refactor(tests): rewrite 5 over-mocked test files to test real behavior

- formatter.test.ts: use dynamic imports with cache-busting to avoid mock pollution from runner.test.ts; test real format output instead of dispatch mocking
- hook.test.ts: rewrite with proper branch coverage (7 tests), add success/guard/subagent paths
- background-update-check.test.ts: rewrite with 10 tests covering all branches (early returns, pinned versions, auto-update success/failure)
- directory-agents-injector/injector.test.ts: replace finder/storage mocks with real filesystem + temp directories, verify actual AGENTS.md injection content
- directory-readme-injector/injector.test.ts: same pattern as agents-injector but for README.md, verifies root inclusion behavior

src/hooks/auto-update-checker/hook.test.ts

@@ -1,4 +1,4 @@
-import { afterEach, describe, it, expect, mock } from "bun:test"
+import { afterEach, beforeEach, describe, expect, it, mock } from "bun:test"
 
 const mockShowConfigErrorsIfAny = mock(async () => {})
 const mockShowModelCacheWarningIfNeeded = mock(async () => {})
@@ -7,7 +7,7 @@ const mockShowLocalDevToast = mock(async () => {})
 const mockShowVersionToast = mock(async () => {})
 const mockRunBackgroundUpdateCheck = mock(async () => {})
 const mockGetCachedVersion = mock(() => "3.6.0")
-const mockGetLocalDevVersion = mock(() => "3.6.0")
+const mockGetLocalDevVersion = mock<(directory: string) => string | null>(() => null)
 
 mock.module("./hook/config-errors-toast", () => ({
   showConfigErrorsIfAny: mockShowConfigErrorsIfAny,
@@ -40,31 +40,49 @@ mock.module("../../shared/logger", () => ({
   log: () => {},
 }))
 
-const { createAutoUpdateCheckerHook } = await import("./hook")
+type HookFactory = typeof import("./hook").createAutoUpdateCheckerHook
+
+async function importFreshHookFactory(): Promise<HookFactory> {
+  const hookModule = await import(`./hook?test-${Date.now()}-${Math.random()}`)
+  return hookModule.createAutoUpdateCheckerHook
+}
+
+function createPluginInput() {
+  return {
+    directory: "/test",
+    client: {} as never,
+  } as never
+}
+
+beforeEach(() => {
+  mockShowConfigErrorsIfAny.mockClear()
+  mockShowModelCacheWarningIfNeeded.mockClear()
+  mockUpdateAndShowConnectedProvidersCacheStatus.mockClear()
+  mockShowLocalDevToast.mockClear()
+  mockShowVersionToast.mockClear()
+  mockRunBackgroundUpdateCheck.mockClear()
+  mockGetCachedVersion.mockClear()
+  mockGetLocalDevVersion.mockClear()
+
+  mockGetCachedVersion.mockReturnValue("3.6.0")
+  mockGetLocalDevVersion.mockReturnValue(null)
+})
 
 afterEach(() => {
   delete process.env.OPENCODE_CLI_RUN_MODE
-  mock.restore()
 })
 
 describe("createAutoUpdateCheckerHook", () => {
   it("skips startup toasts and checks in CLI run mode", async () => {
     //#given - CLI run mode enabled
     process.env.OPENCODE_CLI_RUN_MODE = "true"
-    mockShowConfigErrorsIfAny.mockClear()
-    mockShowModelCacheWarningIfNeeded.mockClear()
-    mockUpdateAndShowConnectedProvidersCacheStatus.mockClear()
-    mockShowLocalDevToast.mockClear()
-    mockShowVersionToast.mockClear()
-    mockRunBackgroundUpdateCheck.mockClear()
+    const createAutoUpdateCheckerHook = await importFreshHookFactory()
 
-    const hook = createAutoUpdateCheckerHook(
-      {
-        directory: "/test",
-        client: {} as never,
-      } as never,
-      { showStartupToast: true, isSisyphusEnabled: true, autoUpdate: true }
-    )
+    const hook = createAutoUpdateCheckerHook(createPluginInput(), {
+      showStartupToast: true,
+      isSisyphusEnabled: true,
+      autoUpdate: true,
+    })
 
     //#when - session.created event arrives
     hook.event({
@@ -73,7 +91,7 @@ describe("createAutoUpdateCheckerHook", () => {
         properties: { info: { parentID: undefined } },
       },
     })
-    await new Promise((resolve) => setTimeout(resolve, 25))
+    await new Promise((resolve) => setTimeout(resolve, 50))
 
     //#then - no update checker side effects run
     expect(mockShowConfigErrorsIfAny).not.toHaveBeenCalled()
@@ -82,6 +100,144 @@ describe("createAutoUpdateCheckerHook", () => {
     expect(mockShowLocalDevToast).not.toHaveBeenCalled()
     expect(mockShowVersionToast).not.toHaveBeenCalled()
     expect(mockRunBackgroundUpdateCheck).not.toHaveBeenCalled()
+  })
 
