Tool"; name: string; uses: number } | { kind: "Part"; name: string; count: number };
-type CraftedItem = { kind: "Tool"; name: string; uses: number } | { kind: "Part"; name: string; count: number };
-interface Surface {
-  id: string;
-  version: number;
-  root: Node | null;
-  outcomes: (GoldenOutcome | null)[];
-  part: Item | null;
-  crafted: CraftedItem | null;
-  missing: Node | null;
-}
-
-const composition = slots<Composition>({ 0: ["name", string], 1: ["body", lazy(() => node)] }, `${CS}Composition`);
-const node: Codec<Node | null> = union<Node>("Node", {
-  0: ["Box", slots<{ id: string; children: (Node | null)[] }>({ 0: ["id", string], 1: ["children", list(lazy(() => node))] })],
-  1: ["Text", slots<{ id: string; content: string }>({ 0: ["id", string], 1: ["content", string] })],
-  2: ["Use", slots<{ id: string; composition: Composition; slots: (Node | null)[] }>({
-    0: ["id", string], 1: ["composition", composition], 2: ["slots", list(lazy(() => node))],
-  })],
-  5: ["Image", slots<{ id: string; uri: string; alt: string }>({ 0: ["id", string], 1: ["uri", string], 3: ["alt", string] })],
-  6: ["Wrap", slots<{ inner: Node | null; id: string }>({ 0: ["inner", lazy(() => node)], 1: ["id", string] })],
-}, `${CS}Node`);
-const outcome = union<Outcome>("Outcome", {
-  0: ["Pending", slots<{ message: string }>({ 0: ["message", string] })],
-  1: ["Completed", slots<{ sourceVersion: number }>({ 0: ["sourceVersion", int32] })],
-  2: ["Denied", unit],
-  [-2147483648]: ["Floor", unit],
-  2147483647: ["Ceiling", unit],
-}, `${CS}Outcome`);
-const idOnly = slots<{ id: string }>({ 0: ["id", string] });
-const goldenOutcome = union<GoldenOutcome>("Outcome", {
-  0: ["Pending", slots<{ message: string; id: string }>({ 0: ["message", string], 1: ["id", string] })],
-  1: ["Completed", slots<{ sourceVersion: number; id: string }>({ 0: ["sourceVersion", int32], 1: ["id", string] })],
-  2: ["Denied", idOnly],
-  [-2147483648]: ["Floor", idOnly],
-  2147483647: ["Ceiling", idOnly],
-}, `${CS}Outcome`);
-const toolArm = slots<{ name: string; uses: number }>({ 0: ["name", string], 1: ["uses", int32] });
-const partArm = slots<{ name: string; count: number }>({ 0: ["name", string], 1: ["count", int32] });
-const item = union<Item>("Item", {
-  0: ["Gem", slots<{ name: string }>({ 0: ["name", string] })],
-  1: ["Tool", toolArm],
-  2: ["Part", partArm],
-}, `${CS}Item`);
-const craftedItem = union<CraftedItem>("CraftedItem", { 0: ["Tool", toolArm], 1: ["Part", partArm] }, `${CS}CraftedItem`);
-const surfaceCodec = slots<Surface>({
-  0: ["id", string],
-  1: ["version", int32],
-  2: ["root", node],
-  3: ["outcomes", list(goldenOutcome)],
-  4: ["part", item],
-  5: ["crafted", craftedItem],
-  6: ["missing", node, null],
-}, `${CS}UnionSurface`);
-
-const nodeSchema: z.ZodType<Node | null> = z.lazy(() =>
-  z.union([
-    z.null(),
-    z.discriminatedUnion("kind", [
-      z.object({ kind: z.literal("Box"), id: z.string(), children: z.array(nodeSchema) }),
-      z.object({ kind: z.literal("Text"), id: z.string(), content: z.string() }),
-      z.object({
-        kind: z.literal("Use"),
-        id: z.string(),
-        composition: z.object({ name: z.string(), body: nodeSchema }),
-        slots: z.array(nodeSchema),
-      }),
-      z.object({ kind: z.literal("Image"), id: z.string(), uri: z.string(), alt: z.string() }),
-      z.object({ kind: z.literal("Wrap"), inner: nodeSchema, id: z.string() }),
-    ]),
-  ]));
-const surfaceSchema = z.object({
-  id: z.string(),
-  version: z.number(),
-  root: nodeSchema,
-  outcomes: z.array(z.union([
-    z.null(),
-    z.discriminatedUnion("kind", [
-      z.object({ kind: z.literal("Pending"), message: z.string(), id: z.string() }),
-      z.object({ kind: z.literal("Completed"), sourceVersion: z.number(), id: z.string() }),
-      z.object({ kind: z.literal("Denied"), id: z.string() }),
-      z.object({ kind: z.literal("Floor"), id: z.string() }),
-      z.object({ kind: z.literal("Ceiling"), id: z.string() }),
-    ]),
-  ])),
-  part: z.union([z.null(), z.discriminatedUnion("kind", [
-    z.object({ kind: z.literal("Gem"), name: z.string() }),
-    z.object({ kind: z.literal("Tool"), name: z.string(), uses: z.number() }),
-    z.object({ kind: z.literal("Part"), name: z.string(), count: z.number() }),
-  ])]),
-  crafted: z.union([z.null(), z.discriminatedUnion("kind", [
-    z.object({ kind: z.literal("Tool"), name: z.string(), uses: z.number() }),
-    z.object({ kind: z.literal("Part"), name: z.string(), count: z.number() }),
-  ])]),
-  missing: nodeSchema,
-}) as unknown as z.ZodType<Surface>;
-
-function surfaceDocument(schemaId?: string) {
-  return defineDocumentType({
-    type: "tests.union_surface",
-    schemaId: schemaId ?? "tests.union_surface.v1",
-    schemaName: "tests.union_surface",
-    schemaVersion: "tests.union_surface.v1",
-    schema: surfaceSchema,
-    codec: surfaceCodec,
-    name: "id",
-  });
-}
-
-const golden: Surface = {
-  id: "surface",
-  version: 3,
-  root: {
-    kind: "Box",
-    id: "0000000000c0",
-    children: [
-      { kind: "Text", id: "0000000000c1", content: "hello" },
-      {
-        kind: "Use",
-        id: "0000000000c2",
-        composition: {
-          name: "comp",
-          body: {
-            kind: "Box",
-            id: "0000000000d0",
-            children: [
-              { kind: "Text", id: "0000000000d1", content: "x" },
-              { kind: "Image", id: "0000000000d2", uri: "uri://a", alt: "alt" },
-            ],
-          },
-        },
-        slots: [{ kind: "Text", id: "0000000000e1", content: "slot" }, null, { kind: "Box", id: "0000000000e2", children: [] }],
-      },
-      { kind: "Image", id: "0000000000c3", uri: "uri://b", alt: "" },
-    ],
-  },
-  outcomes: [
-    { kind: "Pending", message: "wait", id: "0000000000a1" },
-    { kind: "Completed", sourceVersion: 7, id: "0000000000a2" },
-    { kind: "Denied", id: "0000000000a3" },
-  ],
-  part: { kind: "Tool", name: "hammer", uses: 12 },
-  crafted: { kind: "Part", name: "gear", count: 4 },
-  missing: null,
-};
-
-const hex = (data: Uint8Array) => Buffer.from(data).toString("hex");
-
 async function outcomeEntries() {
   const entries = decode(await read("outcomes.msgpack")) as [string, string, string, number | null, string][];
   return entries.map(([file, outcome, unionName, key, detail]) => ({ file, outcome, unionName, key, detail }));
@@ -515,7 +338,7 @@ test("the wire reader keeps 64-bit integers whole, tells a float from an integer
   assert.throws(() => readWire(fromHex("dd")), /truncated/u);
   assert.throws(() => readWire(fromHex("ddffffffff")), /truncated/u, "a huge array header reserves nothing");
   assert.throws(() => readWire(fromHex("a5616263")), /truncated/u);
-  assert.throws(() => readWire(fromHex("0102")), /bytes after its value/u);
+  assert.equal(readWire(fromHex("0102")), 1, "the reader reads one value; the document owner refuses what follows");
   assert.throws(() => readWire(fromHex("81a161a162")), /map, extension or reserved/u);
   assert.throws(() => readWire(fromHex("c1")), /map, extension or reserved/u);
   assert.throws(() => readWire(fromHex("d4010a")), /map, extension or reserved/u);
@@ -729,19 +552,6 @@ test("the Int32 edges of an arm key: the largest is an arm, one past either end
   assert.throws(() => edge.decode(readWire(fromHex("92d3ffffffff8000000090"))), { message: "Union U: unknown arm key -2147483648 (declared keys: 2147483647)." });
 });
 
