perf: reduce memory startup overhead

test/helpers/memory-tool-manager-mock.ts

@@ -33,8 +33,17 @@ const stubManager = {
   close: vi.fn(),
 };
 
+const getMemorySearchManagerMock = vi.fn(async () => ({ manager: stubManager }));
+const readAgentMemoryFileMock = vi.fn(
+  async (params: MemoryReadParams) => await readFileImpl(params),
+);
+
 vi.mock("../../src/memory/index.js", () => ({
-  getMemorySearchManager: async () => ({ manager: stubManager }),
+  getMemorySearchManager: getMemorySearchManagerMock,
+}));
+
+vi.mock("../../src/memory/read-file.js", () => ({
+  readAgentMemoryFile: readAgentMemoryFileMock,
 }));
 
 export function setMemoryBackend(next: MemoryBackend): void {
@@ -63,3 +72,11 @@ export function resetMemoryToolMockState(overrides?: {
     (async (params: MemoryReadParams) => ({ text: "", path: params.relPath }));
   vi.clearAllMocks();
 }
+
+export function getMemorySearchManagerMockCalls(): number {
+  return getMemorySearchManagerMock.mock.calls.length;
+}
+
+export function getReadAgentMemoryFileMockCalls(): number {
+  return readAgentMemoryFileMock.mock.calls.length;
+}