🐛(analytics) filter benign ResizeObserver loop error in Sentry/PostHog

Filter out harmless `ResizeObserver loop limit exceeded` and
`ResizeObserver loop completed with undelivered notifications`
errors via `beforeSend`.

Why this is safe:

* These are W3C spec-mandated browser guards that defer notification
  delivery to the next frame when callbacks alter layout during
  render. They do not cause JS runtime exceptions or break the UX.

Why we actually need to filter them:

* Telemetry platforms like PostHog do not stack/group these well,
  frequently generating distinct error events per browser engine
  and version.
* The unique variants flood reporting dashboards and trigger
  false-positive alerts that clutter real issue triage.

CHANGELOG.md

@@ -8,6 +8,20 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Changed
+
+- 🔥(frontend) drop unused vendored ConnectionObserver
+- 🐛(frontend) vendor formatChatMessageLinks and trim surrounding newlines
+
+### Fixed
+
+- 📈(frontend) downgrade unreachable external home URL from error to event
+- 🐛(frontend) handle 401 responses when syncing user preferences
+- 🐛(frontend) harden speaker test against missing sinks and play errors
+- 🐛(frontend) implement hysteresis band for the control bar layout
+- 🐛(frontend) fix toolbar ResizeObserver loop and alignment drift
+- 🐛(analytics) filter benign ResizeObserver loop error in Sentry/PostHog
+
 ## [1.26.0] - 2026-08-12
 
 ### Added

src/frontend/src/components/SoundTester.tsx

@@ -3,27 +3,30 @@ import { useEffect, useRef, useState } from 'react'
 import { useTranslation } from 'react-i18next'
 import { useMediaDeviceSelect } from '@livekit/components-react'
 import { reportError } from '@/features/analytics/telemetry'
+import { canTestAudioOutput } from '@/features/rooms/utils/canTestAudioOutput'
 
 export const SoundTester = () => {
   const { t } = useTranslation('settings')
   const [isPlaying, setIsPlaying] = useState(false)
   const audioRef = useRef<HTMLAudioElement>(null)
 
-  const { activeDeviceId } = useMediaDeviceSelect({ kind: 'audiooutput' })
+  const { devices, activeDeviceId } = useMediaDeviceSelect({
+    kind: 'audiooutput',
+  })
 
   useEffect(() => {
-    const updateActiveId = async (deviceId: string) => {
+    if (!canTestAudioOutput() || !activeDeviceId) return
-      try {
+    if (!devices.some((device) => device.deviceId === activeDeviceId)) return
-        await audioRef?.current?.setSinkId(deviceId)
+    audioRef.current?.setSinkId(activeDeviceId).catch((error) => {
-      } catch (error) {
+      if (error instanceof DOMException && error.name === 'NotFoundError') {
-        reportError(
+        return
-          'device_switch_failure',
-          new Error(`Error setting sinkId: ${error}`)
-        )
       }
-    }
+      reportError(
-    updateActiveId(activeDeviceId)
+        'device_switch_failure',
-  }, [activeDeviceId])
+        new Error(`Error setting sinkId: ${error}`)
+      )
+    })
+  }, [devices, activeDeviceId])
 
   // prevent pausing the sound
   navigator.mediaSession.setActionHandler('pause', function () {})
@@ -32,9 +35,13 @@ export const SoundTester = () => {
     <>
       <Button
         variant="secondaryText"
-        onPress={() => {
+        onPress={async () => {
-          audioRef?.current?.play()
+          try {
-          setIsPlaying(true)
+            await audioRef?.current?.play()
+            setIsPlaying(true)
+          } catch {
+            setIsPlaying(false)
+          }
         }}
         size="sm"
         isDisabled={isPlaying}
@@ -48,7 +55,7 @@ export const SoundTester = () => {
       {/* eslint-disable jsx-a11y/media-has-caption */}
       <audio
         ref={audioRef}
-        src="sounds/uprise.mp3"
+        src="/sounds/uprise.mp3"
         onEnded={() => setIsPlaying(false)}
       />
     </>

