diff --git a/desktop/src/api/cliTasks.ts b/desktop/src/api/cliTasks.ts
index d659e91a..5e50993d 100644
--- a/desktop/src/api/cliTasks.ts
+++ b/desktop/src/api/cliTasks.ts
@@ -21,6 +21,11 @@ export const cliTasksApi = {
     return api.get<TaskResponse>(`/api/tasks/lists/${encodeURIComponent(taskListId)}/${taskId}`)
   },
 
+  /** Clear all persisted tasks for a completed task list */
+  resetTaskList(taskListId: string) {
+    return api.post<{ ok: true }>(`/api/tasks/lists/${encodeURIComponent(taskListId)}/reset`)
+  },
+
   /** List all tasks across all task lists */
   listAll() {
     return api.get<TasksResponse>('/api/tasks')
diff --git a/desktop/src/components/chat/ComputerUsePermissionModal.test.tsx b/desktop/src/components/chat/ComputerUsePermissionModal.test.tsx
index c2bfce00..c8e372f2 100644
--- a/desktop/src/components/chat/ComputerUsePermissionModal.test.tsx
+++ b/desktop/src/components/chat/ComputerUsePermissionModal.test.tsx
@@ -60,6 +60,7 @@ vi.mock('../../stores/cliTaskStore', () => ({
       clearTasks: vi.fn(),
       setTasksFromTodos: vi.fn(),
       markCompletedAndDismissed: vi.fn(),
+      resetCompletedTasks: vi.fn(async () => {}),
       refreshTasks: vi.fn(),
     }),
   },
diff --git a/desktop/src/components/chat/SessionTaskBar.test.tsx b/desktop/src/components/chat/SessionTaskBar.test.tsx
index 3b7f6bf7..b5607f31 100644
--- a/desktop/src/components/chat/SessionTaskBar.test.tsx
+++ b/desktop/src/components/chat/SessionTaskBar.test.tsx
@@ -4,6 +4,13 @@ import '@testing-library/jest-dom'
 import { SessionTaskBar } from './SessionTaskBar'
 import { useCLITaskStore } from '../../stores/cliTaskStore'
 
+vi.mock('../../api/cliTasks', () => ({
+  cliTasksApi: {
+    getTasksForList: vi.fn(),
+    resetTaskList: vi.fn(async () => ({ ok: true })),
+  },
+}))
+
 vi.mock('../../i18n', () => ({
   useTranslation: () => (key: string) => {
     const translations: Record<string, string> = {
@@ -46,7 +53,7 @@ describe('SessionTaskBar', () => {
     expect(screen.queryByRole('button', { name: 'Hide completed tasks' })).toBeNull()
   })
 
-  it('hides the bar after dismissing a completed task set', () => {
+  it('hides the bar after dismissing a completed task set', async () => {
     act(() => {
       useCLITaskStore.getState().setTasksFromTodos([
         { content: 'first', status: 'completed' },
@@ -58,10 +65,13 @@ describe('SessionTaskBar', () => {
       render(<SessionTaskBar />)
     })
 
-    fireEvent.click(screen.getByRole('button', { name: 'Hide completed tasks' }))
+    await act(async () => {
+      fireEvent.click(screen.getByRole('button', { name: 'Hide completed tasks' }))
+      await Promise.resolve()
+    })
 
     expect(screen.queryByText('Tasks')).toBeNull()
-    expect(useCLITaskStore.getState().completedAndDismissed).toBe(true)
+    expect(useCLITaskStore.getState().tasks).toEqual([])
   })
 
   it('shows the bar again for a new task cycle after a previous completed set was dismissed', () => {
diff --git a/desktop/src/components/chat/SessionTaskBar.tsx b/desktop/src/components/chat/SessionTaskBar.tsx
index 2bc9b05d..07af20f9 100644
--- a/desktop/src/components/chat/SessionTaskBar.tsx
+++ b/desktop/src/components/chat/SessionTaskBar.tsx
@@ -26,7 +26,7 @@ export function SessionTaskBar() {
     expanded,
     toggleExpanded,
     completedAndDismissed,
-    markCompletedAndDismissed,
+    resetCompletedTasks,
   } = useCLITaskStore()
   const t = useTranslation()
 
