diff --git a/apps/server/docs/ai-context/metrics-ownership.md b/apps/server/docs/ai-context/metrics-ownership.md
index c12a0c03e..9a0229a4d 100644
--- a/apps/server/docs/ai-context/metrics-ownership.md
+++ b/apps/server/docs/ai-context/metrics-ownership.md
@@ -115,6 +115,7 @@
 - 前端 `posthog-js` 通过 `packages/stage-ui/src/stores/analytics/posthog.ts` 初始化，三个 app（web / desktop / pocket）按 `isStageTamagotchi()` 等选 project key
 - Server 不接入 `posthog-node`。后端产品事件写 `product_events`，Grafana 展示低基数聚合；需要 PostHog revenue/person analytics 时优先用 PostHog Stripe source connector 或离线导入，不允许在 API 请求路径同步发 PostHog。
 - 前端 identity：`useSharedAnalyticsStore.initialize()` watch `authStore.isAuthenticated` 自动调 `posthog.identify(user.id)` / `reset()`
+- Conversation controls 事件的 `surface` 由 `packages/stage-ui/src/composables/use-analytics.ts` 统一按 runtime 推断，UI 调用点只传业务字段。
 
 已埋点：
 
diff --git a/apps/stage-tamagotchi/src/renderer/components/InteractiveArea.vue b/apps/stage-tamagotchi/src/renderer/components/InteractiveArea.vue
index 1b3b350b5..55f612d23 100644
--- a/apps/stage-tamagotchi/src/renderer/components/InteractiveArea.vue
+++ b/apps/stage-tamagotchi/src/renderer/components/InteractiveArea.vue
@@ -63,7 +63,7 @@ const {
   trackChatMessageRetried,
   trackChatMessagesCleared,
 } = useAnalytics()
-const { showStopSpeakingButton, stopSpeakingFromChat } = useStopSpeakingButton('electron')
+const { showStopSpeakingButton, stopSpeakingFromChat } = useStopSpeakingButton()
 
 const latestImageEntries = computed(() => {
   if (!activeCardId.value)
@@ -207,7 +207,6 @@ async function handleDeleteMessage(index: number) {
   const message = messages.value[index]
   await chatSyncStore.requestDeleteMessage({ index })
   trackChatMessageDeleted({
-    surface: 'electron',
     source: 'history',
     message_role: message?.role ?? 'unknown',
   })
@@ -223,7 +222,6 @@ async function handleRetryMessage(index: number) {
     index,
   })
   trackChatMessageRetried({
-    surface: 'electron',
     source: 'history',
   })
 }
@@ -232,7 +230,6 @@ async function handleCleanupMessages() {
   const messageCount = messages.value.filter(message => message.role !== 'system').length
   await chatSyncStore.requestCleanup()
   trackChatMessagesCleared({
-    surface: 'electron',
     source: 'chat_controls',
     message_count: messageCount,
   })
diff --git a/packages/stage-layouts/src/components/Layouts/InteractiveArea.vue b/packages/stage-layouts/src/components/Layouts/InteractiveArea.vue
index e515ed2cb..62179601d 100644
--- a/packages/stage-layouts/src/components/Layouts/InteractiveArea.vue
+++ b/packages/stage-layouts/src/components/Layouts/InteractiveArea.vue
@@ -27,7 +27,6 @@ function handleDeleteMessage(index: number) {
   const message = messages.value[index]
   messages.value = messages.value.filter((_, messageIndex) => messageIndex !== index)
   trackChatMessageDeleted({
-    surface: 'web',
     source: 'history',
     message_role: message?.role ?? 'unknown',
   })
diff --git a/packages/stage-layouts/src/components/Layouts/MobileInteractiveArea.vue b/packages/stage-layouts/src/components/Layouts/MobileInteractiveArea.vue
index 81b6323f5..f038e08c3 100644
--- a/packages/stage-layouts/src/components/Layouts/MobileInteractiveArea.vue
+++ b/packages/stage-layouts/src/components/Layouts/MobileInteractiveArea.vue
@@ -46,7 +46,6 @@ function handleDeleteMessage(index: number) {
   const message = messages.value[index]
   messages.value = messages.value.filter((_, messageIndex) => messageIndex !== index)
   trackChatMessageDeleted({
-    surface: 'mobile',
     source: 'history',
     message_role: message?.role ?? 'unknown',
   })
@@ -56,7 +55,6 @@ function handleCleanupMessages() {
   const messageCount = messages.value.filter(message => message.role !== 'system').length
   cleanupMessages()
   trackChatMessagesCleared({
-    surface: 'mobile',
     source: 'chat_controls',
     message_count: messageCount,
   })
@@ -94,7 +92,7 @@ const { isListening, startStreamingTranscription, stopStreamingTranscription } =
     isStageTamagotchi,
   },
 )
-const { showStopSpeakingButton, stopSpeakingFromChat } = useStopSpeakingButton('mobile')
+const { showStopSpeakingButton, stopSpeakingFromChat } = useStopSpeakingButton()
 const toggleTranscription = () => isListening.value ? stopStreamingTranscription() : startStreamingTranscription()
 