-function envelopeOf(payload: Uint8Array): CultCacheEnvelope {
-  return { key: "surface", type: "tests.union_surface", payload: documentPayloadFromBytes(payload), storedAt: new Date().toISOString() };
-}
-
-function memoryStore(entries: CultCacheEnvelope[]): CacheBackingStore & { entries: CultCacheEnvelope[] } {
-  return {
-    entries,
-    async pullAll() { return entries.map((entry) => ({ ...entry })); },
-    async push(entry) { entries.push(entry); },
-    async delete() {},
-  };
-}
-
 test("arm keys span Int32 and are listed ascending; slot keys are non-negative Int32", () => {
   const keys = union<{ kind: "High" | "Zero" | "Neg" | "Low" }>("U", {
     2147483647: ["High", unit],
@@ -915,3 +725,114 @@ test("a cache load refuses a store whose record is past the limit, naming the ty
   const refusing = CultCache.builder().withDocumentType(document).withGenericStore(memoryStore([envelopeOf(await read("depth-past-limit.msgpack"))])).build();
   await assert.rejects(() => refusing.pullAllBackingStores(), (error: Error) => error instanceof CultCachePayloadDepthError && !error.message.includes(CANARY));
 });
+
+// ---- bytes-after vectors: a payload is exactly one MessagePack value (tests/vectors/union-parity/README.md) ----
+
+// The C# reference writes the vectors: union-surface.msgpack followed by a tail the first value does not own. The one
+// owner refuses by count, naming the type, from the walk's end; it never walks or echoes the tail.
+async function bytesAfterEntries() {
+  const raw = decode(await read("bytes-after-outcomes.msgpack")) as unknown[][];
+  return raw.map(([file, outcome, unionName, key, detail]) => ({ file: file as string, outcome: outcome as string, unionName: unionName as string, key: key as number | null, detail: detail as string }));
+}
+
+// The C# vector writer's canary (BytesAfterVectorTests): it sits in the deep tail, so an echo of the tail would carry it.
+const TAIL_CANARY = "CANARY-bytes-after-7d1e";
+const valueLength = async () => (await read("union-surface.msgpack")).length;
+const plainDocument = () => defineDocumentType({ type: "tests.plain_surface", schema: z.unknown() });
+const codecDocument = () => defineDocumentType({ type: "tests.codec_surface", schema: surfaceSchema, codec: surfaceCodec });
+
+async function assertBytesAfterRefused(file: string, tail: number, run: () => unknown | Promise<unknown>, type: string) {
+  const clause = `${type}`;
+  await assert.rejects(
+    async () => run(),
+    (error: Error) => {
+      assert.ok(!(error instanceof CultCachePayloadDepthError), `${file}: the tail was walked`);
+      assert.ok(!error.message.includes(CANARY) && !error.message.includes(TAIL_CANARY), `${file}: the refusal echoed the tail`);
+      assert.ok(!error.message.includes("the limit is"), `${file}: the depth refusal`);
+      assert.ok(error.message.includes(clause), `${file}: names the type: ${error.message}`);
+      assert.ok(error.message.includes(`${tail} bytes after its first MessagePack value`), `${file}: names the count: ${error.message}`);
+      return true;
+    },
+    file,
+  );
+}
+
+test("every bytes-after vector is refused by the one owner, by count, on the codec, plain and store paths", async () => {
+  const entries = await bytesAfterEntries();
+  assert.equal(entries.length, 4);
+  const length = await valueLength();
+  const surface = surfaceDocument();
+  const plain = plainDocument();
+  const codecOnly = codecDocument();
+  const dir = await mkdtemp(join(tmpdir(), "bytes-after-"));
+  for (const { file, outcome, unionName, detail } of entries) {
+    assert.equal(outcome, "refused");
+    assert.equal(unionName, "UnionSurface");
+    assert.equal(detail, "bytes-after");
+    const bytes = await read(file);
+    const tail = bytes.length - length;
+    assert.ok(tail > 0, file);
+    if (file === "bytes-after-deep-tail.msgpack") assert.ok(Buffer.from(bytes).includes(TAIL_CANARY), "the deep tail carries the canary the assertions look for");
+    const payload = documentPayloadFromBytes(bytes);
+    await assertBytesAfterRefused(file, tail, () => decodeDocumentPayload(surface, payload), surface.type);
+    await assertBytesAfterRefused(file, tail, () => decodeDocumentPayload(plain, payload), plain.type);
+    await assertBytesAfterRefused(file, tail, () => decodeDocumentPayload(codecOnly, payload), codecOnly.type);
+
+    // The store path: a single-file store holding the vector as a record payload refuses on load.
+    const path = join(dir, `${file}.cc`);
+    await new SingleFileMessagePackBackingStore(path).push(envelopeOf(bytes));
+    const cache = CultCache.builder().withDocumentType(surface).withGenericStore(new SingleFileMessagePackBackingStore(path)).build();
+    await assertBytesAfterRefused(file, tail, () => cache.pullAllBackingStores(), surface.type);
+
+    // The put path: an envelope arriving with the tail is refused and held nowhere.
+    const written: CultCacheEnvelope[] = [];
+    const held = CultCache.builder().withDocumentType(surface).withGenericStore(memoryStore(written)).build();
+    await assertBytesAfterRefused(file, tail, () => held.putEnvelope(surface, envelopeOf(bytes)), surface.type);
+    assert.equal(written.length, 0, `${file}: nothing reached the store`);
+    assert.equal(held.get(surface, "surface"), undefined, `${file}: nothing is held in memory`);
+  }
+});
+
+test("a payload with an unread slot and a tail is refused by count before any slot is marked or the record held", async () => {
+  const withSlot = await read("extra-slot-record.msgpack");
+  const surface = surfaceDocument();
+  const tailed = Uint8Array.from([...withSlot, 0xc0]);
+  const whole = CultCache.builder().withDocumentType(surface).withGenericStore(memoryStore([envelopeOf(withSlot)])).build();
+  await whole.pullAllBackingStores();
+  assert.ok(whole.unreadSlots(surface, "surface"), "without a tail the record is held with its unread slots");
+
+  const loading = CultCache.builder().withDocumentType(surface).withGenericStore(memoryStore([envelopeOf(tailed)])).build();
+  await assertBytesAfterRefused("extra-slot-record+tail", 1, () => loading.pullAllBackingStores(), surface.type);
+  assert.equal(loading.get(surface, "surface"), undefined);
+  assert.equal(loading.unreadSlots(surface, "surface"), undefined);
+
+  const written: CultCacheEnvelope[] = [];
+  const putting = CultCache.builder().withDocumentType(surface).withGenericStore(memoryStore(written)).build();
+  await assertBytesAfterRefused("extra-slot-record+tail", 1, () => putting.putEnvelope(surface, envelopeOf(tailed)), surface.type);
+  assert.equal(written.length, 0);
+  assert.equal(putting.get(surface, "surface"), undefined);
+  assert.equal(putting.unreadSlots(surface, "surface"), undefined);
+});
+
+test("a payload that ends early is not bytes after its value: the decoder refuses it, and a user formatter's bytes are not walked", async () => {
+  const whole = await read("union-surface.msgpack");
+  const surface = surfaceDocument();
+  for (const cut of [0, 1, 10, whole.length - 1]) {
+    assert.throws(
+      () => decodeDocumentPayload(surface, documentPayloadFromBytes(whole.slice(0, cut))),
+      (error: Error) => !error.message.includes("bytes after") && !(error instanceof CultCachePayloadDepthError),
+      `truncated at ${cut}`,
+    );
+  }
+  // A header cut short of its length is an early end too, whatever width it declares.
+  for (const early of ["dc00", "dd000000", "de00", "c4", "d9", "a5616263", "9291"]) {
+    assert.throws(
+      () => decodeDocumentPayload(surface, documentPayloadFromBytes(fromHex(early))),
+      (error: Error) => !error.message.includes("bytes after") && !(error instanceof CultCachePayloadDepthError),
+      `early end ${early}`,
+    );
+  }
+  const opaque = defineDocumentType({ type: "tests.opaque", schema: z.unknown(), formatter: { encode: (value: Uint8Array) => value, decode: (bytes: Uint8Array) => bytes } });
+  const tailed = await read("bytes-after-nil.msgpack");
+  assert.equal((decodeDocumentPayload(opaque, documentPayloadFromBytes(tailed)) as Uint8Array).length, tailed.length);
+});

packages/cultcache-ts/test/union-surface-fixture.ts

@@ -0,0 +1,240 @@
+import { existsSync } from "node:fs";
+import { readFile } from "node:fs/promises";
+import { join, resolve } from "node:path";
+
+import { z } from "zod";
+
+import { codecs } from "../src";
+import type { Codec } from "../src/codec";
+import { defineDocumentType, documentPayloadFromBytes } from "../src/document";
+import type { CacheBackingStore, CultCacheEnvelope } from "../src/types";
+
+// The union-surface fixture: the codecs, schema and value tests/vectors/union-parity was written from, shared by the
+// union-parity walker and the slot-readonly walker so the shape is spelled once.
+const { list, int32, lazy, slots, string, union, unit } = codecs;
+
+
+// The names the C# reference gives the fixture's types (CultSchemaTypeNames.FromType), as union-surface.cc carries them.
+export const CS = "GameCult.Caching.Tests.UnionParityVectorTests+";
+
+// The golden is tests/vectors/union-parity, written by the C# reference. Everything below that is bytes or an expected
+// outcome is read from those committed files; only the value the payload must decode to is spelled here.
+export function findVectors(from: string): string {
+  for (let dir = from; ; dir = resolve(dir, "..")) {
+    if (existsSync(join(dir, "tests", "vectors", "union-parity"))) return join(dir, "tests", "vectors", "union-parity");
+    if (resolve(dir, "..") === dir) throw new Error("tests/vectors/union-parity not found above the test.");
+  }
+}
+export const vectors = findVectors(__dirname);
+export const read = async (name: string) => new Uint8Array(await readFile(join(vectors, name)));
+
+// The string the C# writer put inside every refusal payload, to prove a refusal never echoes the payload.
+export const CANARY = "CANARY-union-golden-4c2a";
+
+export type Node =
+  | { kind: "Box"; id: string; children: (Node | null)[] }
+  | { kind: "Text"; id: string; content: string }
+  | { kind: "Use"; id: string; composition: Composition; slots: (Node | null)[] }
+  | { kind: "Image"; id: string; uri: string; alt: string }
+  | { kind: "Wrap"; inner: Node | null; id: string };
+export interface Composition { name: string; body: Node | null }
+export type Outcome = { kind: "Pending"; message: string } | { kind: "Completed"; sourceVersion: number } | { kind: "Denied" } | { kind: "Floor" } | { kind: "Ceiling" };
+// The golden's Outcome: the arms of a list carry an element id, so Denied, Floor and Ceiling are one-slot records.
+export type GoldenOutcome =
+  | { kind: "Pending"; message: string; id: string }
+  | { kind: "Completed"; sourceVersion: number; id: string }
+  | { kind: "Denied"; id: string }
+  | { kind: "Floor"; id: string }
+  | { kind: "Ceiling"; id: string };
+export type Item = { kind: "Gem"; name: string } | { kind: "Tool"; name: string; uses: number } | { kind: "Part"; name: string; count: number };
+export type CraftedItem = { kind: "Tool"; name: string; uses: number } | { kind: "Part"; name: string; count: number };
+export interface Surface {
+  id: string;
+  version: number;
+  root: Node | null;
+  outcomes: (GoldenOutcome | null)[];
+  part: Item | null;
+  crafted: CraftedItem | null;
+  missing: Node | null;
+}
+
+export const composition = slots<Composition>({ 0: ["name", string], 1: ["body", lazy(() => node)] }, `${CS}Composition`);
+export const node: Codec<Node | null> = union<Node>("Node", {
+  0: ["Box", slots<{ id: string; children: (Node | null)[] }>({ 0: ["id", string], 1: ["children", list(lazy(() => node))] }, `${CS}Box`)],
+  1: ["Text", slots<{ id: string; content: string }>({ 0: ["id", string], 1: ["content", string] }, `${CS}Text`)],
+  2: ["Use", slots<{ id: string; composition: Composition; slots: (Node | null)[] }>({
+    0: ["id", string], 1: ["composition", composition], 2: ["slots", list(lazy(() => node))],
+  })],
+  5: ["Image", slots<{ id: string; uri: string; alt: string }>({ 0: ["id", string], 1: ["uri", string], 3: ["alt", string] })],
+  6: ["Wrap", slots<{ inner: Node | null; id: string }>({ 0: ["inner", lazy(() => node)], 1: ["id", string] })],
+}, `${CS}Node`);
+export const outcome = union<Outcome>("Outcome", {
+  0: ["Pending", slots<{ message: string }>({ 0: ["message", string] })],
+  1: ["Completed", slots<{ sourceVersion: number }>({ 0: ["sourceVersion", int32] })],
+  2: ["Denied", unit],
+  [-2147483648]: ["Floor", unit],
+  2147483647: ["Ceiling", unit],
+}, `${CS}Outcome`);
+export const idOnly = slots<{ id: string }>({ 0: ["id", string] });
+export const goldenOutcome = union<GoldenOutcome>("Outcome", {
+  0: ["Pending", slots<{ message: string; id: string }>({ 0: ["message", string], 1: ["id", string] })],
+  1: ["Completed", slots<{ sourceVersion: number; id: string }>({ 0: ["sourceVersion", int32], 1: ["id", string] })],
+  2: ["Denied", idOnly],
+  [-2147483648]: ["Floor", idOnly],
+  2147483647: ["Ceiling", idOnly],
+}, `${CS}Outcome`);
+export const toolArm = slots<{ name: string; uses: number }>({ 0: ["name", string], 1: ["uses", int32] });
+export const partArm = slots<{ name: string; count: number }>({ 0: ["name", string], 1: ["count", int32] });
+export const item = union<Item>("Item", {
+  0: ["Gem", slots<{ name: string }>({ 0: ["name", string] })],
+  1: ["Tool", toolArm],
+  2: ["Part", partArm],
+}, `${CS}Item`);
+export const craftedItem = union<CraftedItem>("CraftedItem", { 0: ["Tool", toolArm], 1: ["Part", partArm] }, `${CS}CraftedItem`);
+export const surfaceCodecOf = (typeName: string) => slots<Surface>({
+  0: ["id", string],
+  1: ["version", int32],
+  2: ["root", node],
+  3: ["outcomes", list(goldenOutcome)],
+  4: ["part", item],
+  5: ["crafted", craftedItem],
+  6: ["missing", node, null],
+}, typeName);
+export const surfaceCodec = surfaceCodecOf(`${CS}UnionSurface`);
+
+export const nodeSchema: z.ZodType<Node | null> = z.lazy(() =>
+  z.union([
+    z.null(),
+    z.discriminatedUnion("kind", [
+      z.object({ kind: z.literal("Box"), id: z.string(), children: z.array(nodeSchema) }),
+      z.object({ kind: z.literal("Text"), id: z.string(), content: z.string() }),
+      z.object({
+        kind: z.literal("Use"),
+        id: z.string(),
+        composition: z.object({ name: z.string(), body: nodeSchema }),
+        slots: z.array(nodeSchema),
+      }),
+      z.object({ kind: z.literal("Image"), id: z.string(), uri: z.string(), alt: z.string() }),
+      z.object({ kind: z.literal("Wrap"), inner: nodeSchema, id: z.string() }),
+    ]),
+  ]));
+export const surfaceSchema = z.object({
+  id: z.string(),
+  version: z.number(),
+  root: nodeSchema,
+  outcomes: z.array(z.union([
+    z.null(),
+    z.discriminatedUnion("kind", [
+      z.object({ kind: z.literal("Pending"), message: z.string(), id: z.string() }),
+      z.object({ kind: z.literal("Completed"), sourceVersion: z.number(), id: z.string() }),
+      z.object({ kind: z.literal("Denied"), id: z.string() }),
+      z.object({ kind: z.literal("Floor"), id: z.string() }),
+      z.object({ kind: z.literal("Ceiling"), id: z.string() }),
+    ]),
+  ])),
+  part: z.union([z.null(), z.discriminatedUnion("kind", [
+    z.object({ kind: z.literal("Gem"), name: z.string() }),
+    z.object({ kind: z.literal("Tool"), name: z.string(), uses: z.number() }),
+    z.object({ kind: z.literal("Part"), name: z.string(), count: z.number() }),
+  ])]),
+  crafted: z.union([z.null(), z.discriminatedUnion("kind", [
+    z.object({ kind: z.literal("Tool"), name: z.string(), uses: z.number() }),
+    z.object({ kind: z.literal("Part"), name: z.string(), count: z.number() }),
+  ])]),
+  missing: nodeSchema,
+}) as unknown as z.ZodType<Surface>;
+
+// The reference's SurfaceDeclaring: the same layout, schema tests.union_surface.v2, listing the older wide id compatible.
+export function surfaceDeclaringDocument() {
+  return defineDocumentType({
+    type: "tests.union_surface",
+    schemaId: "tests.union_surface.v2",
+    schemaName: "tests.union_surface",
+    schemaVersion: "tests.union_surface.v2",
+    compatibleSchemaIds: ["tests.union_surface.wide"],
+    schema: surfaceSchema,
+    codec: surfaceCodecOf(`${CS}SurfaceDeclaring`),
+    name: "id",
+  });
+}
+
+export function surfaceDocument(schemaId?: string, contentHash?: string) {
+  return defineDocumentType({
+    ...(contentHash === undefined ? {} : { contentHash }),
+    type: "tests.union_surface",
+    schemaId: schemaId ?? "tests.union_surface.v1",
+    schemaName: "tests.union_surface",
+    schemaVersion: "tests.union_surface.v1",
+    schema: surfaceSchema,
+    codec: surfaceCodec,
+    name: "id",
+  });
+}
+
+export const golden: Surface = {
+  id: "surface",
+  version: 3,
+  root: {
+    kind: "Box",
+    id: "0000000000c0",
+    children: [
+      { kind: "Text", id: "0000000000c1", content: "hello" },
+      {
+        kind: "Use",
+        id: "0000000000c2",
+        composition: {
+          name: "comp",
+          body: {
+            kind: "Box",
+            id: "0000000000d0",
+            children: [
+              { kind: "Text", id: "0000000000d1", content: "x" },
+              { kind: "Image", id: "0000000000d2", uri: "uri://a", alt: "alt" },
+            ],
+          },
+        },
+        slots: [{ kind: "Text", id: "0000000000e1", content: "slot" }, null, { kind: "Box", id: "0000000000e2", children: [] }],
+      },
+      { kind: "Image", id: "0000000000c3", uri: "uri://b", alt: "" },
+    ],
+  },
+  outcomes: [
+    { kind: "Pending", message: "wait", id: "0000000000a1" },
+    { kind: "Completed", sourceVersion: 7, id: "0000000000a2" },
+    { kind: "Denied", id: "0000000000a3" },
+  ],
+  part: { kind: "Tool", name: "hammer", uses: 12 },
+  crafted: { kind: "Part", name: "gear", count: 4 },
+  missing: null,
+};
+export const hex = (data: Uint8Array) => Buffer.from(data).toString("hex");
+
+// tests.slot_unit: a document [Name, Outcome: UnitOutcome], whose one arm Denied2 is a unit arm (extra-slot-store.cc, record
+// unit-arm). The reader's names are the reference's: a mark names Denied2.
+export const unitOutcome = union<{ kind: "Denied2" }>("UnitOutcome", { 2: ["Denied2", unit] }, `${CS}UnitOutcome`);
+export function slotUnitDocument(schemaId: string, contentHash?: string) {
+  return defineDocumentType({
+    ...(contentHash === undefined ? {} : { contentHash }),
+    type: "tests.slot_unit",
+    schemaId,
+    schemaName: "tests.slot_unit",
+    schemaVersion: "tests.slot_unit.v1",
+    schema: z.object({ name: z.string(), outcome: z.union([z.null(), z.object({ kind: z.literal("Denied2") })]) }),
+    codec: slots<{ name: string; outcome: { kind: "Denied2" } | null }>({ 0: ["name", string], 1: ["outcome", unitOutcome] }, `${CS}SlotUnit`),
+    name: "name",
+  });
+}
+
+export function envelopeOf(payload: Uint8Array): CultCacheEnvelope {
+  return { key: "surface", type: "tests.union_surface", payload: documentPayloadFromBytes(payload), storedAt: new Date().toISOString() };
+}
+
+export function memoryStore(entries: CultCacheEnvelope[]): CacheBackingStore & { entries: CultCacheEnvelope[] } {
+  return {
+    entries,
+    async pullAll() { return entries.map((entry) => ({ ...entry })); },
+    async push(entry) { entries.push(entry); },
+    async delete() {},
+  };
+}
+

