packages/cultcache-py/tests/test_cultcache.py

@@ -1121,6 +1121,25 @@ class CultCacheTests(unittest.TestCase):
             catalog_entry=catalog_entry,
         )
 
+    def test_pulling_a_synthetic_pre_v1_envelope_array_leaves_the_file_bytes_identical(self) -> None:
+        try:
+            import msgpack  # type: ignore
+        except ImportError:
+            self.skipTest("msgpack optional dependency is not installed")
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "legacy.cc"
+            legacy = msgpack.packb(
+                [{"key": "note:hello", "type": "note", "payload": {"title": "Hello"}, "storedAt": "2026-10-20T00:00:00Z"}],
+                use_bin_type=True,
+            )
+            path.write_bytes(legacy)
+
+            envelopes = SingleFileMessagePackBackingStore(path).pull_all()
+
+            self.assertEqual([e.key for e in envelopes], ["note:hello"])
+            self.assertEqual(path.read_bytes(), legacy)
+            self.assertEqual(sorted(p.name for p in Path(tmp).iterdir()), ["legacy.cc"])
+
     def test_legacy_key_global_loads_without_writing_and_first_write_leaves_one_global(self) -> None:
         with tempfile.TemporaryDirectory() as tmp:
             settings = define_document_type("settings", global_document=True)

packages/cultcache-rs/src/lib.rs

@@ -6136,6 +6136,27 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn pulling_a_synthetic_pre_v1_envelope_array_leaves_the_file_bytes_identical() -> Result<()> {
+        // SYNTHETIC pre-v1 vector: no real file of this shape is known; the Rust envelope payload is binary.
+        let temp = tempfile::tempdir()?;
+        let path = temp.path().join("legacy.cc");
+        let legacy = rmp_serde::to_vec_named(&vec![CultCacheEnvelope {
+            key: "note:hello".to_string(),
+            r#type: "note".to_string(),
+            payload: vec![0x90],
+            stored_at: "2026-10-20T00:00:00Z".to_string(),
+            schema_id: None,
+        }])?;
+        fs::write(&path, &legacy)?;
+
+        let envelopes = SingleFileMessagePackBackingStore::new(&path).pull_all()?;
+
+        assert_eq!(envelopes.iter().map(|e| e.key.as_str()).collect::<Vec<_>>(), ["note:hello"]);
+        assert_eq!(fs::read(&path)?, legacy);
+        Ok(())
+    }
+
     #[test]
     fn a_newer_store_is_named_once_its_header_string_is_complete() -> Result<()> {
         let vector = fs::read(

packages/cultcache-ts/CHANGELOG.md

@@ -3,6 +3,15 @@
 All notable changes to `@gamecult/cultcache-ts` are recorded here, following
 [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
+## [Unreleased]
+
+### Changed
+
+- 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.
+- `SingleFileStoreRead` no longer carries `repairedLegacyPayload`; no consumer used it.
+
 ## [0.15.0]
 
 0.14.1 and 0.14.2 were never tagged or published; this entry carries them with the Unreleased work, and `cultcache-ts-v0.14.0` is the previous release.
@@ -41,8 +50,6 @@ All notable changes to `@gamecult/cultcache-ts` are recorded here, following
 - The Windows replace is a POSIX-semantics rename first (it lands while C# and Rust readers
   hold the store open), falling back to a write-through `MoveFileExW`, with 25 attempts 20 ms
   apart on errors 5, 32 and 33. Writers wait up to 30 s for the lock.
-- Opening a legacy store that needs healing rewrites it under the lock, from a read taken
-  under the lock.
 
 ### Dependencies
 

packages/cultcache-ts/README.md

@@ -357,7 +357,7 @@ That is the TypeScript version of the original CultCache trick:
 - the top-level MessagePack value is `[formatVersion, schemaCatalog, records]`
 - each record is `[key, schemaId, storedAt, payload]`
 - each catalog entry is `[schemaId, schemaName, schemaVersion, contentHash, canonicalSchemaJson, compatibleSchemaIds, members]`
-- it still reads the older TS/Rust-style envelope array and rewrites repaired legacy payloads as v1 snapshots
+- it still reads the older TS/Rust-style envelope array (object payloads are normalized in memory; opening never rewrites the file) and replaces it with a v1 snapshot on the next push, delete or flush
 - it queues local writes in order, then takes the shared `<file>.lock` (`flock` on Unix, `LockFileEx` on Windows, via koffi, loaded on the first write) for each one, so C#, Rust and TypeScript writers exclude each other; the read a write merges from is taken under that lock
 - it fsyncs the staged file and, on Unix, the directory after the replace; on Windows it replaces with a POSIX-semantics rename and falls back to a write-through `MoveFileExW`, retrying briefly on sharing violations
 - it persists raw MessagePack payload bytes inside schema-addressed records

