diff --git a/docs/testing.md b/docs/testing.md
index ffdf41bd07..ecdd039334 100644
--- a/docs/testing.md
+++ b/docs/testing.md
@@ -160,6 +160,8 @@ Legitimate legacy exceptions must be recorded in `scripts/lib/test-timeout-appea
 
 **Non-CLI quarantine sweep pattern (FN-6433):** for engine/core/dashboard batches, first remove quarantine excludes only in temporary local configs and run the exact quarantined files together so suite-load coupling is visible before editing the ledger. Rescue is valid when the grouped package lane proves the invariant now holds (for example, FN-6433 fixed engine cross-file interference by replacing broad `activeSessionRegistry.clear()` cleanup with path-scoped unregistering) or when a prior shared-fixture fix is demonstrated under package load. Delete duplicate/low-value files under the ratchet when another deterministic suite owns the same invariant. Finish by making `scripts/lib/test-quarantine.json` and every package Vitest exclude array converge in one commit, then prove the empty/non-empty state with package lanes, `pnpm test:gate`, `pnpm test`, `pnpm build`, and the bounded temp-leak output from `pnpm test`.
 
+**2026-06-15 rescue batch (FN-6486):** two same-day quarantines were rescued before their 2026-06-29 deletion deadline. `store-concurrent-writes.test.ts` kept its WAL/`transactionImmediate` regression value by making the external lock helper's timed release use synchronous `Atomics.wait` inside the child process, removing event-loop timer scheduling as the load-only flake source without widening retry windows. `extension-task-tools.test.ts` kept its worktree-root task-tool coverage by closing each real `TaskStore` fixture before temp-root removal and using non-hoisted mock cleanup. The reusable pattern is to remove scheduler/resource leaks in the helper or fixture seam, then prove the rescue with repeated exact-file runs plus package lanes, not with timeout bumps, retries, assertion loosening, or worker changes.
+
 **Gate eviction:** a flake inside the merge gate cannot block all merges while red — it is evicted by removing its line from the `engine-core` allow-list (no quarantine entry needed unless it should also leave the non-blocking tier).
 
 **Gate admission:** the mirror operation — add the test's path to the `engine-core` `include` array in `packages/engine/vitest.config.ts`, citing the evidence of value (a real regression it caught) in the PR. Keep the project under its ~60s wall-clock budget.
diff --git a/packages/cli/src/__tests__/extension-task-tools.test.ts b/packages/cli/src/__tests__/extension-task-tools.test.ts
index 182b646381..e76b7a43ab 100644
--- a/packages/cli/src/__tests__/extension-task-tools.test.ts
+++ b/packages/cli/src/__tests__/extension-task-tools.test.ts
@@ -3,6 +3,9 @@ import { describe, expect, it, vi, beforeEach, afterEach } from "vitest";
 FNXC:CliTests 2026-06-14-01:25:
 FN-6430 requires rescued CLI suites to run on the default timeout after shared HOME isolation, not via the older file-wide 20s timeout.
 Keep this worktree-root regression slice fast by relying on module resets and bounded temp fixtures.
+
+FNXC:CliTests 2026-06-15-07:44:
+FN-6486 rescues this load-only timeout by closing each real TaskStore before removing its temp root and by using non-hoisted mock cleanup. The suite keeps the worktree-root regression coverage without widening timeouts, adding retries, or changing package worker settings.
 */
 import { mkdtemp, mkdir, rm, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
@@ -30,7 +33,7 @@ describe("extension task tools resolve repo root from worktrees", () => {
 
   afterEach(() => {
     vi.restoreAllMocks();
-    vi.unmock("@fusion/core");
+    vi.doUnmock("@fusion/core");
   });
 
   it("exports getProjectRootFromWorktree from @fusion/core", () => {
@@ -40,10 +43,11 @@ describe("extension task tools resolve repo root from worktrees", () => {
   it("uses canonical project root for fn_task_show and fn_task_list from worktree cwd", async () => {
     const repoRoot = await mkdtemp(join(tmpdir(), "fn-4904-cli-"));
     const worktreeRoot = join(repoRoot, ".worktrees", "feature");
+    let store: TaskStore | undefined;
     try {
       await mkdir(join(repoRoot, ".fusion"), { recursive: true });
 
