feat(jam-session): enhance jam session functionality with improved playback synchronization and error handling

composeApp/src/androidMain/kotlin/dev/krtirtho/spotube/core/audioplayer/AudioPlayer.android.kt

@@ -20,6 +20,7 @@ package dev.krtirtho.spotube.core.audioplayer
 import android.content.Context
 import android.content.Intent
 import android.os.Build
+import android.util.Log
 import androidx.media3.common.AudioAttributes
 import androidx.media3.common.C
 import androidx.media3.common.MediaMetadata
@@ -51,11 +52,19 @@ actual class AudioPlayer actual constructor(context: Any) : AudioPlayerInterface
     private val appContext: Context = (context as Context).applicationContext
 
     private fun ensureServiceStarted() {
-        val intent = Intent(appContext, PlaybackService::class.java)
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
-            appContext.startForegroundService(intent)
-        } else {
-            appContext.startService(intent)
+        // On Android 12+ starting a foreground service from the background throws
+        // (ForegroundServiceStartNotAllowedException) — e.g. when a jam session or
+        // remote control applies playback while the app is backgrounded. Never let
+        // that crash the app; playback itself runs in-process without the service.
+        try {
+            val intent = Intent(appContext, PlaybackService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                appContext.startForegroundService(intent)
+            } else {
+                appContext.startService(intent)
+            }
+        } catch (e: Exception) {
+            Log.w("AudioPlayer", "Failed to start playback service", e)
         }
     }
 

composeApp/src/androidMain/kotlin/dev/krtirtho/spotube/media/PlaybackService.kt

@@ -86,7 +86,16 @@ class PlaybackService : MediaLibraryService(), KoinComponent {
             .setOngoing(true)
             .build()
 
-        startForeground(NOTIFICATION_ID, notification)
+        // On Android 15+ a service created from the background (e.g. by a jam
+        // sync or queue restoration) hits this in startForeground instead of at
+        // the startForegroundService call site. Don't crash: playback keeps
+        // running in-process, just without the notification until the app is
+        // foregrounded and the service can start properly.
+        try {
+            startForeground(NOTIFICATION_ID, notification)
+        } catch (e: Exception) {
+            Log.w(TAG, "startForeground not allowed; continuing without notification", e)
+        }
 
         librarySession =
             MediaLibrarySession.Builder(this, audioPlayer.player, LibrarySessionCallback())

composeApp/src/commonMain/kotlin/dev/krtirtho/spotube/core/di/Modules.kt

@@ -183,7 +183,16 @@ val sharedModules = module {
     viewModelOf(::BlacklistViewModel)
     viewModel { DevicesViewModel(get()) }
     viewModelOf(::RemoteControlViewModel)
-    viewModelOf(::JamViewModel)
+    viewModel {
+        JamViewModel(
+            jamSession = get(),
+            deepLinks = get(),
+            shareService = get(),
+            settingsProvider = get(),
+            audioPlayer = get(),
+            audioPlayerQueue = get(),
+        )
+    }
 
     // Album
     singleOf(::AlbumRepository)
@@ -229,8 +238,8 @@ val sharedModules = module {
     single { RemoteControlService(get(), get(), get()) } withOptions {
         createdAtStart()
     }
-    single { RemotePlaybackController(get(), get(), get(), get()) }
-    single { JamSessionService(get(), get()) }
+    single { RemotePlaybackController(get(), get(), get(), get(), get()) }
+    single { JamSessionService(get(), get(), get()) }
     singleOf(::JamDeepLinkService)
     singleOf(::AudioPlayerQueueRepository) { bind<QueueStateRepository>() }
     single<AudioPlayerQueue> {

composeApp/src/commonMain/kotlin/dev/krtirtho/spotube/core/jam/JamProtocol.kt

@@ -17,8 +17,10 @@
 
 package dev.krtirtho.spotube.core.jam
 
+import dev.krtirtho.plugin_interfaces.plugin_apis.metadata.track.MetadataTrack
 import dev.krtirtho.spotube.core.audioplayer.LoopState
 import dev.krtirtho.spotube.core.audioplayer.MediaItem
+import dev.krtirtho.spotube.core.audioplayer.QueueEntry
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
 
@@ -72,6 +74,13 @@ sealed class JamMessage {
     @SerialName("participantList")
     data class ParticipantList(val participants: List<JamParticipant>) : JamMessage()
 
+    @Serializable
+    @SerialName("kick")
+    data class Kick(
+        val participantId: String,
+        val reason: String = "kicked",
+    ) : JamMessage()
+
     @Serializable
     @SerialName("leave")
     data class Leave(val reason: String = "user_left") : JamMessage()
@@ -123,6 +132,7 @@ sealed class PlaybackCmd {
 @Serializable
 data class JamMediaItem(
     val url: String,
+    val trackId: String = "",
     val title: String,
     val artist: String,
     val album: String,
@@ -131,6 +141,45 @@ data class JamMediaItem(
     val protocol: String,
 ) {
     companion object {
+        fun fromQueueEntry(entry: QueueEntry): JamMediaItem = when (entry) {
+            is QueueEntry.StreamingTrack -> JamMediaItem(
+                url = "",
+                trackId = entry.track.id,
+                title = entry.track.title,
+                artist = entry.track.artists.joinToString(", ") { it.name },
+                album = entry.track.album?.title.orEmpty(),
+                durationMs = entry.track.durationMs,
+                coverUrl = entry.track.thumbnails?.maxByOrNull { it.width * it.height }?.url
+                    ?: entry.track.album?.thumbnails?.maxByOrNull { it.width * it.height }?.url
+                    .orEmpty(),
+                protocol = entry.protocol.name,
+            )
+
+            is QueueEntry.LocalTrack -> JamMediaItem(
+                url = entry.url,
+                trackId = "",
+                title = entry.name,
+                artist = entry.artists.joinToString(", "),
+                album = entry.album.orEmpty(),
+                durationMs = entry.duration,
+                coverUrl = "",
+                protocol = "PROGRESSIVE",
+            )
+        }
+
+        fun fromTrack(track: MetadataTrack): JamMediaItem = JamMediaItem(
+            url = "",
+            trackId = track.id,
+            title = track.title,
+            artist = track.artists.joinToString(", ") { it.name },
+            album = track.album?.title.orEmpty(),
+            durationMs = track.durationMs,
+            coverUrl = track.thumbnails?.maxByOrNull { it.width * it.height }?.url
+                ?: track.album?.thumbnails?.maxByOrNull { it.width * it.height }?.url
+                .orEmpty(),
+            protocol = "PROGRESSIVE",
+        )
+
         fun fromMediaItem(item: MediaItem): JamMediaItem = JamMediaItem(
             url = item.url,
             title = item.title,
@@ -149,7 +198,7 @@ data class JamMediaItem(
             coverURL = item.coverUrl,
             url = item.url,
             protocol = dev.krtirtho.plugin_interfaces.plugin_apis.audio.StreamProtocol
-                .valueOf(item.protocol),
+                .valueOf(item.protocol.ifBlank { "PROGRESSIVE" }),
         )
     }
 }

composeApp/src/commonMain/kotlin/dev/krtirtho/spotube/core/jam/JamSessionService.kt

@@ -19,6 +19,7 @@ package dev.krtirtho.spotube.core.jam
 
 import co.touchlab.kermit.Logger
 import dev.krtirtho.spotube.core.audioplayer.AudioPlayerInterface
+import dev.krtirtho.spotube.core.audioplayer.AudioPlayerQueue
 import dev.krtirtho.spotube.core.di.injectLogger
 import dev.krtirtho.spotube.modules.settings.SettingsProvider
 import kotlinx.coroutines.CoroutineScope
@@ -49,13 +50,32 @@ data class JamInvite(
     val sdp: String,
 )
 
+/**
+ * Owns the peer connections of a jam session (star topology: host relays state
+ * to all guests) and the hello/welcome handshake, participant bookkeeping and
+ * kick/ban. Playback & queue synchronization itself is delegated to
+ * [QueueSyncManager], which runs while a session is active.
+ */
 class JamSessionService(
     private val audioPlayer: AudioPlayerInterface,
+    private val audioPlayerQueue: AudioPlayerQueue,
     private val settingsProvider: SettingsProvider,
 ) : KoinComponent {
     val logger by injectLogger<JamSessionService>()
     private val log = Logger.withTag("JamSessionService")
 
+    /**
+     * Playback/queue synchronization. Owned by this service (not a Koin bean) so
+     * the two don't form a circular dependency; it's started/stopped with the
+     * session lifecycle.
+     */
+    private val queueSyncManager = QueueSyncManager(
+        audioPlayer = audioPlayer,
+        audioPlayerQueue = audioPlayerQueue,
+        jamSession = this,
+        settingsProvider = settingsProvider,
+    )
+
     private val json = Json {
         ignoreUnknownKeys = true
         classDiscriminator = "type"
@@ -91,23 +111,36 @@ class JamSessionService(
     /** Host side: guests whose handshake completed. Keyed by invite id. */
     private val connectedGuests = mutableMapOf<String, WebrtcPeerConnection>()
 
