diff --git a/notes/postmortem-eureka-schema-phase.md b/notes/postmortem-eureka-schema-phase.md
new file mode 100644
index 00000000..56a26212
--- /dev/null
+++ b/notes/postmortem-eureka-schema-phase.md
@@ -0,0 +1,225 @@
+# Eureka pipeline state, schema-ownership phase: postmortem
+
+Date: 2026-09-16. Written at the phase boundary, not at the end of the
+campaign. Cuts 1-6d closed Epiphany's stake in the work; Cuts 7-16 build
+Huginn and the `eureka-state` client and are still running. Evidence: the cut
+map `notes/eureka-pipeline-state-cut.md`, the branch
+`codex/eureka-pipeline-state`, and the Soul reports recorded in the map's
+Landed section.
+
+## Summary
+
+Epiphany now owns the schemas for Eureka's pipeline state, in one leaf
+library that a separate organ can depend on without dragging the runtime in
+with it. `epiphany-pipeline` is 2,444 lines with its tests, 34 of them, and
+publishes 13 derived schemas. It has no dependency on `epiphany-core`; the
+dependency runs the other way. The public surface is five doors:
+registration, prepare, decode, write-envelope validation, and reference
+validation.
+
+The phase landed across 113 commits in three days. At writing, the leaf is
+pinned by Huginn at `5cda0886` and nothing in Epiphany blocks the organ.
+
+## Scope and invariants
+
+The target was schema ownership, and only that. The organ, the index, the
+CultNet surface and the MCP client were all excluded from this repo by
+design, because the previous shape put a store, a lease and git preconditions
+inside Epiphany and the operator rejected it mid-campaign.
+
+The invariants that had to survive: one owner per decision, a key grammar in
+which no reader can excuse a document it does not like, schemas that derive
+byte for byte from the types rather than being maintained beside them, and a
+leaf that a second repo can consume without inheriting the runtime.
+
+The earlier attempt failed by bundling. The repo-owned store design is kept
+in the map under History, clearly marked dead, rather than deleted, because
+the reason it died is the reason Cut 4 exists.
+
+## Timeline
+
+| Cut | What it owned | Outcome |
+|---|---|---|
+| 1-2 | Re-pin CultLib, collapse to one commit owner | Landed, Soul-closed |
+| 3a | Ten document kinds and schemas, plus store, lease, git gates | Landed, then half of it deleted by Cut 4 |
+| 4 | Delete the repo-owned store whole | 1,302 lines removed, 549 added |
+| 5 | Collapse the store profile back out | Landed |
+| 6 | Extract `epiphany-pipeline` as a leaf | Landed after two fix batches |
+| 6b | The key grammar | Three fix batches; the grammar was redesigned rather than patched a fourth time |
+| 6c | The Ghostlight shapes | Landed, one fix batch plus two harness repairs |
+| 6d | Resolution history and stewardship by sequence | Landed both sides; the Huginn follow-up needed its own fix batch |
+| follow-up | The public reference validator | Landed both sides, `5cda0886` and `5ba7b0c6` |
+
+## Structural delta
+
+Cut 4 is the honest headline: it deleted 1,302 lines and added 549, and
+retired one store format, one lease and two git preconditions. Cut 6 moved
+the types out of `epiphany-core` rather than copying them, so the extraction
+was a move and not a fork.
+
+The estimates were wrong in a consistent direction. Cut 4's test arithmetic
+was off because the deleted module held 20 tests on Windows rather than 15,
+and Cut 6's `epiphany-core` estimate of −623 should have read about −1,060
+once the test module travelled with the code. Both corrections are recorded
+in the map against the sections they falsify. Cut 6d's test delta was +181,
+not the +173 claimed.
+
+Nothing was parked in this phase.
+
+## What Soul caught
+
+Green tests passed all of the following.
+
+**Split and mislocated authority.** The epoch guard had no test that could
+even construct an envelope to reach it, so an `if false` mutation survived.
+Self ruled deletion over testing what nothing can construct, and Cut 8 wrote
+it in the organ where admission can reach it. Separately, the write path was
+believed live and was in fact test-only; `decode` and the CultCache imports
+looked live only because dead code mentioned them.
+
+**A rule open one level up, three times.** The key grammar was patched twice
+and the same invariant came back both times. The third occurrence was the
+signal to redesign rather than patch. Soul then found no collision in 212,450
+adversarial keys against the new grammar.
+
+**Readers excusing what writers refuse.** The reader accepted a trailing dot
+on the root and the local while the writer refused it, so a reference with
+trailing junk passed the reader against its own documentation. A mutant
+excusing the `Instance` root from the kind check survived: exactly the shape
+Cut 6b existed to kill.
+
+**Tests pinning spelling instead of rules.** A depth test restated the
+literal 64 rather than referencing the bound, so moving both to 60 passed it.
+Fixtures that used the sequence 1 at every nesting level left a nested
+resolution's own sequence unpinned.
+
+**A regression introduced by an earlier fix.** An exact replay of any batch
+carrying a derived write was refused rather than recognised as already
+admitted, because the derivation recomputed a sequence over an image that
+already held the first admission's record. The replay test had used only
+batches without derivations.
+
+**Ordering by key rather than by meaning.** The hand-off replay picked its
+subject by key order, so from the eleventh transfer on, where `n11` sorts
+before `n2`, it derived a withdrawal of the wrong record. Ten round trips
+alone did not expose it.
+
+**Dead code with a test that could not reach it.** The resolution-base arm of
+the reinstatement rule was unreachable because the depth cap fired first.
