🐛(frontend) harden speaker test against missing sinks and play errors

- Only call `setSinkId` when supported and the device is actually
  enumerated: LiveKit can fall back to a stale id on browsers (e.g.
  WebKit) that expose no such device, making `setSinkId` throw
  `NotFoundError`.
- Await `audio.play()` and reset the playing state on failure, to
  avoid a stuck button and an unhandled rejection.
- Use an absolute `/sounds/uprise.mp3` URL so the asset resolves
  regardless of the current SPA route.

CHANGELOG.md

@@ -8,10 +8,6 @@ and this project adheres to
 
 ## [Unreleased]
 
-### Changed
-
-- 🔥(frontend) drop unused vendored ConnectionObserver
-
 ### Fixed
 
 - 📈(frontend) downgrade unreachable external home URL from error to event

src/frontend/src/features/rooms/components/Conference.tsx

@@ -30,6 +30,7 @@ import { useConfig } from '@/api/useConfig'
 import { isFireFox } from '@/utils/livekit'
 import { useIsMobile } from '@/utils/useIsMobile'
 import { navigateTo } from '@/navigation/navigateTo'
+import { connectionObserverStore } from '@/stores/connectionObserver'
 import { PictureInPictureConference } from '@/features/pip/components/PictureInPictureConference'
 import { notifyAutoMutedOnJoin } from '@/features/notifications/utils'
 import { useSnapshot } from 'valtio'
@@ -246,8 +247,23 @@ export const Conference = ({
           onDisconnected={(e) => {
             const metadata = {
               room_id: roomId,
+              pc_publisher: connectionObserverStore.publisher && {
+                ...connectionObserverStore.publisher,
+              },
+              pc_subscriber: connectionObserverStore.subscriber && {
+                ...connectionObserverStore.subscriber,
+              },
+              pc_publisher_changes_count:
+                connectionObserverStore.publisherChangesCount,
+              pc_subscriber_changes_count:
+                connectionObserverStore.subscriberChangesCount,
             }
 
+            connectionObserverStore.publisher = null
+            connectionObserverStore.publisherChangesCount = 0
+            connectionObserverStore.subscriber = null
+            connectionObserverStore.subscriberChangesCount = 0
+
             switch (e) {
               case DisconnectReason.CLIENT_INITIATED:
                 navigateTo(

src/frontend/src/features/rooms/components/Rating.tsx

@@ -5,6 +5,7 @@ import { useTranslation } from 'react-i18next'
 import { styled, VStack } from '@/styled-system/jsx'
 import { Button as RACButton } from 'react-aria-components'
 import { useIsAnalyticsEnabled } from '@/features/analytics/hooks/useIsAnalyticsEnabled'
+import type { CandidateInfo } from '@/stores/connectionObserver'
 import { captureEvent } from '@/features/analytics/telemetry'
 
 const Card = styled('div', {
@@ -239,6 +240,10 @@ const ConfirmationMessage = ({ onNext }: { onNext: () => void }) => {
 
 type RatingMetadata = {
   room_id?: string
+  pc_publisher?: CandidateInfo
+  pc_subscriber?: CandidateInfo
+  pc_publisher_changes_count?: number
+  pc_subscriber_changes_count?: number
 }
 
 export const Rating = ({

src/frontend/src/features/rooms/livekit/components/ConnectionObserver.tsx

@@ -9,16 +9,28 @@ import { useSnapshot } from 'valtio'
 import { DisconnectReason, RoomEvent } from 'livekit-client'
 
 import { userPreferencesStore } from '@/stores/userPreferences'
-
-import { captureEvent, captureMediaEvent } from '@/features/analytics/telemetry'
 import { connectionObserverStore } from '@/stores/connectionObserver'
 
+import { useFeatureFlagEnabled } from 'posthog-js/react'
+import { isMobileBrowser } from '@livekit/components-core'
+import { FeatureFlags } from '@/features/analytics/enums'
+import { captureEvent, captureMediaEvent } from '@/features/analytics/telemetry'
+
+const CANDIDATE_POLL_INTERVAL_MS = 5000
+
 export const ConnectionObserver = () => {
   const room = useRoomContext()
   const connectionStartTimeRef = useRef<number | null>(null)
 
   const { data } = useConfig()
   const isAnalyticsEnabled = useIsAnalyticsEnabled()
+
+  const featureEnabled = useFeatureFlagEnabled(FeatureFlags.candidatePolling)
+  const isMobile = isMobileBrowser()
+
+  const isAdvancedConnectionObserverEnabled =
+    !isMobile && isAnalyticsEnabled && featureEnabled
+
   const userPreferencesSnap = useSnapshot(userPreferencesStore)
 
   const idleDisconnectModalTimeoutRef = useRef<ReturnType<
@@ -68,6 +80,100 @@ export const ConnectionObserver = () => {
     userPreferencesSnap.is_idle_disconnect_modal_enabled,
   ])
 