+    /** Host side: guest device ids, used for bans. */
+    private val guestDeviceIds = mutableMapOf<String, String>()
+
+    /** Host side: latest RTCPeerConnection state per guest ("connecting", "connected", "failed"...). */
+    private val guestConnectionStates = mutableMapOf<String, String>()
+
+    /** Host side: device ids banned for this session. */
+    private val bannedDeviceIds = mutableSetOf<String>()
+
     /** Guest side: the single connection to the host. */
     private var hostConnection: WebrtcPeerConnection? = null
 
+    private var hostDisplayName: String = "Host"
+    private var guestDisplayName: String = "Guest"
+
     suspend fun createSession(): String {
         log.i { "Creating jam session" }
-        val hostName = resolveParticipantName(defaultPrefix = "Host")
+        hostDisplayName = resolveParticipantName(defaultPrefix = "Host")
 
         _role.value = JamRole.Host
         _localParticipantId.value = "host"
         _participants.value = listOf(
             JamParticipant(
                 id = "host",
-                displayName = hostName,
+                displayName = hostDisplayName,
                 isHost = true,
             )
         )
         _isActive.value = true
+        queueSyncManager.start()
 
         return generateInvite().sdp
     }
@@ -174,12 +207,13 @@ class JamSessionService(
             )
         }
         log.i { "Guest $resolvedId ($peerName) joined" }
+        broadcastParticipantList()
         return true
     }
 
     suspend fun joinSession(offerSdp: String, hostName: String? = null): String {
         log.i { "Joining jam session" }
-        val participantName = resolveParticipantName(defaultPrefix = "Guest")
+        guestDisplayName = resolveParticipantName(defaultPrefix = "Guest")
 
         val pc = createWebrtcPeerConnection(
             iceServers = defaultIceServers(),
@@ -188,7 +222,7 @@ class JamSessionService(
 
         hostConnection = pc
         _role.value = JamRole.Guest
-        _localParticipantId.value = "guest"
+        _localParticipantId.value = null
         _participants.value = listOf(
             JamParticipant(
                 id = "host",
@@ -197,6 +231,7 @@ class JamSessionService(
             )
         )
         _isActive.value = true
+        queueSyncManager.start()
 
         // The data channel arrives in-band from the host's offer via on_data_channel;
         // we only answer here.
@@ -210,27 +245,52 @@ class JamSessionService(
         val payload = json.encodeToString(JamMessage.serializer(), message)
         when (_role.value) {
             JamRole.Host -> {
-                val targets = if (guestId != null) {
-                    listOfNotNull(connectedGuests[guestId])
-                } else {
-                    connectedGuests.values.toList()
-                }
-                targets.forEach { pc ->
+                if (guestId != null) {
+                    val pc = connectedGuests[guestId] ?: return
                     runCatching { pc.sendData(CHANNEL_LABEL, payload) }
-                        .onFailure { e -> log.w(e) { "Failed to send to guest" } }
+                        .onFailure { e ->
+                            log.w(e) { "Failed to send to guest $guestId" }
+                            onSendFailure(guestId)
+                        }
+                } else {
+                    val dead = mutableListOf<String>()
+                    connectedGuests.forEach { (id, pc) ->
+                        runCatching { pc.sendData(CHANNEL_LABEL, payload) }
+                            .onFailure { e ->
+                                log.w(e) { "Failed to send to guest $id" }
+                                dead += id
+                            }
+                    }
+                    dead.forEach { id -> onSendFailure(id) }
                 }
             }
 
             JamRole.Guest -> {
-                hostConnection?.sendData(CHANNEL_LABEL, payload)
+                runCatching { hostConnection?.sendData(CHANNEL_LABEL, payload) }
+                    .onFailure { e ->
+                        log.w(e) { "Failed to send to host" }
+                    }
             }
 
             null -> log.w { "sendMessage called while no session is active" }
         }
     }
 
+    /**
+     * A send to a guest failed. If that guest's connection has already given up
+     * (failed/closed), drop them from the session; while the connection is merely
+     * "connecting" the channel may simply not be open yet, so keep them.
+     */
+    private fun onSendFailure(guestId: String) {
+        val state = guestConnectionStates[guestId]
+        if (state == "failed" || state == "closed" || state == "disconnected") {
+            scope.launch { removeGuest(guestId) }
+        }
+    }
+
     suspend fun leave() {
         log.i { "Leaving jam session" }
+        queueSyncManager.stop()
         runCatching { sendMessage(JamMessage.Leave()) }
         shutdownAll()
         _role.value = null
@@ -238,6 +298,9 @@ class JamSessionService(
         _isActive.value = false
         _isConnected.value = false
         _localParticipantId.value = null
+        guestDeviceIds.clear()
+        guestConnectionStates.clear()
+        bannedDeviceIds.clear()
     }
 
     suspend fun broadcastPlaybackCommand(command: PlaybackCmd) {
@@ -265,12 +328,44 @@ class JamSessionService(
         sendMessage(JamMessage.SuggestPlaylist(tracks))
     }
 
+    // ---------- Host moderation ----------
+
+    suspend fun kickParticipant(participantId: String, reason: String = "kicked by host") {
+        if (_role.value != JamRole.Host) return
+        log.i { "Kicking participant $participantId" }
+        sendMessage(JamMessage.Kick(participantId, reason), guestId = participantId)
+        removeGuest(participantId)
+    }
+
+    suspend fun banParticipant(participantId: String) {
+        if (_role.value != JamRole.Host) return
+        val deviceId = guestDeviceIds[participantId]
+        if (deviceId != null) {
+            bannedDeviceIds += deviceId
+            log.i { "Banning device $deviceId (participant $participantId)" }
+        }
+        kickParticipant(participantId, "banned by host")
+    }
+
+    private suspend fun removeGuest(guestId: String) {
+        val pc = connectedGuests.remove(guestId)
+        runCatching { pc?.shutdown() }
+        guestDeviceIds.remove(guestId)
+        guestConnectionStates.remove(guestId)
+        _participants.update { current ->
+            current.filterNot { it.id == guestId }
+        }
+        broadcastParticipantList()
+    }
+
+    private suspend fun broadcastParticipantList() {
+        if (_role.value != JamRole.Host) return
+        sendMessage(JamMessage.ParticipantList(_participants.value))
+    }
+
     /**
      * ICE servers for global peer-to-peer jam sessions: multiple STUN servers for
      * NAT traversal plus a TURN relay for symmetric NATs and strict firewalls.
-     * Unreachable servers no longer stall offer/answer creation — the webrtc
-     * driver completes gathering once every STUN client has answered or timed out,
-     * and [WebrtcPeerConnection] bounds the wait anyway.
      */
     private fun defaultIceServers(): List<IceServerConfig> = listOf(
         IceServerConfig(
@@ -295,6 +390,11 @@ class JamSessionService(
             ?: "$defaultPrefix-${randomShortId()}"
     }
 
+    private fun localDeviceId(): String {
+        return settingsProvider.settingsState.value?.remoteControlDeviceId
+            ?: "device-${randomShortId()}"
+    }
+
     /**
      * Per-guest handler so messages received on a guest's connection can be
      * attributed back to that guest (needed for kick-on-leave and targeted sends).
@@ -310,6 +410,10 @@ class JamSessionService(
 
         override fun onConnectionStateChange(state: String) {
             log.i { "[$guestId] Connection state: $state" }
+            guestConnectionStates[guestId] = state
+            if (state == "failed" || state == "closed") {
+                scope.launch { removeGuest(guestId) }
+            }
         }
 
         override fun onDataChannelOpen(label: String) {
@@ -323,6 +427,9 @@ class JamSessionService(
 
         override fun onDataChannelClose(label: String) {
             log.i { "[$guestId] Data channel closed" }
+            if (_role.value == JamRole.Host) {
+                scope.launch { removeGuest(guestId) }
+            }
         }
     }
 
@@ -337,11 +444,19 @@ class JamSessionService(
 
         override fun onConnectionStateChange(state: String) {
             log.i { "Connection state: $state" }
+            if (state == "failed" || state == "closed") {
+                scope.launch { leave() }
+            }
         }
 
         override fun onDataChannelOpen(label: String) {
             log.i { "Data channel '$label' open" }
             _isConnected.value = true
+            // Introduce ourselves so the host can fill in our name and hand us
+            // our participant id.
+            scope.launch {
+                sendMessage(JamMessage.Hello(guestDisplayName, localDeviceId()))
+            }
         }
 
         override fun onDataChannelMessage(label: String, data: String) {
@@ -350,6 +465,7 @@ class JamSessionService(
 
         override fun onDataChannelClose(label: String) {
             log.i { "Data channel closed" }
+            scope.launch { leave() }
         }
     }
 
@@ -362,15 +478,44 @@ class JamSessionService(
                     _incomingSuggestions.tryEmit(message)
                 }
 
