fix(delete): the null-metadata skip closes — index legs run id-keyed or narrate, never silently strand postings

remove() guarded its index legs with 'if (metadata)': a row whose canonical
metadata was unreadable at delete time kept its postings forever, silently
(the leak class a partner audit confirmed at this exact site). Closed at
all three provider shapes: a provider exposing the id-keyed removal
contract (removeEntityById, arriving with the accelerator's next minor)
gets exact per-entity retraction; the JS index gets id-keyed cleanup
(deleted bitmap + id mapper — field stats reconcile at rebuild), narrated;
a native provider without the contract is NEVER called metadata-omitted
(that path walks the store's value space) — its skip is narrated and
tracked in the degraded set for repairIndex, never silent. The pre-reads
are torn-tolerant: a torn record is deletable (the delete is the cure).

Pinned: a metadata-less row with live postings deletes cleanly and leaves
the query universe; the delete-family suites stay green alongside.

tests/integration/null-metadata-delete.test.ts

@@ -0,0 +1,62 @@
+/**
+ * @module tests/integration/null-metadata-delete
+ * @description The null-metadata delete skip is CLOSED. remove() used to
+ * guard its index legs with `if (metadata)` — a row whose canonical
+ * metadata was unreadable at delete time (torn, or a leg lost to an old
+ * defect) kept its postings FOREVER, silently. Now: the JS index gets an
+ * id-keyed cleanup (deleted bitmap + id mapper), the id-keyed native
+ * contract is used when a provider offers it, and the one remaining
+ * skip-shape (native without the contract) is narrated and tracked, never
+ * silent. Pinned: a metadata-less row with live postings deletes cleanly
+ * and leaves the query universe.
+ */
+import { describe, it, expect, afterEach } from 'vitest'
+import { mkdtempSync, rmSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { Brainy } from '../../src/index.js'
+import { NounType } from '../../src/types/graphTypes.js'
+
+type RawBox = {
+  storage: {
+    readNounRaw(id: string): Promise<{ metadata: unknown; vector: unknown }>
+    writeNounRaw(id: string, r: { metadata: unknown; vector: unknown }): Promise<void>
+  }
+}
+
+const dirs: string[] = []
+const brains: Brainy[] = []
+afterEach(async () => {
+  for (const b of brains.splice(0)) await b.close().catch(() => {})
+  for (const d of dirs.splice(0)) rmSync(d, { recursive: true, force: true })
+})
+
+describe('null-metadata delete', () => {
+  it('a row whose metadata leg is gone still deletes — id-keyed cleanup, no silent skip, gone from the query universe', async () => {
+    const dir = mkdtempSync(join(tmpdir(), 'brainy-nullmeta-del-'))
+    dirs.push(dir)
+    const brain = new Brainy({ storage: { type: 'filesystem', path: dir }, requireSubtype: false, silent: true })
+    await brain.init()
+    brains.push(brain)
+
+    const keep = await brain.add({ data: 'survivor', type: NounType.Document, metadata: { team: 'atlas' } })
+    const victim = await brain.add({ data: 'doomed', type: NounType.Document, metadata: { team: 'atlas' } })
+    await brain.flush()
+    expect((await brain.find({ where: { team: 'atlas' } })).length).toBe(2)
+
+    // Manufacture the shape: the victim's metadata leg vanishes behind the
+    // engine's back (vector leg + postings stay live).
+    const storage = (brain as unknown as RawBox).storage
+    const raw = await storage.readNounRaw(victim)
+    await storage.writeNounRaw(victim, { metadata: null, vector: raw.vector })
+
+    // THE PIN: the delete neither throws nor silently strands postings.
+    await brain.remove(victim)
+    await brain.flush()
+
+    const after = await brain.find({ where: { team: 'atlas' } })
+    expect(after.length, 'victim left the query universe; survivor serves').toBe(1)
+    expect(after[0].id).toBe(keep)
+    expect(await brain.get(victim)).toBeNull()
+  }, 120000)
+})