packages/cultmath/README.md

@@ -147,8 +147,8 @@ CultMath names with tests instead of copied project-local helper drift.
 ```powershell
 dotnet build packages/cultmath/src/CultMath/CultMath.csproj
 dotnet test packages/cultmath/tests/CultMath.Tests/CultMath.Tests.csproj
-cargo test --manifest-path packages/cultmath/native/cultmath-core/Cargo.toml
-cargo build --release --manifest-path packages/cultmath/native/cultmath-core/Cargo.toml
+cargo test --locked --manifest-path packages/cultmath/native/cultmath-core/Cargo.toml
+cargo build --locked --release --manifest-path packages/cultmath/native/cultmath-core/Cargo.toml
 .\packages\cultmath\scripts\build-unity-package.ps1
 ```
 

packages/cultmesh-browser/CHANGELOG.md

@@ -9,6 +9,10 @@ All notable changes to `@gamecult/cultmesh-browser` are recorded here, following
 
 - The package is renamed `cultmesh-browser` to `@gamecult/cultmesh-browser` (the repo already scopes `@gamecult/cultcache-ts`), so the unscoped name cannot be claimed by someone else. Import from `@gamecult/cultmesh-browser` and its subpaths; the API is unchanged. Depends on `@gamecult/cultnet-ts`; the interop test uses `@gamecult/cultmesh-ts`.
 
+### Dependencies
+
+- Needs `@gamecult/cultnet-ts` `^0.4.0` (was `^0.3.0`), moving with the `cultnet-ts` 0.4.0 release.
+
 ## [0.4.0]
 
 ### Added

packages/cultmesh-browser/package.json

@@ -42,7 +42,7 @@
   },
   "dependencies": {
     "@gamecult/cultcache-ts": "^0.15.0",
-    "@gamecult/cultnet-ts": "^0.3.0"
+    "@gamecult/cultnet-ts": "^0.4.0"
   },
   "devDependencies": {
     "@types/node": "^24.0.0",

packages/cultmesh-py/pyproject.toml

@@ -16,7 +16,7 @@ classifiers = [
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
 ]
-dependencies = ["cultcache-py>=0.2.0", "cultnet-py>=0.1.0", "cryptography>=41"]
+dependencies = ["cultcache-py>=0.4.0", "cultnet-py>=0.1.0", "cryptography>=41"]
 [project.scripts]
 cultmesh-py-daemon = "cultmesh_py.daemon:main"
 cultmesh-py-verify = "cultmesh_py.verify:main"

packages/cultmesh-py/tests/test_remote_write_authority.py

@@ -180,6 +180,21 @@ class RemoteWriteAuthorityTests(unittest.TestCase):
         reply = self.send(granting, unowned)
         self.assertEqual(reply[0]["code"], "unregistered_document_put", "a granted put still meets the store's refusal")
 
+    def test_a_put_with_a_payload_tail_and_an_unknown_schema_id_is_refused_whole_under_the_canonical_id(self) -> None:
+        # The payload head names the registered schema, so the put routes by stamp; the tail makes the payload more
+        # than one MessagePack value. It is answered message_invalid (not unregistered_document_put), nothing is
+        # stored, and the authority is asked under the canonical id, not the id as sent.
+        authority = Recording(lambda _: CultMeshRemoteWriteDecision.grant())
+        server = self.build(authority)
+        tailed = put_of(KEY_A, "x", schema_id="sha256:nobody-owns-this")
+        tailed["document"]["payload"] = bytes(tailed["document"]["payload"]) + b"\x01"
+
+        replies = self.send(server, tailed)
+
+        self.assertEqual([(reply["code"], reply["details"]["field"]) for reply in replies], [("message_invalid", "document")])
+        self.assertIsNone(self.text_of(server, KEY_A))
+        self.assertEqual([request.schema_id for request in authority.requests], [SCHEMA_ID])
+
     def test_an_authority_that_raises_refuses_and_is_logged_as_an_error(self) -> None:
         def explode(_: Any) -> Any:
             raise RuntimeError("authority exploded")

packages/cultmesh-rs/src/lib.rs

@@ -732,21 +732,37 @@ impl CultMeshNode {
         let cultnet_rs::CultNetMessage::SnapshotResponseRaw { documents, .. } = response else {
             anyhow::bail!("expected cultnet.snapshot_response_raw.v0");
         };
-        let mut applied = 0usize;
+        self.apply_raw_snapshot_documents(documents)
+    }
+
+    /// Applies the snapshot documents as one cache commit, as C# does: a refusal (a key this node holds read-only because
+    /// of unread slots from a newer peer or a payload this build cannot read, or any other the cache judges) applies
+    /// nothing. A schema id the registry does not know is skipped, except one with a `.vN` suffix, which is taken as
+    /// registered and refuses the commit when its type is not (C# throws on an unknown schema too). The commit lands in
+    /// one backing store, so a snapshot spanning stores is refused whole; C# `CultCache.Commit` refuses a cross-store batch too
+    /// ("The batch spans A and B; a commit lands in one home store"), so the two agree.
+    fn apply_raw_snapshot_documents(
+        &mut self,
+        documents: Vec<cultnet_rs::CultNetRawDocumentRecord>,
+    ) -> Result<usize> {
+        let mut staged = Vec::new();
         for document in documents {
             let Some(document_type) =
                 registered_document_type_for_schema(&self.documents, &document.schema_id)
             else {
                 continue;
             };
-            self.cache.put_raw_envelope(CultCacheEnvelope {
+            staged.push(CultCacheEnvelope {
                 key: document.record_key,
                 r#type: document_type,
                 payload: document.payload,
                 stored_at: document.stored_at,
                 schema_id: Some(document.schema_id),
-            })?;
-            applied += 1;
+            });
+        }
+        let applied = staged.len();
+        if applied > 0 {
+            self.cache.put_prepared_batch(staged)?;
         }
         Ok(applied)
     }
@@ -1195,10 +1211,111 @@ mod tests {
         body: String,
     }
 