src/frontend/src/features/analytics/exceptionFilters.ts

@@ -0,0 +1,24 @@
+import type { CaptureResult } from 'posthog-js'
+
+const IGNORED_EXCEPTION_PATTERNS = [
+  /ResizeObserver loop (completed with undelivered notifications|limit exceeded)/,
+]
+
+const shouldIgnoreException = (value: unknown): boolean =>
+  typeof value === 'string' &&
+  IGNORED_EXCEPTION_PATTERNS.some((pattern) => pattern.test(value))
+
+export const filterExceptions = (
+  event: CaptureResult | null
+): CaptureResult | null => {
+  if (event?.event !== '$exception') return event
+
+  const exceptionList = event.properties?.['$exception_list']
+  const values: unknown[] = Array.isArray(exceptionList)
+    ? exceptionList.map((exception) => exception?.value)
+    : []
+
+  values.push(event.properties?.['$exception_message'])
+
+  return values.some(shouldIgnoreException) ? null : event
+}

src/frontend/src/features/analytics/hooks/useAnalytics.ts

@@ -2,6 +2,7 @@ import { useEffect } from 'react'
 import { type ApiUser } from '@/features/auth/api/ApiUser'
 import { useUser } from '@/features/auth/api/useUser'
 import { getPosthog } from '../utils'
+import { filterExceptions } from '../exceptionFilters'
 
 export const startAnalyticsSession = (data: ApiUser) => {
   getPosthog().then((ph) => {
@@ -47,6 +48,7 @@ export const useAnalytics = ({
           capture_unhandled_rejections: true,
           capture_console_errors: true,
         },
+        before_send: filterExceptions,
       })
     })
   }, [id, host, flags_api_host, isDisabled])

src/frontend/src/features/auth/api/useSyncUserPreferencesWithBackend.tsx

@@ -6,6 +6,8 @@ import { queryClient } from '@/api/queryClient'
 import { updateUserPreferences } from './updateUserPreferences'
 import { convertToBackendLanguage } from '@/utils/languages'
 import { useUser } from './useUser'
+import { ApiError } from '@/api/ApiError.ts'
+import { reportError } from '@/features/analytics/telemetry'
 
 /**
  * Hook that synchronizes user browser preferences (language, timezone) with backend user settings.
@@ -42,6 +44,11 @@ export const useSyncUserPreferencesWithBackend = () => {
       }
     }
 
-    syncBrowserPreferencesToBackend()
+    syncBrowserPreferencesToBackend().catch((error) => {
+      if (error instanceof ApiError && error.statusCode === 401) return
+      reportError('generic_failure', error, {
+        context: '[useSyncUserPreferencesWithBackend] Failed to sync:',
+      })
+    })
   }, [i18n.language, isLoggedIn, user, mutateAsync])
 }

src/frontend/src/features/chat/components/ChatMessageBody.tsx

@@ -1,6 +1,6 @@
 import { ChatRow } from '@/stores/chat'
 import React, { useMemo } from 'react'
-import { formatChatMessageLinks } from '@livekit/components-react'
+import { formatChatMessageLinks } from '../utils'
 import { css } from '@/styled-system/css'
 import { Text } from '@/primitives'
 

src/frontend/src/features/chat/utils.tsx

@@ -0,0 +1,32 @@
+import { tokenize, createDefaultGrammar } from '@livekit/components-core'
+import { ReactNode } from 'react'
+
+const defaultGrammar = Object.freeze(createDefaultGrammar())
+
+export function formatChatMessageLinks(message: string): ReactNode {
+  const trimmedMessage = message.replace(/^[\r\n]+|[\r\n]+$/g, '')
+  return tokenize(trimmedMessage, defaultGrammar).map((tok, i) => {
+    if (typeof tok === `string`) {
+      return tok
+    } else {
+      const content = tok.content.toString()
+      const href =
+        tok.type === `url`
+          ? /^http(s?):\/\//.test(content)
+            ? content
+            : `https://${content}`
+          : `mailto:${content}`
+      return (
+        <a
+          className="lk-chat-link"
+          key={i}
+          href={href}
+          target="_blank"
+          rel="noreferrer"
+        >
+          {content}
+        </a>
+      )
+    }
+  })
+}

