FN-6447: rescue session reconnect teardown

Rescue the session reconnect SSE test by shutting down route-owned background work before temp cleanup.

- Isolate the focused API harness from TaskStore EventEmitter startup workers.
- Dispose API routes and scheduled AI session cleanup before deleting the test temp root.
- Remove session-reconnect from the dashboard quarantine ledger and vitest skip list.

Files changed:
 .../src/__tests__/session-reconnect.test.ts        | 22 ++++++++++++++++++----
 packages/dashboard/vitest.config.ts                |  6 ++++--
 scripts/lib/test-quarantine.json                   |  5 -----
 3 files changed, 22 insertions(+), 11 deletions(-)

Fusion-Task-Id: FN-6447

Fusion-Task-Lineage: a3fef28c-b92b-4f47-9181-a63bb31e4f48

packages/dashboard/src/__tests__/session-reconnect.test.ts

@@ -9,7 +9,6 @@ import express from "express";
 import { mkdtempSync } from "node:fs";
 import { rm } from "node:fs/promises";
 import { tmpdir } from "node:os";
-import { setImmediate } from "node:timers";
 import { join } from "node:path";
 import { beforeEach, afterEach, describe, expect, it, vi } from "vitest";
 import { Database, TaskStore } from "@fusion/core";
@@ -105,6 +104,7 @@ describe("session reconnect + replay", () => {
   let db: Database;
   let aiSessionStore: AiSessionStore;
   let app: express.Express;
+  let apiRouter: express.Router & { dispose?: () => void };
 
   beforeEach(async () => {
     vi.clearAllMocks();
@@ -129,7 +129,16 @@ describe("session reconnect + replay", () => {
 
     app = express();
     app.use(express.json());
-    app.use("/api", createApiRoutes(store, { aiSessionStore }));
+    /*
+    FNXC:DashboardSessionTests 2026-06-14-12:05:
+    These SSE replay tests exercise planning/subtask/mission routes, not the EventEmitter-driven GitHub tracking services that createApiRoutes starts for a full TaskStore. Hide on/off for this focused harness so unrelated startup reconcile work cannot touch the temp .fusion tree after the test-owned store closes.
+    */
+    Object.defineProperties(store, {
+      on: { value: undefined, configurable: true },
+      off: { value: undefined, configurable: true },
+    });
+    apiRouter = createApiRoutes(store, { aiSessionStore }) as express.Router & { dispose?: () => void };
+    app.use("/api", apiRouter);
   });
 
   afterEach(async () => {
@@ -138,6 +147,12 @@ describe("session reconnect + replay", () => {
     __resetSubtaskBreakdownState();
     __resetMissionInterviewState();
 
+    try {
+      apiRouter.dispose?.();
+    } catch {
+      // no-op
+    }
+    aiSessionStore.stopScheduledCleanup();
     try {
       store.close();
     } catch {
@@ -148,8 +163,7 @@ describe("session reconnect + replay", () => {
     } catch {
       // no-op
     }
-    // FNXC:DashboardSessionTests 2026-06-14-09:20: TaskStore.close() closes watcher/database handles synchronously but their filesystem close callbacks settle on the next event-loop turn; drain that turn before deleting .fusion.
-    await new Promise<void>((resolve) => setImmediate(resolve));
+    // FNXC:DashboardSessionTests 2026-06-14-12:07: FN-6447 requires teardown to remove tmpRoot only after route-owned background workers are prevented/disposed and both TaskStore/AiSession DB handles are closed; do not use retry-rm loops that can mask a live writer.
     await rm(tmpRoot, { recursive: true, force: true });
   });
 

packages/dashboard/vitest.config.ts

@@ -246,7 +246,10 @@ const quarantinedDashboardTests: string[] = [
   FN-6441 removed the dashboard component orphan batch from the curated skip-list so passing rescues run in backfill and still-failing tests are excluded only through the dated quarantine ledger. Keep these one-line excludes mirrored with scripts/lib/test-quarantine.json until each file is rescued or deleted under the deletion ratchet.
 
   FNXC:DashboardTests 2026-06-14-09:58:
-  FN-6444 applies the same no-silent-orphan invariant to dashboard src route/API tests: rescued files run in backfill, while broad stale mission/planning suites plus the newly observed FN-6447 reconnect temp-cleanup flake are represented only by the dated quarantine ledger.
+  FN-6444 applies the same no-silent-orphan invariant to dashboard src route/API tests: rescued files run in backfill, while broad stale mission/planning suites are represented only by the dated quarantine ledger.
+
+  FNXC:DashboardSessionTests 2026-06-14-12:10:
+  FN-6447 rescued session-reconnect by isolating the SSE harness from unrelated route background workers, so it must stay out of this quarantine list and run in dashboard-api-quality-backfill.
   */
   "app/components/__tests__/ChatView.regular-composer-no-right-line.test.tsx",
   "app/components/__tests__/MissionManager.test.tsx",
@@ -261,7 +264,6 @@ const quarantinedDashboardTests: string[] = [
   "app/components/__tests__/mobile-css.test.tsx",
   "src/__tests__/mission-e2e.test.ts",
   "src/__tests__/planning.test.ts",
-  "src/__tests__/session-reconnect.test.ts",
 ];
 
 const qualityApiTests = [

scripts/lib/test-quarantine.json

@@ -65,11 +65,6 @@
       "file": "packages/dashboard/src/__tests__/planning.test.ts",
       "reason": "FN-6444: orphaned dashboard planning route/API test is slow and fails standalone across stale agent/session mocks plus temp cleanup leakage. Quarantined instead of widening waits/timeouts or weakening assertions.",
       "quarantinedAt": "2026-06-14"
-    },
-    {
-      "file": "packages/dashboard/src/__tests__/session-reconnect.test.ts",
-      "reason": "FN-6444/FN-6447: dashboard API backfill shard 1 observed ENOTEMPTY temp cleanup leakage while replaying planning buffered events. Quarantined on sight for focused rescue/delete review instead of adding waits or weakening assertions.",
-      "quarantinedAt": "2026-06-14"
     }
   ]
 }