 async function handleSubmit() {
diff --git a/packages/stage-layouts/src/components/Widgets/ChatActionButtons.vue b/packages/stage-layouts/src/components/Widgets/ChatActionButtons.vue
index 1871be0c4..185ea66e5 100644
--- a/packages/stage-layouts/src/components/Widgets/ChatActionButtons.vue
+++ b/packages/stage-layouts/src/components/Widgets/ChatActionButtons.vue
@@ -21,7 +21,6 @@ function handleCleanupMessages() {
   const messageCount = messages.value.filter(message => message.role !== 'system').length
   cleanupMessages()
   trackChatMessagesCleared({
-    surface: 'web',
     source: 'chat_controls',
     message_count: messageCount,
   })
diff --git a/packages/stage-layouts/src/components/Widgets/ChatArea.vue b/packages/stage-layouts/src/components/Widgets/ChatArea.vue
index bd0300d18..4d88feb60 100644
--- a/packages/stage-layouts/src/components/Widgets/ChatArea.vue
+++ b/packages/stage-layouts/src/components/Widgets/ChatArea.vue
@@ -60,7 +60,7 @@ const { isListening, startStreamingTranscription, stopStreamingTranscription, au
     isStageTamagotchi,
   },
 )
-const { showStopSpeakingButton, stopSpeakingFromChat } = useStopSpeakingButton('web')
+const { showStopSpeakingButton, stopSpeakingFromChat } = useStopSpeakingButton()
 
 async function handleSend() {
   if (!messageInput.value.trim() || isComposing.value) {
diff --git a/packages/stage-layouts/src/composables/useStopSpeakingButton.test.ts b/packages/stage-layouts/src/composables/useStopSpeakingButton.test.ts
index 631e1902a..776a6ef1a 100644
--- a/packages/stage-layouts/src/composables/useStopSpeakingButton.test.ts
+++ b/packages/stage-layouts/src/composables/useStopSpeakingButton.test.ts
@@ -33,7 +33,7 @@ describe('useStopSpeakingButton', () => {
   it('shows the manual stop button only while the assistant is speaking', () => {
     nowSpeaking.value = false
 
-    const { showStopSpeakingButton } = useStopSpeakingButton('web')
+    const { showStopSpeakingButton } = useStopSpeakingButton()
 
     expect(showStopSpeakingButton.value).toBe(false)
 
@@ -46,13 +46,12 @@ describe('useStopSpeakingButton', () => {
     requestStopSpeakingMock.mockClear()
     trackTtsStopClickedMock.mockClear()
 
-    const { stopSpeakingFromChat } = useStopSpeakingButton('mobile')
+    const { stopSpeakingFromChat } = useStopSpeakingButton()
 
     stopSpeakingFromChat()
 
     expect(requestStopSpeakingMock).toHaveBeenCalledWith('manual-chat')
     expect(trackTtsStopClickedMock).toHaveBeenCalledWith({
-      surface: 'mobile',
       reason: 'manual-chat',
     })
   })
diff --git a/packages/stage-layouts/src/composables/useStopSpeakingButton.ts b/packages/stage-layouts/src/composables/useStopSpeakingButton.ts
index ea35562dc..8c64955d4 100644
--- a/packages/stage-layouts/src/composables/useStopSpeakingButton.ts
+++ b/packages/stage-layouts/src/composables/useStopSpeakingButton.ts
@@ -1,5 +1,3 @@
-import type { ConversationAnalyticsSurface } from '@proj-airi/stage-ui/composables/use-analytics'
-
 import { useAnalytics } from '@proj-airi/stage-ui/composables/use-analytics'
 import { useSpeakingStore } from '@proj-airi/stage-ui/stores/audio'
 import { useSpeechOutputControlStore } from '@proj-airi/stage-ui/stores/speech-output-control'
@@ -18,7 +16,7 @@ import { computed } from 'vue'
  * Returns:
  * - Visibility state for the button and a click handler for manual chat stops.
  */
-export function useStopSpeakingButton(surface: ConversationAnalyticsSurface) {
+export function useStopSpeakingButton() {
   const { nowSpeaking } = storeToRefs(useSpeakingStore())
   const speechOutputControlStore = useSpeechOutputControlStore()
   const { trackTtsStopClicked } = useAnalytics()
@@ -26,7 +24,7 @@ export function useStopSpeakingButton(surface: ConversationAnalyticsSurface) {
   const showStopSpeakingButton = computed(() => nowSpeaking.value)
 