@@ -91,7 +91,7 @@ export function SessionTaskBar() {
             <button
               type="button"
               aria-label={t('tasks.dismissCompleted')}
-              onClick={markCompletedAndDismissed}
+              onClick={() => { void resetCompletedTasks() }}
               className="flex shrink-0 items-center justify-center rounded-[var(--radius-md)] p-1.5 text-[var(--color-text-tertiary)] hover:bg-[var(--color-surface-container-low)] hover:text-[var(--color-text-primary)] transition-colors"
             >
               <span className="material-symbols-outlined text-[16px]">close</span>
diff --git a/desktop/src/stores/chatStore.test.ts b/desktop/src/stores/chatStore.test.ts
index 3b4c0ed6..e8d6ea68 100644
--- a/desktop/src/stores/chatStore.test.ts
+++ b/desktop/src/stores/chatStore.test.ts
@@ -12,7 +12,9 @@ const {
   clearTasksMock,
   setTasksFromTodosMock,
   markCompletedAndDismissedMock,
+  resetCompletedTasksMock,
   refreshTasksMock,
+  cliTaskStoreSnapshot,
 } = vi.hoisted(() => ({
   sendMock: vi.fn(),
   getMemberBySessionIdMock: vi.fn<(sessionId: string) => any>(() => null),
@@ -24,7 +26,12 @@ const {
   clearTasksMock: vi.fn(),
   setTasksFromTodosMock: vi.fn(),
   markCompletedAndDismissedMock: vi.fn(),
+  resetCompletedTasksMock: vi.fn(async () => {}),
   refreshTasksMock: vi.fn(),
+  cliTaskStoreSnapshot: {
+    tasks: [] as Array<{ id: string; subject: string; status: string; activeForm?: string }>,
+    sessionId: null as string | null,
+  },
 }))
 
 vi.mock('../api/websocket', () => ({
@@ -77,11 +84,12 @@ vi.mock('./cliTaskStore', () => ({
   useCLITaskStore: {
     getState: () => ({
       fetchSessionTasks: fetchSessionTasksMock,
-      tasks: [],
-      sessionId: null,
+      tasks: cliTaskStoreSnapshot.tasks,
+      sessionId: cliTaskStoreSnapshot.sessionId,
       clearTasks: clearTasksMock,
       setTasksFromTodos: setTasksFromTodosMock,
       markCompletedAndDismissed: markCompletedAndDismissedMock,
+      resetCompletedTasks: resetCompletedTasksMock,
       refreshTasks: refreshTasksMock,
     }),
   },
@@ -102,7 +110,10 @@ describe('chatStore history mapping', () => {
     clearTasksMock.mockReset()
     setTasksFromTodosMock.mockReset()
     markCompletedAndDismissedMock.mockReset()
+    resetCompletedTasksMock.mockReset()
     refreshTasksMock.mockReset()
+    cliTaskStoreSnapshot.tasks = []
+    cliTaskStoreSnapshot.sessionId = null
     useChatStore.setState({
       ...initialState,
       sessions: {},
@@ -413,6 +424,54 @@ describe('chatStore history mapping', () => {
     expect(useChatStore.getState().sessions[TEST_SESSION_ID]?.streamingText).toBe('')
   })
 
+  it('resets completed CLI tasks before continuing the next user turn', () => {
+    cliTaskStoreSnapshot.sessionId = TEST_SESSION_ID
+    cliTaskStoreSnapshot.tasks = [
+      { id: '1', subject: 'Existing completed task', status: 'completed' },
+      { id: '2', subject: 'Another completed task', status: 'completed' },
+    ]
+
+    useChatStore.setState({
+      sessions: {
+        [TEST_SESSION_ID]: {
+          messages: [],
+          chatState: 'idle',
+          connectionState: 'connected',
+          streamingText: '',
+          streamingToolInput: '',
+          activeToolUseId: null,
+          activeToolName: null,
+          activeThinkingId: null,
+          pendingPermission: null,
+          pendingComputerUsePermission: null,
+          tokenUsage: { input_tokens: 0, output_tokens: 0 },
+          elapsedSeconds: 0,
+          statusVerb: '',
+          slashCommands: [],
+          agentTaskNotifications: {},
+          elapsedTimer: null,
+        },
+      },
+    })
+
+    useChatStore.getState().sendMessage(TEST_SESSION_ID, '继续下一轮')
+
+    expect(resetCompletedTasksMock).toHaveBeenCalledTimes(1)
+    expect(useChatStore.getState().sessions[TEST_SESSION_ID]?.messages).toMatchObject([
+      {
+        type: 'task_summary',
+        tasks: [
+          { id: '1', subject: 'Existing completed task', status: 'completed' },
+          { id: '2', subject: 'Another completed task', status: 'completed' },
+        ],
+      },
+      {
+        type: 'user_text',
+        content: '继续下一轮',
+      },
+    ])
+  })
+
   it('tracks Computer Use approval requests separately from generic tool permissions', () => {
     useChatStore.setState({
       sessions: {
diff --git a/desktop/src/stores/chatStore.ts b/desktop/src/stores/chatStore.ts
index 05e207dc..7bb3b724 100644
--- a/desktop/src/stores/chatStore.ts
+++ b/desktop/src/stores/chatStore.ts
@@ -199,6 +199,13 @@ export const useChatStore = create<ChatStore>((set, get) => ({
 