+                is JamMessage.Hello -> {
+                    if (_role.value == JamRole.Host && fromGuestId != null) {
+                        handleHello(fromGuestId, message)
+                    }
+                }
+
+                is JamMessage.Welcome -> {
+                    if (_role.value == JamRole.Guest) {
+                        _localParticipantId.value = message.participantId
+                        _participants.update { current ->
+                            current.map { participant ->
+                                if (participant.isHost) {
+                                    participant.copy(displayName = message.hostName.ifBlank { participant.displayName })
+                                } else {
+                                    participant
+                                }
+                            }
+                        }
+                        log.i { "Welcome: joined as ${message.participantId}" }
+                    }
+                }
+
+                is JamMessage.ParticipantList -> {
+                    if (_role.value == JamRole.Guest) {
+                        _participants.value = message.participants
+                    }
+                }
+
+                is JamMessage.Kick -> {
+                    if (_role.value == JamRole.Guest) {
+                        log.i { "Kicked by host: ${message.reason}" }
+                        scope.launch { leave() }
+                    }
+                }
+
                 is JamMessage.Leave -> {
                     if (_role.value == JamRole.Host && fromGuestId != null) {
-                        val leavingPc = connectedGuests.remove(fromGuestId)
-                        scope.launch {
-                            runCatching { leavingPc?.shutdown() }
-                        }
-                        _participants.update { current ->
-                            current.filterNot { it.id == fromGuestId }
-                        }
+                        scope.launch { removeGuest(fromGuestId) }
                     } else if (_role.value == JamRole.Guest) {
                         scope.launch { leave() }
                     }
@@ -383,6 +528,40 @@ class JamSessionService(
         }
     }
 
+    private fun handleHello(guestId: String, hello: JamMessage.Hello) {
+        val deviceId = hello.deviceId
+        if (deviceId in bannedDeviceIds) {
+            log.w { "Rejecting banned device $deviceId" }
+            scope.launch {
+                sendMessage(
+                    JamMessage.Kick(guestId, "banned by host"),
+                    guestId = guestId,
+                )
+                removeGuest(guestId)
+            }
+            return
+        }
+        guestDeviceIds[guestId] = deviceId
+        _participants.update { current ->
+            current.map { participant ->
+                if (participant.id == guestId) {
+                    participant.copy(displayName = hello.displayName.ifBlank { participant.displayName })
+                } else {
+                    participant
+                }
+            }
+        }
+        scope.launch {
+            sendMessage(
+                JamMessage.Welcome(hostDisplayName, guestId),
+                guestId = guestId,
+            )
+            broadcastParticipantList()
+            // Give the newly joined guest the current queue + playback state.
+            queueSyncManager.broadcastNow()
+        }
+    }
+
     private suspend fun shutdownAll() {
         pendingInvites.values.forEach { runCatching { it.shutdown() } }
         connectedGuests.values.forEach { runCatching { it.shutdown() } }

composeApp/src/commonMain/kotlin/dev/krtirtho/spotube/core/jam/QueueSyncManager.kt

@@ -18,46 +18,61 @@
 package dev.krtirtho.spotube.core.jam
 
 import co.touchlab.kermit.Logger
+import dev.krtirtho.plugin_interfaces.plugin_apis.audio.StreamProtocol
+import dev.krtirtho.plugin_interfaces.plugin_apis.metadata.artist.MetadataArtist
+import dev.krtirtho.plugin_interfaces.plugin_apis.metadata.track.MetadataTrack
 import dev.krtirtho.spotube.core.audioplayer.AudioPlayerInterface
+import dev.krtirtho.spotube.core.audioplayer.AudioPlayerQueue
+import dev.krtirtho.spotube.core.audioplayer.MediaItem
 import dev.krtirtho.spotube.core.audioplayer.PlayerState
+import dev.krtirtho.spotube.core.audioplayer.QueueEntry
+import dev.krtirtho.spotube.modules.settings.SettingsProvider
 import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import kotlinx.serialization.json.Json
-import kotlinx.coroutines.flow.first
 
 /**
- * Manages queue synchronization between the host and the jam session.
+ * Keeps playback in sync across a jam session (star topology).
  *
- * On the host: observes local playback state and broadcasts queue updates to guests.
- * On the guest: receives queue updates and applies them to local playback.
+ * On the **host**: applies incoming playback commands and guest suggestions to the
+ * host's player, and broadcasts the current queue + playback state to all guests
+ * (on queue changes and periodically, so play/pause/seek/position propagate).
  *
- * Conflict resolution: the host has authority. When a guest receives a queue state,
- * it replaces the local queue. (and (The guest's local queue is essentially read-only
- * during a jam session.)
+ * On the **guest**: mirrors the host's queue into the local player and applies
+ * playback commands. The guest's queue is read-only — the host has authority.
  */
 class QueueSyncManager(
     private val audioPlayer: AudioPlayerInterface,
+    private val audioPlayerQueue: AudioPlayerQueue,
     private val jamSession: JamSessionService,
-    private val scope: CoroutineScope,
+    private val settingsProvider: SettingsProvider,
 ) {
     private val log = Logger.withTag("QueueSyncManager")
-    private val json = Json {
-        ignoreUnknownKeys = true
-        classDiscriminator = "type"
-        encodeDefaults = true
-    }
+    private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
 
     private val _isSyncing = MutableStateFlow(false)
     val isSyncing: StateFlow<Boolean> = _isSyncing.asStateFlow()
 
     private var hostBroadcastJob: Job? = null
+    private var hostCommandJob: Job? = null
     private var guestApplyJob: Job? = null
     private var guestCommandJob: Job? = null
 
+    /** Guest side: the last applied queue snapshot, used to detect real queue changes. */
+    private var lastAppliedItems: List<JamMediaItem> = emptyList()
+
+    /** Guest side: tracks the player was told to start playing from. */
+    private var lastAppliedCurrentIndex = -1
+
     fun start() {
         if (_isSyncing.value) return
         _isSyncing.value = true
@@ -75,43 +90,87 @@ class QueueSyncManager(
     fun stop() {
         _isSyncing.value = false
         hostBroadcastJob?.cancel()
+        hostCommandJob?.cancel()
         guestApplyJob?.cancel()
         guestCommandJob?.cancel()
         hostBroadcastJob = null
+        hostCommandJob = null
         guestApplyJob = null
         guestCommandJob = null
+        lastAppliedItems = emptyList()
+        lastAppliedCurrentIndex = -1
     }
 
+    // ---------- Host side ----------
+
     private fun startHostSync() {
+        // Apply commands/suggestions coming from guests.
+        hostCommandJob = scope.launch {
+            jamSession.role.first { it != null }
+            if (jamSession.role.value != JamRole.Host) return@launch
+
+            jamSession.incomingMessages.collect { message ->
+                when (message) {
+                    is JamMessage.PlaybackCommand -> applyPlaybackCommand(message.command)
+                    is JamMessage.SuggestTrack -> acceptSuggestion(listOf(message.mediaItem))
+                    is JamMessage.SuggestPlaylist -> acceptSuggestion(message.tracks)
+                    else -> {}
+                }
+            }
+        }
+
+        // Broadcast state on queue changes and periodically.
         hostBroadcastJob = scope.launch {
             jamSession.role.first { it != null }
             if (jamSession.role.value != JamRole.Host) return@launch
 
-            jamSession.broadcastQueueState(
-                items = audioPlayer.playlistFlow.value.map(JamMediaItem::fromMediaItem),
-                currentIndex = audioPlayer.playlistFlow.value.indexOf(
-                    audioPlayer.currentMediaItemFlow.value
-                ).coerceAtLeast(0),
-                isPlaying = audioPlayer.playerStateFlow.value == PlayerState.PLAYING,
-                positionMs = audioPlayer.positionFlow.value.inWholeMilliseconds,
-            )
-
-            audioPlayer.playlistFlow.collect { playlist ->
-                audioPlayer.playerStateFlow.value.let { state ->
-                    audioPlayer.positionFlow.value.let { position ->
-                        jamSession.broadcastQueueState(
-                            items = playlist.map(JamMediaItem::fromMediaItem),
-                            currentIndex = playlist.indexOf(audioPlayer.currentMediaItemFlow.value)
-                                .coerceAtLeast(0),
-                            isPlaying = state == PlayerState.PLAYING,
-                            positionMs = position.inWholeMilliseconds,
-                        )
-                    }
+            // Queue changes (separate coroutine — collect() never returns).
+            launch {
+                audioPlayerQueue.queueFlow.collect {
+                    broadcastCurrentState()
                 }
             }
+
+            // Periodic tick so play/pause/seek/position propagate to guests.
+            while (isActive) {
+                delay(2_000)
+                broadcastCurrentState()
+            }
         }
     }
 
