diff --git a/packages/engine/src/__tests__/executor-test-helpers.ts b/packages/engine/src/__tests__/executor-test-helpers.ts
index 347c55998..dc7cb96fa 100644
--- a/packages/engine/src/__tests__/executor-test-helpers.ts
+++ b/packages/engine/src/__tests__/executor-test-helpers.ts
@@ -106,6 +106,13 @@ vi.mock("../worktree-names.js", async () => {
     generateWorktreeName: vi.fn().mockReturnValue("swift-falcon"),
   };
 });
+vi.mock("../worktree-pool.js", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("../worktree-pool.js")>();
+  return {
+    ...actual,
+    isUsableTaskWorktree: vi.fn().mockResolvedValue(true),
+  };
+});
 
 vi.mock("node:child_process", async () => {
   const { promisify } = await import("node:util");
@@ -230,6 +237,7 @@ import { withRateLimitRetry } from "../rate-limit-retry.js";
 import { execSync } from "node:child_process";
 import { existsSync, realpathSync } from "node:fs";
 import { hydrateWorktreeDb } from "../worktree-db-hydrate.js";
+import { isUsableTaskWorktree } from "../worktree-pool.js";
 
 export const mockedCreateFnAgent = vi.mocked(createFnAgent);
 export const mockedSessionManager = vi.mocked(SessionManager);
@@ -241,6 +249,7 @@ export const mockedExecSync = vi.mocked(execSync);
 export const mockedExistsSync = vi.mocked(existsSync);
 export const mockedRealpathSync = vi.mocked(realpathSync);
 export const mockedHydrateWorktreeDb = vi.mocked(hydrateWorktreeDb);
+export const mockedIsUsableTaskWorktree = vi.mocked(isUsableTaskWorktree);
 
 export type EventListener = (...args: unknown[]) => void;