fix: prevent node:fs mock pollution in directory injector tests

Move mock.module() calls from top-level to beforeEach and restore in
afterEach to prevent readFileSync mock from leaking into other test
files. Use dynamic import with cache-busting query to get fresh modules.

src/hooks/directory-agents-injector/injector.test.ts

@@ -1,12 +1,39 @@
-import { beforeEach, describe, expect, it, mock } from "bun:test"
+import { beforeEach, afterEach, describe, expect, it, mock, afterAll } from "bun:test"
 
-const readFileSyncMock = mock((_: string, __: string) => "# AGENTS")
+const realNodeFs = await import("node:fs")
+const realFinder = await import("./finder")
+const realStorage = await import("./storage")
+
+const originalReadFileSync = realNodeFs.readFileSync
+const readFileSyncMock = mock((filePath: string, encoding?: string) => {
+  if (String(filePath).endsWith("AGENTS.md")) {
+    return "# AGENTS"
+  }
+  return originalReadFileSync(filePath as never, encoding as never)
+})
 const findAgentsMdUpMock = mock((_: { startDir: string; rootDir: string }) => [] as string[])
 const resolveFilePathMock = mock((_: string, path: string) => path)
 const loadInjectedPathsMock = mock((_: string) => new Set<string>())
 const saveInjectedPathsMock = mock((_: string, __: Set<string>) => {})
 
+afterAll(() => {
+  mock.module("node:fs", () => ({ ...realNodeFs }))
+  mock.module("./finder", () => ({ ...realFinder }))
+  mock.module("./storage", () => ({ ...realStorage }))
+})
+
+let processFilePathForAgentsInjection: typeof import("./injector").processFilePathForAgentsInjection
+
+describe("processFilePathForAgentsInjection", () => {
+  beforeEach(async () => {
+    readFileSyncMock.mockClear()
+    findAgentsMdUpMock.mockClear()
+    resolveFilePathMock.mockClear()
+    loadInjectedPathsMock.mockClear()
+    saveInjectedPathsMock.mockClear()
+
     mock.module("node:fs", () => ({
+      ...realNodeFs,
       readFileSync: readFileSyncMock,
     }))
 
@@ -20,15 +47,13 @@ mock.module("./storage", () => ({
       saveInjectedPaths: saveInjectedPathsMock,
     }))
 
-const { processFilePathForAgentsInjection } = await import("./injector")
+    ;({ processFilePathForAgentsInjection } = await import(`./injector?${Date.now()}`))
+  })
 
-describe("processFilePathForAgentsInjection", () => {
+  afterEach(() => {
-  beforeEach(() => {
+    mock.module("node:fs", () => ({ ...realNodeFs }))
-    readFileSyncMock.mockClear()
+    mock.module("./finder", () => ({ ...realFinder }))
-    findAgentsMdUpMock.mockClear()
+    mock.module("./storage", () => ({ ...realStorage }))
-    resolveFilePathMock.mockClear()
-    loadInjectedPathsMock.mockClear()
-    saveInjectedPathsMock.mockClear()
   })
 
   it("does not save when all discovered paths are already cached", async () => {

src/hooks/directory-readme-injector/injector.test.ts

@@ -1,12 +1,39 @@
-import { beforeEach, describe, expect, it, mock } from "bun:test"
+import { beforeEach, afterEach, describe, expect, it, mock, afterAll } from "bun:test"
 
-const readFileSyncMock = mock((_: string, __: string) => "# README")
+const realNodeFs = await import("node:fs")
+const realFinder = await import("./finder")
+const realStorage = await import("./storage")
+
+const originalReadFileSync = realNodeFs.readFileSync
+const readFileSyncMock = mock((filePath: string, encoding?: string) => {
+  if (String(filePath).endsWith("README.md")) {
+    return "# README"
+  }
+  return originalReadFileSync(filePath as never, encoding as never)
+})
 const findReadmeMdUpMock = mock((_: { startDir: string; rootDir: string }) => [] as string[])
 const resolveFilePathMock = mock((_: string, path: string) => path)
 const loadInjectedPathsMock = mock((_: string) => new Set<string>())
 const saveInjectedPathsMock = mock((_: string, __: Set<string>) => {})
 
+afterAll(() => {
+  mock.module("node:fs", () => ({ ...realNodeFs }))
+  mock.module("./finder", () => ({ ...realFinder }))
+  mock.module("./storage", () => ({ ...realStorage }))
+})
+
+let processFilePathForReadmeInjection: typeof import("./injector").processFilePathForReadmeInjection
+
+describe("processFilePathForReadmeInjection", () => {
+  beforeEach(async () => {
+    readFileSyncMock.mockClear()
+    findReadmeMdUpMock.mockClear()
+    resolveFilePathMock.mockClear()
+    loadInjectedPathsMock.mockClear()
+    saveInjectedPathsMock.mockClear()
+
     mock.module("node:fs", () => ({
+      ...realNodeFs,
       readFileSync: readFileSyncMock,
     }))
 
@@ -20,15 +47,13 @@ mock.module("./storage", () => ({
       saveInjectedPaths: saveInjectedPathsMock,
     }))
 
-const { processFilePathForReadmeInjection } = await import("./injector")
+    ;({ processFilePathForReadmeInjection } = await import(`./injector?${Date.now()}`))
+  })
 
-describe("processFilePathForReadmeInjection", () => {
+  afterEach(() => {
-  beforeEach(() => {
+    mock.module("node:fs", () => ({ ...realNodeFs }))
-    readFileSyncMock.mockClear()
+    mock.module("./finder", () => ({ ...realFinder }))
-    findReadmeMdUpMock.mockClear()
+    mock.module("./storage", () => ({ ...realStorage }))
-    resolveFilePathMock.mockClear()
-    loadInjectedPathsMock.mockClear()
-    saveInjectedPathsMock.mockClear()
   })
 
   it("does not save when all discovered paths are already cached", async () => {