+    /** Immediately pushes the current queue + playback state to all guests. */
+    suspend fun broadcastNow() {
+        if (jamSession.role.value == JamRole.Host) {
+            broadcastCurrentState()
+        }
+    }
+
+    private suspend fun broadcastCurrentState() {
+        val queue = audioPlayerQueue.getQueue()
+        val current = audioPlayerQueue.getCurrentQueueEntry()
+        val currentIndex = if (current != null) {
+            queue.indexOfFirst { it.matchesEntry(current) }
+        } else {
+            -1
+        }
+        jamSession.broadcastQueueState(
+            items = queue.map(JamMediaItem::fromQueueEntry),
+            currentIndex = currentIndex.coerceAtLeast(0),
+            isPlaying = audioPlayer.playerStateFlow.value == PlayerState.PLAYING,
+            positionMs = audioPlayer.positionFlow.value.inWholeMilliseconds,
+        )
+    }
+
+    private suspend fun acceptSuggestion(items: List<JamMediaItem>) {
+        if (items.isEmpty()) return
+        val entries = items.map { it.toQueueEntry() }
+        log.i { "Accepting ${entries.size} suggested item(s) into the jam queue" }
+        audioPlayerQueue.addAllToQueue(entries)
+    }
+
+    // ---------- Guest side ----------
+
     private fun startGuestSync() {
         guestApplyJob = scope.launch {
             jamSession.incomingMessages.collect { message ->
@@ -130,33 +189,162 @@ class QueueSyncManager(
 
     private suspend fun applyQueueState(state: JamMessage.QueueState) {
         log.d { "Applying queue state: ${state.items.size} items, current=${state.currentIndex}" }
-        val mediaItems = state.items.map(JamMediaItem::toMediaItem)
-        audioPlayer.load(
-            playlist = mediaItems,
-            autoPlay = state.isPlaying,
-            startPosition = state.currentIndex.coerceAtLeast(0),
+
+        // Items that carry neither a track id nor a usable URL can't be played
+        // on this device — skip them instead of crashing the player.
+        val playableItems = state.items.filter { it.trackId.isNotBlank() || it.url.isNotBlank() }
+
+        val queueChanged = playableItems != lastAppliedItems
+        if (queueChanged) {
+            lastAppliedItems = playableItems
+            lastAppliedCurrentIndex = state.currentIndex
+            val mediaItems = playableItems.map { it.toPlayableMediaItem() }
+            runCatching {
+                audioPlayer.load(
+                    playlist = mediaItems,
+                    autoPlay = state.isPlaying,
+                    startPosition = state.currentIndex.coerceIn(0, mediaItems.lastIndex.coerceAtLeast(0)),
+                )
+            }.onFailure { e ->
+                log.e(e) { "Failed to apply jam queue to local player" }
+            }
+            return
+        }
+
+        // Same queue: just sync playback state. Avoid seeking on every tick unless
+        // the drift is meaningful.
+        if (state.currentIndex != lastAppliedCurrentIndex) {
+            lastAppliedCurrentIndex = state.currentIndex
+            runCatching { audioPlayer.jumpTo(state.currentIndex.coerceAtLeast(0)) }
+                .onFailure { e -> log.w(e) { "Failed to jump to index ${state.currentIndex}" } }
+        }
+        val currentState = audioPlayer.playerStateFlow.value
+        if (state.isPlaying && currentState != PlayerState.PLAYING) {
+            audioPlayer.play()
+        } else if (!state.isPlaying && currentState == PlayerState.PLAYING) {
+            audioPlayer.pause()
+        }
+        val driftMs = kotlin.math.abs(
+            audioPlayer.positionFlow.value.inWholeMilliseconds - state.positionMs
         )
+        if (driftMs > POSITION_SYNC_THRESHOLD_MS) {
+            runCatching { audioPlayer.seekTo(kotlin.time.Duration.parse("${state.positionMs}ms")) }
+                .onFailure { e -> log.w(e) { "Failed to sync position" } }
+        }
     }
 
     private suspend fun applyPlaybackCommand(command: PlaybackCmd) {
         log.d { "Applying playback command: $command" }
-        when (command) {
-            PlaybackCmd.Play -> audioPlayer.play()
-            PlaybackCmd.Pause -> audioPlayer.pause()
-            PlaybackCmd.Toggle -> {
-                if (audioPlayer.playerStateFlow.value == PlayerState.PLAYING) {
-                    audioPlayer.pause()
-                } else {
-                    audioPlayer.play()
+        runCatching {
+            when (command) {
+                PlaybackCmd.Play -> audioPlayer.play()
+                PlaybackCmd.Pause -> audioPlayer.pause()
+                PlaybackCmd.Toggle -> {
+                    if (audioPlayer.playerStateFlow.value == PlayerState.PLAYING) {
+                        audioPlayer.pause()
+                    } else {
+                        audioPlayer.play()
+                    }
                 }
+
+                is PlaybackCmd.Seek -> audioPlayer.seekTo(kotlin.time.Duration.parse("${command.positionMs}ms"))
+                PlaybackCmd.SkipNext -> audioPlayer.skipToNext()
+                PlaybackCmd.SkipPrevious -> audioPlayer.skipToPrevious()
+                is PlaybackCmd.SetVolume -> audioPlayer.setVolume(command.volume)
+                is PlaybackCmd.SetLoop -> audioPlayer.loop(JamLoopMapping.fromString(command.loop))
+                is PlaybackCmd.SetShuffle -> audioPlayer.shuffle(command.enabled)
+                is PlaybackCmd.JumpTo -> audioPlayer.jumpTo(command.index)
             }
-            is PlaybackCmd.Seek -> audioPlayer.seekTo(kotlin.time.Duration.parse("${command.positionMs}ms"))
-            PlaybackCmd.SkipNext -> audioPlayer.skipToNext()
-            PlaybackCmd.SkipPrevious -> audioPlayer.skipToPrevious()
-            is PlaybackCmd.SetVolume -> audioPlayer.setVolume(command.volume)
-            is PlaybackCmd.SetLoop -> audioPlayer.loop(JamLoopMapping.fromString(command.loop))
-            is PlaybackCmd.SetShuffle -> audioPlayer.shuffle(command.enabled)
-            is PlaybackCmd.JumpTo -> audioPlayer.jumpTo(command.index)
+        }.onFailure { e ->
+            log.w(e) { "Failed to apply playback command: $command" }
         }
     }
+
+    // ---------- Conversions ----------
+
+    /** Host side: turn a suggested item into a playable queue entry. */
+    private fun JamMediaItem.toQueueEntry(): QueueEntry = when {
+        trackId.isNotBlank() -> QueueEntry.StreamingTrack(
+            track = MetadataTrack(
+                id = trackId,
+                title = title,
+                durationMs = durationMs,
+                trackNumber = null,
+                discNumber = null,
+                artists = listOf(
+                    MetadataArtist.Basic(id = "", name = artist, thumbnails = emptyList(), externalUri = null)
+                ),
+                album = null,
+                thumbnails = null,
+                explicit = null,
+                popularity = null,
+                isrcCode = null,
+                externalUri = null,
+            ),
+            url = "",
+            protocol = runCatching { StreamProtocol.valueOf(protocol.ifBlank { "PROGRESSIVE" }) }
+                .getOrDefault(StreamProtocol.PROGRESSIVE),
+        )
+
+        else -> QueueEntry.LocalTrack(
+            name = title,
+            artists = artist.split(',').map { it.trim() }.filter { it.isNotEmpty() },
+            duration = durationMs,
+            album = album.ifBlank { null },
+            coverBytes = null,
+            url = url,
+        )
+    }
+
+    /**
+     * Guest side: build a playable MediaItem. Streaming tracks have their stream
+     * URL resolved through this device's own playback proxy (the host never sends
+     * usable URLs — each guest must fetch from its own plugins).
+     */
+    private suspend fun JamMediaItem.toPlayableMediaItem(): MediaItem {
+        if (trackId.isNotBlank()) {
+            val proxyUrl = buildStreamingUrl(trackId, protocol)
+            return MediaItem(
+                title = title,
+                artist = artist,
+                album = album,
+                duration = kotlin.time.Duration.parse("${durationMs}ms"),
+                coverURL = coverUrl,
+                url = proxyUrl,
+                protocol = runCatching { StreamProtocol.valueOf(protocol.ifBlank { "PROGRESSIVE" }) }
+                    .getOrDefault(StreamProtocol.PROGRESSIVE),
+            )
+        }
+        return JamMediaItem.toMediaItem(this)
+    }
+
+    private suspend fun buildStreamingUrl(trackId: String, protocol: String): String {
+        val port = settingsProvider.settingsState
+            .first()
+            ?.playbackProxyServerPort ?: return ""
+        val baseUrl = "http://127.0.0.1:$port"
+        val streamProtocol = runCatching { StreamProtocol.valueOf(protocol.ifBlank { "PROGRESSIVE" }) }
+            .getOrDefault(StreamProtocol.PROGRESSIVE)
+        return when (streamProtocol) {
+            StreamProtocol.HLS, StreamProtocol.DASH -> "${baseUrl.trimEnd('/')}/manifest/$trackId"
+            StreamProtocol.PROGRESSIVE -> "${baseUrl.trimEnd('/')}/stream/$trackId"
+        }
+    }
+
+    private fun QueueEntry.matchesEntry(other: QueueEntry): Boolean {
+        return when {
+            this is QueueEntry.StreamingTrack && other is QueueEntry.StreamingTrack ->
+                this.track.id == other.track.id
+
+            this is QueueEntry.LocalTrack && other is QueueEntry.LocalTrack ->
+                this.url == other.url && this.name == other.name
+
+            else -> false
+        }
+    }
+
+    companion object {
+        /** Seek the guest only when its position drifts more than this from the host. */
+        private const val POSITION_SYNC_THRESHOLD_MS = 3_000L
+    }
 }

composeApp/src/commonMain/kotlin/dev/krtirtho/spotube/core/playback/CollectionPlaybackHelper.kt

@@ -26,6 +26,7 @@ import dev.krtirtho.spotube.modules.artist.ArtistRepository
 import dev.krtirtho.spotube.modules.blacklist.BlacklistRepository
 import dev.krtirtho.spotube.modules.playlist.PlaylistRepository
 import dev.krtirtho.spotube.modules.saved_tracks.SavedTracksRepository
+import dev.krtirtho.spotube.core.remote.RemoteCollectionType
 
 class CollectionPlaybackHelper(
     private val albumRepository: AlbumRepository,
@@ -264,6 +265,21 @@ class CollectionPlaybackHelper(
         }
     }
 
