diff --git a/src/features/agents/Agents.module.css b/src/features/agents/Agents.module.css
index b52ea530..39722d6f 100644
--- a/src/features/agents/Agents.module.css
+++ b/src/features/agents/Agents.module.css
@@ -39,6 +39,17 @@
   text-overflow: ellipsis;
   white-space: nowrap;
 }
+.title[data-unread] {
+  color: var(--fg-strong);
+  font-weight: 600;
+}
+.unreadDot {
+  flex: none;
+  width: 6px;
+  height: 6px;
+  border-radius: 50%;
+  background: var(--accent);
+}
 .detail {
   flex: 1 1 0;
   min-width: 0;
diff --git a/src/features/agents/AgentsStatus.tsx b/src/features/agents/AgentsStatus.tsx
index 2b955f12..b0a759c9 100644
--- a/src/features/agents/AgentsStatus.tsx
+++ b/src/features/agents/AgentsStatus.tsx
@@ -5,11 +5,13 @@ import styles from "./Agents.module.css";
 
 export function AgentsStatus() {
   const tasks = useAgents((s) => s.tasks);
+  const unread = useAgents((s) => s.unread);
   const list = [...tasks.values()];
+  const unseen = list.filter((t) => unread.has(t.id)).sort((a, b) => (b.updatedMs ?? 0) - (a.updatedMs ?? 0));
   const input = list.filter((t) => t.status === "needsInput");
   const running = list.filter((t) => t.status === "running" || t.status === "starting").length;
-  if (!input.length && !running) return null;
-  const target = input[0] ?? list.find((t) => t.status === "running");
+  if (!input.length && !running && !unseen.length) return null;
+  const target = input[0] ?? unseen[0] ?? list.find((t) => t.status === "running" || t.status === "starting");
   return (
     <button type="button" className={styles.statusItem} onClick={() => target && openTask(target.id)}>
       {input.length > 0 && (
@@ -24,6 +26,12 @@ export function AgentsStatus() {
           {running} <T>running</T>
         </span>
       )}
+      {unseen.length > 0 && (
+        <span className={styles.statusPart}>
+          <span className={styles.unreadDot} aria-hidden="true" />
+          {unseen.length} <T>unread</T>
+        </span>
+      )}
     </button>
   );
 }
diff --git a/src/features/agents/AgentsView.tsx b/src/features/agents/AgentsView.tsx
index 8d9c1338..2f899c16 100644
--- a/src/features/agents/AgentsView.tsx
+++ b/src/features/agents/AgentsView.tsx
@@ -8,7 +8,7 @@ import { EmptyState, Icon, IconButton, Spinner, T, Tree, showContextMenu, type M
 import { SESSION_KIND, age, branchLabel, groupTasks, isBusy, type TaskGroup } from "./model";
 import { archiveTask, deleteTask, openHome, openTask, useAgents } from "./store";
 import styles from "./Agents.module.css";
-import { tx } from "@/platform/i18n";
+import { tx, useTx } from "@/platform/i18n";
 
 export function AgentsHeaderActions() {
   return (
@@ -44,9 +44,11 @@ export function TaskStatusIcon({ status }: { status: Status }) {
 }
 
 export function AgentsView() {
+  const tx = useTx();
   const loaded = useAgents((s) => s.loaded);
   const error = useAgents((s) => s.error);
   const tasks = useAgents((s) => s.tasks);
+  const unread = useAgents((s) => s.unread);
   const providers = useAgents((s) => s.providers);
   const [collapsed, setCollapsed] = useState<Set<string>>(() => new Set(["g:archived"]));
   const [selected, setSelected] = useState<Set<string>>(() => {
@@ -115,7 +117,12 @@ export function AgentsView() {
           ) : (
             <span className={styles.row} title={n.task.error ?? n.task.title}>
               <TaskStatusIcon status={n.task.status} />
-              <span className={styles.title}>{n.task.title}</span>
+              <span className={styles.title} data-unread={unread.has(n.task.id) || undefined}>
+                {n.task.title}
+              </span>
+              {unread.has(n.task.id) && (