src/frontend/src/features/home/routes/Home.tsx

@@ -15,7 +15,7 @@ import { css } from '@/styled-system/css'
 import { useConfig } from '@/api/useConfig'
 import { LoginButton } from '@/components/LoginButton'
 import { LoadingScreen } from '@/components/LoadingScreen'
-import { reportError } from '@/features/analytics/telemetry'
+import { captureEvent } from '@/features/analytics/telemetry'
 
 const Columns = ({ children }: { children?: ReactNode }) => {
   return (
@@ -161,8 +161,10 @@ const Home = () => {
           window.location.replace(data.external_home_url)
         } catch (error) {
           setRedirectFailed(true)
-          reportError('generic_failure', error, {
+          captureEvent('external-home-unreachable', {
-            context: 'Site is not reachable:',
+            error_name: error instanceof Error ? error.name : 'Unknown',
+            error_message:
+              error instanceof Error ? error.message : String(error),
           })
         }
       }

src/frontend/src/features/notifications/hooks/useSoundNotification.tsx

@@ -6,7 +6,7 @@ import type { NotificationType } from '@/features/notifications/NotificationType
 // fixme - handle dynamic audio output changes
 export const useNotificationSound = () => {
   const notificationsSnap = useSnapshot(notificationsStore)
-  const [play] = useSound('./sounds/notifications.mp3', {
+  const [play] = useSound('/sounds/notifications.mp3', {
     sprite: {
       participantJoined: [0, 1150],
       handRaised: [1400, 180],

src/frontend/src/features/reactions/components/toolbar/ReactionButtonsContainer.tsx

@@ -26,8 +26,8 @@ const StyledContainer = styled('div', {
     backgroundColor: 'primaryDark.100',
     maxWidth: '100%',
     opacity: 0,
-    transform: 'translateY(3.25rem)',
+    translate: '0 3.25rem',
-    transition: 'opacity, transform',
+    transition: 'opacity, translate',
     transitionDuration: '0.5s',
     transitionTimingFunction: 'cubic-bezier(0.4, 0, 0.2, 1)',
     pointerEvents: 'none',
@@ -36,7 +36,7 @@ const StyledContainer = styled('div', {
     isVisible: {
       true: {
         opacity: 1,
-        transform: 'translateY(0)',
+        translate: '0 0',
         pointerEvents: 'auto',
       },
     },
@@ -84,7 +84,7 @@ export const ReactionButtonsContainer = ({
     shouldBeCenteredWithToggleButton,
     setShouldBeCenteredWithToggleButton,
   ] = useState(false)
-  const [rightOffset, setRightOffset] = useState(0)
+  const [offsetX, setOffsetX] = useState(0)
 
   const updateArrows = useCallback(() => {
     const el = scrollRef.current
@@ -115,7 +115,7 @@ export const ReactionButtonsContainer = ({
 
   useLayoutEffect(() => {
     if (!shouldBeCenteredWithToggleButton || isMobile) {
-      setRightOffset(0)
+      setOffsetX(0)
       return
     }
 
@@ -133,7 +133,7 @@ export const ReactionButtonsContainer = ({
       const containerCenterX = containerRect.left + containerRect.width / 2
       const shift = toggleCenterX - containerCenterX
       if (Math.abs(shift) < 0.5) return
-      setRightOffset((prev) => prev - shift * 2)
+      setOffsetX((prev) => prev + shift)
     }
 
     const schedule = () => {
@@ -182,7 +182,7 @@ export const ReactionButtonsContainer = ({
       isVisible={isVisible}
       style={
         shouldBeCenteredWithToggleButton && !isMobile && adjustedCentering
-          ? { marginRight: `${rightOffset}px` }
+          ? { transform: `translateX(${offsetX}px)` }
           : { margin: '0 15px' }
       }
     >

