feat: fix voice join/leave, channel edit defaults, channel-update stream restart

Three bugs fixed across the full stack (proto/server/core/ABI/Win/macOS/iOS): 1. Join/Leave Voice now truly subscribes/unsubscribes from the voice plane. Previously the button only toggled the local mic — receiving was always on (gated by channel membership alone). Added a protocol-level voice subscription concept: new SubscribeVoiceRequest/UnsubscribeVoiceRequest/VoiceSubscriptionResult proto messages, User.voice_subscribed field, vc_join_voice/vc_leave_voice C ABI functions, VC_EVENT_VOICE_STATE event, server-side voice_subscribed flag checked by the SFU relay recipient filter, and core-client gating of remote-stream decoder setup. All three clients rewired to subscribe+mic on Join / unsubscribe on Leave. Text chat works regardless of voice subscription. 2. Channel edit dialog now shows the channel's actual current settings. The read struct vc_channel was missing sort_order and audio fields — only the write struct vc_channel_info had them. Extended vc_channel with both (additive, no ABI break), updated the session model and list_channels marshaling to populate them, and updated all three clients' edit callers to use actual channel info instead of hardcoded defaults. 3. Channel parameter updates now automatically restart everyone's streams. Previously editing a channel's audio config persisted and broadcast a ChannelEvent::UPDATED, but no layer restarted streams — encoders/decoders are frozen at announce time. handle_channel_event now detects audio-config changes on the user's current channel and stop->starts each active local stream. The server reads the updated config on re-announce; peers wire up fresh decoders at the new ssrc. All 29 CTest tests pass; Windows DLL + C# client build clean. Apple clients not yet compile-verified (Windows environment).
2026-06-24 14:29:39 +02:00
parent 2baefddbe4
commit 6fe7bf0158
40 changed files with 701 additions and 71 deletions
--- a/PROGRESS.md
+++ b/PROGRESS.md
@@ -10,6 +10,38 @@ up instantly. Newest status at the top.

 ## ▶ Where we left off / next action

+- **Done (2026-06-24):** **Three bug fixes — voice join/leave, channel edit defaults, channel-update stream restart.**
+  1. **Join/Leave Voice now truly subscribes/unsubscribes from the voice plane.** Previously
+     "Join Voice" only started the local mic — receiving was always on (gated by channel
+     membership alone). Added a protocol-level voice subscription concept: new
+     `SubscribeVoiceRequest`/`UnsubscribeVoiceRequest`/`VoiceSubscriptionResult` proto messages
+     (`core/proto/voicecat.proto`), `User.voice_subscribed` field, `vc_join_voice`/`vc_leave_voice`
+     C ABI functions (`core/include/voicecat.h`), `VC_EVENT_VOICE_STATE` event, server-side
+     `voice_subscribed_` flag on `ConnSession` checked by the SFU relay's recipient filter
+     (`SessionRegistry::find_channel_sessions` excludes non-subscribers; `MediaRelay::on_udp_frame`
+     also skips non-subscribed senders). The core client gates `sync_remote_streams` on
+     `voice_subscribed_`, tears down all remote decoders + stops local streams on leave, and
+     re-syncs from the session model on join. All three clients (Windows/macOS/iOS) rewired
+     their Join/Leave Voice button to call `joinVoice`+start mic / `leaveVoice`+core stops mic.
+     The configured input mode (PTT/VAD/AlwaysOn) takes effect on join — no extra mic button.
+     Text chat works regardless of voice subscription. **Apple clients not yet compile-verified
+     (Windows environment).**
+  2. **Channel edit dialog now shows the channel's actual current settings.** The read struct
+     `vc_channel` (`voicecat.h`) was missing `sort_order` and `audio` fields — only the write
+     struct `vc_channel_info` had them. Extended `vc_channel` with both (additive, no ABI break),
+     updated the session model (`session::Channel`) and `apply_snapshot`/`apply_channel_event`
+     to populate them, and updated `vc_list_channels` marshaling. All three clients now build
+     the edit descriptor from the actual channel info instead of hardcoded defaults.
+  3. **Channel parameter updates now automatically restart everyone's streams.** Previously
+     editing a channel's audio config (codec/bitrate/sample-rate/FEC/DTX/etc.) persisted and
+     broadcast a `ChannelEvent::UPDATED`, but no layer restarted streams — encoders/decoders
+     are frozen at announce time. `handle_channel_event` (`core/src/core/client.cpp`) now
+     detects audio-config changes on the user's current channel and calls
+     `restart_active_streams_for_channel`, which stop→starts each active local stream. The
+     server reads the updated channel config on re-announce, and peers' `sync_remote_streams`
+     wire up fresh decoders at the new ssrc. The `LocalStream` struct now retains the stream
+     label across restarts. No server or protocol change needed.
+
 - **[ ] Soon — jitter buffer should measure REAL arrival jitter (RFC 3550), not sender
  timestamps.** `JitterBuffer::push` (`core/src/audio/audio_engine.cpp:84-108`) estimates
  jitter from `gap = ts - last_push_ts_`, where `ts` is the **sender's timestamp** — which is
--- a/clients/apple/Sources/VoiceCatCore/Enums.swift
+++ b/clients/apple/Sources/VoiceCatCore/Enums.swift
@@ -133,6 +133,8 @@ public enum VoiceCatEventType: UInt32, Sendable, Equatable {
    case genericResult = 14
    /// M5: reply to `requestAccountList()` — call `listAccounts()` to read.
    case accountList = 15
+    /// Voice-plane subscription state. `u32a` = 1 (subscribed) or 0 (unsubscribed).
+    case voiceState = 16