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

@@ -47,21 +47,11 @@ export class SingleFileMessagePackBackingStore implements CacheBackingStore {
   }
 
   async pullAll(): Promise<CultCacheEnvelope[]> {
-    // The disk decides the header: a file that is gone or legacy is not marked.
-    this.#format = STORE_FORMAT_VERSION;
+    // A pure read: the disk decides the header, and a legacy file is normalized in memory only. The file is rewritten
+    // as v1 by the next push, delete or flush, which merges what this read returns; opening never replaces bytes the
+    // consumer's codec has not yet accepted.
     const disk = this.#readDisk();
     this.#format = disk.format;
-    if (disk.repairedLegacyPayload) {
-      // The heal decides from its own read, taken under the store lock.
-      await this.#enqueue(async () => {
-        const again = this.#readDisk();
-        this.#format = again.format;
-        if (again.repairedLegacyPayload) {
-          await this.#writeAll([], again.envelopes);
-        }
-      });
-    }
-
     return disk.envelopes;
   }
 
@@ -158,7 +148,7 @@ export class SingleFileMessagePackBackingStore implements CacheBackingStore {
 export function readSingleFileStore(path: string): SingleFileStoreRead {
   const data = readStoreBytes(path);
   if (data === undefined) {
-    return { absent: true, format: STORE_FORMAT_VERSION, envelopes: [], repairedLegacyPayload: false };
+    return { absent: true, format: STORE_FORMAT_VERSION, envelopes: [] };
   }
 
   try {
@@ -395,8 +385,6 @@ export type SingleFileStoreRead = {
   absent: boolean;
   format: StoreFormat;
   envelopes: CultCacheEnvelope[];
-  // A legacy file whose payloads were not bytes: reading it repairs them, and the store rewrites the file.
-  repairedLegacyPayload: boolean;
 };
 
 function decodeStoreFile(data: Uint8Array): Omit<SingleFileStoreRead, "absent"> {
@@ -420,7 +408,7 @@ function decodeStoreFile(data: Uint8Array): Omit<SingleFileStoreRead, "absent">
         storedAt: record.storedAt,
       };
     });
-    return { format: snapshot.format, envelopes, repairedLegacyPayload: false };
+    return { format: snapshot.format, envelopes };
   }
 
   const legacy = decodeLegacyEnvelopeArray(decoded);
@@ -428,19 +416,8 @@ function decodeStoreFile(data: Uint8Array): Omit<SingleFileStoreRead, "absent">
     throw new Error("CultCache file is not a recognized CultCache MessagePack store.");
   }
 
-  let repairedLegacyPayload = false;
-  const normalized = legacy.map((entry) => {
-    const payload = normalizePayload(entry.payload);
-    if (payload !== entry.payload) {
-      repairedLegacyPayload = true;
-    }
-
-    return {
-      ...entry,
-      payload,
-    };
-  });
-  return { format: STORE_FORMAT_VERSION, envelopes: envelopeArraySchema.parse(normalized).map((entry) => ({ ...entry, payload: documentPayloadFromBytes(entry.payload) })) as CultCacheEnvelope[], repairedLegacyPayload };
+  const normalized = legacy.map((entry) => ({ ...entry, payload: normalizePayload(entry.payload) }));
+  return { format: STORE_FORMAT_VERSION, envelopes: envelopeArraySchema.parse(normalized).map((entry) => ({ ...entry, payload: documentPayloadFromBytes(entry.payload) })) as CultCacheEnvelope[] };
 }
 
 function decodeSnapshot(decoded: unknown): DecodedSnapshot | undefined {

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

@@ -504,46 +504,56 @@ test("SingleFileMessagePackBackingStore refuses a record whose schema the catalo
   await assert.rejects(() => cache.pullAllBackingStores(), StoreUnreadableError);
 });
 
-test("SingleFileMessagePackBackingStore heals legacy envelopes whose payload was persisted as an object", async () => {
-  const noteDocument = defineDocumentType({
-    type: "note",
-    schema: z.object({
-      title: z.string(),
-      body: z.string(),
-    }),
-  });
+const legacyNoteType = defineDocumentType({
+  type: "note",
+  schema: z.object({ title: z.string(), body: z.string().optional() }),
+});
 