+  useEffect(() => {
+    if (!isAdvancedConnectionObserverEnabled) return
+    if (!room) return
+
+    let interval: ReturnType<typeof setInterval> | null = null
+
+    const pollCandidate = async (
+      label: 'publisher' | 'subscriber',
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      pc?: any
+    ) => {
+      if (!pc) return
+
+      let stats: RTCStatsReport
+      try {
+        stats = await pc.getStats()
+      } catch {
+        return
+      }
+
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      stats.forEach((report: any) => {
+        if (
+          report.type === 'candidate-pair' &&
+          report.state === 'succeeded' &&
+          report.nominated
+        ) {
+          const remoteCandidate = stats.get(report.remoteCandidateId)
+          if (!remoteCandidate) return
+
+          const next = {
+            type: remoteCandidate.candidateType,
+            address: remoteCandidate.address,
+            protocol: remoteCandidate.protocol,
+          }
+
+          const current = connectionObserverStore[label]
+
+          const hasChanged =
+            current?.type !== next.type ||
+            current?.address !== next.address ||
+            current?.protocol !== next.protocol
+
+          if (hasChanged) {
+            connectionObserverStore[label] = next
+            const key = `${label}ChangesCount` as const
+            connectionObserverStore[key] =
+              (connectionObserverStore[key] || 0) + 1
+          }
+        }
+      })
+    }
+
+    const poll = async () => {
+      const publisher = room.engine?.pcManager?.publisher
+      const subscriber = room.engine?.pcManager?.subscriber
+
+      await Promise.all([
+        pollCandidate('publisher', publisher),
+        pollCandidate('subscriber', subscriber),
+      ])
+    }
+
+    const startPolling = async () => {
+      if (interval) return // prevent duplicates
+
+      // Initial snapshot
+      await poll()
+
+      interval = setInterval(poll, CANDIDATE_POLL_INTERVAL_MS)
+    }
+
+    const stopPolling = () => {
+      if (!interval) return
+      clearInterval(interval)
+      interval = null
+    }
+
+    room.on(RoomEvent.Connected, startPolling)
+    room.on(RoomEvent.Reconnected, startPolling)
+
+    room.on(RoomEvent.Reconnecting, stopPolling)
+    room.on(RoomEvent.Disconnected, stopPolling)
+
+    return () => {
+      stopPolling()
+
+      room.off(RoomEvent.Connected, startPolling)
+      room.off(RoomEvent.Reconnected, startPolling)
+      room.off(RoomEvent.Reconnecting, stopPolling)
+      room.off(RoomEvent.Disconnected, stopPolling)
+    }
+  }, [room, isAdvancedConnectionObserverEnabled])
+
   useEffect(() => {
     if (!isAnalyticsEnabled) return
 

src/frontend/src/features/rooms/routes/Feedback.tsx

@@ -6,6 +6,7 @@ import { Rating } from '@/features/rooms/components/Rating.tsx'
 import { useLocation } from 'wouter'
 import { useMemo } from 'react'
 import { DisconnectReason } from 'livekit-client'
+import type { CandidateInfo } from '@/stores/connectionObserver'
 
 // fixme - duplicated with home, refactor in a proper style
 const Heading = styled('h1', {
@@ -47,6 +48,10 @@ const FeedbackRoute = () => {
     const state = window.history.state
     return {
       room_id: state?.room_id as string,
+      pc_publisher: state?.pc_publisher as CandidateInfo,
+      pc_publisher_changes_count: state?.pc_publisher_changes_count as number,
+      pc_subscriber: state?.pc_subscriber as CandidateInfo,
+      pc_subscriber_changes_count: state?.pc_subscriber_changes_count as number,
     }
   }, [])
 

src/frontend/src/stores/connectionObserver.ts

@@ -1,9 +1,23 @@
 import { proxy } from 'valtio'
 
+export type CandidateInfo = {
+  type: string
+  address: string
+  protocol: string
+}
+
 type State = {
   isIdleDisconnectModalOpen: boolean
+  publisher: CandidateInfo | null
+  publisherChangesCount: number
+  subscriber: CandidateInfo | null
+  subscriberChangesCount: number
 }
 
 export const connectionObserverStore = proxy<State>({
   isIdleDisconnectModalOpen: false,
+  publisher: null,
+  publisherChangesCount: 0,
+  subscriber: null,
+  subscriberChangesCount: 0,
 })