    public init(_ cValue: vc_event_type) {
        self = VoiceCatEventType(rawValue: cValue.rawValue) ?? .error
--- a/clients/apple/Sources/VoiceCatCore/Marshaling.swift
+++ b/clients/apple/Sources/VoiceCatCore/Marshaling.swift
@@ -38,7 +38,8 @@ internal enum Marshaling {
            let c = items.advanced(by: i).pointee
            result.append(Channel(id: c.id, parentId: c.parent_id, name: string(c.name),
                                  topic: string(c.topic), passwordProtected: c.password_protected != 0,
-                                  maxUsers: c.max_users))
+                                  maxUsers: c.max_users, sortOrder: c.sort_order,
+                                  audio: audioConfig(c.audio)))
        }
        vc_free_channel_list(&list)
        return result
@@ -53,7 +54,8 @@ internal enum Marshaling {
            result.append(User(id: u.id, nickname: string(u.nickname), isGuest: u.is_guest != 0,
                               channelId: u.channel_id, selfMicMuted: u.self_mic_muted != 0,
                               selfDeafened: u.self_deafened != 0, serverMuted: u.server_muted != 0,
-                               serverDeafened: u.server_deafened != 0))
+                               serverDeafened: u.server_deafened != 0,
+                               voiceSubscribed: u.voice_subscribed != 0))
        }
        vc_free_user_list(&list)
        return result
--- a/clients/apple/Sources/VoiceCatCore/Models.swift
+++ b/clients/apple/Sources/VoiceCatCore/Models.swift
@@ -16,11 +16,17 @@ public struct Channel: Sendable, Equatable, Identifiable {
    public let passwordProtected: Bool
    /// 0 = unlimited.
    public let maxUsers: UInt32
+    public let sortOrder: UInt32
+    /// Authoritative channel Opus params (docs/voice.md §3). Populated from the Channel proto
+    /// so the edit dialog can read back the current config.
+    public let audio: AudioConfig

    public init(id: UInt32, parentId: UInt32, name: String, topic: String,
-                passwordProtected: Bool, maxUsers: UInt32) {
+                passwordProtected: Bool, maxUsers: UInt32, sortOrder: UInt32,
+                audio: AudioConfig) {
        self.id = id; self.parentId = parentId; self.name = name; self.topic = topic
        self.passwordProtected = passwordProtected; self.maxUsers = maxUsers
+        self.sortOrder = sortOrder; self.audio = audio
    }
 }