+// SYNTHETIC pre-v1 file (no real one is known): an envelope array with object payloads.
+async function legacyNoteStore(second: unknown): Promise<{ storePath: string; bytes: Uint8Array }> {
   const storePath = join(await mkdtemp(join(tmpdir(), "cultcache-ts-")), "legacy.msgpack");
-  const envelopePayload = {
-    title: "Hello",
-    body: "world",
-  };
-
-  await writeFile(
-    storePath,
-    encode([
-      {
-        key: "note:hello",
-        type: "note",
-        payload: envelopePayload,
-        storedAt: new Date().toISOString(),
-      },
-    ]),
-  );
+  const bytes = encode([
+    { key: "note:hello", type: "note", payload: { title: "Hello", body: "world" }, storedAt: "2026-10-20T00:00:00Z" },
+    { key: "note:other", type: "note", payload: second, storedAt: "2026-10-20T00:00:00Z" },
+  ]);
+  await writeFile(storePath, bytes);
+  return { storePath, bytes };
+}
 
+test("a codec that refuses a synthetic pre-v1 store's content leaves the file byte-identical", async () => {
+  const { storePath, bytes } = await legacyNoteStore({ title: 42 });
   const cache = CultCache.builder()
-    .withDocumentType(noteDocument)
+    .withDocumentType(legacyNoteType)
+    .withGenericStore(new SingleFileMessagePackBackingStore(storePath))
+    .build();
+
+  await assert.rejects(() => cache.pullAllBackingStores());
+  assert.deepEqual([...(await readFile(storePath))], [...bytes]);
+  assert.deepEqual((await readdir(dirname(storePath))).sort(), ["legacy.msgpack"]);
+});
+
+test("a synthetic pre-v1 store is read untouched and becomes v1 only when the consumer writes, keeping its other entries", async () => {
+  const { storePath, bytes } = await legacyNoteStore({ title: "Other" });
+  const cache = CultCache.builder()
+    .withDocumentType(legacyNoteType)
     .withGenericStore(new SingleFileMessagePackBackingStore(storePath))
     .build();
 
   await cache.pullAllBackingStores();
-  assert.deepEqual(cache.getRequired(noteDocument, "note:hello"), envelopePayload);
+  assert.deepEqual(cache.getRequired(legacyNoteType, "note:hello"), { title: "Hello", body: "world" });
+  assert.deepEqual([...(await readFile(storePath))], [...bytes], "reading does not rewrite the file");
 
-  const rewritten = decode(await readFile(storePath)) as unknown[];
-  assert.equal(rewritten[0], "cultcache.store.v1");
-  const records = rewritten[2] as unknown[][];
-  assert.equal(records.length, 1);
-  assert.ok(records[0]?.[3] instanceof Uint8Array);
+  await cache.put(legacyNoteType, "note:new", { title: "New" });
+  assert.equal((decode(await readFile(storePath)) as unknown[])[0], "cultcache.store.v1");
+
+  const reopened = CultCache.builder()
+    .withDocumentType(legacyNoteType)
+    .withGenericStore(new SingleFileMessagePackBackingStore(storePath))
+    .build();
+  await reopened.pullAllBackingStores();
+  assert.deepEqual(reopened.getRequired(legacyNoteType, "note:hello"), { title: "Hello", body: "world" });
+  assert.deepEqual(reopened.getRequired(legacyNoteType, "note:other"), { title: "Other" });
+  assert.deepEqual(reopened.getRequired(legacyNoteType, "note:new"), { title: "New" });
 });
 
 test("CultCache rejects a second generic backing store", async () => {

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

@@ -471,44 +471,70 @@ test("the store lock is released when the operation throws", async () => {
   }
 });
 
+// SYNTHETIC pre-v1 vector: no real file of this shape is known to exist. A top-level array of {key,type,payload,storedAt}
+// whose payload is not binary (an object, a Node Buffer JSON, an int array) is what the removed heal-on-open rewrote.
 const legacyObjectPayload = (): Uint8Array =>
   encode([{ key: "note:hello", type: "note", payload: { title: "Hello" }, storedAt: "2026-10-20T00:00:00Z" }]);
 
