feat(FN-4962): complete Step 4 — dashboard fallback and reliability coverage

Fusion-Task-Id: FN-4962
Fusion-Task-Lineage: de4ce54b-c5e4-40f9-a048-677adac3e1a0

packages/engine/src/__tests__/reliability-interactions/worktree-metadata-reconcile.test.ts

@@ -0,0 +1,84 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { EventEmitter } from "node:events";
+import type { Task, TaskStore } from "@fusion/core";
+import { SelfHealingManager } from "../../self-healing.js";
+import * as worktreePoolModule from "../../worktree-pool.js";
+
+function task(id: string, overrides: Partial<Task> = {}): Task {
+  return {
+    id,
+    title: id,
+    description: id,
+    column: "todo",
+    dependencies: [],
+    steps: [],
+    currentStep: 0,
+    log: [],
+    createdAt: new Date().toISOString(),
+    updatedAt: new Date().toISOString(),
+    ...overrides,
+  } as Task;
+}
+
+function makeStore(tasks: Task[]): TaskStore & EventEmitter {
+  const map = new Map(tasks.map((t) => [t.id, t]));
+  return Object.assign(new EventEmitter(), {
+    getSettings: vi.fn(async () => ({ globalPause: false, enginePaused: false })),
+    listTasks: vi.fn(async () => [...map.values()]),
+    updateTask: vi.fn(async (id: string, patch: Partial<Task>) => {
+      map.set(id, { ...(map.get(id) as Task), ...patch });
+      return map.get(id);
+    }),
+    getTask: vi.fn(async (id: string) => map.get(id)),
+    recordRunAuditEvent: vi.fn(async () => undefined),
+    moveTask: vi.fn(async () => undefined),
+    logEntry: vi.fn(async () => undefined),
+  }) as unknown as TaskStore & EventEmitter;
+}
+
+describe("reliability interactions: worktree metadata reconcile", () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it("defers while task is in executingTaskIds (recoverOrphaned/resume interaction)", async () => {
+    const store = makeStore([task("FN-1", { column: "in-review", worktree: "/missing", branch: null })]);
+    vi.spyOn(worktreePoolModule, "getRegisteredWorktreeBranchMap").mockResolvedValue(new Map([["fusion/fn-1", "/live"]]));
+
+    const manager = new SelfHealingManager(store, {
+      rootDir: "/repo",
+      getExecutingTaskIds: () => new Set(["FN-1"]),
+    });
+
+    const repaired = await manager.reconcileTaskWorktreeMetadata();
+    expect(repaired).toBe(0);
+    expect((store as any).updateTask).not.toHaveBeenCalled();
+  });
+
+  it("rebinds exactly once after deferred pass (acquireTaskWorktree interaction)", async () => {
+    const store = makeStore([task("FN-2", { column: "todo", worktree: "/missing", branch: null })]);
+    vi.spyOn(worktreePoolModule, "getRegisteredWorktreeBranchMap").mockResolvedValue(new Map([["fusion/fn-2", "/live"]]));
+
+    let executing = true;
+    const manager = new SelfHealingManager(store, {
+      rootDir: "/repo",
+      getExecutingTaskIds: () => (executing ? new Set(["FN-2"]) : new Set<string>()),
+    });
+
+    expect(await manager.reconcileTaskWorktreeMetadata()).toBe(0);
+    executing = false;
+    expect(await manager.reconcileTaskWorktreeMetadata()).toBe(1);
+    expect((store as any).updateTask).toHaveBeenCalledTimes(1);
+  });
+
+  it("skips done tasks during periodic reconcile (completion fan-out owns done lifecycle)", async () => {
+    const store = makeStore([task("FN-3", { column: "done", worktree: "/missing", branch: null })]);
+    vi.spyOn(worktreePoolModule, "getRegisteredWorktreeBranchMap").mockResolvedValue(new Map([["fusion/fn-3", "/live"]]));
+
+    const manager = new SelfHealingManager(store, { rootDir: "/repo" });
+    const repaired = await manager.reconcileTaskWorktreeMetadata();
+
+    expect(repaired).toBe(0);
+    expect((store as any).updateTask).not.toHaveBeenCalled();
+  });
+});