@@ -57,13 +63,15 @@ public struct User: Sendable, Equatable, Identifiable {
    public let selfDeafened: Bool
    public let serverMuted: Bool
    public let serverDeafened: Bool
+    public let voiceSubscribed: Bool

    public init(id: UInt32, nickname: String, isGuest: Bool, channelId: UInt32,
                selfMicMuted: Bool, selfDeafened: Bool, serverMuted: Bool,
-                serverDeafened: Bool) {
+                serverDeafened: Bool, voiceSubscribed: Bool) {
        self.id = id; self.nickname = nickname; self.isGuest = isGuest; self.channelId = channelId
        self.selfMicMuted = selfMicMuted; self.selfDeafened = selfDeafened
        self.serverMuted = serverMuted; self.serverDeafened = serverDeafened
+        self.voiceSubscribed = voiceSubscribed
    }
 }

--- a/clients/apple/Sources/VoiceCatCore/VoiceCatClient.swift
+++ b/clients/apple/Sources/VoiceCatCore/VoiceCatClient.swift
@@ -256,6 +256,16 @@ public final class VoiceCatClient {
        VoiceCatResult(vc_leave_channel(handle))
    }

+    @discardableResult
+    public func joinVoice() -> VoiceCatResult {
+        VoiceCatResult(vc_join_voice(handle))
+    }
+
+    @discardableResult
+    public func leaveVoice() -> VoiceCatResult {
+        VoiceCatResult(vc_leave_voice(handle))
+    }
+
    /// Pull the current channel tree. Re-call after `.channelList`/`.userJoined`/`.userLeft`/
    /// `.userUpdated` events. The native list is freed inside this call — callers never
    /// manage native lifetime.
--- a/clients/apple/iOS/VoiceCatiOS/AppState.swift
+++ b/clients/apple/iOS/VoiceCatiOS/AppState.swift
@@ -98,7 +98,7 @@ final class AppState {
    }

    func disconnect() {
-        session?.stopMicStream()
+        session?.leaveVoice()
        session?.client.disconnect()
        IOSAudioEngine.shared.stop()
        AudioSessionManager.shared.deactivateSession()
--- a/clients/apple/iOS/VoiceCatiOS/SessionState.swift
+++ b/clients/apple/iOS/VoiceCatiOS/SessionState.swift
@@ -20,6 +20,7 @@ struct ActivityEntry: Identifiable {

 struct VoiceState {
    var micActive = false
+    var voiceSubscribed = false
    var selfMuted = false
    var selfDeafened = false
    var serverMuted = false
@@ -151,8 +152,6 @@ final class SessionState {
                addActivity("Sharing screen audio (\(channels == 2 ? "stereo" : "mono"))")
                break
            }
-            // A remote user started a stream — ensure the audio session is active so we can
-            // hear them even if we haven't joined voice ourselves.
            if ev.userId != selfUserId {
                do {
                    try AudioSessionManager.shared.ensureSessionActive()
@@ -163,7 +162,25 @@ final class SessionState {
            AudioSessionManager.shared.logSessionState("stream started (user \(ev.userId))")
            addActivity("Stream started (user \(ev.userId))")
        case .streamStopped:
+            if ev.userId == selfUserId {
+                if ev.streamId == voiceState.localStreamId {
+                    voiceState.localStreamId = 0
+                    voiceState.micActive = false
+                    voiceState.level = 0
+                }
+            } else {
                addActivity("Stream stopped (user \(ev.userId))")
+            }
+        case .voiceState:
+            let subscribed = ev.u32a != 0
+            voiceState.voiceSubscribed = subscribed
+            if subscribed {
+                doStartMicStream()
+            } else {
+                voiceState.micActive = false
+                voiceState.level = 0
+                EventFeedback.shared.play(.voiceOff)
+            }
        case .joinResult:
            if ev.result == .ok {
                currentChannelId = ev.channelId
@@ -234,12 +251,15 @@ final class SessionState {
        currentChannelId = 0
    }