+                <span className={styles.unreadDot} role="img" aria-label={tx("Unread")} title={tx("Unread")} />
+              )}
               <span className={styles.detail}>
                 {providerName(n.task.provider)}
                 {n.task.isolation === "worktree" ? ` · ${branchLabel(n.task.branch)}` : ""}
diff --git a/src/features/agents/index.ts b/src/features/agents/index.ts
index 180e19e6..2deed65d 100644
--- a/src/features/agents/index.ts
+++ b/src/features/agents/index.ts
@@ -54,7 +54,9 @@ export function activate(): () => void {
       component: lazyComponent(() => import("./AgentsView").then((m) => m.AgentsView)),
       headerActions: lazyComponent(() => import("./AgentsView").then((m) => m.AgentsHeaderActions)),
       useBadge: () => {
-        const n = useAgents((s) => [...s.tasks.values()].filter((t) => t.status === "needsInput").length);
+        const n = useAgents(
+          (s) => [...s.tasks.values()].filter((t) => t.status === "needsInput" || s.unread.has(t.id)).length,
+        );
         return n || null;
       },
     }),
diff --git a/src/features/agents/store.ts b/src/features/agents/store.ts
index 06c2e836..d284121f 100644
--- a/src/features/agents/store.ts
+++ b/src/features/agents/store.ts
@@ -44,6 +44,8 @@ interface AgentsState {
   /** Why the tasks could not be loaded. */
   error: string | null;
   tasks: Map<string, AgentTask>;
+  /** Tasks with unseen replies or status changes in this project. */
+  unread: Set<string>;
   /** Entries of the tasks (and subagents) opened in this window, by `entriesKey`. */
   entries: Map<string, AgentEntry[]>;
   changes: Map<string, AgentChange[]>;
@@ -85,6 +87,7 @@ export const useAgents = create<AgentsState>(() => ({
   loaded: false,
   error: null,
   tasks: new Map(),
+  unread: new Set(),
   entries: new Map(),
   changes: new Map(),
   providers: [],
@@ -110,11 +113,40 @@ export function updateComposer(key: string, patch: Partial<ComposerDraft>) {
   }));
 }
 
-/** Session tabs on screen; their tasks do not notify. */
-const visible = new Set<string>();
+/** Session tabs on screen; a task can be shown in more than one split. */
+const visible = new Map<string, number>();
+const windowFocused = () => document.visibilityState !== "hidden" && document.hasFocus();
+const viewing = (task: string) => visible.has(task) && windowFocused();
+
+function setUnread(task: string, value: boolean) {
+  const s = useAgents.getState();
+  if (s.unread.has(task) === value) return;
+  const unread = new Set(s.unread);
+  if (value) unread.add(task);
+  else unread.delete(task);
+  useAgents.setState({ unread });
+}
+
+function markUnread(task: string) {
+  const current = useAgents.getState().tasks.get(task);
+  if (current && current.status !== "archived" && !viewing(task)) setUnread(task, true);
+}
+
 export function markVisible(task: string): () => void {
-  visible.add(task);
-  return () => visible.delete(task);
+  visible.set(task, (visible.get(task) ?? 0) + 1);
+  const read = () => {
+    if (viewing(task)) setUnread(task, false);
+  };
+  read();
+  window.addEventListener("focus", read);
+  document.addEventListener("visibilitychange", read);
+  return () => {
+    const count = (visible.get(task) ?? 1) - 1;
+    if (count) visible.set(task, count);
+    else visible.delete(task);
+    window.removeEventListener("focus", read);
+    document.removeEventListener("visibilitychange", read);
+  };
 }
 
 let generation = 0;
@@ -154,7 +186,14 @@ export async function connect(): Promise<void> {
 
 export function disconnect() {
   generation++;
-  useAgents.setState({ loaded: false, error: null, tasks: new Map(), entries: new Map(), changes: new Map() });
+  useAgents.setState({
+    loaded: false,