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

@@ -30,7 +30,6 @@ 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'
@@ -247,23 +246,8 @@ 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

@@ -5,7 +5,6 @@ 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', {
@@ -240,10 +239,6 @@ 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

@@ -9,14 +9,9 @@ import { useSnapshot } from 'valtio'
 import { DisconnectReason, RoomEvent } from 'livekit-client'
 
 import { userPreferencesStore } from '@/stores/userPreferences'
-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'
-
+import { connectionObserverStore } from '@/stores/connectionObserver'
-const CANDIDATE_POLL_INTERVAL_MS = 5000
 
 export const ConnectionObserver = () => {
   const room = useRoomContext()
@@ -24,13 +19,6 @@ export const ConnectionObserver = () => {
 
   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<
@@ -80,100 +68,6 @@ 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/livekit/components/controls/Device/OutputSoundTester.tsx

@@ -126,7 +126,7 @@ export const OutputSoundTester = ({
       {/* eslint-disable-next-line jsx-a11y/media-has-caption */}
       <audio
         ref={audioRef}
-        src="sounds/uprise.mp3"
+        src="/sounds/uprise.mp3"
         onEnded={() => setIsPlaying(false)}
       />
     </StyledContainer>

src/frontend/src/features/rooms/livekit/prefabs/ControlBar/MoreOptions.tsx

@@ -12,7 +12,8 @@ import type { ToggleButtonProps } from '@/primitives/ToggleButton'
 import { RiArrowDownSLine, RiArrowUpSLine } from '@remixicon/react'
 import { useTranslation } from 'react-i18next'
 
-const CONTROL_BAR_BREAKPOINT = 1100
+const CONTROL_BAR_BREAKPOINT_WIDE = 1100
+const CONTROL_BAR_BREAKPOINT_NARROW = 1050
 
 const NavigationControls = ({
   onPress,
@@ -65,10 +66,9 @@ export const LateralMenu = () => {
     </DialogTrigger>
   )
 }
-
 interface BreakpointObserverProps {
   containerRef: RefObject<HTMLDivElement>
-  onWideChange: (isWide: boolean) => void
+  onWideChange: (isWide: boolean | null) => void
 }
 
 const BreakpointObserver = ({
@@ -76,7 +76,20 @@ const BreakpointObserver = ({
   onWideChange,
 }: BreakpointObserverProps) => {
   const { width } = useSize(containerRef)
-  const isWide = width > CONTROL_BAR_BREAKPOINT
+  const [isWide, setIsWide] = useState<boolean | null>(null)
+
+  useEffect(() => {
+    if (!width) {
+      return
+    }
+    if (width > CONTROL_BAR_BREAKPOINT_WIDE) {
+      setIsWide(true)
+    } else if (width <= CONTROL_BAR_BREAKPOINT_NARROW) {
+      setIsWide(false)
+    } else {
+      setIsWide((prev) => (prev === null ? false : prev))
+    }
+  }, [width])
 
   useEffect(() => {
     onWideChange(isWide)
@@ -90,7 +103,7 @@ export const MoreOptions = ({
 }: {
   parentElement: RefObject<HTMLDivElement>
 }) => {
-  const [isWide, setIsWide] = useState(false)
+  const [isWide, setIsWide] = useState<boolean | null>(null)
 
   return (
     <nav
@@ -107,7 +120,7 @@ export const MoreOptions = ({
         containerRef={parentElement}
         onWideChange={setIsWide}
       />
-      {isWide ? <NavigationControls /> : <LateralMenu />}
+      {isWide !== null && (isWide ? <NavigationControls /> : <LateralMenu />)}
     </nav>
   )
 }

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

@@ -6,7 +6,6 @@ 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', {
@@ -48,10 +47,6 @@ 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

@@ -1,23 +1,9 @@
 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,
 })