test(hygiene): close every brain the unit suite creates

Each file opened one or more Brainy instances (beforeEach, or a small
per-test helper like migration-gate-family-scoped's module-level seed())
and never closed them. migration-gate-family-scoped.test.ts now tracks
every brain seed() hands back in a describe-scoped array drained by
afterEach, since the helper itself lives outside the describe block.

tests/unit/brainy/metadata-provider-contract.test.ts

@@ -18,7 +18,7 @@
  * exercised by cor's combined matrix); they inject probe/spy hooks onto the live JS
  * metadata index, which has neither method by default.
  */
-import { describe, it, expect, beforeEach } from 'vitest'
+import { describe, it, expect, beforeEach, afterEach } from 'vitest'
 import { Brainy } from '../../../src/brainy'
 import { NounType } from '../../../src/types/graphTypes'
 
@@ -34,6 +34,10 @@ describe('metadata-provider contract wiring (getIdsForFilter opts)', () => {
     mi = (brain as any).metadataIndex
   })
 
+  afterEach(async () => {
+    await brain.close()
+  })
+
   it('RETIRED: a read never calls probeConsistency() / self-heals via detectAndRepairCorruption — that is the read-triggered dark rebuild the health-gate law forbids', async () => {
     let probes = 0
     let repairs = 0

tests/unit/brainy/migration-gate-family-scoped.test.ts

@@ -8,7 +8,7 @@
  * gate that hung getStats / readdir / readFile behind an unrelated family's
  * migration until the wait timed out.
  */
-import { describe, it, expect, beforeEach } from 'vitest'
+import { describe, it, expect, beforeEach, afterEach } from 'vitest'
 import { Brainy } from '../../../src/brainy.js'
 import { MigrationInProgressError } from '../../../src/errors/brainyError.js'
 
@@ -38,12 +38,19 @@ const jam = (provider: unknown) => {
 }
 
 describe('migration LOCK is family-scoped', () => {
+  const opened: Brainy[] = []
+
   beforeEach(() => {
     process.env.BRAINY_DETERMINISTIC_EMBEDDINGS = 'true'
   })
 
+  afterEach(async () => {
+    for (const b of opened.splice(0)) await b.close().catch(() => {})
+  })
+
   it('a stuck VECTOR migration does not block canonical or graph/metadata reads', async () => {
     const brain = await seed()
+    opened.push(brain)
     const childId = (
       (await brain.vfs.readdir('/notes', { withFileTypes: true })) as Array<{ entityId: string }>
     )[0].entityId
@@ -60,6 +67,7 @@ describe('migration LOCK is family-scoped', () => {
 
   it('a stuck VECTOR migration STILL blocks a read that needs the vector family', async () => {
     const brain = await seed()
+    opened.push(brain)
     jam((brain as any).index)
 
     // A semantic query consults the vector index — it must wait, and (bounded by
@@ -70,6 +78,7 @@ describe('migration LOCK is family-scoped', () => {
 
   it('a stuck GRAPH migration blocks traversal but not vector/canonical reads', async () => {
     const brain = await seed()
+    opened.push(brain)
     const childId = (
       (await brain.vfs.readdir('/notes', { withFileTypes: true })) as Array<{ entityId: string }>
     )[0].entityId
@@ -87,6 +96,7 @@ describe('migration LOCK is family-scoped', () => {
 
   it('with no migration in flight, every read serves (the fast path is a no-op)', async () => {
     const brain = await seed()
+    opened.push(brain)
     await expect(brain.getStats()).resolves.toBeDefined()
     await expect(brain.find({ query: 'doc' })).resolves.toBeDefined()
     await expect(brain.vfs.readdir('/notes')).resolves.toHaveLength(1)

tests/unit/brainy/relate-duplicate-optimization.test.ts

@@ -18,7 +18,7 @@ describe('Duplicate Check Optimization', () => {
   })
 
   afterEach(async () => {
-    // Cleanup is automatic with memory storage
+    await brain.close()
   })
 
   it('should detect duplicate relationships using GraphAdjacencyIndex', async () => {