FN-6626: close cached CLI extension task stores

Close cached TaskStore handles so CLI extension task-tool tests shut down cleanly.\n\n- Add deterministic cached-store shutdown for the CLI extension and invoke it from extension teardown.\n- Expose the shutdown helper for tests and call it after canonical-project-root task-tool cases.\n- Add a patch changeset for the published @runfusion/fusion package.\n\nFiles changed:\n .changeset/fn-6626-close-cached-stores.md             |  5 +++++\n .../cli/src/__tests__/extension-task-tools.test.ts    |  8 ++++++++\n packages/cli/src/extension.ts                         | 19 ++++++++++++++++++-\n 3 files changed, 31 insertions(+), 1 deletion(-)

Fusion-Task-Id: FN-6626

Fusion-Task-Lineage: 65791502-8992-4037-8ca0-fe21c8283506

.changeset/fn-6626-close-cached-stores.md

@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": patch
+---
+
+Close cached CLI extension TaskStore instances on session shutdown so task-tool runs do not leave SQLite handles behind.

packages/cli/src/__tests__/extension-task-tools.test.ts

@@ -6,6 +6,9 @@ Keep this worktree-root regression slice fast by relying on module resets and bo
 
 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.
+
+FNXC:CliTests 2026-06-17-23:58:
+FN-6626 requires these canonical-project-root tool tests to close the extension module's cached TaskStore instances after every case, because fixture-store cleanup alone does not close the second store opened by fn_task_show/fn_task_list.
 */
 import { mkdtemp, mkdir, rm, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
@@ -17,8 +20,11 @@ function makeCtx(cwd: string) {
   return { cwd } as any;
 }
 
+let closeLoadedExtensionStores: (() => void) | undefined;
+
 async function loadExtension() {
   const mod = await import("../extension.js");
+  closeLoadedExtensionStores = mod.closeCachedStores;
   return mod.default;
 }
 
@@ -32,6 +38,8 @@ describe("extension task tools resolve repo root from worktrees", () => {
   });
 
   afterEach(() => {
+    closeLoadedExtensionStores?.();
+    closeLoadedExtensionStores = undefined;
     vi.restoreAllMocks();
     vi.doUnmock("@fusion/core");
   });

packages/cli/src/extension.ts

@@ -152,6 +152,23 @@ async function getStore(cwd: string): Promise<TaskStore> {
   return store;
 }
 
+/** @internal Exposed so tests and the extension shutdown hook can close cached stores deterministically; not a public CLI API contract. */
+export function closeCachedStores(): void {
+  /*
+  FNXC:CliTests 2026-06-17-23:58:
+  FN-6626 found the CLI extension cache cleared real TaskStore instances without closing them, leaving SQLite/WAL handles to survive module resets and making canonical-project-root task-tool tests timeout under suite load.
+  Close every cached store deterministically on extension shutdown and in tests; do not appease the load-sensitive seam with timeouts, retries, or worker changes.
+  */
+  for (const store of storeCache.values()) {
+    try {
+      store.close();
+    } catch (error) {
+      console.warn("[fusion-extension] cached TaskStore close skipped", error);
+    }
+  }
+  storeCache.clear();
+}
+
 function getFusionDir(cwd: string): string {
   return join(resolveProjectRoot(cwd), ".fusion");
 }
@@ -4572,6 +4589,6 @@ export default function kbExtension(pi: ExtensionAPI) {
       dashboardProcess = null;
       dashboardPort = null;
     }
-    storeCache.clear();
+    closeCachedStores();
   });
 }