diff --git a/apps/mobile/src/features/threads/thread-list-v2-items.tsx b/apps/mobile/src/features/threads/thread-list-v2-items.tsx
index 3951ffef8cab2..717872c77b6af 100644
--- a/apps/mobile/src/features/threads/thread-list-v2-items.tsx
+++ b/apps/mobile/src/features/threads/thread-list-v2-items.tsx
@@ -14,17 +14,14 @@ import { appAtomRegistry } from "../../state/atom-registry";
 import { threadArrangementOpenAtom } from "../../state/thread-order";
 import { threadEnvironment } from "../../state/threads";
 import { useAtomCommand } from "../../state/use-atom-command";
-import { useVisibleSecondClock } from "./use-visible-second-clock";
+import { useVisibleWorkingDurationLabel } from "./use-visible-working-duration-label";
 import type { ThreadMoveDestination } from "./threadOrder";
 import type {
   EnvironmentProject,
   EnvironmentThreadShell,
 } from "@t3tools/client-runtime/state/shell";
 import type { EnvironmentThreadSearchMatch } from "@t3tools/client-runtime/state/thread-search";
-import {
-  formatWorkingDurationLabel,
-  resolveThreadWorkingStartedAt,
-} from "@t3tools/client-runtime/state/models";
+import { resolveThreadWorkingStartedAt } from "@t3tools/client-runtime/state/models";
 import { AuthOrchestrationOperateScope, type EnvironmentMachineKind } from "@t3tools/contracts";
 import type { SnoozePresetSetting } from "@t3tools/contracts/settings";
 import { canSnooze } from "@t3tools/client-runtime/state/thread-settled";
@@ -140,10 +137,7 @@ const DONE_STATUS_LABEL: StatusLabel = {
 };
 
 function ThreadListV2Duration(props: { readonly startedAt: string | null }) {
-  const startedAtMs = Date.parse(props.startedAt ?? "");
-  const nowMs = useVisibleSecondClock(Number.isFinite(startedAtMs));
-  if (!Number.isFinite(startedAtMs)) return null;
-  return ` ${formatWorkingDurationLabel(nowMs - startedAtMs)}`;
+  return useVisibleWorkingDurationLabel(props.startedAt);
 }
 
 const CARD_MENU_ACTIONS: MenuAction[] = [
diff --git a/apps/mobile/src/features/threads/use-visible-working-duration-label.test.tsx b/apps/mobile/src/features/threads/use-visible-working-duration-label.test.tsx
new file mode 100644
index 0000000000000..042c7437f4ed2
--- /dev/null
+++ b/apps/mobile/src/features/threads/use-visible-working-duration-label.test.tsx
@@ -0,0 +1,265 @@
+import {
+  NavigationContext,
+  type NavigationProp,
+  type ParamListBase,
+} from "@react-navigation/native";
+import { act } from "react";
+import { createRoot } from "react-dom/client";
+import { expect, it, vi } from "vite-plus/test";
+
+const native = vi.hoisted(() => ({
+  appState: {
+    currentState: "active",
+    listeners: new Set<(state: string) => void>(),
+    addEventListener(_event: string, listener: (state: string) => void) {
+      native.appState.listeners.add(listener);
+      return { remove: () => native.appState.listeners.delete(listener) };
+    },
+  },
+}));
+
+vi.mock("react-native", () => ({ AppState: native.appState }));
+vi.mock("@react-navigation/native", async () => {
+  const { createRequire } = await import("node:module");
+  const requireNavigation = createRequire(
+    createRequire(import.meta.url).resolve("@react-navigation/native/package.json"),
+  );
+  // Exercise the real focus subscription without loading native navigation views.