+    error: null,
+    tasks: new Map(),
+    unread: new Set(),
+    entries: new Map(),
+    changes: new Map(),
+  });
 }
 
 function onEvent(e: AgentEvent) {
@@ -163,6 +202,8 @@ function onEvent(e: AgentEvent) {
     case "task": {
       const prev = s.tasks.get(e.task.id);
       useAgents.setState({ tasks: new Map(s.tasks).set(e.task.id, e.task) });
+      if (e.task.status === "archived") setUnread(e.task.id, false);
+      else if (attentionChange(prev?.status, e.task.status)) markUnread(e.task.id);
       notifyChange(prev, e.task);
       if (prev?.status !== e.task.status && !isBusy(e.task.status)) {
         void refreshChanges(e.task.id);
@@ -175,7 +216,9 @@ function onEvent(e: AgentEvent) {
       tasks.delete(e.id);
       const composers = new Map(s.composers);
       composers.delete(e.id);
-      useAgents.setState({ tasks, composers });
+      const unread = new Set(s.unread);
+      unread.delete(e.id);
+      useAgents.setState({ tasks, composers, unread });
       editorService().closeInput?.(sessionKey(e.id));
       break;
     }
@@ -186,6 +229,14 @@ function onEvent(e: AgentEvent) {
       break;
     }
     case "entry": {
+      if (
+        !e.subagent &&
+        ((e.entry.type === "agent" && e.entry.text.trim()) ||
+          e.entry.type === "error" ||
+          (e.entry.type === "permission" && e.entry.chosen === null))
+      ) {
+        markUnread(e.task);
+      }
       const key = entriesKey(e.task, e.subagent);
       const current = s.entries.get(key);
       if (!current) return;
@@ -203,7 +254,7 @@ function onEvent(e: AgentEvent) {
 function notifyChange(prev: AgentTask | undefined, task: AgentTask) {
   const change = attentionChange(prev?.status, task.status);
   if (!change) return;
-  if (visible.has(task.id) && document.hasFocus()) return;
+  if (viewing(task.id)) return;
   const body =
     change === "input"
       ? "Waiting for your answer"
diff --git a/src/features/agents/unread.test.tsx b/src/features/agents/unread.test.tsx
new file mode 100644
index 00000000..3c78162e
--- /dev/null
+++ b/src/features/agents/unread.test.tsx
@@ -0,0 +1,224 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { act, fireEvent, render, screen } from "@testing-library/react";
+import type { AgentEntry, AgentEvent, AgentTask } from "@/bindings";
+import { useContributions } from "@/workbench/contributions";
+import { AgentsView } from "./AgentsView";
+import { AgentsStatus } from "./AgentsStatus";
+import { activate } from "./index";
+import { connect, disconnect, markVisible, useAgents } from "./store";
+
+const backend = vi.hoisted(() => ({
+  channel: null as { onmessage: (event: AgentEvent) => void } | null,
+  tasks: [] as AgentTask[],
+  notify: vi.fn(),
+  openInput: vi.fn(),
+  closeInput: vi.fn(),
+}));
+
+vi.mock("@tauri-apps/api/core", async (original) => ({
+  ...(await original<typeof import("@tauri-apps/api/core")>()),
+  Channel: class {
+    onmessage = () => {};
+  },
+}));
+vi.mock("@/platform/ipc", async (original) => ({
+  ...(await original<typeof import("@/platform/ipc")>()),
+  isTauri: () => true,
+  commands: {
+    agentSubscribe: async (channel: typeof backend.channel) => {
+      backend.channel = channel;
+      return { status: "ok", data: backend.tasks };
+    },
+    agentProviders: async () => ({ status: "ok", data: [] }),
+    agentChanges: async () => ({ status: "ok", data: [] }),
+  },
+}));
+vi.mock("@/workbench/contributions", async (original) => ({
+  ...(await original<typeof import("@/workbench/contributions")>()),
+  editorService: () => ({ openInput: backend.openInput, closeInput: backend.closeInput }),
+  notifications: () => ({ notify: backend.notify }),
+}));
+
