fix(namespace): noun-record updates preserve legacy inline HNSW adjacency — the placeholder-adjacency write stamped out pre-codec records' stored connections (crash-window unreachability); codec-era records were never at risk (empty field is the blob marker); pin covers the legacy shape

tests/integration/level-field-shadow.test.ts

@@ -145,3 +145,50 @@ describe('level field shadow — user metadata named level is a real field', ()
     expect(EXPECTED_INDEX_EPOCH).toBe(2)
   })
 })
+
+describe('noun-record writes never stamp over stored graph state', () => {
+  let brain: Brainy
+
+  beforeEach(async () => {
+    brain = new Brainy({
+      requireSubtype: false,
+      storage: { type: 'memory' as const },
+      embeddingFunction: stubEmbedding
+    })
+    await brain.init()
+  })
+
+  afterEach(async () => {
+    await brain.close()
+  })
+
+  it('a data-changing update preserves LEGACY inline connections in the record', async () => {
+    // Codec-era records carry an EMPTY connections field by design (the
+    // adjacency lives in a separate compressed blob) — the clobber window
+    // exists only for legacy pre-codec records whose adjacency is inline.
+    // Simulate one: write the record with inline connections directly.
+    const id = await brain.add({
+      data: 'legacy-shaped node',
+      type: NounType.Concept,
+      metadata: { n: 1 }
+    })
+    const storage = (brain as any).storage
+    const rec = await storage.getNoun(id)
+    const legacy = {
+      ...rec,
+      connections: new Map([[0, new Set(['00000000-0000-4000-8000-00000000aaaa'])]]),
+      level: 1
+    }
+    await storage.saveNoun(legacy)
+    const before = await storage.getNoun(id)
+    expect(before.connections.size).toBeGreaterThan(0)
+
+    // A data-changing update stages SaveNounOperation with placeholder
+    // adjacency — the legacy inline connections must survive the write.
+    await brain.update({ id, data: 'completely re-embedded text' })
+
+    const after = await storage.getNoun(id)
+    expect(after.connections.size).toBeGreaterThan(0)
+    expect(after.level).toBe(1)
+  })
+})