test(FN-4761): complete Step 5 — add review transition regression coverage

Fusion-Task-Id: FN-4761
Fusion-Task-Lineage: b6b1ed73-c396-4dd2-b97f-366272d05c7f

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

@@ -0,0 +1,53 @@
+// @vitest-environment node
+
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { mkdtempSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { TaskStore } from "@fusion/core";
+
+describe("PR changes-requested fallback behavior", () => {
+  let rootDir: string;
+  let globalDir: string;
+  let store: TaskStore;
+
+  beforeEach(async () => {
+    rootDir = mkdtempSync(join(tmpdir(), "fn-4761-engine-root-"));
+    globalDir = mkdtempSync(join(tmpdir(), "fn-4761-engine-global-"));
+    store = new TaskStore(rootDir, globalDir, { inMemoryDb: true });
+    await store.init();
+  });
+
+  afterEach(() => {
+    store.stopWatching();
+    store.close();
+    rmSync(rootDir, { recursive: true, force: true });
+    rmSync(globalDir, { recursive: true, force: true });
+  });
+
+  it("keeps progress and persists review feedback when moving in-review tasks back to todo", async () => {
+    const created = await store.createTask({ description: "Test task" });
+    await store.moveTask(created.id, "todo");
+    await store.moveTask(created.id, "in-progress");
+    await store.moveTask(created.id, "in-review");
+
+    await store.upsertTaskDocument(created.id, {
+      key: "review-feedback",
+      content: "**Reviewer feedback for next run:**\n\n- Please fix failing tests",
+      author: "github-review",
+    });
+
+    await store.moveTask(created.id, "todo", {
+      preserveProgress: true,
+      preserveWorktree: true,
+      moveSource: "engine",
+    });
+
+    const updated = await store.getTask(created.id);
+    expect(updated?.column).toBe("todo");
+
+    const feedbackDoc = await store.getTaskDocument(created.id, "review-feedback");
+    expect(feedbackDoc?.content).toContain("Reviewer feedback for next run");
+    expect(feedbackDoc?.content).toContain("Please fix failing tests");
+  });
+});