+    #[derive(Clone, Debug, PartialEq, Eq, cultcache_rs::DatabaseEntry)]
+    #[cultcache(type = "cultmesh.test.memo", schema = "CultMeshTestMemo")]
+    struct Memo {
+        #[cultcache(key = 0)]
+        body: String,
+    }
+
     cultmesh_documents!(TestDocuments {
         Note => "cultmesh.test.note.v0",
     });
 
+    cultmesh_documents!(TwoTypeDocuments {
+        Note => "cultmesh.test.note.v0",
+        Memo => "cultmesh.test.memo.v0",
+    });
+
+    fn raw_note(key: &str, payload: Vec<u8>) -> cultnet_rs::CultNetRawDocumentRecord {
+        cultnet_rs::CultNetRawDocumentRecord {
+            schema_id: "cultmesh.test.note.v0".to_string(),
+            record_key: key.to_string(),
+            stored_at: "2026-01-01T00:00:00Z".to_string(),
+            payload_encoding: cultnet_rs::CultNetRawPayloadEncoding::Messagepack,
+            payload,
+            source_runtime_id: None,
+            source_agent_id: None,
+            source_role: None,
+            tags: None,
+        }
+    }
+
+    #[test]
+    fn a_snapshot_document_for_a_read_only_key_refuses_the_whole_pull_as_csharp_does() -> Result<()> {
+        let temp = tempfile::tempdir()?;
+        let mut node = CultMesh::create_node(temp.path().join("m.cc"), TestDocuments, Default::default())?;
+        // A newer peer's note: one slot past the declared one.
+        let newer = rmp_serde::to_vec(&("newer body", "extra slot"))?;
+        let plain = |body: &str| rmp_serde::to_vec(&(body,));
+        assert_eq!(node.apply_raw_snapshot_documents(vec![raw_note("held", newer)])?, 1);
+        assert_eq!(node.get_required::<Note>("held")?.body, "newer body");
+
+        let error = node
+            .apply_raw_snapshot_documents(vec![
+                raw_note("before", plain("b")?),
+                raw_note("held", plain("overwrite")?),
+                raw_note("after", plain("a")?),
+            ])
+            .unwrap_err();
+        let conflict = error.downcast_ref::<cultcache_rs::SchemaConflictError>().expect("typed refusal");
+        assert_eq!(conflict.record_key, "held");
+        assert!(conflict.unread_slots.is_some());
+        assert!(!error.to_string().contains("extra slot"));
+        assert!(node.get::<Note>("before")?.is_none());
+        assert_eq!(node.get_required::<Note>("held")?.body, "newer body");
+        assert!(node.get::<Note>("after")?.is_none());
+        Ok(())
+    }
+
+    #[test]
+    fn a_snapshot_spanning_two_backing_stores_is_refused_whole_and_applies_nothing() -> Result<()> {
+        let temp = tempfile::tempdir()?;
+        let mut node = CultMesh::create_node(temp.path().join("m.cc"), TwoTypeDocuments, Default::default())?;
+        // A node has one store through the public API; route Memo to a second one by hand (C# refuses the same commit).
+        node.cache.add_backing_store(
+            SingleFileMessagePackBackingStore::new(temp.path().join("memo.cc")),
+            [Memo::TYPE],
+        )?;
+        node.cache.pull_all_backing_stores()?;
+        let plain = |body: &str| rmp_serde::to_vec(&(body,));
+        let memo = |key: &str, payload| {
+            let mut record = raw_note(key, payload);
+            record.schema_id = "cultmesh.test.memo.v0".to_string();
+            record
+        };
+        let error = node
+            .apply_raw_snapshot_documents(vec![
+                raw_note("n", plain("note")?),
+                memo("m", plain("memo")?),
+            ])
+            .unwrap_err();
+        assert!(error.to_string().contains("cannot span backing stores"), "{error}");
+        assert!(node.get::<Note>("n")?.is_none());
+        assert!(node.get::<Memo>("m")?.is_none());
+        assert!(!temp.path().join("m.cc").exists() && !temp.path().join("memo.cc").exists());
+
+        // Each store alone still takes its own snapshot.
+        assert_eq!(node.apply_raw_snapshot_documents(vec![memo("m", plain("memo")?)])?, 1);
+        assert_eq!(node.get_required::<Memo>("m")?.body, "memo");
+        Ok(())
+    }
+
+    #[test]
+    fn a_snapshot_applied_to_a_stale_node_keeps_the_records_another_writer_added() -> Result<()> {
+        let temp = tempfile::tempdir()?;
+        let path = temp.path().join("m.cc");
+        let mut node = CultMesh::create_node(&path, TestDocuments, Default::default())?;
+        let mut other = CultMesh::create_node(&path, TestDocuments, Default::default())?;
+        other.put("added", &Note { body: "other writer".to_string() })?;
+        let plain = |body: &str| rmp_serde::to_vec(&(body,));
+        assert_eq!(node.apply_raw_snapshot_documents(vec![raw_note("snap", plain("s")?)])?, 1);
+        let reopened = CultMesh::create_node(&path, TestDocuments, Default::default())?;
+        assert_eq!(reopened.get_required::<Note>("added")?.body, "other writer");
+        assert_eq!(reopened.get_required::<Note>("snap")?.body, "s");
+        Ok(())
+    }
+
     #[test]
     fn node_round_trips_registered_documents() -> Result<()> {
         let temp = tempfile::tempdir()?;

packages/cultmesh-ts/CHANGELOG.md

@@ -29,6 +29,8 @@ All notable changes to `@gamecult/cultmesh-ts` are recorded here, following
 
 - Needs the cultcache-ts release that ships with this change (its manifest range moves with that release): it imports `schemaIdentityOf` and `SchemaConflictError`, which 0.14.x does not export.
 
+- Needs `@gamecult/cultnet-ts` `^0.4.0` (was `^0.3.0`): this package imports names that `cultnet-ts` 0.3.0 does not export (`cultNetMessageInvalidError`, `cultNetTextError`, `cultNetWriteNotAuthorizedError`, `WriteTracker`, `CULTNET_WRITE_RECEIPT_MESSAGE_VERSIONS`, `helloAdvertisesWriteReceipts`, `resultWindowMs`). The declared-range check (`npm run test:pack:ts`) found the old range admitting a release that lacks them.
+
 ## [0.2.0]
 
 ### Added

packages/cultmesh-ts/package.json

@@ -50,7 +50,7 @@
   },
   "dependencies": {
     "@gamecult/cultcache-ts": "^0.15.0",
-    "@gamecult/cultnet-ts": "^0.3.0",
+    "@gamecult/cultnet-ts": "^0.4.0",
     "koffi": "3.3.0"
   },
   "devDependencies": {

packages/cultmesh-ts/src/index.ts

@@ -3933,7 +3933,7 @@ export class CultMeshNode {
   }
 
   public async flush(soft = false): Promise<void> {
-    await this.store.pushAll?.(this.cache.snapshot(), { soft });
+    await this.store.pushAll?.(this.cache.storedSnapshot(), { soft });
   }
 }
 

packages/cultmesh-ts/test/cultmesh.test.ts

@@ -6,7 +6,7 @@ import test from "node:test";
 import assert from "node:assert/strict";
 import { decodeWireValue, encodeWireValue } from "@gamecult/cultnet-ts/wire";
 import { z } from "zod";
-import { SchemaConflictError, defineDocumentType, documentPayloadBytes, documentPayloadFromBytes } from "@gamecult/cultcache-ts";
+import { SchemaConflictError, SingleFileMessagePackBackingStore, defineDocumentType, documentPayloadBytes, documentPayloadFromBytes } from "@gamecult/cultcache-ts";
 import {
   CultNetDocumentRegistry,
   CultNetPeer,
@@ -109,6 +109,34 @@ test("CultMesh TS opens a durable local node and registers document bindings", a
   assert.ok(reopened.documents.getBySchemaId("cultmesh.note.v0"));
 });
 
+test("CultMesh TS flush from a node that never pulled leaves the records the store holds", async () => {
+  const filePath = join(await mkdtemp(join(tmpdir(), "cultmesh-ts-flush-")), "node.ccmp");
+  const first = await CultMesh.startNode(filePath, { documents: [noteDocument] });
+  await first.put(noteDocument, "note:held", { noteId: "note:held", body: "already in the store" });
+  await first.flush();
+
+  const unpulled = await CultMesh.startNode(filePath, { documents: [noteDocument], pullOnStart: false });
+  await unpulled.flush();
+
+  const reopened = await CultMesh.startNode(filePath, { documents: [noteDocument] });
+  assert.equal(reopened.getRequired(noteDocument, "note:held").body, "already in the store");
+});
+
+test("CultMesh TS flush of a node that loaded a legacy-key global leaves the store reopenable", async () => {
+  const settings = defineDocumentType({ type: "cultmesh.settings", schema: z.object({ theme: z.string() }), global: true });
+  const filePath = join(await mkdtemp(join(tmpdir(), "cultmesh-ts-legacy-flush-")), "node.ccmp");
+  const seed = await CultMesh.startNode(join(await mkdtemp(join(tmpdir(), "cultmesh-ts-seed-")), "seed.ccmp"), { documents: [settings] });
+  await seed.cache.putGlobal(settings, { theme: "iron" });
+  const legacy = { ...seed.cache.getRequiredEnvelope(settings, "__global__"), key: "legacy" };
+  await new SingleFileMessagePackBackingStore(filePath).push(legacy);
+
+  const node = await CultMesh.startNode(filePath, { documents: [settings] });
+  await node.flush();
+
+  const reopened = await CultMesh.startNode(filePath, { documents: [settings] });
+  assert.deepEqual(reopened.cache.getRequiredGlobal(settings), { theme: "iron" });
+});
+
 test("CultMesh TS document handles hide local cache plumbing behind typed reactive reads", async () => {
   const filePath = join(await mkdtemp(join(tmpdir(), "cultmesh-ts-doc-")), "node.ccmp");
   const node = await CultMesh.startNode(filePath, {

packages/cultmesh-ts/test/interop/write-receipt-interop.test.ts

@@ -122,7 +122,7 @@ const rust: Target = {
   name: "rust",
   payload: (text) => encode({ text }),
   async start() {
-    if (!prebuilt) await execFileAsync(cargo, ["build", "--example", "receipt_interop_server", "--message-format", "short"], { cwd: rustManifestDir });
+    if (!prebuilt) await execFileAsync(cargo, ["build", "--locked", "--example", "receipt_interop_server", "--message-format", "short"], { cwd: rustManifestDir });
     const metadata = spawnSync(cargo, ["metadata", "--format-version", "1", "--no-deps"], { cwd: rustManifestDir, encoding: "utf8" });
     if (metadata.status !== 0) throw new Error(`cargo metadata failed: ${metadata.stderr}`);
     const exe = join(JSON.parse(metadata.stdout).target_directory, "debug", "examples", `receipt_interop_server${process.platform === "win32" ? ".exe" : ""}`);

packages/cultmesh-ts/test/provider-session-wire.test.ts

@@ -83,3 +83,16 @@ test("a provider command that is not a map, or lacks a required field, is refuse
     (error: Error) => error.message === "CultMesh provider command must be a MessagePack map.",
   );
 });
+
+test("a provider command payload with bytes after its first value is refused by count, without echoing the tail", () => {
+  const command = { commandId: "c1", commandKind: "k", providerId: "p", serviceInstanceId: "s", payload: { n: 1 } };
+  const whole = documentPayloadBytes(encodeDocumentPayload(providerCommandDocument, command));
+  const tailed = documentPayloadFromBytes(Uint8Array.from([...whole, ...Buffer.from("canary-tail-8c1f")]));
+  assert.throws(
+    () => decodeProviderCommandDocument({
+      schemaId: cultMeshProviderSessionSchemas.command, recordKey: "p/s/c1", storedAt: "2026-10-11T00:00:00Z",
+      payloadEncoding: "messagepack" as const, payload: tailed,
+    }),
+    (error: Error) => error.message.includes("16 bytes after its first MessagePack value") && !error.message.includes("canary-tail-8c1f"),
+  );
+});

packages/cultnet-py/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased (breaking; version 0.x, so the next minor)
 
