diff --git a/apps/desktop/src/components/assistant-ui/thread/status.tsx b/apps/desktop/src/components/assistant-ui/thread/status.tsx
index b239f0fb8a8..5b9a5837c26 100644
--- a/apps/desktop/src/components/assistant-ui/thread/status.tsx
+++ b/apps/desktop/src/components/assistant-ui/thread/status.tsx
@@ -142,7 +142,11 @@ export const StreamStallIndicator: FC = () => {
     return `${s.message.content.length}:${textLength}`
   })
 
-  const [stalled, setStalled] = useState(false)
+  // Timestamp of the activity that preceded the current quiet spell, set once
+  // the spell qualifies as a stall. Holding the timestamp (not a boolean) is
+  // what lets the timer read "quiet for 12s" rather than the age of this
+  // component, which is the whole turn so far.
+  const [quietSince, setQuietSince] = useState<number | undefined>(undefined)
   const compacting = useStore($compactionActive)
   const turnTimerKey = useActiveTurnTimerKey()
   // A pending clarify / approval / sudo / secret means the turn is paused on the
@@ -151,14 +155,18 @@ export const StreamStallIndicator: FC = () => {
   const awaitingInput = useStore($activeSessionAwaitingInput)
 
   useEffect(() => {
-    setStalled(false)
-    const id = window.setTimeout(() => setStalled(true), STREAM_STALL_S * 1000)
+    setQuietSince(undefined)
+    const seenAt = Date.now()
+    const id = window.setTimeout(() => setQuietSince(seenAt), STREAM_STALL_S * 1000)
 
     return () => window.clearTimeout(id)
   }, [activity])
 
-  const active = (stalled || compacting) && !awaitingInput
-  const elapsed = useElapsedSeconds(active, compacting ? turnTimerKey : undefined)
+  const active = (quietSince !== undefined || compacting) && !awaitingInput
+
+  // Compaction owns the whole turn, so it keeps counting from the turn's start;
+  // a plain stall counts from the last thing the stream produced.
+  const elapsed = useElapsedSeconds(active, compacting ? turnTimerKey : undefined, compacting ? undefined : quietSince)
 
   if (!active) {
     return null
diff --git a/apps/desktop/src/components/chat/activity-timer.test.tsx b/apps/desktop/src/components/chat/activity-timer.test.tsx
index acc70a99ed0..4768f60c56e 100644
--- a/apps/desktop/src/components/chat/activity-timer.test.tsx
+++ b/apps/desktop/src/components/chat/activity-timer.test.tsx
@@ -3,8 +3,8 @@ import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 
 import { __resetElapsedTimerRegistryForTests, useElapsedSeconds } from './activity-timer'
 
-function Probe({ active, timerKey }: { active: boolean; timerKey?: string }) {
-  const elapsed = useElapsedSeconds(active, timerKey)
+function Probe({ active, since, timerKey }: { active: boolean; since?: number; timerKey?: string }) {
+  const elapsed = useElapsedSeconds(active, timerKey, since)
 
   return <span data-testid="elapsed">{elapsed}</span>
 }
@@ -40,4 +40,30 @@ describe('useElapsedSeconds', () => {
 
     expect(screen.getByTestId('elapsed').textContent).toBe('8')
   })
+
+  it('counts from an explicit epoch rather than mount time', () => {
+    const mountedAt = Date.now()
+
+    act(() => {
+      vi.advanceTimersByTime(30_000)
+    })
+
+    render(<Probe active since={mountedAt + 28_000} />)
+
+    expect(screen.getByTestId('elapsed').textContent).toBe('2')
+  })
+
+  it('re-anchors when the epoch moves', () => {
+    const { rerender } = render(<Probe active since={Date.now()} />)
+
+    act(() => {
+      vi.advanceTimersByTime(10_000)
+    })
+
+    expect(screen.getByTestId('elapsed').textContent).toBe('10')
+
+    rerender(<Probe active since={Date.now()} />)
+
+    expect(screen.getByTestId('elapsed').textContent).toBe('0')
+  })
 })
diff --git a/apps/desktop/src/components/chat/activity-timer.ts b/apps/desktop/src/components/chat/activity-timer.ts
index afb27fb02f3..9fe67642239 100644
--- a/apps/desktop/src/components/chat/activity-timer.ts
+++ b/apps/desktop/src/components/chat/activity-timer.ts
@@ -30,13 +30,22 @@ export function formatElapsed(seconds: number): string {
   return `${Math.floor(seconds / 60)}:${String(seconds % 60).padStart(2, '0')}`
 }
 
-export function useElapsedSeconds(active = true, timerKey?: string): number {
-  const start = useRef(startedAt(timerKey))
+/**
+ * Seconds since the timer's origin, reported once a second while `active`.
+ *
+ * Origin, in order: an explicit `since` timestamp, else the `timerKey`'s
+ * registry entry (survives unmount/remount), else mount time. Pass `since` when
+ * the thing being measured started at a moment the caller knows and that moment
+ * isn't the mount — otherwise an anonymous timer reports the component's age,
+ * which is only the same number by accident.
+ */
+export function useElapsedSeconds(active = true, timerKey?: string, since?: number): number {
+  const start = useRef(since ?? startedAt(timerKey))
   const lastKey = useRef(timerKey)
   const [elapsed, setElapsed] = useState(() => Math.max(0, Math.floor((Date.now() - start.current) / 1000)))
 
   if (lastKey.current !== timerKey) {
-    start.current = startedAt(timerKey)
+    start.current = since ?? startedAt(timerKey)
     lastKey.current = timerKey
   }
 
@@ -46,7 +55,9 @@ export function useElapsedSeconds(active = true, timerKey?: string): number {
       return
     }
 
-    if (timerKey) {
+    if (since !== undefined) {
+      start.current = since
+    } else if (timerKey) {
       start.current = startedAt(timerKey)
     }
 
@@ -55,7 +66,7 @@ export function useElapsedSeconds(active = true, timerKey?: string): number {
     const id = window.setInterval(tick, 1000)
 
     return () => window.clearInterval(id)
-  }, [active, timerKey])
+  }, [active, since, timerKey])
 
   return elapsed
 }