+  const { NavigationContext, useIsFocused } = requireNavigation("@react-navigation/core");
+  return { NavigationContext, useIsFocused };
+});
+
+import { useVisibleWorkingDurationLabel } from "./use-visible-working-duration-label";
+
+const timestamp = (ms: number) => new Date(ms).toISOString();
+
+function setup(startedAt: string | null, nowMs = 0, active = true, focusedInitially = true) {
+  (globalThis as { IS_REACT_ACT_ENVIRONMENT?: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
+  vi.useFakeTimers();
+  vi.setSystemTime(nowMs);
+  native.appState.currentState = active ? "active" : "background";
+  native.appState.listeners.clear();
+  let focused = focusedInitially;
+  const focusListeners = new Set<() => void>();
+  const navigation = {
+    isFocused: () => focused,
+    addListener: (_event: string, listener: () => void) => {
+      focusListeners.add(listener);
+      return () => focusListeners.delete(listener);
+    },
+  } as unknown as NavigationProp<ParamListBase>;
+  let executions = 0;
+  const starts = [{ id: "first", value: startedAt }];
+  function Probe(props: { readonly startedAt: string | null }) {
+    executions++;
+    return useVisibleWorkingDurationLabel(props.startedAt);
+  }
+  const host = document.createElement("div");
+  const root = createRoot(host);
+  const render = (start: string | null) => {
+    starts[0]!.value = start;
+    act(() =>
+      root.render(
+        <NavigationContext.Provider value={navigation}>
+          {starts.map(({ id, value }) => (
+            <span key={id}>
+              <Probe startedAt={value} />
+            </span>
+          ))}
+        </NavigationContext.Provider>,
+      ),
+    );
+  };
+  render(startedAt);
+  return {
+    label: () => host.textContent,
+    labels: () => Array.from(host.children, (element) => element.textContent),
+    addLabel: (start: string | null) => {
+      starts.push({ id: `label-${starts.length}`, value: start });
+      render(starts[0]!.value);
+    },
+    executions: () => executions,
+    rebind: render,
+    advance: (ms: number) => act(() => vi.advanceTimersByTime(ms)),
+    focus: (next: boolean) =>
+      act(() => {
+        focused = next;
+        for (const listener of focusListeners) listener();
+      }),
+    appState: (state: string) =>
+      act(() => {
+        native.appState.currentState = state;
+        for (const listener of native.appState.listeners) listener(state);
+      }),
+    [Symbol.dispose]: () => {
+      act(() => root.unmount());
+      expect(vi.getTimerCount()).toBe(0);
+      expect(native.appState.listeners.size).toBe(0);
+      expect(focusListeners.size).toBe(0);
+      vi.useRealTimers();
+    },
+  };
+}
+
+it("publishes only the two label changes across 120 individually delivered minute-age ticks", () => {
+  using screen = setup(timestamp(0), 180_000);
+  const initialExecutions = screen.executions();
+  const labels = [screen.label()];
+  for (let second = 1; second <= 120; second++) {
+    screen.advance(1_000);
+    labels.push(screen.label());
+  }
+  expect(labels).toEqual([
+    ...Array.from({ length: 60 }, () => " 3m"),
+    ...Array.from({ length: 60 }, () => " 4m"),
+    " 5m",
+  ]);
+  expect(screen.executions() - initialExecutions).toBe(2);
+  expect(vi.getTimerCount()).toBe(1);
+});
+
+it("keeps second labels and on-phase minute and hour boundaries", () => {
+  using screen = setup(timestamp(0), 58_000);
+  screen.advance(1_000);
+  expect(screen.label()).toBe(" 59s");
+  screen.advance(999);
+  expect(screen.label()).toBe(" 59s");
+  screen.advance(1);
+  expect(screen.label()).toBe(" 1m");
+  screen.rebind(timestamp(-60_000));
+  expect(screen.label()).toBe(" 2m");
+  screen.rebind(timestamp(-3_539_000));
+  expect(screen.label()).toBe(" 59m");
+  screen.advance(1_000);
+  expect(screen.label()).toBe(" 1h 0m");
+});
+
+it.each([
+  [59_999, " 59s", " 1m"],
+  [119_999, " 1m", " 2m"],
+  [3_599_999, " 59m", " 1h 0m"],
+] as const)("matches the shared wall-clock boundary across age %i", (age, before, after) => {
+  using screen = setup(timestamp(0), age);
+  expect(screen.label()).toBe(before);
+  screen.advance(1);
+  expect(screen.label()).toBe(after);
+});
+
+it("uses the shared second sample for off-grid and rebound starts", () => {
+  using screen = setup(timestamp(500), 180_250);
+  expect(screen.label()).toBe(" 2m");
+  screen.advance(749);
+  expect(screen.label()).toBe(" 2m");
+  screen.advance(1);
+  expect(screen.label()).toBe(" 3m");
+  screen.advance(600);
+  screen.rebind(timestamp(121_500));
+  expect(screen.label()).toBe(" 59s");
+  screen.advance(399);
+  expect(screen.label()).toBe(" 59s");
+  screen.advance(1);
+  expect(screen.label()).toBe(" 1m");
+  expect(vi.getTimerCount()).toBe(1);
+});
+
+it("shares one aligned timer across staggered labels and releases it when all pause", () => {
+  using screen = setup(timestamp(0), 59_250);
+  screen.advance(250);
+  screen.addLabel(timestamp(0));
+  screen.advance(250);
+  screen.addLabel(timestamp(0));
+  expect(screen.labels()).toEqual([" 59s", " 59s", " 59s"]);