     const taskStore = useCLITaskStore.getState()
     const allTasksDone = taskStore.tasks.length > 0 && taskStore.tasks.every((t) => t.status === 'completed')
+    const completedTaskSummary = allTasksDone
+      ? taskStore.tasks.map((t) => ({ id: t.id, subject: t.subject, status: t.status, activeForm: t.activeForm }))
+      : []
+
+    if (!isMemberSession && allTasksDone) {
+      void taskStore.resetCompletedTasks()
+    }
 
     set((s) => {
       const session = s.sessions[sessionId] ?? createDefaultSessionState()
@@ -225,10 +232,9 @@ export const useChatStore = create<ChatStore>((set, get) => ({
         newMessages.push({
           id: nextId(),
           type: 'task_summary',
-          tasks: taskStore.tasks.map((t) => ({ id: t.id, subject: t.subject, status: t.status, activeForm: t.activeForm })),
+          tasks: completedTaskSummary,
           timestamp: Date.now(),
         })
-        taskStore.clearTasks()
       }
       newMessages.push({
         id: nextId(),
diff --git a/desktop/src/stores/cliTaskStore.test.ts b/desktop/src/stores/cliTaskStore.test.ts
index 8ec9aa2d..fa338e1e 100644
--- a/desktop/src/stores/cliTaskStore.test.ts
+++ b/desktop/src/stores/cliTaskStore.test.ts
@@ -6,6 +6,7 @@ import { useCLITaskStore } from './cliTaskStore'
 vi.mock('../api/cliTasks', () => ({
   cliTasksApi: {
     getTasksForList: vi.fn(),
+    resetTaskList: vi.fn(),
   },
 }))
 