   function stopSpeakingFromChat() {
-    trackTtsStopClicked({ surface, reason: 'manual-chat' })
+    trackTtsStopClicked({ reason: 'manual-chat' })
     speechOutputControlStore.requestStopSpeaking('manual-chat')
   }
 
diff --git a/packages/stage-ui/src/components/scenarios/chat/components/sessions-drawer.vue b/packages/stage-ui/src/components/scenarios/chat/components/sessions-drawer.vue
index 2967ade77..306a6c137 100644
--- a/packages/stage-ui/src/components/scenarios/chat/components/sessions-drawer.vue
+++ b/packages/stage-ui/src/components/scenarios/chat/components/sessions-drawer.vue
@@ -157,7 +157,6 @@ async function selectSession(sessionId: string) {
   const selectedRow = rows.value.find(row => row.meta.sessionId === sessionId)
   if (sessionId !== activeSessionId.value && selectedRow) {
     trackChatSessionSelected({
-      surface: isDesktop.value ? 'web' : 'mobile',
       source: 'sessions_drawer',
       message_count: (sessionMessages.value[sessionId] ?? []).filter(message => message.role !== 'system').length,
       cloud_synced: !!selectedRow.meta.cloudChatId,
diff --git a/packages/stage-ui/src/composables/use-analytics.test.ts b/packages/stage-ui/src/composables/use-analytics.test.ts
index d0ca05763..73d8460ec 100644
--- a/packages/stage-ui/src/composables/use-analytics.test.ts
+++ b/packages/stage-ui/src/composables/use-analytics.test.ts
@@ -5,11 +5,18 @@ import { useAnalytics } from './use-analytics'
 
 const analyticsMocks = vi.hoisted(() => ({
   ensurePosthogInitializedMock: vi.fn(() => true),
+  isStageCapacitorMock: vi.fn(() => false),
+  isStageTamagotchiMock: vi.fn(() => false),
   isPosthogAvailableInBuildMock: vi.fn(() => true),
   markFirstMessageTrackedMock: vi.fn(),
   posthogCaptureMock: vi.fn(),
 }))
 
+vi.mock('@proj-airi/stage-shared', () => ({
+  isStageCapacitor: analyticsMocks.isStageCapacitorMock,
+  isStageTamagotchi: analyticsMocks.isStageTamagotchiMock,
+}))
+
 vi.mock('posthog-js', () => ({
   default: {
     capture: analyticsMocks.posthogCaptureMock,
@@ -56,56 +63,57 @@ describe('useAnalytics conversation product events', () => {
     analyticsMocks.posthogCaptureMock.mockClear()
     analyticsMocks.markFirstMessageTrackedMock.mockClear()
     analyticsMocks.ensurePosthogInitializedMock.mockClear()
+    analyticsMocks.isStageCapacitorMock.mockReset()
+    analyticsMocks.isStageTamagotchiMock.mockReset()
+    analyticsMocks.isStageCapacitorMock.mockReturnValue(false)
+    analyticsMocks.isStageTamagotchiMock.mockReturnValue(false)
     analyticsMocks.isPosthogAvailableInBuildMock.mockClear()
   })
 
-  it('tracks manual TTS stop clicks with the UI surface and reason', () => {
+  it('infers the web surface for browser conversation actions', () => {
     const analytics = useAnalytics()
 
     analytics.trackTtsStopClicked({
-      surface: 'mobile',
       reason: 'manual-chat',
     })
 
     expect(analyticsMocks.posthogCaptureMock).toHaveBeenCalledWith('tts_stop_clicked', {
-      surface: 'mobile',
+      surface: 'web',
       reason: 'manual-chat',
     })
   })
 
-  it('tracks chat session selection from the sessions drawer', () => {
+  it('infers the mobile surface for capacitor conversation actions', () => {
+    analyticsMocks.isStageCapacitorMock.mockReturnValue(true)
     const analytics = useAnalytics()
 
     analytics.trackChatSessionSelected({
-      surface: 'web',
       source: 'sessions_drawer',
       message_count: 4,
       cloud_synced: true,
     })
 
     expect(analyticsMocks.posthogCaptureMock).toHaveBeenCalledWith('chat_session_selected', {
-      surface: 'web',
+      surface: 'mobile',
       source: 'sessions_drawer',
       message_count: 4,
       cloud_synced: true,
     })
   })
 