+  expect(vi.getTimerCount()).toBe(1);
+  screen.advance(249);
+  expect(screen.labels()).toEqual([" 59s", " 59s", " 59s"]);
+  screen.advance(1);
+  expect(screen.labels()).toEqual([" 1m", " 1m", " 1m"]);
+  screen.focus(false);
+  expect(vi.getTimerCount()).toBe(0);
+  screen.advance(60_000);
+  expect(screen.labels()).toEqual([" 1m", " 1m", " 1m"]);
+  screen.focus(true);
+  expect(screen.labels()).toEqual([" 2m", " 2m", " 2m"]);
+  expect(vi.getTimerCount()).toBe(1);
+});
+
+it.each([null, "", "invalid"])("does not tick for missing/invalid start %s", (start) => {
+  using screen = setup(start, 180_000);
+  expect(screen.label()).toBe("");
+  expect(vi.getTimerCount()).toBe(0);
+  screen.advance(15_000);
+  screen.rebind(timestamp(0));
+  expect(screen.label()).toBe(" 3m");
+  expect(vi.getTimerCount()).toBe(1);
+  screen.rebind(start);
+  expect(screen.label()).toBe("");
+  expect(vi.getTimerCount()).toBe(0);
+});
+
+it("clamps future starts without publishing equal zero labels", () => {
+  using screen = setup(timestamp(2_000));
+  const initialExecutions = screen.executions();
+  screen.advance(1_000);
+  screen.advance(1_000);
+  expect(screen.label()).toBe(" 0s");
+  expect(screen.executions()).toBe(initialExecutions);
+  screen.advance(1_000);
+  expect(screen.label()).toBe(" 1s");
+});
+
+it("pauses on blur, reads the shared sample on rebinding, and refreshes on focus", () => {
+  using screen = setup(timestamp(0), 59_250);
+  screen.advance(350);
+  screen.focus(false);
+  expect(vi.getTimerCount()).toBe(0);
+  const pausedExecutions = screen.executions();
+  screen.advance(60_000);
+  expect(screen.label()).toBe(" 59s");
+  expect(screen.executions()).toBe(pausedExecutions);
+  screen.rebind(timestamp(-1_000));
+  expect(screen.label()).toBe(" 2m");
+  screen.focus(true);
+  expect(screen.label()).toBe(" 2m");
+  screen.rebind(timestamp(60_000));
+  expect(screen.label()).toBe(" 59s");
+  screen.advance(399);
+  expect(screen.label()).toBe(" 59s");
+  screen.advance(1);
+  expect(screen.label()).toBe(" 1m");
+});
+
+it.each(["inactive", "background"])(
+  "pauses while %s and refreshes immediately on active",
+  (state) => {
+    using screen = setup(timestamp(0), 59_250);
+    screen.appState(state);
+    expect(vi.getTimerCount()).toBe(0);
+    screen.advance(61_000);
+    expect(screen.label()).toBe(" 59s");
+    screen.appState("active");
+    expect(screen.label()).toBe(" 2m");
+    expect(vi.getTimerCount()).toBe(1);
+    screen.focus(false);
+    screen.appState("background");
+    screen.advance(60_000);
+    screen.appState("active");
+    expect(vi.getTimerCount()).toBe(0);
+    expect(screen.label()).toBe(" 3m");
+    screen.focus(true);
+    expect(screen.label()).toBe(" 3m");
+  },
+);
+
+it.each([
+  [false, true],
+  [true, false],
+] as const)("starts paused when active=%s focused=%s", (active, focused) => {
+  using screen = setup(timestamp(0), 59_000, active, focused);
+  expect(screen.label()).toBe(" 59s");
+  expect(vi.getTimerCount()).toBe(0);
+  screen.advance(61_000);
+  screen.appState("active");
+  screen.focus(true);
+  expect(screen.label()).toBe(" 2m");
+  expect(vi.getTimerCount()).toBe(1);
+});
diff --git a/apps/mobile/src/features/threads/use-visible-working-duration-label.ts b/apps/mobile/src/features/threads/use-visible-working-duration-label.ts
new file mode 100644
index 0000000000000..e965828e522d5
--- /dev/null
+++ b/apps/mobile/src/features/threads/use-visible-working-duration-label.ts
@@ -0,0 +1,26 @@
+import { formatWorkingDurationLabel } from "@t3tools/client-runtime/state/models";
+import { secondTick } from "@t3tools/client-runtime/clock";
+import { useIsFocused } from "@react-navigation/native";
+import { useCallback, useSyncExternalStore } from "react";
+import { useAppActive } from "../../lib/appState";
+
+const subscribeNever = () => () => undefined;
+
+export function useVisibleWorkingDurationLabel(startedAt: string | null): string | null {
+  const startedAtMs = Date.parse(startedAt ?? "");
+  const focused = useIsFocused();
+  const appActive = useAppActive();
+  const ticking = Number.isFinite(startedAtMs) && focused && appActive;
+  const getSnapshot = useCallback(
+    () =>
+      Number.isFinite(startedAtMs)
+        ? ` ${formatWorkingDurationLabel(secondTick.getSnapshot() - startedAtMs)}`
+        : null,
+    [startedAtMs],
+  );
+  return useSyncExternalStore(
+    ticking ? secondTick.subscribe : subscribeNever,
+    getSnapshot,
+    getSnapshot,
+  );
+}
diff --git a/apps/mobile/vite.config.ts b/apps/mobile/vite.config.ts
index 6e24636671608..988623be26967 100644
--- a/apps/mobile/vite.config.ts
+++ b/apps/mobile/vite.config.ts
@@ -4,6 +4,7 @@ import { defineConfig, normalizePath } from "vite-plus";
 import "vite-plus/test/config";
 
 const reactTests = [
+  "src/features/threads/use-visible-working-duration-label.test.tsx",
   "src/features/workspace/workspace-tabs-state.test.ts",
   "src/state/use-thread-pr.demand.test.tsx",
   "src/features/threads/git/GitBranchesSheet.occupancy.test.tsx",