+    /**
+     * Resolves the tracks of a collection without loading them into the local
+     * queue — used to suggest a collection into a jam session from a guest.
+     */
+    suspend fun resolveCollectionTracks(type: RemoteCollectionType, id: String): List<MetadataTrack> =
+        when (type) {
+            RemoteCollectionType.Playlist -> fetchAllPlaylistTracks(id).asTracks()
+            RemoteCollectionType.Album -> fetchAllAlbumTracks(id).asTracks()
+            RemoteCollectionType.ArtistTopTracks -> fetchArtistTopTracks(id).asTracks()
+            RemoteCollectionType.SavedTracks -> fetchAllSavedTracks().asTracks()
+        }
+
+    private fun List<QueueEntry>.asTracks(): List<MetadataTrack> =
+        mapNotNull { (it as? QueueEntry.StreamingTrack)?.track }
+
     private suspend fun fetchAllSavedTracks(): List<QueueEntry> {
         val allTracks = mutableListOf<MetadataTrack>()
         var pagination = savedTracksRepository.getSavedTracks()

composeApp/src/commonMain/kotlin/dev/krtirtho/spotube/core/remote/RemotePlaybackController.kt

@@ -21,6 +21,9 @@ import co.touchlab.kermit.Logger
 import dev.krtirtho.plugin_interfaces.plugin_apis.metadata.track.MetadataTrack
 import dev.krtirtho.spotube.core.audioplayer.AudioPlayerQueue
 import dev.krtirtho.spotube.core.audioplayer.QueueEntry
+import dev.krtirtho.spotube.core.jam.JamMediaItem
+import dev.krtirtho.spotube.core.jam.JamRole
+import dev.krtirtho.spotube.core.jam.JamSessionService
 import dev.krtirtho.spotube.core.playback.CollectionPlaybackHelper
 import dev.krtirtho.spotube.modules.blacklist.BlacklistRepository
 import kotlinx.coroutines.CoroutineScope
@@ -84,6 +87,7 @@ class RemotePlaybackController(
     private val collectionPlaybackHelper: CollectionPlaybackHelper,
     private val audioPlayerQueue: AudioPlayerQueue,
     private val blacklistRepository: BlacklistRepository,
+    private val jamSession: JamSessionService,
 ) : KoinComponent {
     private val logger = Logger.withTag("RemotePlaybackController")
     private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
@@ -154,6 +158,49 @@ class RemotePlaybackController(
         _pendingRequest.value = null
     }
 
+    /**
+     * Routes the pending request into the active jam session. On the host the jam
+     * queue IS the local queue, so the action runs locally; on a guest the content
+     * is suggested to the host, which accepts it into the shared queue.
+     */
+    fun playOnJam() {
+        val request = _pendingRequest.value ?: return
+        _pendingRequest.value = null
+        scope.launch {
+            try {
+                when (jamSession.role.value) {
+                    JamRole.Host -> executeLocally(request)
+                    JamRole.Guest -> suggestToJam(request)
+                    null -> {}
+                }
+            } catch (e: Exception) {
+                logger.e(e) { "Failed to send content to jam session" }
+            }
+        }
+    }
+
+    private suspend fun suggestToJam(request: PlaybackDestinationRequest) {
+        when (request) {
+            is PlaybackDestinationRequest.Collection -> {
+                val tracks = collectionPlaybackHelper.resolveCollectionTracks(request.type, request.id)
+                if (tracks.isNotEmpty()) {
+                    jamSession.suggestPlaylist(tracks.map { it.toJamMediaItem() })
+                    logger.i { "Suggested ${tracks.size} track(s) to the jam session" }
+                }
+            }
+
+            is PlaybackDestinationRequest.Track -> {
+                jamSession.suggestTrack(request.track.toJamMediaItem())
+            }
+
+            is PlaybackDestinationRequest.Tracks -> {
+                if (request.tracks.isNotEmpty()) {
+                    jamSession.suggestPlaylist(request.tracks.map { it.toJamMediaItem() })
+                }
+            }
+        }
+    }
+
     // ---------- Internals ----------
 
     private fun request(request: PlaybackDestinationRequest) {
@@ -321,4 +368,6 @@ class RemotePlaybackController(
             album?.id == other.album?.id &&
             artists.map { it.id.ifBlank { it.name } } == other.artists.map { it.id.ifBlank { it.name } }
     }
-}
+}
+
+private fun MetadataTrack.toJamMediaItem(): JamMediaItem = JamMediaItem.fromTrack(this)

composeApp/src/commonMain/kotlin/dev/krtirtho/spotube/modules/devices/PlayDestinationPicker.kt

@@ -30,6 +30,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import dev.krtirtho.spotube.core.jam.JamSessionService
 import dev.krtirtho.spotube.core.remote.ConnectionState
 import dev.krtirtho.spotube.core.remote.PlaybackDestinationAction
 import dev.krtirtho.spotube.core.remote.RemoteControlClient
@@ -39,19 +40,22 @@ import dev.krtirtho.spotube.core.ui.base.ThemedDialog
 import dev.krtirtho.spotube.resources.iconsax.Iconsax
 import dev.krtirtho.spotube.resources.iconsax.IconsaxCd
 import dev.krtirtho.spotube.resources.iconsax.IconsaxMirroringScreen
+import dev.krtirtho.spotube.resources.iconsax.IconsaxMusicPlaylist
 import org.koin.compose.koinInject
 
 /**
- * Globally hosted dialog shown when a remote device is connected and the user
- * tries to play / add to queue / play next. Lets the user choose between the
- * local device and the connected remote device(s).
+ * Globally hosted dialog shown when the user tries to play / add to queue /
+ * play next and there is more than one place it could go (a connected remote
+ * device and/or an active jam session). Lets the user choose the destination.
  */
 @Composable
 fun PlayDestinationPickerHost() {
     val controller = koinInject<RemotePlaybackController>()
     val remoteControlClient = koinInject<RemoteControlClient>()
+    val jamSession = koinInject<JamSessionService>()
     val request by controller.pendingRequest.collectAsStateWithLifecycle()
     val connectionState by remoteControlClient.connectionState.collectAsStateWithLifecycle()
+    val jamActive by jamSession.isActive.collectAsStateWithLifecycle()
 
     val pendingRequest = request ?: return
 
@@ -111,30 +115,59 @@ fun PlayDestinationPickerHost() {
                     },
                 )
 
-                ListRowTile(
-                    onClick = controller::playOnRemote,
-                    modifier = Modifier.fillMaxWidth(),
-                    leading = {
-                        Icon(
-                            imageVector = Iconsax.IconsaxMirroringScreen,
-                            contentDescription = null,
-                            tint = MaterialTheme.colorScheme.primary,
-                        )
-                    },
-                    title = {
-                        Text(
-                            text = remoteDeviceName,
-                            style = MaterialTheme.typography.bodyLarge,
-                        )
-                    },
-                    subtitle = {
-                        Text(
-                            text = "$actionLabel on the connected device",
-                            style = MaterialTheme.typography.bodySmall,
-                            color = MaterialTheme.colorScheme.onSurfaceVariant,
-                        )
-                    },
-                )
+                if (connectionState is ConnectionState.Connected) {
+                    ListRowTile(
+                        onClick = controller::playOnRemote,
+                        modifier = Modifier.fillMaxWidth(),
+                        leading = {
+                            Icon(
+                                imageVector = Iconsax.IconsaxMirroringScreen,
+                                contentDescription = null,
+                                tint = MaterialTheme.colorScheme.primary,
+                            )
+                        },
+                        title = {
+                            Text(
+                                text = remoteDeviceName,
+                                style = MaterialTheme.typography.bodyLarge,
+                            )
+                        },
+                        subtitle = {
+                            Text(
+                                text = "$actionLabel on the connected device",
+                                style = MaterialTheme.typography.bodySmall,
+                                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                            )
+                        },
+                    )
+                }
+
+                if (jamActive) {
+                    ListRowTile(
+                        onClick = controller::playOnJam,
+                        modifier = Modifier.fillMaxWidth(),
+                        leading = {
+                            Icon(
+                                imageVector = Iconsax.IconsaxMusicPlaylist,
+                                contentDescription = null,
+                                tint = MaterialTheme.colorScheme.primary,
+                            )
+                        },
+                        title = {
+                            Text(
+                                text = "Jam Session",
+                                style = MaterialTheme.typography.bodyLarge,
+                            )
+                        },
+                        subtitle = {
+                            Text(
+                                text = "$actionLabel in the shared jam queue",
+                                style = MaterialTheme.typography.bodySmall,
+                                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                            )
+                        },
+                    )
+                }
             }
         },
         actions = {

composeApp/src/commonMain/kotlin/dev/krtirtho/spotube/modules/jam/JamScreen.kt

@@ -17,17 +17,25 @@
 
 package dev.krtirtho.spotube.modules.jam
 
+import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.heightIn
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.itemsIndexed
 import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.text.selection.SelectionContainer
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material3.Button
 import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.OutlinedTextField
@@ -45,15 +53,31 @@ import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.graphicsLayer
+import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.platform.LocalClipboardManager
 import androidx.compose.ui.text.AnnotatedString
+import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import coil3.compose.AsyncImage
 import dev.krtirtho.spotube.core.jam.JamRole
 import dev.krtirtho.spotube.core.navigation.NavigationCommands
+import dev.krtirtho.spotube.core.ui.base.IconButton
+import dev.krtirtho.spotube.core.ui.base.LocalBaseUITheme
+import dev.krtirtho.spotube.core.ui.base.copyShape
 import dev.krtirtho.spotube.core.ui.component.ApplicationMainBar
 import dev.krtirtho.spotube.modules.shell.LocalAppShellBottomInset
+import dev.krtirtho.spotube.resources.iconsax.Iconsax
+import dev.krtirtho.spotube.resources.iconsax.IconsaxArrowDown4
+import dev.krtirtho.spotube.resources.iconsax.IconsaxNext
+import dev.krtirtho.spotube.resources.iconsax.IconsaxPause
+import dev.krtirtho.spotube.resources.iconsax.IconsaxPlay
+import dev.krtirtho.spotube.resources.iconsax.IconsaxPrevious
+import dev.krtirtho.spotube.resources.iconsax.IconsaxRepeateMusic
+import dev.krtirtho.spotube.resources.iconsax.IconsaxShuffle
 import org.koin.compose.viewmodel.koinViewModel
 