-test("an open that heals a legacy store waits for the store lock and heals from its own read", async () => {
+test("opening a synthetic pre-v1 store with object payloads returns them normalized and leaves the file untouched, even while another holder has the lock", async () => {
   const directory = await scratch();
   try {
     const path = join(directory, "legacy.cc");
     const legacy = legacyObjectPayload();
     await writeFile(path, legacy);
     const store = new SingleFileMessagePackBackingStore(path);
-    let healed: Promise<unknown> | undefined;
-    let settled = false;
     await withStoreWriteLock(path, async () => {
-      healed = store.pullAll().then(() => {
-        settled = true;
-      });
-      await sleepFor(300);
-      assert.equal(settled, false, "the heal must wait for the lock");
-      assert.deepEqual([...(await readFile(path))], [...legacy], "the file keeps its legacy bytes while the lock is held elsewhere");
+      const [lockHeld] = await Promise.all([readdir(directory)]);
+      const envelopes = await within(store.pullAll(), 5000, "an open does not wait for the write lock");
+      assert.deepEqual(envelopes.map((entry) => entry.key), ["note:hello"]);
+      assert.deepEqual(decode(documentPayloadBytes(envelopes[0].payload)), { title: "Hello" });
+      assert.deepEqual([...(await readFile(path))], [...legacy]);
+      assert.deepEqual((await readdir(directory)).sort(), lockHeld.sort(), "an open adds no lock or temp file");
     });
-    await within(healed!, 5000, "the heal");
-    assert.equal((decode(await readFile(path)) as unknown[])[0], "cultcache.store.v1");
+    assert.deepEqual([...(await readFile(path))], [...legacy]);
+    assert.deepEqual((await readdir(directory)).filter((name) => name !== "legacy.cc" && name !== "legacy.cc.lock"), []);
   } finally {
     await rm(directory, { recursive: true, force: true });
   }
 });
 
-test("push and delete over a legacy store that needs healing finish instead of waiting on their own lock", async () => {
+test("opening a synthetic pre-v1 store with Buffer-JSON and int-array payloads normalizes them in memory and leaves the file untouched", async () => {
+  const directory = await scratch();
+  try {
+    const path = join(directory, "legacy.cc");
+    const inner = encode({ title: "Hello" });
+    const legacy = encode([
+      { key: "a", type: "note", payload: { type: "Buffer", data: [...inner] }, storedAt: "2026-10-20T00:00:00Z" },
+      { key: "b", type: "note", payload: [...inner], storedAt: "2026-10-20T00:00:00Z" },
+    ]);
+    await writeFile(path, legacy);
+    const envelopes = await new SingleFileMessagePackBackingStore(path).pullAll();
+    assert.deepEqual(envelopes.map((entry) => entry.key), ["a", "b"]);
+    for (const envelope of envelopes) {
+      assert.deepEqual(decode(documentPayloadBytes(envelope.payload)), { title: "Hello" });
+    }
+    assert.deepEqual([...(await readFile(path))], [...legacy]);
+    assert.deepEqual(await readdir(directory), ["legacy.cc"]);
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+});
+
+test("push and delete over a synthetic pre-v1 store write v1 and keep the other legacy entries, normalized payloads included", async () => {
   const directory = await scratch();
   try {
     const path = join(directory, "legacy.cc");
     await writeFile(path, legacyObjectPayload());
     const store = new SingleFileMessagePackBackingStore(path);
     await within(store.push(entryOf("a")), 5000, "push");
+    assert.equal((decode(await readFile(path)) as unknown[])[0], "cultcache.store.v1");
+    assert.deepEqual((await store.pullAll()).map((entry) => entry.key).sort(), ["a", "note:hello"]);
     await writeFile(path, legacyObjectPayload());
     await within(store.delete(entryOf("a")), 5000, "delete");
-    const keys = (await store.pullAll()).map((entry) => entry.key);
-    assert.deepEqual(keys, ["note:hello"]);
+    assert.equal((decode(await readFile(path)) as unknown[])[0], "cultcache.store.v1");
+    const kept = await store.pullAll();
+    assert.deepEqual(kept.map((entry) => entry.key), ["note:hello"]);
+    assert.deepEqual(decode(documentPayloadBytes(kept[0].payload)), { title: "Hello" });
   } finally {
     await rm(directory, { recursive: true, force: true });
   }
@@ -697,7 +723,7 @@ test("a store file of an unrecognized shape is refused, and a store naming a mis
   }
 });
 
-test("opening a store that needs no healing writes nothing: a missing store leaves no lock file, a legacy store with byte payloads keeps its bytes", async () => {
+test("opening writes nothing: a missing store leaves no lock file, a legacy store with byte payloads keeps its bytes", async () => {
   const directory = await scratch();
   try {
     const absent = join(directory, "nested", "absent.cc");