-  it('tracks destructive and recovery chat message actions', () => {
+  it('infers the electron surface for destructive and recovery chat message actions', () => {
+    analyticsMocks.isStageTamagotchiMock.mockReturnValue(true)
     const analytics = useAnalytics()
 
     analytics.trackChatMessageDeleted({
-      surface: 'electron',
       source: 'history',
       message_role: 'assistant',
     })
     analytics.trackChatMessagesCleared({
-      surface: 'electron',
       source: 'chat_controls',
       message_count: 3,
     })
     analytics.trackChatMessageRetried({
-      surface: 'electron',
       source: 'history',
     })
 
diff --git a/packages/stage-ui/src/composables/use-analytics.ts b/packages/stage-ui/src/composables/use-analytics.ts
index ac4e99128..9bdcda375 100644
--- a/packages/stage-ui/src/composables/use-analytics.ts
+++ b/packages/stage-ui/src/composables/use-analytics.ts
@@ -1,5 +1,6 @@
 import posthog from 'posthog-js'
 
+import { isStageCapacitor, isStageTamagotchi } from '@proj-airi/stage-shared'
 import { computed } from 'vue'
 import { useI18n } from 'vue-i18n'
 
@@ -19,6 +20,16 @@ export type ConversationAnalyticsSurface = 'web' | 'mobile' | 'electron'
  */
 export type ConversationAnalyticsSource = 'chat_controls' | 'history' | 'sessions_drawer'
 
+function getConversationAnalyticsSurface(): ConversationAnalyticsSurface {
+  if (isStageTamagotchi())
+    return 'electron'
+
+  if (isStageCapacitor())
+    return 'mobile'
+
+  return 'web'
+}
+
 export function useAnalytics() {
   const analyticsStore = useSharedAnalyticsStore()
   const settingsAnalytics = useSettingsAnalytics()
@@ -219,34 +230,49 @@ export function useAnalytics() {
 
   // ─── Conversation action events ─────────────────────────────────────
 
-  function trackTtsStopClicked(properties: { surface: ConversationAnalyticsSurface, reason: 'manual-chat' }) {
+  function trackTtsStopClicked(properties: { reason: 'manual-chat' }) {
     if (!canCapture())
       return
-    posthog.capture('tts_stop_clicked', properties)
+    posthog.capture('tts_stop_clicked', {
+      ...properties,
+      surface: getConversationAnalyticsSurface(),
+    })
   }
 
-  function trackChatSessionSelected(properties: { surface: ConversationAnalyticsSurface, source: 'sessions_drawer', message_count: number, cloud_synced: boolean }) {
+  function trackChatSessionSelected(properties: { source: 'sessions_drawer', message_count: number, cloud_synced: boolean }) {
     if (!canCapture())
       return
-    posthog.capture('chat_session_selected', properties)
+    posthog.capture('chat_session_selected', {
+      ...properties,
+      surface: getConversationAnalyticsSurface(),
+    })
   }
 
-  function trackChatMessageDeleted(properties: { surface: ConversationAnalyticsSurface, source: 'history', message_role: string }) {
+  function trackChatMessageDeleted(properties: { source: 'history', message_role: string }) {
     if (!canCapture())
       return
-    posthog.capture('chat_message_deleted', properties)
+    posthog.capture('chat_message_deleted', {
+      ...properties,
+      surface: getConversationAnalyticsSurface(),
+    })
   }
 
-  function trackChatMessagesCleared(properties: { surface: ConversationAnalyticsSurface, source: 'chat_controls', message_count: number }) {
+  function trackChatMessagesCleared(properties: { source: 'chat_controls', message_count: number }) {
     if (!canCapture())
       return
-    posthog.capture('chat_messages_cleared', properties)
+    posthog.capture('chat_messages_cleared', {
+      ...properties,
+      surface: getConversationAnalyticsSurface(),
+    })
   }
 
-  function trackChatMessageRetried(properties: { surface: ConversationAnalyticsSurface, source: 'history' }) {
+  function trackChatMessageRetried(properties: { source: 'history' }) {
     if (!canCapture())
       return
-    posthog.capture('chat_message_retried', properties)
+    posthog.capture('chat_message_retried', {
+      ...properties,
+      surface: getConversationAnalyticsSurface(),
+    })
   }
 
   // ─── STT events ──────────────────────────────────────────────────────