-      const store = new TaskStore(repoRoot);
+      store = new TaskStore(repoRoot);
       await store.init();
       const created = await store.createTask({ description: "Task from canonical root" });
 
@@ -74,6 +78,7 @@ describe("extension task tools resolve repo root from worktrees", () => {
       expect(show.content[0].text).toContain("Task from canonical root");
       expect(list.content[0].text).toContain(created.id);
     } finally {
+      store?.close();
       await rm(repoRoot, { recursive: true, force: true });
     }
   });
@@ -81,6 +86,7 @@ describe("extension task tools resolve repo root from worktrees", () => {
   it("uses canonical project root for task tools from AI merge temp linked worktrees", async () => {
     const repoRoot = await mkdtemp(join(tmpdir(), "fn-6079-cli-"));
     const mergeRoot = await mkdtemp(join(tmpdir(), "fusion-ai-merge-fn-6079-"));
+    let store: TaskStore | undefined;
     try {
       git(repoRoot, "init -q -b main");
       git(repoRoot, "config user.email test@example.com");
@@ -89,7 +95,7 @@ describe("extension task tools resolve repo root from worktrees", () => {
       git(repoRoot, "add -A");
       git(repoRoot, "commit -q -m base");
 
-      const store = new TaskStore(repoRoot);
+      store = new TaskStore(repoRoot);
       await store.init();
       const created = await store.createTask({ description: "Task visible from merge worktree" });
       git(repoRoot, `worktree add --detach ${JSON.stringify(mergeRoot)} HEAD`);
@@ -116,6 +122,7 @@ describe("extension task tools resolve repo root from worktrees", () => {
       expect(show.content[0].text).toContain("Task visible from merge worktree");
       expect(list.content[0].text).toContain(created.id);
     } finally {
+      store?.close();
       try {
         git(repoRoot, `worktree remove --force ${JSON.stringify(mergeRoot)}`);
       } catch {
@@ -129,10 +136,11 @@ describe("extension task tools resolve repo root from worktrees", () => {
   it("falls back when getProjectRootFromWorktree is unavailable in no-task context", async () => {
     const repoRoot = await mkdtemp(join(tmpdir(), "fn-4927-cli-"));
     const worktreeRoot = join(repoRoot, ".worktrees", "ambient");
+    let store: TaskStore | undefined;
     try {
       await mkdir(join(repoRoot, ".fusion"), { recursive: true });
 
-      const store = new TaskStore(repoRoot);
+      store = new TaskStore(repoRoot);
       await store.init();
       const created = await store.createTask({ description: "Ambient tool check" });
 
@@ -169,6 +177,7 @@ describe("extension task tools resolve repo root from worktrees", () => {
       expect(show.content[0]?.text).toContain(created.id);
       expect(warnSpy).toHaveBeenCalledTimes(1);
     } finally {
+      store?.close();
       await rm(repoRoot, { recursive: true, force: true });
     }
   });
diff --git a/packages/cli/vitest.config.ts b/packages/cli/vitest.config.ts
index 821685e4aa..76b9498c77 100644
--- a/packages/cli/vitest.config.ts
+++ b/packages/cli/vitest.config.ts
@@ -21,8 +21,10 @@ const quarantinedCliTests: string[] = [
   FNXC:CliTests 2026-06-15-04:07:
   FN-6483 observed extension-task-tools timing out only under the full @runfusion/fusion package lane while passing standalone immediately afterward.
   Quarantine the suite for the 14-day deletion ratchet instead of appeasing the load-sensitive timeout with wider test timeouts, retries, or worker changes.
+
+  FNXC:CliTests 2026-06-15-07:46:
+  FN-6486 rescued extension-task-tools by closing real TaskStore fixtures and replacing hoisted mock cleanup, then removed the quarantine in lockstep with scripts/lib/test-quarantine.json. Keep this array empty unless a future observed CLI flake is mirrored in the ledger in the same commit.
   */
-  "src/__tests__/extension-task-tools.test.ts",
 ];
 