@@ -67,4 +68,42 @@ describe('cliTaskStore', () => {
       { taskListId: 'session-2', status: 'completed' },
     ])
   })
+
+  it('resets a completed task list locally before clearing it remotely', async () => {
+    let resolveReset: ((value: { ok: true }) => void) | null = null
+
+    vi.mocked(cliTasksApi.resetTaskList).mockImplementation(
+      () => new Promise<{ ok: true }>((resolve) => {
+        resolveReset = resolve
+      }),
+    )
+
+    useCLITaskStore.setState({
+      sessionId: 'session-1',
+      tasks: [
+        makeTask('session-1', 'completed'),
+        { ...makeTask('session-1', 'completed'), id: '2', subject: 'Second completed task' },
+      ],
+      expanded: true,
+      completedAndDismissed: true,
+      dismissedCompletionKey: 'session-1::done',
+    })
+
+    const resetPromise = useCLITaskStore.getState().resetCompletedTasks()
+
+    expect(vi.mocked(cliTasksApi.resetTaskList)).toHaveBeenCalledWith('session-1')
+    expect(useCLITaskStore.getState()).toMatchObject({
+      tasks: [],
+      resetting: true,
+      completedAndDismissed: false,
+      dismissedCompletionKey: null,
+      expanded: false,
+    })
+
+    expect(resolveReset).not.toBeNull()
+    resolveReset!({ ok: true })
+    await resetPromise
+
+    expect(useCLITaskStore.getState().resetting).toBe(false)
+  })
 })
diff --git a/desktop/src/stores/cliTaskStore.ts b/desktop/src/stores/cliTaskStore.ts
index 979b145e..3b8db3a0 100644
--- a/desktop/src/stores/cliTaskStore.ts
+++ b/desktop/src/stores/cliTaskStore.ts
@@ -13,6 +13,8 @@ type CLITaskStore = {
   sessionId: string | null
   /** Tasks for the current session */
   tasks: CLITask[]
+  /** True while the persisted task list is being cleared remotely */
+  resetting: boolean
   /** Whether the task bar is expanded */
   expanded: boolean
   /** True when all tasks completed and the user already continued chatting.
@@ -29,6 +31,8 @@ type CLITaskStore = {
   setTasksFromTodos: (todos: TodoItem[]) => void
   /** Mark that completed tasks were already dismissed (conversation continued) */
   markCompletedAndDismissed: () => void
+  /** Clear a completed task list locally and remotely so the next cycle starts clean */
+  resetCompletedTasks: () => Promise<void>
   /** Clear task tracking state */
   clearTasks: () => void
   /** Toggle expanded state */
@@ -78,6 +82,7 @@ function mapTodosToTasks(todos: TodoItem[], sessionId: string | null): CLITask[]
 export const useCLITaskStore = create<CLITaskStore>((set, get) => ({
   sessionId: null,
   tasks: [],
+  resetting: false,
   expanded: false,
   completedAndDismissed: false,
   dismissedCompletionKey: null,
@@ -87,6 +92,7 @@ export const useCLITaskStore = create<CLITaskStore>((set, get) => ({
       set({
         sessionId,
         tasks: [],
+        resetting: false,
         completedAndDismissed: false,
         dismissedCompletionKey: null,
         expanded: false,
@@ -96,7 +102,7 @@ export const useCLITaskStore = create<CLITaskStore>((set, get) => ({
     try {
       const { tasks } = await cliTasksApi.getTasksForList(sessionId)
       // Only update if still tracking the same session
-      if (get().sessionId === sessionId) {
+      if (get().sessionId === sessionId && !get().resetting) {
         set((state) => ({
           tasks,
           ...resolveDismissState(tasks, state.dismissedCompletionKey),
@@ -104,7 +110,7 @@ export const useCLITaskStore = create<CLITaskStore>((set, get) => ({
       }
     } catch {
       // No tasks for this session — that's fine
-      if (get().sessionId === sessionId) {
+      if (get().sessionId === sessionId && !get().resetting) {
         set({ tasks: [], completedAndDismissed: false, dismissedCompletionKey: null, expanded: false })
       }
     }
@@ -115,7 +121,7 @@ export const useCLITaskStore = create<CLITaskStore>((set, get) => ({
     if (!sessionId) return
     try {
       const { tasks } = await cliTasksApi.getTasksForList(sessionId)
-      if (get().sessionId === sessionId) {
+      if (get().sessionId === sessionId && !get().resetting) {
         set((state) => ({
           tasks,
           ...resolveDismissState(tasks, state.dismissedCompletionKey),
@@ -145,10 +151,33 @@ export const useCLITaskStore = create<CLITaskStore>((set, get) => ({
     })
   },
 
+  resetCompletedTasks: async () => {
+    const { sessionId, tasks } = get()
+    const completionKey = buildCompletedTaskKey(tasks)
+    if (!sessionId || !completionKey) return
+
+    set({
+      tasks: [],
+      resetting: true,
+      completedAndDismissed: false,
+      dismissedCompletionKey: null,
+      expanded: false,
+    })
+
+    try {
+      await cliTasksApi.resetTaskList(sessionId)
+    } finally {
+      if (get().sessionId === sessionId) {
+        set({ resetting: false })
+      }
+    }
+  },
+
   clearTasks: () => {
     set({
       sessionId: null,
       tasks: [],
+      resetting: false,
       completedAndDismissed: false,
       dismissedCompletionKey: null,
       expanded: false,
diff --git a/src/server/__tests__/e2e/business-flow.test.ts b/src/server/__tests__/e2e/business-flow.test.ts
index ad04e6fd..1f22455a 100644
--- a/src/server/__tests__/e2e/business-flow.test.ts
+++ b/src/server/__tests__/e2e/business-flow.test.ts
@@ -204,6 +204,64 @@ describe('Business Flow: Permission Modes', () => {
   })
 })
 
