♻️(frontend) refactor raised hand to rely on participant's attributes

Previously managed participant hand raised using raw metadata. LiveKit
introduced attributes concept, saves as metadata under hood but makes
update/handling easier.

Still pain that attributes must be strings, cannot pass boolean…

Refactor whole app to use attributes instead of metadata for the raised
hand feature. This commit might introduce regressions. I've double
checked participant list side pannel and the notification features.

Previously I persisted a boolean, I now persist the timestamp at which
the hand was raised. This will be useful in upcoming commits, especially
for sorting raised hands by order of arrival.

src/frontend/src/features/notifications/MainNotificationToast.tsx

@@ -18,7 +18,6 @@ import {
   ANIMATION_DURATION,
   ReactionPortals,
 } from '@/features/rooms/livekit/components/ReactionPortal'
-import { safeParseMetadata } from '@/features/rooms/utils/safeParseMetadata'
 
 export const MainNotificationToast = () => {
   const room = useRoomContext()
@@ -155,17 +154,14 @@ export const MainNotificationToast = () => {
 
   useEffect(() => {
     const handleNotificationReceived = (
-      prevMetadataStr: string | undefined,
+      changedAttributes: Record<string, string>,
       participant: Participant
     ) => {
       if (!participant) return
       if (isMobileBrowser()) return
       if (participant.isLocal) return
 
-      const prevMetadata = safeParseMetadata(prevMetadataStr)
+      if (!('handRaisedAt' in changedAttributes)) return
-      const metadata = safeParseMetadata(participant.metadata)
-
-      if (prevMetadata?.raised == metadata?.raised) return
 
       const existingToast = toastQueue.visibleToasts.find(
         (toast) =>
@@ -173,12 +169,12 @@ export const MainNotificationToast = () => {
           toast.content.type === NotificationType.HandRaised
       )
 
-      if (existingToast && prevMetadata.raised && !metadata.raised) {
+      if (existingToast && !changedAttributes?.handRaisedAt) {
         toastQueue.close(existingToast.key)
         return
       }
 
-      if (!existingToast && !prevMetadata.raised && metadata.raised) {
+      if (!existingToast && !!changedAttributes?.handRaisedAt) {
         triggerNotificationSound(NotificationType.HandRaised)
         toastQueue.add(
           {
@@ -190,10 +186,13 @@ export const MainNotificationToast = () => {
       }
     }
 
-    room.on(RoomEvent.ParticipantMetadataChanged, handleNotificationReceived)
+    room.on(RoomEvent.ParticipantAttributesChanged, handleNotificationReceived)
 
     return () => {
-      room.off(RoomEvent.ParticipantMetadataChanged, handleNotificationReceived)
+      room.off(
+        RoomEvent.ParticipantAttributesChanged,
+        handleNotificationReceived
+      )
     }
   }, [room, triggerNotificationSound])
 

src/frontend/src/features/rooms/livekit/api/lowerHandParticipant.ts

@@ -2,7 +2,6 @@ import { Participant } from 'livekit-client'
 import { fetchServerApi } from './fetchServerApi'
 import { buildServerApiUrl } from './buildServerApiUrl'
 import { useRoomData } from '../hooks/useRoomData'
-import { safeParseMetadata } from '@/features/rooms/utils/safeParseMetadata'
 
 export const useLowerHandParticipant = () => {
   const data = useRoomData()
@@ -11,8 +10,12 @@ export const useLowerHandParticipant = () => {
     if (!data || !data?.livekit) {
       throw new Error('Room data is not available')
     }
-    const newMetadata = safeParseMetadata(participant.metadata) || {}
+
-    newMetadata.raised = !newMetadata.raised
+    const newAttributes = {
+      ...participant.attributes,
+      handRaisedAt: '',
+    }
+
     return fetchServerApi(
       buildServerApiUrl(
         data.livekit.url,
@@ -24,7 +27,7 @@ export const useLowerHandParticipant = () => {
         body: JSON.stringify({
           room: data.livekit.room,
           identity: participant.identity,
-          metadata: JSON.stringify(newMetadata),
+          attributes: newAttributes,
           permission: participant.permissions,
         }),
       }

src/frontend/src/features/rooms/livekit/components/controls/Participants/ParticipantsList.tsx

@@ -11,7 +11,6 @@ import { WaitingParticipantListItem } from './WaitingParticipantListItem'
 import { useWaitingParticipants } from '@/features/rooms/hooks/useWaitingParticipants'
 import { Participant } from 'livekit-client'
 import { WaitingParticipant } from '@/features/rooms/api/listWaitingParticipants'
-import { safeParseMetadata } from '@/features/rooms/utils/safeParseMetadata'
 
 // TODO: Optimize rendering performance, especially for longer participant lists, even though they are generally short.
 export const ParticipantsList = () => {
@@ -36,8 +35,7 @@ export const ParticipantsList = () => {
   ]
 
   const raisedHandParticipants = participants.filter((participant) => {
-    const data = safeParseMetadata(participant.metadata)
+    return !!participant.attributes.handRaisedAt
-    return data.raised
   })
 
   const { waitingParticipants, handleParticipantEntry } =

src/frontend/src/features/rooms/livekit/hooks/useRaisedHand.ts

@@ -1,5 +1,5 @@
 import { LocalParticipant, Participant } from 'livekit-client'
-import { useParticipantInfo } from '@livekit/components-react'
+import { useParticipantAttribute } from '@livekit/components-react'
 import { isLocal } from '@/utils/livekit'
 
 type useRaisedHandProps = {
@@ -7,17 +7,22 @@ type useRaisedHandProps = {
 }
 
 export function useRaisedHand({ participant }: useRaisedHandProps) {
-  // fixme - refactor this part to rely on attributes
+  const handRaisedAtAttribute = useParticipantAttribute('handRaisedAt', {
-  const { metadata } = useParticipantInfo({ participant })
+    participant,
-  const parsedMetadata = JSON.parse(metadata || '{}')
+  })
 
-  const toggleRaisedHand = () => {
+  const isHandRaised = !!handRaisedAtAttribute
-    if (isLocal(participant)) {
+
-      parsedMetadata.raised = !parsedMetadata.raised
+  const toggleRaisedHand = async () => {
-      const localParticipant = participant as LocalParticipant
+    if (!isLocal(participant)) return
-      localParticipant.setMetadata(JSON.stringify(parsedMetadata))
+    const localParticipant = participant as LocalParticipant
+
+    const attributes: Record<string, string> = {
+      handRaisedAt: !isHandRaised ? new Date().toISOString() : '',
     }
+
+    await localParticipant.setAttributes(attributes)
   }
 
-  return { isHandRaised: parsedMetadata.raised ?? false, toggleRaisedHand }
+  return { isHandRaised, toggleRaisedHand }
 }

src/frontend/src/features/rooms/utils/safeParseMetadata.tsx

@@ -1,22 +0,0 @@
-export const safeParseMetadata = (
-  metadataStr: string | null | undefined
-): Record<string, unknown> => {
-  if (!metadataStr) {
-    return {}
-  }
-
-  try {
-    const parsed = JSON.parse(metadataStr)
-
-    // Ensure the result is an object
-    if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) {
-      console.warn('Metadata parsed to non-object value:', parsed)
-      return {}
-    }
-
-    return parsed as Record<string, unknown>
-  } catch (error) {
-    console.error('Failed to parse metadata:', error)
-    return {}
-  }
-}