 export default defineConfig({
diff --git a/packages/core/src/__tests__/store-concurrent-writes.test.ts b/packages/core/src/__tests__/store-concurrent-writes.test.ts
index bc61e13ea0..5a20eebb78 100644
--- a/packages/core/src/__tests__/store-concurrent-writes.test.ts
+++ b/packages/core/src/__tests__/store-concurrent-writes.test.ts
@@ -36,7 +36,13 @@ async function holdWriteLock(
       process.exit(0);
     };
     if (${JSON.stringify(releaseMode)} === "timer") {
-      setTimeout(release, ${holdMs});
+      /*
+      FNXC:CoreTests 2026-06-15-07:38:
+      FN-6486 rescues this WAL lock-recovery regression by removing the helper's event-loop timer dependency. Under package-lane load, a delayed setTimeout could keep the external writer lock past the recovery window and mimic a product failure; a synchronous child-process sleep preserves the transient lock invariant without widening test or SQLite retry timeouts.
+      */
+      const signal = new Int32Array(new SharedArrayBuffer(4));
+      Atomics.wait(signal, 0, 0, ${holdMs});
+      release();
     } else {
       process.stdin.setEncoding("utf8");
       process.stdin.on("data", (chunk) => {
diff --git a/packages/core/vitest.config.ts b/packages/core/vitest.config.ts
index 89784d741f..c6681f3e6e 100644
--- a/packages/core/vitest.config.ts
+++ b/packages/core/vitest.config.ts
@@ -14,8 +14,10 @@ const quarantinedCoreTests = [
 
   FNXC:CoreTests 2026-06-15-03:13:
   FN-6481 observed the disk-backed concurrent write test fail in the changed-package workspace lane with a transient SQLite BEGIN IMMEDIATE lock after the gate had already passed. Quarantine the flaky file instead of widening lock-recovery timeouts or weakening assertions.
+
+  FNXC:CoreTests 2026-06-15-07:39:
+  FN-6486 rescued store-concurrent-writes by making the transient lock helper release independent of event-loop timer scheduling, then removed the quarantine in lockstep with scripts/lib/test-quarantine.json. Keep this array empty unless a future observed flake is mirrored in the ledger in the same commit.
   */
-  "src/__tests__/store-concurrent-writes.test.ts",
 ];
 
 export default defineConfig({
diff --git a/scripts/lib/test-quarantine.json b/scripts/lib/test-quarantine.json
index b855367abc..39eac9c428 100644
--- a/scripts/lib/test-quarantine.json
+++ b/scripts/lib/test-quarantine.json
@@ -1,15 +1,4 @@
 {
   "$comment": "Flaky-test quarantine ledger (deletion ratchet — see AGENTS.md 'Flaky tests: quarantine on sight' and docs/testing.md 'Quarantine ledger and the deletion ratchet'). A test observed failing without a corresponding real bug is quarantined ON SIGHT: add an entry here AND a matching one-line `exclude` entry in that package's vitest config, in the same commit. Every entry needs a non-empty `reason` (link the failing run) and a `quarantinedAt` date — the entry expires 14 days later, at which point the test file is DELETED unless someone rescues it with evidence it catches real regressions plus a root-cause fix (never appeasement). There is deliberately no loader module and no automation around this file: it is a dated record, the vitest config exclude is the mechanism, and the sweep is policy executed by whoever touches the suite.",
-  "entries": [
-    {
-      "file": "packages/core/src/__tests__/store-concurrent-writes.test.ts",
-      "reason": "FN-6481 pnpm test 2026-06-15 failed unrelated core SQLite lock recovery concurrency test with `SQLite BEGIN IMMEDIATE failed after 7 attempts: database is locked`; quarantine on sight per flaky-test policy.",
-      "quarantinedAt": "2026-06-15"
-    },
-    {
-      "file": "packages/cli/src/__tests__/extension-task-tools.test.ts",
-      "reason": "FN-6483: @runfusion/fusion package lane under load timed out after 5000ms in uses canonical project root for fn_task_show and fn_task_list from worktree cwd during the 2026-06-15 verification rerun, matching the FN-6482 reported load-only CLI timeout signature. The same file passed standalone immediately afterward (4 tests passed in 5.90s), so quarantine per the deletion ratchet rather than widening timeouts or changing worker knobs.",
-      "quarantinedAt": "2026-06-15"
-    }
-  ]
+  "entries": []
 }