+describe('Business Flow: Task Lists API', () => {
+  beforeAll(startTestServer)
+  afterAll(async () => {
+    server?.stop()
+    await fs.rm(tmpDir, { recursive: true, force: true })
+  })
+
+  it('should reset a persisted task list through the API', async () => {
+    const taskListDir = path.join(tmpDir, 'tasks', 'desktop-session-1')
+    await fs.mkdir(taskListDir, { recursive: true })
+    await fs.writeFile(
+      path.join(taskListDir, '1.json'),
+      JSON.stringify({
+        id: '1',
+        subject: 'First task',
+        description: '',
+        status: 'completed',
+        blocks: [],
+        blockedBy: [],
+      }),
+      'utf-8',
+    )
+    await fs.writeFile(
+      path.join(taskListDir, '2.json'),
+      JSON.stringify({
+        id: '2',
+        subject: 'Second task',
+        description: '',
+        status: 'completed',
+        blocks: [],
+        blockedBy: [],
+      }),
+      'utf-8',
+    )
+
+    const { status: beforeStatus, data: beforeData } = await api(
+      'GET',
+      '/api/tasks/lists/desktop-session-1',
+    )
+    expect(beforeStatus).toBe(200)
+    expect(beforeData.tasks).toHaveLength(2)
+
+    const { status: resetStatus, data: resetData } = await api(
+      'POST',
+      '/api/tasks/lists/desktop-session-1/reset',
+    )
+    expect(resetStatus).toBe(200)
+    expect(resetData.ok).toBe(true)
+
+    const { status: afterStatus, data: afterData } = await api(
+      'GET',
+      '/api/tasks/lists/desktop-session-1',
+    )
+    expect(afterStatus).toBe(200)
+    expect(afterData.tasks).toEqual([])
+  })
+})
+
 describe('Business Flow: Agent Management', () => {
   beforeAll(startTestServer)
   afterAll(async () => {
diff --git a/src/server/api/agents.ts b/src/server/api/agents.ts
index ca95bd8f..de23d84b 100644
--- a/src/server/api/agents.ts
+++ b/src/server/api/agents.ts
@@ -14,6 +14,7 @@
 import { AgentService } from '../services/agentService.js'
 import { taskService } from '../services/taskService.js'
 import { ApiError, errorResponse } from '../middleware/errorHandler.js'
+import { resetTaskList } from '../../utils/tasks.js'
 import {
   resolveAgentModelDisplay,
   resolveAgentOverrides,
@@ -124,26 +125,31 @@ async function handleAgents(
 // GET /api/tasks/lists                   → list all task lists with summaries
 // GET /api/tasks/lists/:taskListId       → get all tasks for a specific task list
 // GET /api/tasks/lists/:taskListId/:id   → get a single task
+// POST /api/tasks/lists/:taskListId/reset → clear a completed task list
 
 async function handleTasksApi(
   req: Request,
   segments: string[],
 ): Promise<Response> {
-  if (req.method !== 'GET') {
-    throw new ApiError(
-      405,
-      `Method ${req.method} not allowed on /api/tasks`,
-      'METHOD_NOT_ALLOWED',
-    )
-  }
-
   const sub = segments[2] // 'lists' or undefined
 
-  // GET /api/tasks/lists — list all task lists
   if (sub === 'lists') {
     const taskListId = segments[3]
     const taskId = segments[4]
 
+    if (req.method === 'POST' && taskListId && taskId === 'reset') {
+      await resetTaskList(taskListId)
+      return Response.json({ ok: true })
+    }
+
+    if (req.method !== 'GET') {
+      throw new ApiError(
+        405,
+        `Method ${req.method} not allowed on /api/tasks/lists`,
+        'METHOD_NOT_ALLOWED',
+      )
+    }
+
     if (taskListId && taskId) {
       // GET /api/tasks/lists/:taskListId/:taskId
       const task = await taskService.getTask(taskListId, taskId)
@@ -162,6 +168,14 @@ async function handleTasksApi(
     return Response.json({ lists })
   }
 
+  if (req.method !== 'GET') {
+    throw new ApiError(
+      405,
+      `Method ${req.method} not allowed on /api/tasks`,
+      'METHOD_NOT_ALLOWED',
+    )
+  }
+
   // GET /api/tasks — list all tasks
   const tasks = await taskService.listTasks()
   return Response.json({ tasks })