+Deleting it was the point: a rule defended by a test that cannot run is the
+failure mode of subtraction, not a defence against it.
+
+## Operator corrections
+
+**The repo-owned store.** The operator rejected it mid-campaign, and Cut 4
+deleted it whole rather than demoting it. This is the single largest
+correction of the phase and the reason the leaf is clean.
+
+**A hand-off is a transfer, not a lease.** Self had modelled every stewardship
+hand-off as a loan that returns. The operator's example was Odin holding a
+swarm of infrastructure tools and spinning off a new steward when the
+workload justifies it, with no return. The missing context was that Self had
+only ever seen the cross-cutting case, where borrowing is the natural reading.
+
+**Withdrawn resolutions are kept.** Self's default threw the record away.
+The operator's model was a subject as a question with one canonical answer
+and an affordance for withdrawal, where the withdrawn answer is context to
+learn from. The operator also named the assumption the ruling rests on: that
+the context actually reaches the agents. Self had landed the opposite default
+and reverted it.
+
+**Single-writer semantics are CultCache's.** Self attributed them to redb.
+redb is the storage engine underneath; the owned store lock and the
+compare-and-swap batch are CultCache's, and were built in this same session.
+
+**Stop spending the scarce model on Hands.** The default model inherits the
+root's, so every dispatch had been running on Fable without anyone choosing
+it. The rule now is to name the model on every dispatch.
+
+## Incidents
+
+**Cargo through the Bash tool.** `CARGO_TARGET_DIR=C:\...` has its
+backslashes collapsed, and cargo starts a from-scratch build into a path that
+does not exist. Nothing landed in the shared directory. Cargo on this host
+runs through PowerShell only.
+
+**A scoped `cargo clean` against the brief.** Hands freed and partly retook
+about 400 MB of the shared target directory. Soul could not establish that
+another crate's artifacts were evicted. The next brief forbids it by name.
+
+**Agents ending their turn mid-job, three times.** The briefs now name the
+mechanism rather than the intent: a wait is a foreground poll loop inside one
+tool call. One agent left detached timers that re-fired notifications for an
+hour, so the briefs also forbid background monitors that outlive the run.
+
+**The harness ate fixes.** An early mutation runner restored from a sidecar
+that predated the fix it was testing, reverting real work. A later version
+committed a NUL byte and a literal control character into a target. The
+current harness reads the original as bytes, writes the sidecar before any
+write, restores hash-first, attempts every target, and prints the original
+digest before rethrowing. A tool-enforced timeout was the exact path that
+left a tree mutated, so the harness now owns its own timeout and kills the
+process tree inside its own cleanup.
+
+**Map splices landing at the wrong heading depth.** A specification written
+in a scratchpad began one level deeper than the map's section, and the fold
+put every heading under it a level too deep.
+
+**My own errors in the map**, each corrected in place: a follow-up number
+used twice, an ungreppable regex, seventeen entries described as nineteen, a
+zip digest labelled as the DLL's, a claim that CI was green throughout, an
+overstated scar, and one commit attributed to its neighbour.
+
+## What worked
+
+**Mutation suites as the unit of proof, not test counts.** Every operator
+ruling and every new rule gets a test that fails under its own mutation, and
+the suite is committed with a no-op control that proves the harness restores
+bytes exactly. The controls caught the harness eating fixes; test counts
+never would have.
+
+**A revert mutation and a loosening mutation per rule.** A plain revert is
+too easy a target. The loosening is what found the reader excusing a root
+kind and the unpinned nested sequence. When a loosening turns out to be
+unfalsifiable by construction, it is demoted to a recorded note with the
+reason rather than left in the suite implying coverage it does not have.
+
+**Redesigning on the third occurrence.** The key grammar came back twice
+under patches. The rule that emerged is to treat the third appearance of an
+invariant as evidence about the design, not about the instance.
+
+**Keeping dead designs marked rather than deleted.** The repo-owned store
+sections carry banners naming their false sentences. A reader who finds the
+old model finds it labelled.
+
+**Not capping the Soul loop on a foundation cut.** Cuts 6 and 6b each took
+four passes and the later passes still found real defects.
+
+## What to change in the pipeline
+
+All four of these were approved by the operator on 2026-09-16 after a cost
+review that put roughly half the overhead on process waste and roughly half
+on the inescapable cost of a second agent.
+
+1. **A loosening mutation per rule, alongside the revert.** Landed in the
+   Hands brief.
+2. **One harness in the Eureka repository.** Owed. The PowerShell harness
+   still lives in `F:\Projects\Epiphany\tools\` and Huginn reaches across for
+   it; CultLib's JavaScript runner needs the same contract by name.
+3. **Reports are findings, promises and numbers only, and a second Soul pass
+   is scoped to the fix batch diff.** Landed in both briefs.
+4. **A map commit per cut, rulings excepted.** In effect.
+
+## Open follow-ups
+
+- **Cut 9's spec text calls the `V10L` loosening failable.** It was demoted
+  when the reference validator made it unfalsifiable. Stale text in the map's
+  Cut 9 section, harmless to the code.
+- **FU-9: CultLib's lock failure is text-matched.** `cultcache-rs` needs a
+  typed error. Owner is CultLib, and it can wait because the only consumer
+  matching the text is a test.
+- **FU-1 through FU-8** stand as recorded in the map, each with its file and
+  its reason.
+- **Cut 11 must index withdrawn resolutions with their reasons.** This is the
+  second obligation the operator's Q17 ruling created; the first, a history
+  view, landed in Cut 9.