test(FN-4092): complete Step 1 — reproduce unavailable stall baseline

Fusion-Task-Id: FN-4092
Fusion-Task-Lineage: fcee3a44-5c36-4899-bf9d-835d36abdf2e

packages/engine/src/__tests__/plan-review-unavailable-recovery.test.ts

@@ -0,0 +1,69 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("../pi.js", () => ({
+  describeModel: vi.fn().mockReturnValue("mock-provider/mock-model"),
+  promptWithFallback: vi.fn(async (session: any, prompt: string, options?: any) => {
+    if (options == null) await session.prompt(prompt);
+    else await session.prompt(prompt, options);
+  }),
+}));
+
+vi.mock("../agent-session-helpers.js", () => ({
+  createResolvedAgentSession: vi.fn(),
+  extractRuntimeHint: vi.fn().mockReturnValue(undefined),
+}));
+
+import { reviewStep } from "../reviewer.js";
+import { createResolvedAgentSession } from "../agent-session-helpers.js";
+
+const mockedCreateResolvedAgentSession = vi.mocked(createResolvedAgentSession);
+
+function buildSession(reviewText: string) {
+  return {
+    session: {
+      prompt: vi.fn().mockResolvedValue(undefined),
+      subscribe: vi.fn().mockImplementation((cb: any) => {
+        cb({
+          type: "message_update",
+          assistantMessageEvent: { type: "text_delta", delta: reviewText },
+        });
+      }),
+      dispose: vi.fn(),
+    },
+  } as any;
+}
+
+describe("FN-4068 baseline — plan review UNAVAILABLE", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("returns UNAVAILABLE without recovery log when verdict is not parseable", async () => {
+    mockedCreateResolvedAgentSession.mockResolvedValue(buildSession("Reviewer output without verdict heading."));
+
+    const store = {
+      getSettings: vi.fn().mockResolvedValue({}),
+      logEntry: vi.fn().mockResolvedValue(undefined),
+      appendAgentLog: vi.fn().mockResolvedValue(undefined),
+    } as any;
+
+    const result = await reviewStep(
+      "/tmp/worktree",
+      "FN-4092",
+      2,
+      "Reproduce stall",
+      "plan",
+      "# prompt",
+      undefined,
+      { store, taskId: "FN-4092" },
+    );
+
+    expect(result.verdict).toBe("UNAVAILABLE");
+    expect(result.review).toContain("without verdict");
+    expect(mockedCreateResolvedAgentSession).toHaveBeenCalledTimes(1);
+    expect(store.logEntry).not.toHaveBeenCalledWith(
+      "FN-4092",
+      expect.stringContaining("retry with fallback model"),
+    );
+  });
+});