-    func startMicStream() {
+    func joinVoice() {
        AVAudioApplication.requestRecordPermission { [weak self] granted in
            DispatchQueue.main.async {
                guard let self else { return }
                if granted {
-                    self.doStartMicStream()
+                    let result = self.client.joinVoice()
+                    if result != .ok {
+                        self.addActivity("Failed to join voice: \(result.description)")
+                    }
                } else {
                    self.addActivity("Microphone permission denied — grant in Settings > Privacy > Microphone")
                }
@@ -255,10 +275,6 @@ final class SessionState {
            return
        }

-        // Unified iOS path: the core is always external (set at connect via setExternalPlayback +
-        // every MIC stream external_feed), and `IOSAudioEngine` drives capture + playback. So the
-        // mic stream is just started with external_feed=true and the engine is told the mic is now
-        // active — no setExternalPlayback toggle, no audioRestart ordering, no VPIO/miniaudio fork.
        let desc = StreamDescriptor(kind: .mic, deviceId: voiceState.currentDeviceId, label: "Mic",
                                    externalFeed: true)
        let (result, streamId) = client.startStream(desc)
@@ -274,25 +290,14 @@ final class SessionState {
        if channels != 1 {
            client.setCaptureChannels(streamId: streamId, channels: channels)
        }
-        // Engage the mic: installs the input tap and (per preset) VPIO, in one engine rebuild.
        IOSAudioEngine.shared.startMic(streamId: streamId, channels: channels)
    }

-    func stopMicStream() {
-        // Disengage the mic (removes the tap + VPIO) but keep the engine running for any remaining
-        // remote audio. Then stop the core's MIC stream. The core stays external throughout — no
-        // setExternalPlayback toggle, no audioRestart.
+    func leaveVoice() {
+        if voiceState.screenStreamId != 0 { stopScreenShare() }
+        client.setPushToTalk(false)
        IOSAudioEngine.shared.stopMic()
-        if voiceState.localStreamId != 0 {
-            client.stopStream(voiceState.localStreamId)
-            voiceState.localStreamId = 0
-            EventFeedback.shared.play(.voiceOff)
-        }
-        voiceState.micActive = false
-        voiceState.level = 0
-        // Do NOT deactivate the AVAudioSession here — the user may still want to hear
-        // remote audio (other people talking). The session is deactivated only when
-        // disconnecting from the server (see AppState.disconnect / .disconnected event).
+        client.leaveVoice()
    }

    // MARK: - Screen audio share
--- a/clients/apple/iOS/VoiceCatiOS/Views/ChannelEditView.swift
+++ b/clients/apple/iOS/VoiceCatiOS/Views/ChannelEditView.swift
@@ -15,8 +15,7 @@ struct ChannelEditView: View {
    @State private var maxUsers = "0"
    @State private var sortOrder = "0"

-    // Audio (Opus). Note: the channel list does not carry the current audio config, so when
-    // editing an existing channel these start from the codec defaults (same as macOS/Windows).
+    // Audio (Opus) — populated from the channel's current config when editing.
    @State private var stereo = false
    @State private var bitrate = "64000"
    @State private var sampleRate = "48000"
@@ -122,6 +121,17 @@ struct ChannelEditView: View {
        parentId = ch.parentId
        passwordProtected = ch.passwordProtected
        maxUsers = "\(ch.maxUsers)"
+        sortOrder = "\(ch.sortOrder)"
+        stereo = ch.audio.stereo
+        bitrate = "\(ch.audio.bitrateBps)"
+        sampleRate = "\(ch.audio.sampleRate)"
+        frameMs = ch.audio.frameMs
+        application = ch.audio.application
+        packetLoss = "\(ch.audio.expectedPacketLoss)"
+        complexity = ch.audio.complexity
+        fec = ch.audio.fec
+        dtx = ch.audio.dtx
+        dred = ch.audio.dred
    }

