test(FN-4992): add changes-requested reliability interaction coverage

Fusion-Task-Id: FN-4992
Fusion-Task-Lineage: 133d5e6a-0612-4f67-9105-3b7dbabd5ec0

packages/engine/src/__tests__/reliability-interactions/pr-changes-requested-reexecution.test.ts

@@ -0,0 +1,131 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { EventEmitter } from "node:events";
+import type { Settings, Task, TaskStore } from "@fusion/core";
+import * as worktreePool from "../../worktree-pool.js";
+import { activeSessionRegistry } from "../../active-session-registry.js";
+import { PrCommentHandler } from "../../pr-comment-handler.js";
+
+function task(overrides: Partial<Task> = {}): Task {
+  return {
+    id: "FN-4992",
+    title: "t",
+    description: "d",
+    column: "in-review",
+    branch: "fusion/fn-4992",
+    worktree: "/tmp/test/.worktrees/fn-4992",
+    paused: false,
+    userPaused: false,
+    dependencies: [],
+    steps: [],
+    currentStep: 0,
+    log: [],
+    createdAt: new Date().toISOString(),
+    updatedAt: new Date().toISOString(),
+    ...overrides,
+  } as Task;
+}
+
+function store(t: Task): TaskStore & EventEmitter {
+  const emitter = new EventEmitter();
+  const settings = { globalPause: false, enginePaused: false } as Settings;
+  return Object.assign(emitter, {
+    getSettings: vi.fn(async () => settings),
+    getTask: vi.fn(async (id: string) => (id === t.id ? t : null)),
+    updateTask: vi.fn(async (_id: string, updates: Partial<Task>) => Object.assign(t, updates)),
+    addTaskComment: vi.fn(async () => undefined),
+    moveTask: vi.fn(async (_id: string, column: Task["column"]) => {
+      t.column = column;
+      return t;
+    }),
+    logEntry: vi.fn(async () => undefined),
+  }) as unknown as TaskStore & EventEmitter;
+}
+
+describe("reliability interaction (FN-4766): PR changes-requested re-execution", () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+    activeSessionRegistry.clear();
+    vi.spyOn(worktreePool, "isUsableTaskWorktree").mockResolvedValue(true);
+  });
+
+  it.each([
+    { column: "in-review" as const, shouldMove: true },
+    { column: "in-progress" as const, shouldMove: false },
+  ])("enforces in-review precondition for re-execution move: $column", async ({ column, shouldMove }) => {
+    const t = task({ column });
+    const s = store(t);
+    const handler = new PrCommentHandler(s as any);
+
+    await handler.handleChangesRequested(
+      t.id,
+      { url: "https://github.com/o/r/pull/1", number: 1, status: "open", title: "pr", headBranch: "h", baseBranch: "main", commentCount: 0 },
+      "reviewer",
+      "please fix X",
+    );
+
+    expect((s as any).moveTask).toHaveBeenCalledTimes(shouldMove ? 1 : 0);
+    expect((s as any).logEntry).toHaveBeenCalledTimes(shouldMove ? 1 : 0);
+  });
+
+  it("preserves task branch/worktree metadata and paused state while moving engine-sourced to in-progress", async () => {
+    const t = task({ column: "in-review", paused: true });
+    const s = store(t);
+    const handler = new PrCommentHandler(s as any);
+
+    await handler.handleChangesRequested(
+      t.id,
+      { url: "https://github.com/o/r/pull/2", number: 2, status: "open", title: "pr", headBranch: "h", baseBranch: "main", commentCount: 0 },
+      "reviewer",
+      "please fix Y",
+    );
+
+    expect((s as any).moveTask).toHaveBeenCalledWith(t.id, "in-progress");
+    expect((s as any).moveTask.mock.calls[0].length).toBe(2);
+    expect(t.branch).toBe("fusion/fn-4992");
+    expect(t.worktree).toBe("/tmp/test/.worktrees/fn-4992");
+    expect(t.paused).toBe(true);
+  });
+
+  it("materializes feedback in ordered write sequence comment -> review item -> move -> log", async () => {
+    const t = task();
+    const s = store(t);
+    const handler = new PrCommentHandler(s as any);
+
+    await handler.handleChangesRequested(
+      t.id,
+      { url: "https://github.com/o/r/pull/3", number: 3, status: "open", title: "pr", headBranch: "h", baseBranch: "main", commentCount: 0 },
+      "reviewer",
+      "please fix Z",
+    );
+
+    expect((s as any).addTaskComment).toHaveBeenCalledTimes(1);
+    expect((s as any).updateTask).toHaveBeenCalledTimes(1);
+    expect((s as any).moveTask).toHaveBeenCalledTimes(1);
+    expect((s as any).logEntry).toHaveBeenCalledTimes(1);
+
+    const commentOrder = (s as any).addTaskComment.mock.invocationCallOrder[0];
+    const reviewOrder = (s as any).updateTask.mock.invocationCallOrder[0];
+    const moveOrder = (s as any).moveTask.mock.invocationCallOrder[0];
+    const logOrder = (s as any).logEntry.mock.invocationCallOrder[0];
+
+    expect(commentOrder).toBeLessThan(reviewOrder);
+    expect(reviewOrder).toBeLessThan(moveOrder);
+    expect(moveOrder).toBeLessThan(logOrder);
+  });
+
+  it("swallows moveTask failures as best-effort", async () => {
+    const t = task();
+    const s = store(t);
+    (s as any).moveTask = vi.fn().mockRejectedValueOnce(new Error("boom"));
+    const handler = new PrCommentHandler(s as any);
+
+    await expect(
+      handler.handleChangesRequested(
+        t.id,
+        { url: "https://github.com/o/r/pull/4", number: 4, status: "open", title: "pr", headBranch: "h", baseBranch: "main", commentCount: 0 },
+        "reviewer",
+        "please fix boom",
+      ),
+    ).resolves.toBeUndefined();
+  });
+});