+- `decode_witness_artifact_bundle_payload` (and `CultNetWitnessArtifactBundle.from_payload`) read the payload through `cultcache_py.read_payload_tree`: bytes after its first MessagePack value raise `ValueError` `cultnet.witness_artifact_bundle payload has N bytes after its first MessagePack value (refused on read).` instead of `msgpack.ExtraData`, and a payload nested past 256 raises `CultCachePayloadDepthError`. Needs `cultcache-py` 0.4.0, the release that exports `read_payload_tree`: the dependency is now `cultcache-py>=0.4.0` (it was `>=0.2.0`, which admits releases whose `import cultnet_py` fails), and `tests/test_declared_dependency_ranges.py` fails when a declared bound admits a tagged release lacking a name the package imports. The same check found `cultmesh-py` importing `cache.index_text`, which `cultcache-py` 0.2.0 lacks; its bound is `cultcache-py>=0.4.0` too (it has no changelog of its own). `resolve_document_for_raw_record` reads the schema hint from a raw record's first value whether or not bytes follow it, so a record routed by its stamp is refused by count when applied (`ValueError`, in a snapshot, a shard log and a direct apply) like one routed by a registered schema id; `apply_shard_log_response` used to skip it silently as an unknown schema. A tail on a payload whose first value names no registered schema is still `KeyError`, which a shard log skips.
+- `apply_raw_document_record` and `apply_raw_snapshot` raise `SchemaConflictError` when a remote record is of another type than the one the cache holds at its key (`cultcache-py` holds one record per key whatever its type); the cache is unchanged, and the caller decides whether to drop the record or the peer. `cultmesh-py`'s server answers such a put with `message_invalid`; its client's `read_next_change` lets the error out.
 - `CultNetDatabaseChange` carries `commit_id` and `commit_count` (`commitId`/`commitCount`; None outside a multi-record commit, as C# writes nil): `from_wire` refuses an empty or non-string id and a count that is not an integer of at least 2, `to_wire` writes them when set, and the published `database_change_raw` schema lists both. Python applies no batch. The `simulation_fact` document's `shard`, `frame`, `subject` and `claim_kind` aliases are `roles` (many facts share each); the catalog bytes do not move.
 - Decodes the write receipt frames of `contracts/cultnet/interop/write-receipt.md`: `parse_message` validates `cultnet.write_admitted.v0` and `cultnet.error.v1` against their closed schemas (unknown keys, empty or non-string ids, an unknown operation or code are refused; `error.v1` requires `messageId`, string or null; `limit_reached` is `error.v1` only). Added `CULTNET_ERROR_V1_CODES`, `CULTNET_WRITE_RECEIPT_MESSAGE_VERSIONS`, `write_content_hash` and `hello_advertises_write_receipts`; `hello` takes `supported_message_versions`. `tests/test_write_receipt.py` replays the vectors' `contentHash`, `wire` and `schemaInvalid` sections. Not implemented here: the client write tracker (`scenarios`) and the server rules (`dedupe`, `blankFields`); this package has no receipt server and no write client.
 - Added `message_invalid` to `CULTNET_ERROR_CODES` and `message_invalid_error(field, reason)`, byte-identical to the C# `ForMessageInvalid`. `cultmesh-py` refuses a malformed put or delete with it instead of the out-of-schema `malformed_document_put` and `malformed_document_delete`, which are removed.

packages/cultnet-py/pyproject.toml

@@ -16,7 +16,7 @@ classifiers = [
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
 ]
-dependencies = ["cultcache-py>=0.2.0", "msgpack>=1.0"]
+dependencies = ["cultcache-py>=0.4.0", "msgpack>=1.0"]
 [project.optional-dependencies]
 crypto = ["cryptography>=42"]
 

packages/cultnet-py/src/cultnet_py/messages.py

@@ -5,6 +5,7 @@ from dataclasses import dataclass
 from typing import Any
 
 import msgpack
+from cultcache_py import read_payload_tree
 
 from .unicode_messageid_tables import DEFAULT_IGNORABLE, LETTER_OR_NUMBER
 
@@ -544,7 +545,7 @@ def encode_witness_artifact_bundle_payload(bundle: dict[str, Any] | CultNetWitne
 
 
 def decode_witness_artifact_bundle_payload(payload: bytes) -> dict[str, Any]:
-    slots = msgpack.unpackb(payload, raw=False)
+    slots = read_payload_tree("cultnet.witness_artifact_bundle", payload)
     if not isinstance(slots, list) or len(slots) < 8:
         raise ValueError("CultNet witness artifact bundle payload must be an 8-slot MessagePack array")
     return {

packages/cultnet-py/src/cultnet_py/replication.py

@@ -171,9 +171,14 @@ def resolve_document_for_raw_record(
 
 
 def _infer_schema_version_from_payload(payload: bytes) -> str | None:
+    import msgpack  # type: ignore
     try:
-        import msgpack  # type: ignore
         decoded = msgpack.unpackb(payload, raw=False)
+    except msgpack.ExtraData as extra:
+        # The hint is read from the first value; the tail is not this function's to judge. The routed definition refuses
+        # it by count when the record is applied, as it does for a record routed by a registered schema id. Treating a
+        # tail as "no hint" made a stamp-routed record look like an unknown schema, which a shard log skips silently.
+        decoded = extra.unpacked
     except Exception:
         return None
     if isinstance(decoded, list) and decoded and isinstance(decoded[0], str):

packages/cultnet-py/tests/test_cultnet.py

@@ -14,7 +14,7 @@ from pathlib import Path
 from typing import Callable
 from uuid import uuid4
 import msgpack
-from cultcache_py import CultCache, define_database_entry_type
+from cultcache_py import CultCache, SchemaConflictError, define_database_entry_type
 from cultnet_py.benchmark import run_benchmark
 from cultnet_py.compare_csharp import (
     DEFAULT_PARITY_THRESHOLD,
@@ -1942,6 +1942,78 @@ class CultNetTests(unittest.TestCase):
         self.assertEqual(raised.exception.response["messageId"], "subscription-error")
         thread.join(2.0)
 
+    def test_replication_refuses_a_remote_record_of_another_type_at_a_held_key_and_changes_nothing(self) -> None:
+        # variants:ruling:cache-refuses-retype: a cache holds one record per key whatever its type, so a peer that reuses a
+        # key across types is refused where the record is applied; replication does not catch it.
+        first = define_database_entry_type("replica.first", [("name", 0), ("category", 1), ("value", 2, 0)], cls=Item)
+        second = define_database_entry_type("replica.second", [("name", 0), ("category", 1), ("value", 2, 0)], cls=Item)
+        cache = CultCache()
+        cache.register_document_type(first)
+        cache.register_document_type(second)
+        cache.put(first, "shared", Item("held", "", 0))
+
+        def raw(document):
+            return {
+                "schemaId": document.catalog_entry().schema_id,
+                "recordKey": "shared",
+                "storedAt": "2026-06-13T00:00:00Z",
+                "payloadEncoding": "messagepack",
+                "payload": document.encode_payload(Item("remote", "", 0)),
+            }
+
+        with self.assertRaises(SchemaConflictError):
+            apply_raw_document_record(cache, schema_document_map([first, second]), raw(second))
+        snapshot = {"schemaVersion": "cultnet.snapshot_response_raw.v0", "messageId": "s", "documents": [raw(second)]}
+        with self.assertRaises(SchemaConflictError):
+            apply_raw_snapshot(cache, [first, second], snapshot)
+        self.assertEqual(cache.get_required(first, "shared").name, "held")
+        self.assertIsNone(cache.get(second, "shared"))
+        apply_raw_document_record(cache, schema_document_map([first, second]), raw(first))  # the same type still replaces
+        self.assertEqual(cache.get_required(first, "shared").name, "remote")
+
+    def test_a_raw_record_with_a_tail_is_routed_by_its_stamp_and_refused_by_count_on_every_apply_path(self) -> None:
+        import msgpack  # type: ignore
+        from cultcache_py import define_document_type
+        from cultnet_py import resolve_document_for_raw_record
+
+        document = define_document_type("tests.tail_note", schema_id="tests.tail_note", schema_version="tests.tail_note.v1",
+                                   payload_encoder=msgpack.packb, payload_decoder=lambda payload: msgpack.unpackb(payload, raw=False))
+        known = document.catalog_entry().schema_id
+        head = msgpack.packb(["tests.tail_note.v1", "x"], use_bin_type=True)
+
+        def raw(schema_id: str, payload: bytes) -> dict:
+            return {"schemaId": schema_id, "recordKey": "k", "storedAt": "2026-06-13T00:00:00Z",
+                    "payloadEncoding": "messagepack", "payload": payload}
+
+        documents = schema_document_map([document])
+        # The stamp is read from the first value whether or not a tail follows, so an unknown schema id whose payload names
+        # a registered schema routes to it; the tail is then refused by count where the record is applied.
+        self.assertIs(resolve_document_for_raw_record(documents, "unknown", raw("unknown", head + b"\xc0")), document)
+        for schema_id in (known, "unknown"):
+            cache = CultCache()
+            cache.register_document_type(document)
+            with self.assertRaises(ValueError, msg=schema_id) as caught:
+                apply_raw_document_record(cache, documents, raw(schema_id, head + b"\xc0"))
+            self.assertIn("1 bytes after its first MessagePack value", str(caught.exception))
+            self.assertIsNone(cache.get(document, "k"))
+            snapshot = {"schemaVersion": "cultnet.snapshot_response_raw.v0", "messageId": "s",
+                        "documents": [raw(schema_id, head + b"\xc0")]}
+            with self.assertRaises(ValueError, msg=schema_id):
+                apply_raw_snapshot(cache, [document], snapshot)
+            log = {"schemaVersion": "cultnet.shard_log_response.v0", "messageId": "l", "shardId": "s", "shardEpoch": 1,
+                   "resyncRequired": False,
+                   "entries": [{"sequence": 0, "changeKind": "updated",
+                                "put": {"schemaVersion": "cultnet.document_put_raw.v0", "messageId": "p",
+                                        "document": raw(schema_id, head + b"\xc0"), "shardId": "s", "shardEpoch": 1}}]}
+            with self.assertRaises(ValueError, msg=schema_id) as caught:
+                apply_shard_log_response(cache, [document], log)
+            self.assertIn("1 bytes after its first MessagePack value", str(caught.exception))
+            self.assertIsNone(cache.get(document, "k"))
+        # A tail on a payload that names no registered schema is still an unknown schema, which a shard log skips.
+        stranger = msgpack.packb(["tests.stranger.v1", "x"], use_bin_type=True) + b"\xc0"
+        with self.assertRaises(KeyError):
+            resolve_document_for_raw_record(documents, "unknown", raw("unknown", stranger))
+
     def test_cultnet_replication_helpers_apply_raw_snapshot_and_shard_log(self) -> None:
         document = define_database_entry_type(
             "replica.item",
@@ -2632,6 +2704,23 @@ class CultNetTests(unittest.TestCase):
                 self.assertEqual(responses[0]["details"]["value"], schema_version)
                 self.assertNotIn("messageId", responses[0])
 
