fix(storage): avoid rewriting satisfied data directory compatibility markers

packages/node-runtime/src/data-dir-compat.test.ts

@@ -291,3 +291,63 @@ test('raising minRuntimeVersion records prerelease runtime by stable core versio
     version: '0.26.4',
   })
 })
+
+test('satisfied compatibility requirements preserve the original metadata across runtime upgrades', () => {
+  for (const minRuntimeVersion of ['0.25.1', '0.26.0']) {
+    const userDataDir = makeTempDir()
+    const provider = makePathProvider(userDataDir)
+    const existing = raiseDataDirMinRuntimeVersion(provider, {
+      minRuntimeVersion,
+      dataCompatibilityVersion: 2,
+      reason: 'segment-schema',
+      runtime: { version: '0.37.3', kind: 'cli' },
+      module: 'chat-db-migration',
+      now: () => 1000,
+    })
+    const metaPath = path.join(userDataDir, '.chatlab-meta.json')
+    const original = fs.readFileSync(metaPath, 'utf-8')
+
+    const result = raiseDataDirMinRuntimeVersion(provider, {
+      minRuntimeVersion: '0.25.1',
+      dataCompatibilityVersion: 1,
+      reason: 'segment-schema',
+      runtime: { version: '0.37.4', kind: 'desktop' },
+      module: 'chat-db-migration',
+      now: () => 2000,
+    })
+
+    assert.deepEqual(result, existing)
+    assert.equal(fs.readFileSync(metaPath, 'utf-8'), original)
+  }
+})
+
+test('required compatibility updates propagate replacement failures and preserve the previous metadata', (t) => {
+  const userDataDir = makeTempDir()
+  const provider = makePathProvider(userDataDir)
+  const input = {
+    minRuntimeVersion: '0.25.1',
+    dataCompatibilityVersion: 1,
+    reason: 'segment-schema',
+    runtime: { version: '0.37.4', kind: 'desktop' as const },
+    module: 'chat-db-migration',
+  }
+  const existing = raiseDataDirMinRuntimeVersion(provider, input)
+  const metaPath = path.join(userDataDir, '.chatlab-meta.json')
+  const original = fs.readFileSync(metaPath, 'utf-8')
+  const denied = Object.assign(new Error('Metadata replacement denied'), { code: 'EPERM' })
+  const renameSync = fs.renameSync
+  t.mock.method(fs, 'renameSync', (source: fs.PathLike, target: fs.PathLike) => {
+    if (target === metaPath) throw denied
+    renameSync(source, target)
+  })
+
+  for (const update of [{ minRuntimeVersion: '0.26.0' }, { dataCompatibilityVersion: 2 }, { reason: 'new-schema' }]) {
+    assert.throws(
+      () => raiseDataDirMinRuntimeVersion(provider, { ...input, ...update }),
+      (error) => error === denied
+    )
+    assert.equal(fs.readFileSync(metaPath, 'utf-8'), original)
+    assert.deepEqual(readDataDirCompatibilityMeta(userDataDir), existing)
+    assert.deepEqual(fs.readdirSync(userDataDir), ['.chatlab-meta.json'])
+  }
+})

packages/node-runtime/src/data-dir-compat.ts

@@ -157,6 +157,17 @@ export function raiseDataDirMinRuntimeVersion(
   }
 
   const existing = readDataDirCompatibilityMeta(userDataDir)
+  // This is a migration marker, not a last-open timestamp. Replacing an already sufficient file
+  // can fail on Windows even when the metadata and chat databases are readable.
+  if (
+    existing &&
+    compareStableSemver(existing.minRuntimeVersion, input.minRuntimeVersion) >= 0 &&
+    existing.dataCompatibilityVersion >= input.dataCompatibilityVersion &&
+    existing.reasons.includes(input.reason)
+  ) {
+    return existing
+  }
+
   const minRuntimeVersion =
     existing && compareStableSemver(existing.minRuntimeVersion, input.minRuntimeVersion) > 0
       ? existing.minRuntimeVersion

packages/node-runtime/src/database-manager.test.ts

@@ -999,6 +999,56 @@ test('open repairs the data directory gate for existing current-schema databases
   assert.deepEqual(meta?.reasons, ['segment-schema'])
 })
 
+test('existing sessions remain readable after upgrades when compatible metadata cannot be replaced', (t) => {
+  const root = makeTempDir()
+  const provider = createPathProvider(root)
+  fs.mkdirSync(provider.getDatabaseDir(), { recursive: true })
+  for (const id of ['first', 'second']) {
+    const db = new Database(path.join(provider.getDatabaseDir(), `${id}.db`), { nativeBinding })
+    try {
+      db.exec(CHAT_DB_SCHEMA)
+      db.prepare('INSERT INTO meta (name, platform, type, imported_at) VALUES (?, ?, ?, ?)').run(
+        id,
+        'qq',
+        'group',
+        1000
+      )
+      db.exec(`
+        INSERT INTO member (platform_id, account_name) VALUES ('u1', 'Test Member');
+        INSERT INTO message (sender_id, ts, type, content) VALUES (1, 1000, 0, 'Saved message');
+      `)
+    } finally {
+      db.close()
+    }
+  }
+
+  const previousManager = new DatabaseManager(provider, {
+    nativeBinding,
+    runtime: { version: '0.37.3', kind: 'desktop' },
+  })
+  previousManager.raiseCurrentChatDbCompatibilityGate()
+  const metaPath = path.join(provider.getUserDataDir(), '.chatlab-meta.json')
+  const original = fs.readFileSync(metaPath, 'utf-8')
+  const renameSync = fs.renameSync
+  t.mock.method(fs, 'renameSync', (source: fs.PathLike, target: fs.PathLike) => {
+    if (target === metaPath) throw Object.assign(new Error('Metadata replacement denied'), { code: 'EPERM' })
+    renameSync(source, target)
+  })
+
+  for (const kind of ['desktop', 'cli'] as const) {
+    const manager = new DatabaseManager(provider, { nativeBinding, runtime: { version: '0.37.4', kind } })
+    t.after(() => manager.closeAll())
+    assert.deepEqual(manager.listSessionIds().sort(), ['first', 'second'])
+    for (const id of manager.listSessionIds()) {
+      const db = manager.open(id)
+      assert.ok(db)
+      assert.equal(getSessionInfo(db)?.name, id)
+      assert.deepEqual(db.prepare('SELECT content FROM message').all(), [{ content: 'Saved message' }])
+    }
+    assert.equal(fs.readFileSync(metaPath, 'utf-8'), original)
+  }
+})
+
 test('open keeps a higher existing data directory runtime requirement after migration', () => {
   const root = makeTempDir()
   const dbDir = path.join(root, 'data', 'databases')