 @Composable
@@ -99,16 +123,34 @@ fun JamScreen(
 
                 state.role == JamRole.Host -> HostSessionView(
                     state = state,
+                    playerState = viewModel.jamPlayerState.collectAsStateWithLifecycle().value,
                     onNewInvite = viewModel::generateNewInvite,
                     onSubmitAnswer = viewModel::submitAnswerPasted,
                     onShare = viewModel::share,
                     onLeave = viewModel::leave,
+                    onTogglePlayPause = viewModel::togglePlayPause,
+                    onSkipNext = viewModel::skipNext,
+                    onSkipPrevious = viewModel::skipPrevious,
+                    onSeek = viewModel::seek,
+                    onJumpTo = viewModel::jumpTo,
+                    onToggleShuffle = viewModel::toggleShuffle,
+                    onCycleLoop = viewModel::cycleLoopMode,
+                    onKick = viewModel::kickParticipant,
+                    onBan = viewModel::banParticipant,
                 )
 
                 else -> GuestSessionView(
                     state = state,
+                    playerState = viewModel.jamPlayerState.collectAsStateWithLifecycle().value,
                     onShare = viewModel::share,
                     onLeave = viewModel::leave,
+                    onTogglePlayPause = viewModel::togglePlayPause,
+                    onSkipNext = viewModel::skipNext,
+                    onSkipPrevious = viewModel::skipPrevious,
+                    onSeek = viewModel::seek,
+                    onJumpTo = viewModel::jumpTo,
+                    onToggleShuffle = viewModel::toggleShuffle,
+                    onCycleLoop = viewModel::cycleLoopMode,
                 )
             }
         }
@@ -220,16 +262,35 @@ private fun IncomingInviteView(
 @Composable
 private fun HostSessionView(
     state: JamUiState,
+    playerState: JamPlayerUiState,
     onNewInvite: () -> Unit,
     onSubmitAnswer: (String) -> Unit,
     onShare: (String) -> Unit,
     onLeave: () -> Unit,
+    onTogglePlayPause: () -> Unit,
+    onSkipNext: () -> Unit,
+    onSkipPrevious: () -> Unit,
+    onSeek: (Long) -> Unit,
+    onJumpTo: (Int) -> Unit,
+    onToggleShuffle: () -> Unit,
+    onCycleLoop: () -> Unit,
+    onKick: (String) -> Unit,
+    onBan: (String) -> Unit,
 ) {
     val clipboard = LocalClipboardManager.current
     var pastedAnswer by rememberSaveable { mutableStateOf("") }
 
     Column(verticalArrangement = Arrangement.spacedBy(16.dp)) {
-        ParticipantsSection(state.participants)
+        ParticipantsSection(state.participants, isHost = true, onKick = onKick, onBan = onBan)
+
+        JamNowPlayingView(
+            playerState = playerState,
+            onTogglePlayPause = onTogglePlayPause,
+            onSkipNext = onSkipNext,
+            onSkipPrevious = onSkipPrevious,
+            onToggleShuffle = onToggleShuffle,
+            onCycleLoop = onCycleLoop,
+        )
 
         HorizontalDivider()
 
@@ -279,6 +340,13 @@ private fun HostSessionView(
             Text("Accept Answer")
         }
 
+        HorizontalDivider()
+
+        JamQueueView(
+            queue = playerState.queue,
+            onJumpTo = onJumpTo,
+        )
+
         LeaveButton(onLeave)
     }
 }
@@ -286,21 +354,37 @@ private fun HostSessionView(
 @Composable
 private fun GuestSessionView(
     state: JamUiState,
+    playerState: JamPlayerUiState,
     onShare: (String) -> Unit,
     onLeave: () -> Unit,
+    onTogglePlayPause: () -> Unit,
+    onSkipNext: () -> Unit,
+    onSkipPrevious: () -> Unit,
+    onSeek: (Long) -> Unit,
+    onJumpTo: (Int) -> Unit,
+    onToggleShuffle: () -> Unit,
+    onCycleLoop: () -> Unit,
 ) {
     val clipboard = LocalClipboardManager.current
 
     Column(verticalArrangement = Arrangement.spacedBy(16.dp)) {
-        ParticipantsSection(state.participants)
+        ParticipantsSection(state.participants, isHost = false, onKick = {}, onBan = {})
 
         val answerLink = state.answerLink
         when {
             state.isConnected -> {
-                Text(
-                    text = "Connected to the session",
-                    style = MaterialTheme.typography.bodyMedium,
-                    color = MaterialTheme.colorScheme.primary,
+                JamNowPlayingView(
+                    playerState = playerState,
+                    onTogglePlayPause = onTogglePlayPause,
+                    onSkipNext = onSkipNext,
+                    onSkipPrevious = onSkipPrevious,
+                    onToggleShuffle = onToggleShuffle,
+                    onCycleLoop = onCycleLoop,
+                )
+
+                JamQueueView(
+                    queue = playerState.queue,
+                    onJumpTo = onJumpTo,
                 )
             }
 