+  it("runs all startup checks on normal session.created", async () => {
+    //#given - normal mode and no local dev version
+    const createAutoUpdateCheckerHook = await importFreshHookFactory()
+    const hook = createAutoUpdateCheckerHook(createPluginInput())
+
+    //#when - session.created event arrives on primary session
+    hook.event({
+      event: {
+        type: "session.created",
+      },
+    })
+    await new Promise((resolve) => setTimeout(resolve, 50))
+
+    //#then - startup checks, toast, and background check run
+    expect(mockShowConfigErrorsIfAny).toHaveBeenCalledTimes(1)
+    expect(mockUpdateAndShowConnectedProvidersCacheStatus).toHaveBeenCalledTimes(1)
+    expect(mockShowModelCacheWarningIfNeeded).toHaveBeenCalledTimes(1)
+    expect(mockShowVersionToast).toHaveBeenCalledTimes(1)
+    expect(mockRunBackgroundUpdateCheck).toHaveBeenCalledTimes(1)
+  })
+
+  it("ignores subagent sessions (parentID present)", async () => {
+    //#given - a subagent session with parentID
+    const createAutoUpdateCheckerHook = await importFreshHookFactory()
+    const hook = createAutoUpdateCheckerHook(createPluginInput())
+
+    //#when - session.created event contains parentID
+    hook.event({
+      event: {
+        type: "session.created",
+        properties: { info: { parentID: "parent-123" } },
+      },
+    })
+    await new Promise((resolve) => setTimeout(resolve, 50))
+
+    //#then - no startup actions run
+    expect(mockShowConfigErrorsIfAny).not.toHaveBeenCalled()
+    expect(mockUpdateAndShowConnectedProvidersCacheStatus).not.toHaveBeenCalled()
+    expect(mockShowModelCacheWarningIfNeeded).not.toHaveBeenCalled()
+    expect(mockShowLocalDevToast).not.toHaveBeenCalled()
+    expect(mockShowVersionToast).not.toHaveBeenCalled()
+    expect(mockRunBackgroundUpdateCheck).not.toHaveBeenCalled()
+  })
+
+  it("runs only once (hasChecked guard)", async () => {
+    //#given - one hook instance in normal mode
+    const createAutoUpdateCheckerHook = await importFreshHookFactory()
+    const hook = createAutoUpdateCheckerHook(createPluginInput())
+
+    //#when - session.created event is fired twice
+    hook.event({
+      event: {
+        type: "session.created",
+      },
+    })
+    hook.event({
+      event: {
+        type: "session.created",
+      },
+    })
+    await new Promise((resolve) => setTimeout(resolve, 50))
+
+    //#then - side effects execute only once
+    expect(mockShowConfigErrorsIfAny).toHaveBeenCalledTimes(1)
+    expect(mockUpdateAndShowConnectedProvidersCacheStatus).toHaveBeenCalledTimes(1)
+    expect(mockShowModelCacheWarningIfNeeded).toHaveBeenCalledTimes(1)
+    expect(mockShowVersionToast).toHaveBeenCalledTimes(1)
+    expect(mockRunBackgroundUpdateCheck).toHaveBeenCalledTimes(1)
+  })
+
+  it("shows localDevToast when local dev version exists", async () => {
+    //#given - local dev version is present
+    mockGetLocalDevVersion.mockReturnValue("3.6.0-dev")
+    const createAutoUpdateCheckerHook = await importFreshHookFactory()
+    const hook = createAutoUpdateCheckerHook(createPluginInput())
+
+    //#when - session.created event arrives
+    hook.event({
+      event: {
+        type: "session.created",
+      },
+    })
+    await new Promise((resolve) => setTimeout(resolve, 50))
+
+    //#then - local dev toast is shown and background check is skipped
+    expect(mockShowConfigErrorsIfAny).toHaveBeenCalledTimes(1)
+    expect(mockUpdateAndShowConnectedProvidersCacheStatus).toHaveBeenCalledTimes(1)
+    expect(mockShowModelCacheWarningIfNeeded).toHaveBeenCalledTimes(1)
+    expect(mockShowLocalDevToast).toHaveBeenCalledTimes(1)
+    expect(mockShowVersionToast).not.toHaveBeenCalled()
+    expect(mockRunBackgroundUpdateCheck).not.toHaveBeenCalled()
+  })
+
+  it("ignores non-session.created events", async () => {
+    //#given - a hook instance in normal mode
+    const createAutoUpdateCheckerHook = await importFreshHookFactory()
+    const hook = createAutoUpdateCheckerHook(createPluginInput())
+
+    //#when - a non-session.created event arrives
+    hook.event({
+      event: {
+        type: "session.deleted",
+      },
+    })
+    await new Promise((resolve) => setTimeout(resolve, 50))
+
+    //#then - no startup actions run
+    expect(mockShowConfigErrorsIfAny).not.toHaveBeenCalled()
+    expect(mockUpdateAndShowConnectedProvidersCacheStatus).not.toHaveBeenCalled()
+    expect(mockShowModelCacheWarningIfNeeded).not.toHaveBeenCalled()
+    expect(mockShowLocalDevToast).not.toHaveBeenCalled()
+    expect(mockShowVersionToast).not.toHaveBeenCalled()
+    expect(mockRunBackgroundUpdateCheck).not.toHaveBeenCalled()
+  })
+
+  it("passes correct toast message with sisyphus enabled", async () => {
+    //#given - sisyphus mode enabled
+    const createAutoUpdateCheckerHook = await importFreshHookFactory()
+    const hook = createAutoUpdateCheckerHook(createPluginInput(), {
+      isSisyphusEnabled: true,
+    })
+
+    //#when - session.created event arrives
+    hook.event({
+      event: {
+        type: "session.created",
+      },
+    })
+    await new Promise((resolve) => setTimeout(resolve, 50))
+
+    //#then - startup toast includes sisyphus wording
+    expect(mockShowVersionToast).toHaveBeenCalledTimes(1)
+    expect(mockShowVersionToast).toHaveBeenCalledWith(
+      expect.anything(),
+      "3.6.0",
+      expect.stringContaining("Sisyphus")
+    )
   })
 })