+    def test_witness_artifact_bundle_payload_is_one_value_and_depth_wins_over_a_tail(self) -> None:
+        import msgpack  # type: ignore
+        from cultcache_py import CultCachePayloadDepthError
+
+        payload = msgpack.packb(["b", "k", "t", {}, [], [], [], {}], use_bin_type=True)
+        decode_witness_artifact_bundle_payload(payload)
+        for tail, count in ((b"\xc0", 1), (b"\xc1\xc1", 2)):
+            with self.assertRaises(ValueError) as caught:
+                decode_witness_artifact_bundle_payload(payload + tail)
+            self.assertIs(type(caught.exception), ValueError)
+            self.assertEqual(
+                str(caught.exception),
+                f"cultnet.witness_artifact_bundle payload has {count} bytes after its first MessagePack value (refused on read).",
+            )
+        with self.assertRaises(CultCachePayloadDepthError):
+            decode_witness_artifact_bundle_payload(b"\x91" * 300 + b"\xc0\xc0")
+
     def test_cultnet_simulation_consensus_dedupes_witnesses_and_requires_quorum(self) -> None:
         from cultnet_py import CultNetSimulationConsensus
 

packages/cultnet-py/tests/test_declared_dependency_ranges.py

@@ -0,0 +1,94 @@
+"""A sibling package resolves through the workspace's editable install, so a package that starts importing a new name from
+cultcache-py passes whatever range it declares. A consumer outside the workspace installs the newest release the range
+admits. This is the Python form of scripts/test-declared-dependency-ranges.mjs: for every tagged cultcache-py release
+(`cultcache-py-vX.Y.Z`) that the `cultcache-py>=` bound of cultnet-py or cultmesh-py admits, every name those packages
+import from cultcache_py must be defined by that release's source. It needs git with the release tags and skips without
+them. Only `>=` bounds are read; star imports and names reached by attribute access are not checked."""
+
+from __future__ import annotations
+
+import ast
+import re
+import subprocess
+import unittest
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[3]
+PACKAGES = ROOT / "packages"
+CONSUMERS = ("cultnet-py", "cultmesh-py")
+
+
+def _version(text: str) -> tuple[int, ...]:
+    return tuple(int(part) for part in text.split("."))
+
+
+def _git(*args: str) -> str | None:
+    try:
+        done = subprocess.run(["git", *args], cwd=ROOT, capture_output=True, text=True, check=True)
+    except (OSError, subprocess.CalledProcessError):
+        return None
+    return done.stdout
+
+
+def _lower_bound(package: str) -> tuple[int, ...]:
+    manifest = (PACKAGES / package / "pyproject.toml").read_text(encoding="utf-8")
+    match = re.search(r'"cultcache-py>=(\d+\.\d+\.\d+)"', manifest)
+    assert match, f"{package} declares no cultcache-py>= bound"
+    return _version(match.group(1))
+
+
+def _imports(package: str) -> dict[str, set[str]]:
+    """module -> names imported from it, for every `from cultcache_py[.x] import names` under the package's src."""
+    found: dict[str, set[str]] = {}
+    for source in (PACKAGES / package / "src").rglob("*.py"):
+        for node in ast.walk(ast.parse(source.read_text(encoding="utf-8-sig"))):
+            if isinstance(node, ast.ImportFrom) and node.level == 0 and node.module:
+                if node.module == "cultcache_py" or node.module.startswith("cultcache_py."):
+                    found.setdefault(node.module, set()).update(alias.name for alias in node.names if alias.name != "*")
+    return found
+
+
+def _defined(tag: str, module: str) -> set[str] | None:
+    base = "packages/cultcache-py/src/" + module.replace(".", "/")
+    for path in (base + ".py", base + "/__init__.py"):
+        text = _git("show", f"{tag}:{path}")
+        if text is None:
+            continue
+        names: set[str] = set()
+        for node in ast.parse(text.lstrip("\ufeff")).body:
+            if isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef, ast.ClassDef)):
+                names.add(node.name)
+            elif isinstance(node, (ast.Import, ast.ImportFrom)):
+                names.update((alias.asname or alias.name).split(".")[0] for alias in node.names)
+            elif isinstance(node, (ast.Assign, ast.AnnAssign)):
+                for target in node.targets if isinstance(node, ast.Assign) else [node.target]:
+                    if isinstance(target, ast.Name):
+                        names.add(target.id)
+        return names
+    return None
+
+
+class DeclaredDependencyRangeTests(unittest.TestCase):
+    def test_every_admitted_cultcache_release_defines_what_the_consumers_import(self) -> None:
+        listed = _git("tag", "--list", "cultcache-py-v*")
+        tags = sorted((t for t in (listed or "").split() if re.fullmatch(r"cultcache-py-v\d+\.\d+\.\d+", t)),
+                      key=lambda t: _version(t.rsplit("v", 1)[1]))
+        if not tags:
+            self.skipTest("git with the cultcache-py release tags is not available")
+        current = re.search(r'^version = "(\d+\.\d+\.\d+)"', (PACKAGES / "cultcache-py" / "pyproject.toml").read_text(encoding="utf-8"), re.M)
+        assert current
+        for package in CONSUMERS:
+            bound = _lower_bound(package)
+            self.assertLessEqual(bound, _version(current.group(1)), f"{package}'s bound is above the workspace cultcache-py")
+            imports = _imports(package)
+            for tag in tags:
+                if _version(tag.rsplit("v", 1)[1]) < bound:
+                    continue
+                for module, names in imports.items():
+                    defined = _defined(tag, module)
+                    self.assertIsNotNone(defined, f"{package} imports {module}, which {tag} does not have")
+                    self.assertEqual(sorted(names - defined), [], f"{package} imports names {tag} lacks from {module}")
+
+
+if __name__ == "__main__":
+    unittest.main()

packages/cultnet-rs/.gitignore

@@ -1,2 +1 @@
 /target
-Cargo.lock

packages/cultnet-rs/CHANGELOG.md

@@ -15,5 +15,6 @@ only in git history.
 
 ### Breaking
 
+- A CultNet frame with bytes after its message is refused, by count (through `cultcache_rs::decode_payload`); the decoder used to read the message and drop the tail. No producer emits one. Behaviour change: the next release is a minor bump (0.x breaking).
 - `CultNetDocumentRegistry::register` returns `Result<&mut Self>` where it returned `&mut Self`. A binding that claims a document type or a schema id another binding already holds is refused with `cultcache_rs::SchemaConflictError` (naming the new binding's schema id and both document types) and nothing is bound; binding a type to the schema id it already holds still replaces that binding. Callers chain `register(...)?`.
 - `CultMeshCdnChunkRef` gains a public `id` field, the decimal text of `offset` (the reference's element id, slot 4). A manifest written before ids reads `""`; encoding writes the slot.

packages/cultnet-rs/README.md

@@ -30,7 +30,7 @@ knock on the contract before touching the furniture.
 ## Receipts
 
 ```powershell
-cargo test
+cargo test --locked
 ```
 
 The initial tests prove:

packages/cultnet-rs/examples/cultnet_impair/main.rs

@@ -7,7 +7,7 @@
 //! traffic crosses the same schedule. The schedule is `policy.rs`.
 //!
 //! ```text
-//! cargo run --release --example cultnet_impair -- \
+//! cargo run --locked --release --example cultnet_impair -- \
 //!   --listen 0.0.0.0:17890 --upstream 127.0.0.1:17990 \
 //!   --profile tests/impairment/loss-1pct.toml --seed 424242 --metrics loss-1pct.csv
 //! ```

packages/cultnet-rs/src/replication.rs

@@ -146,6 +146,7 @@ impl CultNetDocumentRegistry {
                 schema_id: binding.schema_id.clone(),
                 schema_names: vec![holder.document_type.clone(), binding.document_type.clone()],
                 record_key: String::new(),
+                unread_slots: None,
             }));
         }
         self.bindings_by_schema_id

packages/cultnet-rs/tests/cultnet.rs

@@ -1810,12 +1810,10 @@ fn a_replicated_payload_nested_past_the_bound_is_refused_typed_on_apply() -> Res
     };
     assert_eq!(documents.len(), 1);
 
-    backing.push(&envelope("past", limit + 1))?;
-    let mut cache = CultCache::new();
-    cache.register_entry_type::<GhostlightAgentStateFixture>()?;
-    cache.add_generic_backing_store(SingleFileMessagePackBackingStore::new(&store))?;
-    cache.pull_all_backing_stores()?;
-    let past = registry.create_raw_snapshot_response(&cache, "past", None, Some(&["past".to_string()]))?;
+    // The sender cannot load a payload past the bound, so the frame is the at-limit one with its bytes swapped.
+    let mut past = at_limit.clone();
+    let CultNetMessage::SnapshotResponseRaw { documents, .. } = &mut past else { unreachable!() };
+    documents[0].payload = envelope("past", limit + 1).payload;
     let mut target = CultCache::new();
     target.register_entry_type::<GhostlightAgentStateFixture>()?;
     let error = registry

packages/cultnet-rs/tests/decode_door.rs

@@ -190,6 +190,16 @@ fn message_past_the_bound_is_refused_typed() {
     });
 }
 
+// A frame is one message: cultcache's payload rule refuses bytes after it, by count.
+#[test]
+fn frame_with_bytes_after_is_refused() {
+    let mut bytes = hello_with(&nested(0));
+    assert!(decode_message(bytes.clone(), BIG).is_ok());
+    bytes.push(0xc0);
+    let error = format!("{:#}", decode_message(bytes, BIG).unwrap_err());
+    assert!(error.contains("1 bytes after its first MessagePack value"), "{error}");
+}
+
 fn raw_v1_bytes(header_unknown: Option<&[u8]>) -> Vec<u8> {
     let mut header: Vec<(rmpv::Value, rmpv::Value)> = vec![
         ("schemaId".into(), "s".into()),

packages/cultnet-rs/tests/media_fec_bench.rs

@@ -3,7 +3,7 @@
 //! Ignored by default; run in release, where the numbers mean something:
 //!
 //! ```text
-//! cargo test --release --test media_fec_bench -- --ignored --nocapture
+//! cargo test --locked --release --test media_fec_bench -- --ignored --nocapture
 //! ```
 //!
 //! Each line is nanoseconds per call through the public surface, so record

packages/cultnet-ts/CHANGELOG.md

@@ -3,10 +3,17 @@
 All notable changes to `@gamecult/cultnet-ts` are recorded here, following
 [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
-## Unreleased
+## [0.4.0]
+
+### Breaking
+
+- `decodeManifest` refuses a manifest with bytes after its first MessagePack value (`CDN artifact manifest has N bytes after its first MessagePack value.`), as the C# reference does; before, the tail was ignored. `contracts/cultmesh/content-acceptance-vectors.json` now holds `trailing_nil`, `trailing_reserved_code` and `trailing_truncated_array` as refused.
 