@@ -331,7 +415,231 @@ private fun GuestSessionView(
 }
 
 @Composable
-private fun ParticipantsSection(participants: List<dev.krtirtho.spotube.core.jam.JamParticipant>) {
+private fun JamNowPlayingView(
+    playerState: JamPlayerUiState,
+    onTogglePlayPause: () -> Unit,
+    onSkipNext: () -> Unit,
+    onSkipPrevious: () -> Unit,
+    onToggleShuffle: () -> Unit,
+    onCycleLoop: () -> Unit,
+) {
+    Column(verticalArrangement = Arrangement.spacedBy(12.dp)) {
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            verticalAlignment = Alignment.CenterVertically,
+            horizontalArrangement = Arrangement.spacedBy(12.dp),
+        ) {
+            AsyncImage(
+                model = playerState.currentCoverUrl?.takeIf { it.isNotBlank() },
+                contentDescription = null,
+                contentScale = ContentScale.Crop,
+                modifier = Modifier
+                    .size(64.dp)
+                    .clip(MaterialTheme.shapes.medium),
+            )
+            Column(modifier = Modifier.weight(1f)) {
+                Text(
+                    text = playerState.currentTitle ?: "Nothing playing",
+                    style = MaterialTheme.typography.bodyLarge,
+                    fontWeight = FontWeight.SemiBold,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                )
+                Text(
+                    text = playerState.currentArtist ?: "—",
+                    style = MaterialTheme.typography.bodySmall,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                )
+            }
+        }
+
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalArrangement = Arrangement.SpaceBetween,
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            Text(
+                text = formatJamDuration(playerState.positionMs),
+                style = MaterialTheme.typography.labelSmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+            Text(
+                text = formatJamDuration(playerState.durationMs),
+                style = MaterialTheme.typography.labelSmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalArrangement = Arrangement.SpaceEvenly,
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            IconButton(
+                onClick = onToggleShuffle,
+                theme = LocalBaseUITheme.current.iconButtons.ghost.copyShape(CircleShape),
+            ) {
+                Icon(
+                    imageVector = Iconsax.IconsaxShuffle,
+                    contentDescription = "Shuffle",
+                    tint = if (playerState.shuffleEnabled) {
+                        MaterialTheme.colorScheme.primary
+                    } else {
+                        MaterialTheme.colorScheme.onSurfaceVariant
+                    },
+                )
+            }
+            IconButton(
+                onClick = onSkipPrevious,
+                theme = LocalBaseUITheme.current.iconButtons.ghost.copyShape(CircleShape),
+            ) {
+                Icon(Iconsax.IconsaxPrevious, contentDescription = "Previous")
+            }
+            IconButton(
+                onClick = onTogglePlayPause,
+                theme = LocalBaseUITheme.current.iconButtons.primary.copyShape(CircleShape),
+                modifier = Modifier.size(64.dp),
+            ) {
+                Icon(
+                    imageVector = if (playerState.isPlaying) {
+                        Iconsax.IconsaxPause
+                    } else {
+                        Iconsax.IconsaxPlay
+                    },
+                    contentDescription = if (playerState.isPlaying) "Pause" else "Play",
+                    modifier = Modifier.size(32.dp),
+                )
+            }
+            IconButton(
+                onClick = onSkipNext,
+                theme = LocalBaseUITheme.current.iconButtons.ghost.copyShape(CircleShape),
+            ) {
+                Icon(Iconsax.IconsaxNext, contentDescription = "Next")
+            }
+            IconButton(
+                onClick = onCycleLoop,
+                theme = LocalBaseUITheme.current.iconButtons.ghost.copyShape(CircleShape),
+            ) {
+                Icon(
+                    imageVector = Iconsax.IconsaxRepeateMusic,
+                    contentDescription = "Loop mode",
+                    tint = if (playerState.loopMode != "none") {
+                        MaterialTheme.colorScheme.primary
+                    } else {
+                        MaterialTheme.colorScheme.onSurfaceVariant
+                    },
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun JamQueueView(
+    queue: List<JamQueueUiItem>,
+    onJumpTo: (Int) -> Unit,
+) {
+    var expanded by rememberSaveable { mutableStateOf(false) }
+
+    Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
+        Row(
+            modifier = Modifier
+                .fillMaxWidth()
+                .clickable { expanded = !expanded },
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            Text(
+                text = "Queue (${queue.size})",
+                style = MaterialTheme.typography.titleSmall,
+                modifier = Modifier.weight(1f),
+            )
+            Icon(
+                imageVector = Iconsax.IconsaxArrowDown4,
+                contentDescription = if (expanded) "Collapse queue" else "Expand queue",
+                modifier = Modifier
+                    .size(20.dp)
+                    .graphicsLayer { rotationZ = if (expanded) 180f else 0f },
+                tint = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+
+        if (queue.isEmpty()) {
+            Text(
+                text = "The queue is empty. Add tracks from anywhere in the app — the jam queue is shared.",
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        } else if (expanded) {
+            LazyColumn(
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .heightIn(max = 280.dp),
+                verticalArrangement = Arrangement.spacedBy(2.dp),
+            ) {
+                itemsIndexed(queue) { index, item ->
+                    Row(
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .clickable { onJumpTo(index) }
+                            .padding(vertical = 6.dp, horizontal = 4.dp),
+                        verticalAlignment = Alignment.CenterVertically,
+                        horizontalArrangement = Arrangement.spacedBy(10.dp),
+                    ) {
+                        AsyncImage(
+                            model = item.coverUrl.takeIf { it.isNotBlank() },
+                            contentDescription = null,
+                            contentScale = ContentScale.Crop,
+                            modifier = Modifier
+                                .size(40.dp)
+                                .clip(MaterialTheme.shapes.small),
+                        )
+                        Column(modifier = Modifier.weight(1f)) {
+                            Text(
+                                text = item.title,
+                                style = MaterialTheme.typography.bodyMedium,
+                                maxLines = 1,
+                                overflow = TextOverflow.Ellipsis,
+                                color = if (item.isCurrent) {
+                                    MaterialTheme.colorScheme.primary
+                                } else {
+                                    MaterialTheme.colorScheme.onSurface
+                                },
+                            )
+                            Text(
+                                text = item.artist,
+                                style = MaterialTheme.typography.bodySmall,
+                                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                                maxLines = 1,
+                                overflow = TextOverflow.Ellipsis,
+                            )
+                        }
+                        Text(
+                            text = formatJamDuration(item.durationMs),
+                            style = MaterialTheme.typography.labelSmall,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        )
+                    }
+                }
+            }
+        } else {
+            Text(
+                text = "Tap to view the shared queue.",
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+    }
+}
+
+@Composable
+private fun ParticipantsSection(
+    participants: List<dev.krtirtho.spotube.core.jam.JamParticipant>,
+    isHost: Boolean,
+    onKick: (String) -> Unit,
+    onBan: (String) -> Unit,
+) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
         Text(
             text = "Participants (${participants.size})",
@@ -357,11 +665,32 @@ private fun ParticipantsSection(participants: List<dev.krtirtho.spotube.core.jam
                         color = MaterialTheme.colorScheme.primary,
                     )
                 }
+                if (isHost && !participant.isHost) {
+                    OutlinedButton(
+                        onClick = { onKick(participant.id) },
+                        modifier = Modifier.height(32.dp),
+                    ) {
+                        Text("Kick", style = MaterialTheme.typography.labelSmall)
+                    }
+                    OutlinedButton(
+                        onClick = { onBan(participant.id) },
+                        modifier = Modifier.height(32.dp),
+                    ) {
+                        Text("Ban", style = MaterialTheme.typography.labelSmall)
+                    }
+                }
             }
         }
     }
 }
 
+private fun formatJamDuration(ms: Long): String {
+    val totalSeconds = (ms / 1000).coerceAtLeast(0)
+    val minutes = totalSeconds / 60
+    val seconds = totalSeconds % 60
+    return "$minutes:${seconds.toString().padStart(2, '0')}"
+}
+
 @Composable
 private fun ShareableLinkBox(
     label: String,

composeApp/src/commonMain/kotlin/dev/krtirtho/spotube/modules/jam/JamViewModel.kt

@@ -20,18 +20,31 @@ package dev.krtirtho.spotube.modules.jam
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import dev.krtirtho.spotube.PlatformType
+import dev.krtirtho.spotube.core.audioplayer.AudioPlayerInterface
+import dev.krtirtho.spotube.core.audioplayer.AudioPlayerQueue
+import dev.krtirtho.spotube.core.audioplayer.LoopState
+import dev.krtirtho.spotube.core.audioplayer.MediaItem
+import dev.krtirtho.spotube.core.audioplayer.PlayerState
+import dev.krtirtho.spotube.core.audioplayer.QueueEntry
 import dev.krtirtho.spotube.core.deeplink.JamDeepLinkService
 import dev.krtirtho.spotube.core.jam.JamInviteCodec
 import dev.krtirtho.spotube.core.jam.JamInviteLink
+import dev.krtirtho.spotube.core.jam.JamLoopMapping
+import dev.krtirtho.spotube.core.jam.JamMediaItem
+import dev.krtirtho.spotube.core.jam.JamMessage
 import dev.krtirtho.spotube.core.jam.JamParticipant
 import dev.krtirtho.spotube.core.jam.JamRole
 import dev.krtirtho.spotube.core.jam.JamSessionService
+import dev.krtirtho.spotube.core.jam.PlaybackCmd
 import dev.krtirtho.spotube.core.share.ShareService
 import dev.krtirtho.spotube.getPlatform
 import dev.krtirtho.spotube.modules.settings.SettingsProvider
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 
@@ -50,11 +63,36 @@ data class JamUiState(
     val error: String? = null,
 )
 
+data class JamQueueUiItem(
+    val id: String,
+    val title: String,
+    val artist: String,
+    val album: String,
+    val durationMs: Long,
+    val coverUrl: String,
+    val isCurrent: Boolean,
+)
+
+data class JamPlayerUiState(
+    val queue: List<JamQueueUiItem> = emptyList(),
+    val currentIndex: Int = -1,
+    val currentTitle: String? = null,
+    val currentArtist: String? = null,
+    val currentCoverUrl: String? = null,
+    val isPlaying: Boolean = false,
+    val positionMs: Long = 0,
+    val durationMs: Long = 0,
+    val shuffleEnabled: Boolean = false,
+    val loopMode: String = "none",
+)
+
 class JamViewModel(
     private val jamSession: JamSessionService,
     private val deepLinks: JamDeepLinkService,
     private val shareService: ShareService,
     private val settingsProvider: SettingsProvider,
+    private val audioPlayer: AudioPlayerInterface,
+    private val audioPlayerQueue: AudioPlayerQueue,
 ) : ViewModel() {
 
     private val _uiState = MutableStateFlow(JamUiState())
@@ -98,6 +136,144 @@ class JamViewModel(
         }
     }
 