+const task = (id: string, status: AgentTask["status"] = "running"): AgentTask => ({
+  id,
+  title: id,
+  status,
+  provider: "codex",
+  isolation: "local",
+  model: null,
+  cwd: "/project",
+  branch: null,
+  base: null,
+  baseCommit: null,
+  error: null,
+  createdMs: 0,
+  updatedMs: 0,
+  config: [],
+  commands: [],
+  usage: null,
+  queue: [],
+});
+
+const emit = (event: AgentEvent) => act(() => backend.channel!.onmessage(event));
+const reply = (id = "one", text = "New reply") =>
+  emit({ type: "entry", task: id, subagent: null, index: 0, entry: { type: "agent", text } });
+const visible: Array<() => void> = [];
+const show = (id = "one") => {
+  let hide!: () => void;
+  act(() => {
+    hide = markVisible(id);
+  });
+  visible.push(hide);
+  return () => visible.splice(visible.indexOf(hide), 1)[0]!();
+};
+
+beforeEach(async () => {
+  vi.clearAllMocks();
+  vi.spyOn(document, "hasFocus").mockReturnValue(true);
+  vi.spyOn(document, "visibilityState", "get").mockReturnValue("visible");
+  disconnect();
+  backend.tasks = [task("one"), task("two", "ready")];
+  await connect();
+});
+afterEach(() => {
+  visible.splice(0).forEach((hide) => hide());
+  disconnect();
+  vi.restoreAllMocks();
+});
+
+describe("agent unread activity", () => {
+  it("does not mark historical tasks unread, but tracks replies even without loaded entries", () => {
+    expect(useAgents.getState().unread.size).toBe(0);
+    reply();
+    reply("one", "New reply, streamed further");
+    reply("two");
+    expect([...useAgents.getState().unread]).toEqual(["one", "two"]);
+    expect(useAgents.getState().entries.size).toBe(0);
+    expect(backend.notify).not.toHaveBeenCalled();
+  });
+
+  it.each(["ready", "needsInput", "failed", "limited"] as const)("marks background %s transitions unread", (status) => {
+    emit({ type: "task", task: task("one", status) });
+    expect(useAgents.getState().unread.has("one")).toBe(true);
+    expect(backend.notify).toHaveBeenCalledTimes(1);
+    show();
+    emit({ type: "task", task: task("one", status) });
+    expect(useAgents.getState().unread.size).toBe(0);
+    expect(backend.notify).toHaveBeenCalledTimes(1);
+  });
+
+  it("ignores user messages, thoughts, empty replies and subagent streaming", () => {
+    const entries: AgentEntry[] = [
+      { type: "user", text: "Do this", attachments: [] },
+      { type: "thought", text: "Thinking" },
+      { type: "agent", text: " " },
+    ];
+    for (const entry of entries) emit({ type: "entry", task: "one", subagent: null, index: 0, entry });
+    emit({ type: "entry", task: "one", subagent: "child", index: 0, entry: { type: "agent", text: "Working" } });
+    emit({ type: "task", task: { ...task("one"), title: "Renamed" } });
+    expect(useAgents.getState().unread.size).toBe(0);
+  });
+
+  it("clears only the viewed task and keeps reading while either split shows it", () => {
+    reply();
+    reply("two");
+    const hide = show();
+    show();
+    hide();
+    reply();
+    emit({ type: "task", task: task("one", "ready") });
+    expect([...useAgents.getState().unread]).toEqual(["two"]);
+    expect(backend.notify).not.toHaveBeenCalled();
+  });
+
+  it("keeps a visible session unread while the window is unfocused, then clears on focus", () => {
+    vi.mocked(document.hasFocus).mockReturnValue(false);
+    reply();
+    show();
+    expect(useAgents.getState().unread.has("one")).toBe(true);
+    vi.mocked(document.hasFocus).mockReturnValue(true);
+    fireEvent(window, new Event("focus"));
+    expect(useAgents.getState().unread.size).toBe(0);
+    reply();
+    expect(useAgents.getState().unread.size).toBe(0);
+  });
+