 ### Added
 
+- Fork card (`contracts/cultnet/governance/fork-card.md`): `raised_at`, a required key holding an RFC3339 instant string or nil (the question's first admission time), outside `options_hash`; the card vectors are re-pinned with the key, three negatives (epoch integer, date-only string, missing key) and a nil-`raised_at` valid card; every `optionsHash` digest is unchanged.
+- Fork card reader views (`fork-card.md`, "Reader views"): the card gains `decider_count` (required, 1 to 64) and `deciders` may be empty (ids withheld from a non-decider); the record gains `answerer_count` (distinct answerers over every stored answer, refusals included); `answerer` is nullable inside a record shown to a non-decider. Card and record vectors are re-pinned (card map header `DE0011` to `DE0012`, record `85` to `86`); withheld twins, the R-card, R-record, R-entry, R-list and R-answer-result rule vectors and a no-leak byte check are new; every `optionsHash` and `bodyDigests` digest is unchanged.
+- Fork card vectors: a nil `answerer` is now pinned for Revision and Retraction as well as Counted and Refused (`deskAnswer` `withheld_answerer_revision`, `withheld_answerer_retraction`; entries `open_counted_revision_and_retraction` and its withheld twin; a list scenario pair; negatives for a nil answerer in an `answer_result` and for a named Retraction or an over-count in a withheld entry). Additive: every existing vector, `optionsHash` and `bodyDigests` digest is unchanged.
 - `WriteTracker`: a write sent after `sessionEnd` settles unconfirmed `session_ended` when it is sent (it stayed unanswered forever). The replay runner now fails on an event key outside `scenarios.semantics` and on a vector count that differs from the file's `counts`; seven tracker vectors are new. A blank text in a raw frame is Unicode White_Space, not `String.prototype.trim()`.
 - Write receipt, client side (`contracts/cultnet/interop/write-receipt.md`): `cultnet.write_admitted.v0` and `cultnet.error.v1` (v0 plus `messageId`; its closed code set adds `limit_reached`, `CULTNET_ERROR_V1_CODES`) parse and encode, and `CULTNET_WRITE_RECEIPT_MESSAGE_VERSIONS` / `helloAdvertisesWriteReceipts` name the hello capability. `cultnet.error.v0` and its code set are unchanged. `WriteTracker` settles each write as admitted, refused or unconfirmed (windows `RECEIPT_RESULT_WINDOW_MS` 5000 and `LEGACY_RESULT_WINDOW_MS` 500, counted from the send; late answers recorded as `admitted_late` / `refused_late`), and `tools/replay-write-receipt-vectors.mjs` replays the vectors against it (see README, "Write receipt replay runner"). The interop schemas are read from `contracts/cultnet/interop/`.
 - `message_invalid` joins the closed `cultnet.error.v0` code set, with `cultNetMessageInvalidError(field, reason)` (`details.field` names the request field at fault), byte-identical to the C# `ForMessageInvalid`.

packages/cultnet-ts/README.md

@@ -144,8 +144,8 @@ imports no `node:` module, so a browser bundle can take it.
   past the shared depth limit are refused.
 - The decoder reads what MessagePack-CSharp reads and refuses what it refuses:
   nil in a string, tag or metadata slot is `null` and is written back as nil,
-  a missing trailing slot takes the reference's default, extra slots and trailing
-  bytes are skipped (a chunk reference's fifth slot is its element id, a string
+  a missing trailing slot takes the reference's default, extra slots are skipped and bytes
+  after the manifest's first value are refused (a chunk reference's fifth slot is its element id, a string
   or nil, `""` when absent; `packContent` writes the decimal offset as the id, as the
   reference does), a float-encoded integer is refused, and invalid UTF-8
   decodes to U+FFFD. A nil `chunks` is refused, as the reference's

packages/cultnet-ts/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@gamecult/cultnet-ts",
-  "version": "0.3.0",
+  "version": "0.4.0",
   "description": "CultNet-style typed direct-pipe messaging and state replication for TypeScript runtimes.",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",

packages/cultnet-ts/src/content.ts

@@ -249,7 +249,7 @@ class Reader {
 export function decodeManifest(bytes: Uint8Array): CultMeshCdnArtifactManifest {
   checkPayloadDepth(bytes, "CDN artifact manifest");
   const reader = new Reader(bytes);
-  // A slot the array does not reach keeps the property initialiser; a slot past the tenth is skipped. Trailing bytes are not read.
+  // A slot the array does not reach keeps the property initialiser; a slot past the tenth is skipped.
   const count = reader.array("manifest");
   let index = 0;
   const slot = <T>(read: () => T, initial: T): T => index++ < count ? read() : initial;
@@ -267,6 +267,8 @@ export function decodeManifest(bytes: Uint8Array): CultMeshCdnArtifactManifest {
       [reader.string("metadata") ?? wrongType("metadata"), reader.string("metadata")] as const), []),
   };
   for (; index < count; index += 1) reader.skip();
+  // A manifest is one record payload: exactly one MessagePack value, as the reference's one-value rule has it.
+  if (reader.position < bytes.length) throw new Error(`CDN artifact manifest has ${bytes.length - reader.position} bytes after its first MessagePack value.`);
   validateManifest(manifest);
   return manifest;
 }

packages/cultnet-ts/test/content.test.ts

@@ -392,6 +392,13 @@ test("decodeManifest accepts and refuses exactly what the reference does, and re
   }
 });
 
+test("a manifest with bytes after its first value is refused by count, whatever the tail is", () => {
+  const whole = encodeManifest(manifestOf());
+  for (const tail of [[0xc0], [0xc1, 0xc1], [0x90]]) {
+    assert.throws(() => decodeManifest(Uint8Array.from([...whole, ...tail])), new RegExp(`${tail.length} bytes after its first MessagePack value`));
+  }
+});
+
 test("a manifest written as a map names the manifest, not a field inside it", () => {
   assert.throws(() => decodeManifest(encode({ 0: "a", 9: { k: "v" } })), /field 'manifest' has the wrong type/);
 });

packages/cultnet-ts/test/cultnet.test.ts

@@ -14,6 +14,8 @@ import {
   SchemaConflictError,
   SingleFileMessagePackBackingStore,
   defineDocumentType,
+  documentPayloadBytes,
+  documentPayloadFromBytes,
   schemaIdentityOf,
 } from "@gamecult/cultcache-ts";
 
@@ -3140,3 +3142,24 @@ test("CultNet registry names the canonical schema id of a compatible alias, and
   assert.equal(registry.canonicalSchemaId("p3.nobody"), undefined);
   assert.equal(registry.canonicalSchemaId("p3.shared"), undefined, "an id several bindings claim resolves to none");
 });
+
+test("a replicated record with bytes after its first MessagePack value is refused by count and held nowhere", async () => {
+  const definition = defineDocumentType({ type: "tails.note", schemaId: "tails.note.v1", schema: z.object({ body: z.string() }) });
+  const registry = new CultNetDocumentRegistry([defineCultNetDocumentBinding({ definition })]);
+  const origin = CultCache.builder().withDocumentType(definition).build();
+  await origin.put(definition, "k", { body: "x" });
+  const document = registry.createRawSnapshotResponse(origin, "tails").documents[0]!;
+  const whole = documentPayloadBytes(document.payload);
+  const target = CultCache.builder().withDocumentType(definition).build();
+  await assert.rejects(
+    registry.applyRawDocumentPutMessage(target, {
+      schemaVersion: "cultnet.document_put_raw.v0",
+      messageId: "tails",
+      document: { ...document, payload: documentPayloadFromBytes(Uint8Array.from([...whole, 0xc0, 0xc1])) },
+    }),
+    (error: Error) => error.message.includes('document type "tails.note" payload has 2 bytes after its first MessagePack value'),
+  );
+  assert.deepEqual(target.snapshot(), []);
+  await registry.applyRawDocumentPutMessage(target, { schemaVersion: "cultnet.document_put_raw.v0", messageId: "whole", document });
+  assert.deepEqual(target.getRequired(definition, "k"), { body: "x" });
+});

packages/cultnet-ts/test/fixtures/idunn-runtime/README.md

@@ -6,7 +6,7 @@ cultnet-rs only, and Idunn's `IdunnRuntimeActivationLaunch` is that same crate's
 It needs Linux and a machine-id equal to the `machine-id` file here, because the
 provider identity is bound to it. On Yggdrasil:
 
-    DOCKER_ARGS='--cap-add SYS_ADMIN --security-opt apparmor=unconfined'     bash ygg-verify.sh <CultLib> HEAD rust 'cd packages/cultnet-rs &&       cp <fixed-machine-id> /tmp/mid && mount --bind /tmp/mid /etc/machine-id &&       cargo run -q --example idunn_runtime_fixture /tmp/out'
+    DOCKER_ARGS='--cap-add SYS_ADMIN --security-opt apparmor=unconfined'     bash ygg-verify.sh <CultLib> HEAD rust 'cd packages/cultnet-rs &&       cp <fixed-machine-id> /tmp/mid && mount --bind /tmp/mid /etc/machine-id &&       cargo run --locked -q --example idunn_runtime_fixture /tmp/out'
 
 then copy `/tmp/out` over this directory. `--cap-add SYS_ADMIN` exists only so the bind mount can present the committed `machine-id`, which keeps Yggdrasil's real machine-id out of the repo. Every `presence-*.bin` was accepted by
 `authenticate_runtime_presence_claim` and correlated by
@@ -26,7 +26,7 @@ The generator takes its specification as input, so a consumer needs no patch to
 specification is command-line flags; `@<file>` splices in a response file (one `--flag value`
 per line, `#` comments). CultLib's own sets are `fixture.args` here:
 
-    cargo run -q --example idunn_runtime_fixture /tmp/out @<path>/fixture.args
+    cargo run --locked -q --example idunn_runtime_fixture /tmp/out @<path>/fixture.args
 
 The consumer keeps its own `.args` file in its repository and runs the same command with the
 same machine-id bind mount as above. Global flags: `--source-repository`, `--detail`. Each

packages/cultnet-ts/test/governance-vectors.test.ts

@@ -90,7 +90,7 @@ const jstr = (s: string): string => {
 };
 type Option = { id: string; text: string };
 type Shown = { title: string; context: string; options: Option[]; recommendation: string; depends: string[] };
-type Card = Shown & { fork_id: string; leans: string | null; deciders: string[]; status: string; ruling: string | null; ruled_from: string[]; options_hash: string };
+type Card = Shown & { fork_id: string; leans: string | null; raised_at: string | null; deciders: string[]; decider_count: number; status: string; ruling: string | null; ruled_from: string[]; options_hash: string };
 // RFC 8785 over the five shown members, every string NFC-normalised first; keys sorted; no numbers in the member set.
 const nfc = (s: string): string => s.normalize("NFC");
 const canonical = (c: Shown): Buffer =>
@@ -104,6 +104,7 @@ const cardRuleErrors = (c: Card): string[] => {
   if (!ids.includes(c.recommendation)) errors.push("recommendation is not an option");
   if (c.leans !== null && !ids.includes(c.leans)) errors.push("leans is not an option");
   if (new Set(c.deciders).size !== c.deciders.length) errors.push("duplicate deciders");
+  if (c.deciders.length > 0 && c.deciders.length !== c.decider_count) errors.push("R-card: shown deciders are not exactly decider_count ids");
   if (c.depends.some((d) => Buffer.byteLength(d, "utf8") > 1000)) errors.push("a depends line is over 1000 UTF-8 bytes");
   if (c.status === "open" && c.ruling !== null) errors.push("an open card names a ruling");
   if (c.ruling === null && c.ruled_from.length > 0) errors.push("ruled_from without a ruling");
@@ -121,6 +122,15 @@ test("fork card: options hash is SHA-256 of the canonical JSON, computed here, a
   const byName = new Map<string, string>(fork.optionsHash.map((h: { name: string; sha256: string }) => [h.name, h.sha256]));
   const base = byName.get("heimdall_A_five_members")!;
   assert.equal(byName.get("hidden_members_do_not_move_it"), base);
+  const card0 = fork.card.valid[0].message as Card;
+  for (const raised_at of [null, "2027-01-02T03:04:05.123Z"]) {
+    const stamped: Card = { ...card0, raised_at };
+    assert.equal(optionsHash(stamped), card0.options_hash, "raised_at stays outside the hash");
+  }
+  for (const [deciders, decider_count] of [[[], 2], [card0.deciders, 64]] as const) {
+    const shown: Card = { ...card0, deciders: [...deciders], decider_count };
+    assert.equal(optionsHash(shown), card0.options_hash, "decider_count and the emptiness of deciders stay outside the hash");
+  }
   assert.equal(byName.get("heimdall_E_decomposed_equals_D"), byName.get("heimdall_D_nfc_escapes_astral"), "an NFD and an NFC spelling hash alike");
   for (const moved of ["heimdall_B_recommendation_changed", "heimdall_C_option_order_changed", "heimdall_F_option_id_changed", "heimdall_G_depends_emptied", "option_text_changed",
                        "title_changed", "context_changed", "depends_order_changed", "depends_order_changed_reversed"]) {
@@ -171,7 +181,7 @@ test("fork card: mutating any shown member, an option id included, changes the h
     assert.notEqual(optionsHash(copy), base, `mutation ${i}`);
   }
   const hidden = structuredClone(card);
-  hidden.fork_id = "other:question:id"; hidden.leans = "yes"; hidden.deciders = ["x"]; hidden.status = "closed"; hidden.ruled_from = ["n1"];
+  hidden.fork_id = "other:question:id"; hidden.leans = "yes"; hidden.deciders = []; hidden.decider_count = 7; hidden.status = "closed"; hidden.ruled_from = ["n1"];
   assert.equal(optionsHash(hidden), base, "fork_id and the unshown members stay outside the hash");
 });
 