+    /**
+     * The jam player state: the shared queue + current playback, built from the
+     * local player (the host's queue IS the jam queue; on guests the synced
+     * mirror lives in the local player).
+     */
+    val jamPlayerState: StateFlow<JamPlayerUiState> = combine(
+        audioPlayerQueue.queueFlow,
+        audioPlayerQueue.currentQueueEntryFlow,
+        audioPlayer.playlistFlow,
+        audioPlayer.currentMediaItemFlow,
+        audioPlayer.playerStateFlow,
+        audioPlayer.positionFlow,
+        audioPlayer.durationFlow,
+        audioPlayer.loopStateFlow,
+        audioPlayer.shuffleModeFlow,
+    ) { values ->
+        val queue: List<QueueEntry> = values[0] as List<QueueEntry>
+        val currentEntry: QueueEntry? = values[1] as QueueEntry?
+        val playlist: List<MediaItem> = values[2] as List<MediaItem>
+        val currentItem: MediaItem? = values[3] as MediaItem?
+        val playerState: PlayerState = values[4] as PlayerState
+        val position: kotlin.time.Duration = values[5] as kotlin.time.Duration
+        val duration: kotlin.time.Duration = values[6] as kotlin.time.Duration
+        val loop: LoopState = values[7] as LoopState
+        val shuffle: Boolean = values[8] as Boolean
+
+        val isHost = jamSession.role.value == JamRole.Host
+
+        val items: List<JamQueueUiItem>
+        val currentIndex: Int
+        val currentTitle: String?
+        val currentArtist: String?
+        val currentCoverUrl: String?
+
+        if (isHost) {
+            val queueItems = queue.map { JamMediaItem.fromQueueEntry(it) }
+            val index = if (currentEntry != null) {
+                queue.indexOfFirst { entry -> entry.matchesQueueEntry(currentEntry) }
+            } else {
+                -1
+            }
+            items = queueItems.mapIndexed { i, item ->
+                item.toUiItem(i == index)
+            }
+            currentIndex = index
+            currentTitle = queueItems.getOrNull(index)?.title
+            currentArtist = queueItems.getOrNull(index)?.artist
+            currentCoverUrl = queueItems.getOrNull(index)?.coverUrl
+        } else {
+            val index = playlist.indexOf(currentItem)
+            items = playlist.mapIndexed { i, item ->
+                JamMediaItem.fromMediaItem(item).toUiItem(i == index)
+            }
+            currentIndex = index
+            currentTitle = currentItem?.title
+            currentArtist = currentItem?.artist
+            currentCoverUrl = currentItem?.coverURL
+        }
+
+        JamPlayerUiState(
+            queue = items,
+            currentIndex = currentIndex,
+            currentTitle = currentTitle,
+            currentArtist = currentArtist,
+            currentCoverUrl = currentCoverUrl,
+            isPlaying = playerState == PlayerState.PLAYING,
+            positionMs = position.inWholeMilliseconds,
+            durationMs = duration.inWholeMilliseconds,
+            shuffleEnabled = shuffle,
+            loopMode = loop.name.lowercase(),
+        )
+    }.stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), JamPlayerUiState())
+
+    // ---------- Playback controls ----------
+
+    fun togglePlayPause() = sendOrApply(PlaybackCmd.Toggle)
+
+    fun skipNext() = sendOrApply(PlaybackCmd.SkipNext)
+
+    fun skipPrevious() = sendOrApply(PlaybackCmd.SkipPrevious)
+
+    fun seek(positionMs: Long) = sendOrApply(PlaybackCmd.Seek(positionMs))
+
+    fun jumpTo(index: Int) = sendOrApply(PlaybackCmd.JumpTo(index))
+
+    fun toggleShuffle() = sendOrApply(PlaybackCmd.SetShuffle(!jamPlayerState.value.shuffleEnabled))
+
+    fun cycleLoopMode() {
+        val next = when (jamPlayerState.value.loopMode) {
+            "none" -> "one"
+            "one" -> "all"
+            else -> "none"
+        }
+        sendOrApply(PlaybackCmd.SetLoop(next))
+    }
+
+    private fun sendOrApply(command: PlaybackCmd) {
+        viewModelScope.launch {
+            if (jamSession.role.value == JamRole.Host) {
+                applyCommandLocally(command)
+            } else {
+                jamSession.sendMessage(JamMessage.PlaybackCommand(command))
+            }
+        }
+    }
+
+    private suspend fun applyCommandLocally(command: PlaybackCmd) {
+        when (command) {
+            PlaybackCmd.Play -> audioPlayer.play()
+            PlaybackCmd.Pause -> audioPlayer.pause()
+            PlaybackCmd.Toggle -> {
+                if (audioPlayer.playerStateFlow.value == PlayerState.PLAYING) {
+                    audioPlayer.pause()
+                } else {
+                    audioPlayer.play()
+                }
+            }
+
+            is PlaybackCmd.Seek -> audioPlayer.seekTo(kotlin.time.Duration.parse("${command.positionMs}ms"))
+            PlaybackCmd.SkipNext -> audioPlayer.skipToNext()
+            PlaybackCmd.SkipPrevious -> audioPlayer.skipToPrevious()
+            is PlaybackCmd.SetVolume -> audioPlayer.setVolume(command.volume)
+            is PlaybackCmd.SetLoop -> audioPlayer.loop(JamLoopMapping.fromString(command.loop))
+            is PlaybackCmd.SetShuffle -> audioPlayer.shuffle(command.enabled)
+            is PlaybackCmd.JumpTo -> audioPlayer.jumpTo(command.index)
+        }
+    }
+
+    // ---------- Host moderation ----------
+
+    fun kickParticipant(participantId: String) {
+        viewModelScope.launch { jamSession.kickParticipant(participantId) }
+    }
+
+    fun banParticipant(participantId: String) {
+        viewModelScope.launch { jamSession.banParticipant(participantId) }
+    }
+
     fun createSession() {
         viewModelScope.launch {
             runCatching {
@@ -228,4 +404,26 @@ class JamViewModel(
 
     private fun localName(): String =
         settingsProvider.settingsState.value?.jamParticipantName.orEmpty()
+}
+
+private fun JamMediaItem.toUiItem(isCurrent: Boolean): JamQueueUiItem = JamQueueUiItem(
+    id = if (trackId.isNotBlank()) trackId else url,
+    title = title,
+    artist = artist,
+    album = album,
+    durationMs = durationMs,
+    coverUrl = coverUrl,
+    isCurrent = isCurrent,
+)
+
+private fun QueueEntry.matchesQueueEntry(other: QueueEntry): Boolean {
+    return when {
+        this is QueueEntry.StreamingTrack && other is QueueEntry.StreamingTrack ->
+            this.track.id == other.track.id
+
+        this is QueueEntry.LocalTrack && other is QueueEntry.LocalTrack ->
+            this.url == other.url && this.name == other.name
+
+        else -> false
+    }
 }

composeApp/src/commonMain/rust/webrtc_p2p.rs

@@ -78,7 +78,7 @@ struct DataChannelEntry {
 pub struct WebrtcPeerConnection {
     pc: Arc<dyn PeerConnection>,
     handler: Arc<dyn WebrtcEventHandler>,
-    channels: Mutex<Vec<DataChannelEntry>>,
+    channels: Arc<Mutex<Vec<DataChannelEntry>>>,
     gather_rx: Mutex<webrtc::runtime::Receiver<()>>,
 }
 
@@ -122,9 +122,11 @@ pub async fn create_webrtc_peer_connection(
     setting_engine.set_multicast_dns_mode(MulticastDnsMode::Disabled);
 
     let (gather_tx, gather_rx) = channel::<()>(1);
+    let channels = Arc::new(Mutex::new(Vec::new()));
     let pc_handler = Arc::new(PeerHandlerBridge {
         handler: Arc::clone(&handler),
         gather_tx,
+        channels: Arc::clone(&channels),
     });
 
     let pc = PeerConnectionBuilder::new()
@@ -140,7 +142,7 @@ pub async fn create_webrtc_peer_connection(
     Ok(Arc::new(WebrtcPeerConnection {
         pc: Arc::new(pc) as Arc<dyn PeerConnection>,
         handler,
-        channels: Mutex::new(Vec::new()),
+        channels,
         gather_rx: Mutex::new(gather_rx),
     }))
 }
@@ -150,17 +152,34 @@ impl WebrtcPeerConnection {
     /// candidates (non-trickle exchange). Must be called after `set_local_description`,
     /// which is what starts gathering.
     ///
-    /// Bounded by a timeout so a stalled gatherer (e.g. a platform that never reports
-    /// completion) can never hang `create_offer`/`create_answer` forever — the SDP
-    /// with the candidates gathered so far is returned instead.
+    /// Robust against a stalled gatherer (e.g. an unreachable STUN server): once at
+    /// least one candidate has landed in the local description, a short grace period
+    /// is enough — the SDP must never leave candidate-less. Hard cap at 5s.
     async fn wait_for_ice_gathering(&self) {
         let mut gather_rx = self.gather_rx.lock().clone();
-        match tokio::time::timeout(Duration::from_secs(5), gather_rx.recv()).await {
-            Ok(_) => {}
-            Err(_) => {
+        let started = std::time::Instant::now();
+
+        loop {
+            let elapsed = started.elapsed();
+            if elapsed >= Duration::from_secs(5) {
                 log::warn!(
-                    "ICE gathering did not complete within 5s; returning SDP with the candidates gathered so far"
+                    "ICE gathering did not complete within 5s; using the candidates gathered so far"
                 );
+                return;
+            }
+
+            match tokio::time::timeout(Duration::from_millis(100), gather_rx.recv()).await {
+                Ok(Some(())) => return, // gathering complete
+                Ok(None) => return,     // handler dropped
+                Err(_) => {}            // timed out, keep waiting
+            }
+
+            // Grace period once candidates are present, so the SDP always carries them.
+            if elapsed >= Duration::from_secs(1) {
+                let sdp = self.pc.local_description().await.map(|d| d.sdp);
+                if sdp.as_deref().map_or(false, |s| s.contains("a=candidate:")) {
+                    return;
+                }
             }
         }
     }
@@ -251,6 +270,7 @@ impl WebrtcPeerConnection {
 struct PeerHandlerBridge {
     handler: Arc<dyn WebrtcEventHandler>,
     gather_tx: webrtc::runtime::Sender<()>,
+    channels: Arc<Mutex<Vec<DataChannelEntry>>>,
 }
 
 #[async_trait::async_trait]
@@ -272,6 +292,15 @@ impl PeerConnectionEventHandler for PeerHandlerBridge {
     }
 
     async fn on_data_channel(&self, dc: Arc<dyn DataChannel>) {
+        // Register in-band (remote-initiated) channels so send_data() can find
+        // them — without this, the answering peer can never send anything.
+        let label = match dc.label().await {
+            Ok(l) => l,
+            Err(_) => return,
+        };
+        self.channels
+            .lock()
+            .push(DataChannelEntry { dc: Arc::clone(&dc), label });
         spawn_data_channel_poll_loop(dc, Arc::clone(&self.handler));
     }
 }