+  it("does not read hidden windows and removes focus listeners when the session closes", () => {
+    vi.spyOn(document, "visibilityState", "get").mockReturnValue("hidden");
+    const hide = show();
+    reply();
+    fireEvent(window, new Event("focus"));
+    expect(useAgents.getState().unread.has("one")).toBe(true);
+    vi.spyOn(document, "visibilityState", "get").mockReturnValue("visible");
+    fireEvent(document, new Event("visibilitychange"));
+    expect(useAgents.getState().unread.size).toBe(0);
+    hide();
+    reply();
+    fireEvent(window, new Event("focus"));
+    expect(useAgents.getState().unread.has("one")).toBe(true);
+  });
+
+  it("cleans up archived and deleted tasks, ignores late replies, and resets on project switch", async () => {
+    reply();
+    reply("two");
+    emit({ type: "task", task: task("one", "archived") });
+    reply();
+    expect([...useAgents.getState().unread]).toEqual(["two"]);
+    emit({ type: "removed", id: "two" });
+    reply("two");
+    expect(useAgents.getState().unread.size).toBe(0);
+    emit({ type: "task", task: task("one") });
+    reply();
+    const oldChannel = backend.channel!;
+    disconnect();
+    backend.tasks = [task("other")];
+    await connect();
+    oldChannel.onmessage({ type: "task", task: task("one", "ready") });
+    expect(useAgents.getState().unread.size).toBe(0);
+    expect([...useAgents.getState().tasks.keys()]).toEqual(["other"]);
+  });
+});
+
+describe("agent unread indicators", () => {
+  it("shows a dot on the task and a clickable status count even when all tasks are idle", () => {
+    emit({ type: "task", task: task("one", "ready") });
+    render(
+      <>
+        <AgentsView />
+        <AgentsStatus />
+      </>,
+    );
+    expect(screen.getByRole("img", { name: "Unread" })).toBeInTheDocument();
+    fireEvent.click(screen.getByRole("button", { name: "1 unread" }));
+    expect(backend.openInput).toHaveBeenCalledWith(expect.objectContaining({ data: { task: "one", title: "one" } }), {
+      focus: true,
+    });
+    show();
+    expect(screen.queryByRole("img", { name: "Unread" })).not.toBeInTheDocument();
+    expect(screen.queryByRole("button", { name: /unread/ })).not.toBeInTheDocument();
+  });
+
+  it("counts unread and needs-input tasks once each in the sidebar badge", () => {
+    const dispose = activate();
+    try {
+      const useBadge = useContributions.getState().toolWindows.get("agents")!.useBadge!;
+      function Badge() {
+        return <span data-testid="badge">{useBadge()}</span>;
+      }
+      act(() =>
+        useAgents.setState({
+          tasks: new Map([task("one", "needsInput"), task("two", "ready")].map((t) => [t.id, t])),
+          unread: new Set(["one", "two"]),
+        }),
+      );
+      render(<Badge />);
+      expect(screen.getByTestId("badge")).toHaveTextContent("2");
+      show("two");
+      expect(screen.getByTestId("badge")).toHaveTextContent("1");
+      show("one");
+      expect(screen.getByTestId("badge")).toHaveTextContent("1");
+    } finally {
+      act(dispose);
+    }
+  });
+});
diff --git a/src/platform/locales/text/zh.json b/src/platform/locales/text/zh.json
index fba57530..d9b6ffed 100644
--- a/src/platform/locales/text/zh.json
+++ b/src/platform/locales/text/zh.json
@@ -2152,6 +2152,7 @@
   "Underscored": "下划线",
   "Underwaved": "波浪线",
   "Undo": "撤消",
+  "Unread": "未读",
   "Undo Commit": "撤消提交",
   "Undo Commit…": "撤消提交…",
   "Undo Move / Rename": "撤消移动/重命名",
@@ -3244,6 +3245,7 @@
   "Also remove its worktree folder": "同时删除它的 worktree 目录",
   "needs input": "等待输入",
   "running": "正在运行",
+  "unread": "未读",
   "This agent task no longer exists": "这个 Agent 任务已不存在",
   "Local checkout": "当前工作区",
   "Needs input": "等待输入",