@@ -195,6 +205,11 @@ test("fork card: documents validate and encode to the vector bytes", () => {
     assert.ok(check(forkSchema, "answerResult", v.message), v.name);
     assert.equal(hexOf(v.message), v.messagePackHex, v.name);
     assert.equal(v.message.card !== null, v.name === "stale_fork", "only a stale refusal shows the new fork");
+    assert.deepEqual(resultRuleErrors(v.message), [], v.name);
+  }
+  for (const v of fork.resultsInvalid) {
+    assert.ok(!check(forkSchema, "answerResult", v.message) || resultRuleErrors(v.message).length > 0, `${v.name}: ${v.why}`);
+    assert.equal(hexOf(v.message), v.messagePackHex, v.name);
   }
   for (const v of fork.unavailable) {
     assert.ok(check(forkSchema, "unavailable", v.message), v.name);
@@ -223,12 +238,16 @@ test("fork card: every negative is refused by the schema or a stated rule", () =
   }
 });
 
+// R-answer-result: the answer in an answer_result is the sender's own, stamped with their account, never nil (nil exists only in a record shown to a non-decider).
+const resultRuleErrors = (r: { answer: { answerer: string | null } }): string[] => (r.answer.answerer === null ? ["R-answer-result: the answerer is nil"] : []);
+
 // Rules a JSON Schema cannot say: a note is at most 4000 UTF-8 bytes (maxLength counts code points and is only the looser bound).
 const noteRuleErrors = (def: string, message: any): string[] => {
   const note = def === "answerRequest" ? message?.answer?.note : def === "deskAnswer" ? message?.note : null;
   return note != null && Buffer.byteLength(note, "utf8") > 4000 ? ["note is over 4000 UTF-8 bytes"] : [];
 };
 
+const OP_ID = "e0d1c2b3-a495-4687-8879-6a5b4c3d2e1f";
 const TAILS: Record<string, string> = {
   unauthenticated: "a verified session is required",
   body_forbidden_field: "answerer and authority are set by the receiver",
@@ -300,7 +319,7 @@ function judge(start: Card, steps: { kind: string; body: Record<string, any> | n
     }
     responses.push(down && reached ? unavailable() : response);
   }
-  return { responses, record: { schemaVersion: "gamecult.fork.record.v0", fork_id: card.fork_id, options_hash: optionsHash(card), counted_answer_id: counted(), answers } };
+  return { responses, record: { schemaVersion: "gamecult.fork.record.v0", fork_id: card.fork_id, options_hash: optionsHash(card), counted_answer_id: counted(), answerer_count: new Set(answers.map((a) => a.answerer)).size, answers } };
 }
 
 test("fork card: every scenario replays to the vector's responses and record, bytes included", () => {
@@ -312,6 +331,7 @@ test("fork card: every scenario replays to the vector's responses and record, by
     assert.deepEqual(record, sc.record, sc.name);
     assert.ok(check(forkSchema, "record", record), sc.name);
     assert.equal(hexOf(record), sc.recordHex, sc.name);
+    for (const s of sc.steps) if (s.response?.answer) assert.deepEqual(resultRuleErrors(s.response), [], sc.name);
     for (const s of sc.steps) if (s.response) assert.ok(check(forkSchema, "answerResult", s.response) || check(forkSchema, "refusal", s.response) || check(forkSchema, "unavailable", s.response), sc.name);
   }
 });
@@ -378,15 +398,34 @@ test("fork card: operator authority needs a cited Counted answer record", () =>
 });
 
 // ---- transport: list, read, auth (fork-card.md "Transport") ----
-const entryRuleErrors = (e: { card: Card; record: { fork_id: string; options_hash: string; counted_answer_id: string | null; answers: Record<string, any>[] } }): string[] => {
+type Entry = { card: Card; record: { fork_id: string; options_hash: string; counted_answer_id: string | null; answerer_count: number; answers: Record<string, any>[] } };
+const entryRuleErrors = (e: Entry): string[] => {
   const errors = cardRuleErrors(e.card);
   if (e.record.fork_id !== e.card.fork_id) errors.push("record of another fork");
   if (e.record.options_hash !== e.card.options_hash) errors.push("record under another hash");
   const counted = e.record.answers.find((a) => (a.outcome === "Counted" || a.outcome === "Revision") && a.options_hash === e.card.options_hash
     && !e.record.answers.some((r) => r.outcome === "Retraction" && r.retracts === a.answer_id));
   if ((counted?.answer_id ?? null) !== e.record.counted_answer_id) errors.push("counted_answer_id is not derived");
+  // R-record: named answerers are counted by distinct id, nil ones by a bound
+  const named = e.record.answers.filter((a) => a.answerer !== null).length, total = e.record.answers.length, n = e.record.answerer_count;
+  if (total === 0 && n !== 0) errors.push("R-record: no answers and a count other than 0");
+  else if (named === total && total > 0 && n !== new Set(e.record.answers.map((a) => a.answerer)).size) errors.push("R-record: answerer_count is not the distinct answerers");
+  else if (named === 0 && total > 0 && (n < 1 || n > total)) errors.push("R-record: a withheld count outside 1..answers");
+  // R-entry: the card's view and the record's view agree, so a withheld card never rides beside a named account
+  if (e.card.deciders.length > 0 && named < total) errors.push("R-entry: a decider-view card with withheld answerers");
+  if (e.card.deciders.length === 0 && named > 0) errors.push("R-entry: a withheld card beside a named answerer");
   return errors;
 };
+// R-list: all entries of one page are one reader's view
+const viewRuleErrors = (forks: { card: Card }[]): string[] => (new Set(forks.map((f) => f.card.deciders.length > 0)).size > 1 ? ["R-list: a page mixes views"] : []);
+// The non-decider twin of a decider-view entry: ids withheld, counts kept.
+const withheld = (e: Entry): Entry => ({ ...e, card: { ...e.card, deciders: [] }, record: { ...e.record, answers: e.record.answers.map((a) => ({ ...a, answerer: null })) } });
+const idsOf = (e: Entry): string[] => [...e.card.deciders, ...e.record.answers.map((a) => a.answerer as string)];
+const bytesHaveNoId = (hex: string, ids: string[], name: string): void => {
+  const bytes = Buffer.from(hex, "hex");
+  assert.ok(ids.length > 0, name);
+  for (const id of ids) assert.ok(!bytes.includes(Buffer.from(id, "utf8")), `${name}: the withheld bytes carry ${id}`);
+};
 
 // Order is a unique rank per Mind: the refusal names both fork ids, the first holder and the second.
 const orderErrors = (cards: { fork_id: string; order: number }[]): string[] => {
@@ -465,6 +504,13 @@ test("fork transport: requests and entries validate and encode to the vector byt
     for (const v of t[section].valid) {
       assert.ok(check(forkSchema, def, v.message), v.name);
       if (def === "entry") assert.deepEqual(entryRuleErrors(v.message), [], v.name);
+      if (def === "entry" && v.twin !== undefined) {
+        const twin = t.entry.valid.find((x: any) => x.name === v.twin);
+        assert.deepEqual(v.message, withheld(twin.message), `${v.name}: the twin of ${v.twin}`);
+        assert.equal(v.message.record.answerer_count, twin.message.record.answerer_count, "a decider and a non-decider read the same count");
+        bytesHaveNoId(v.messagePackHex, idsOf(twin.message), v.name);
+        assert.ok(twin.messagePackHex.includes(Buffer.from(idsOf(twin.message)[0], "utf8").toString("hex").toUpperCase()), "the decider view does carry the ids");
+      }
       assert.equal(hexOf(v.message), v.messagePackHex, v.name);
     }
     for (const v of t[section].invalid) {
@@ -473,9 +519,10 @@ test("fork transport: requests and entries validate and encode to the vector byt
     }
   }
   for (const v of t.listInvalid) {
-    const refused = !check(forkSchema, "list", v.message) || orderErrors(v.message.forks.map((f: any) => f.card)).length > 0;
+    const refused = !check(forkSchema, "list", v.message) || orderErrors(v.message.forks.map((f: any) => f.card)).length > 0 || viewRuleErrors(v.message.forks).length > 0;
     assert.ok(refused, `${v.name}: ${v.why}`);
     if (v.refusal !== undefined) assert.deepEqual(orderErrors(v.message.forks.map((f: any) => f.card)), [v.refusal], v.name);
+    if (v.name === "a_page_mixes_views") assert.equal(viewRuleErrors(v.message.forks).length, 1, v.name);
     assert.equal(hexOf(v.message), v.messagePackHex, v.name);
   }
 });
@@ -484,12 +531,26 @@ test("fork transport: every list request replays to the vector's response, newes
   for (const sc of fork.transport.listScenarios) {
     for (const e of sc.entries) assert.deepEqual(entryRuleErrors(e), [], sc.name);
     assert.deepEqual(orderErrors(sc.entries.map((e: any) => e.card)), [], sc.name);
+    if (sc.twin !== undefined) {
+      // the non-decider page is the decider page with the ids withheld: counts, order, cursor and stamp equal, byte for byte but the withheld members
+      const twin = fork.transport.listScenarios.find((x: any) => x.name === sc.twin);
+      assert.deepEqual(sc.entries, twin.entries.map(withheld), sc.name);
+      assert.equal(sc.steps.length, twin.steps.length);
+      sc.steps.forEach((step: any, i: number) => {
+        const other = twin.steps[i].response;
+        assert.deepEqual(step.response, { ...other, forks: other.forks.map(withheld) }, sc.name);
+        assert.ok(twin.entries.length > 0 && step.response.forks.length > 0);
+        bytesHaveNoId(step.responseHex, twin.entries.flatMap(idsOf), sc.name);
+      });
+      assert.ok(twin.steps[0].responseHex.includes(Buffer.from(OP_ID, "utf8").toString("hex").toUpperCase()), "the decider page does carry the ids");
+    }
     let previous: { next_cursor: string | null } | null = null;
     for (const step of sc.steps) {
       const response = judgeList(sc.entries, sc.ordinal, step.request);
       assert.deepEqual(response, step.response, sc.name);
       assert.ok(check(forkSchema, "list", response), sc.name);
       assert.equal(hexOf(response), step.responseHex, sc.name);
+      assert.deepEqual(viewRuleErrors(response.forks), [], sc.name);
       const orders = response.forks.map((f: any) => f.card.order);
       assert.deepEqual(orders, [...orders].sort((a: number, b: number) => b - a), sc.name);
       if (previous !== null) assert.equal(step.request.cursor, previous.next_cursor, `${sc.name}: the second request follows the first page's cursor`);

packages/cultnet-ts/test/interop/cultnet-interop.test.ts

@@ -2795,7 +2795,7 @@ async function buildInteropPeers(): Promise<void> {
 }
 
 async function buildRustInteropPeer(): Promise<void> {
-  rustInteropPeerBuild ??= execFileAsync(cargoCommand, ["build", "--quiet", "--example", "cultnet_interop_peer"], {
+  rustInteropPeerBuild ??= execFileAsync(cargoCommand, ["build", "--locked", "--quiet", "--example", "cultnet_interop_peer"], {
     cwd: cultnetRsRoot,
   }).then(() => undefined);
   await rustInteropPeerBuild;