    private func save() {
--- a/clients/apple/iOS/VoiceCatiOS/Views/SettingsView.swift
+++ b/clients/apple/iOS/VoiceCatiOS/Views/SettingsView.swift
@@ -294,7 +294,7 @@ struct SettingsView: View {
                // MARK: - Server
                Section("Server") {
                    Button(role: .destructive) {
-                        session.stopMicStream()
+                        session.leaveVoice()
                        appState.disconnect()
                    } label: {
                        Label("Disconnect", systemImage: "phone.down")
--- a/clients/apple/iOS/VoiceCatiOS/Views/VoiceControlsView.swift
+++ b/clients/apple/iOS/VoiceCatiOS/Views/VoiceControlsView.swift
@@ -14,9 +14,9 @@ struct VoiceControlsView: View {
            } else {
                Button {
                    if session.voiceState.micActive {
-                        session.stopMicStream()
+                        session.leaveVoice()
                    } else {
-                        session.startMicStream()
+                        session.joinVoice()
                    }
                } label: {
                    Text(session.voiceState.micActive ? "Leave Voice" : "Join Voice")
@@ -28,7 +28,7 @@ struct VoiceControlsView: View {
                        .foregroundStyle(session.voiceState.micActive ? .green : .accentColor)
                }
                .disabled(session.currentChannelId == 0)
-                .accessibilityLabel(session.voiceState.micActive ? "Leave Voice — stop sending microphone audio" : "Join Voice — start sending microphone audio")
+                .accessibilityLabel(session.voiceState.micActive ? "Leave Voice" : "Join Voice")
            }

            // Level meter
@@ -81,7 +81,7 @@ struct VoiceControlsView: View {

            // Disconnect
            Button(role: .destructive) {
-                session.stopMicStream()
+                session.leaveVoice()
                session.client.disconnect()
            } label: {
                Image(systemName: "phone.down.fill")
@@ -115,13 +115,13 @@ private struct PTTButton: View {
                    .updating($isPressing) { _, state, _ in state = true }
                    .onChanged { _ in
                        if !isPressing { return }
-                        if !session.voiceState.micActive { session.startMicStream() }
+                        if !session.voiceState.micActive { session.joinVoice() }
                        session.setPushToTalk(true)
                        UIImpactFeedbackGenerator(style: .medium).impactOccurred()
                    }
                    .onEnded { _ in
                        session.setPushToTalk(false)
-                        session.stopMicStream()
+                        session.leaveVoice()
                    }
            )
            .accessibilityLabel("Push to talk, hold to transmit")
--- a/clients/apple/macOS/VoiceCatMac/Windows/MainWindowController.swift
+++ b/clients/apple/macOS/VoiceCatMac/Windows/MainWindowController.swift
@@ -497,7 +497,8 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
                         isGuest: true,
                         channelId: event.channelId,
                         selfMicMuted: false, selfDeafened: false,
-                         serverMuted: false, serverDeafened: false)
+                         serverMuted: false, serverDeafened: false,
+                         voiceSubscribed: false)
            users[event.userId] = u
            refreshChannelTree(); refreshUserList()
            if event.channelId == currentChannelId && event.userId != selfUserId {
@@ -540,7 +541,8 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
                    users[selfUserId] = User(id: self_.id, nickname: self_.nickname, isGuest: self_.isGuest,
                                            channelId: event.channelId,
                                            selfMicMuted: self_.selfMicMuted, selfDeafened: self_.selfDeafened,
-                                            serverMuted: self_.serverMuted, serverDeafened: self_.serverDeafened)
+                                            serverMuted: self_.serverMuted, serverDeafened: self_.serverDeafened,
+                                            voiceSubscribed: self_.voiceSubscribed)
                }
                refreshChannelTree(); refreshUserList(); updateStatusLabel()
                let name = channels.first(where: { $0.id == event.channelId })?.name ?? "Channel #\(event.channelId)"
@@ -589,10 +591,18 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
            addActivity("\(u.nickname) started \(kindStr) stream")

        case .streamStopped:
-            if let u = users[event.userId], u.channelId == currentChannelId {
+            if event.userId == selfUserId {
+                if event.streamId == micStreamId {
+                    micStreamId = 0
+                    settingsWindowController?.resetLevel()
+                }
+            } else if let u = users[event.userId], u.channelId == currentChannelId {
                addActivity("\(u.nickname) stopped a stream")
            }

+        case .voiceState:
+            handleVoiceState(event)
+
        case .disconnected:
            handleDisconnected(event)

@@ -783,14 +793,27 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {

    @objc private func micToggleClicked() {
        if micStreamId == 0 {
+            let result = client.joinVoice()
+            if result != .ok {
+                addActivity("Failed to join voice: \(result)")
+            }
+        } else {
+            stopAuxStream()
+            if screenStreamId != 0 { stopScreenAudio() }
+            client.setPushToTalk(false)
+            client.leaveVoice()
+        }
+    }
+
+    private func handleVoiceState(_ event: VoiceCatEvent) {
+        let subscribed = event.u32a != 0
+        if subscribed {
            let (result, streamId) = client.startStream(StreamDescriptor(kind: .mic, deviceId: nil, label: "Microphone"))
            if result == .ok {
                micStreamId = streamId
                if let devId = selectedInputDeviceId {
                    client.setInputDevice(streamId: streamId, deviceId: devId)
                }
-                // Stored on the stream before the announce round-trip completes, so the core's
-                // first capture-device open (ensure_audio_running) picks up the channel count.
                client.setCaptureChannels(streamId: streamId, channels: stereoMic ? 2 : 1)
                client.setInputMode(selectedInputMode)
                if selectedInputMode == .voiceActivation {
@@ -803,14 +826,11 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
                EventFeedback.shared.play(.voiceOn)
                NSAccessibility.post(element: logTextView, notification: .announcementRequested,
                                     userInfo: [.announcement: "Joined voice", .priority: NSAccessibilityPriorityLevel.medium])
-                startAuxStream() // no-op unless the aux stream is enabled in settings
+                startAuxStream()
            } else {
                addActivity("Failed to start microphone: \(result)")
            }
        } else {
-            stopAuxStream()
-            client.setPushToTalk(false)
-            client.stopStream(micStreamId)
            micStreamId = 0
            settingsWindowController?.resetLevel()
            setVoiceJoinedState(false)
@@ -933,6 +953,15 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
        }
    }

+    private func stopScreenAudio() {
+        guard screenStreamId != 0 else { return }
+        stopScreenCapture()
+        client.stopStream(screenStreamId)
+        screenStreamId = 0
+        setShareScreenButton(active: false)
+        addActivity("Stopped sharing screen audio")
+    }
+
    /// Announce the SCREEN_AUDIO stream with the chosen selection in hand. ScreenCaptureKit
    /// capture starts once the server's StreamAnnounceResult lands (the .streamStarted event),
    /// when the effective audio config — and thus the channel count — is known. See
@@ -1449,7 +1478,7 @@ extension MainWindowController: NSMenuDelegate {
        let info = ChannelEdit(id: ch.id, parentId: ch.parentId, name: ch.name,
                               topic: ch.topic, passwordProtected: ch.passwordProtected,
                               password: nil, maxUsers: ch.maxUsers,
-                               sortOrder: 0, audio: AudioConfig())
+                               sortOrder: ch.sortOrder, audio: ch.audio)
        let sheet = ChannelEditSheet(channels: channels, editing: info)
        sheet.onComplete = { [weak self] edited in
            guard let edited else { return }
--- a/clients/windows/VoiceCat.App/Forms/MainForm.cs
+++ b/clients/windows/VoiceCat.App/Forms/MainForm.cs
@@ -349,10 +349,21 @@ public partial class MainForm : Form
                HandleStreamStarted(ev);
                break;
            case VcEventType.StreamStopped:
-                if (_users.TryGetValue(ev.UserId, out var stUser) &&
+                if (ev.UserId == _selfUserId)
+                {
+                    if (ev.StreamId == _micStreamId)
+                    {
+                        _micStreamId = 0;
+                        pbLevel.Value = 0;
+                    }
+                }
+                else if (_users.TryGetValue(ev.UserId, out var stUser) &&
                    stUser.ChannelId == _currentChannelId)
                    AddActivity($"{stUser.Nickname} stopped a stream");
                break;
+            case VcEventType.VoiceState:
+                HandleVoiceState(ev);
+                break;
            case VcEventType.Disconnected:
                HandleDisconnected(ev);
                break;
@@ -378,7 +389,7 @@ public partial class MainForm : Form
    private void HandleUserJoined(VoiceCatEvent ev)
    {
        var user = new UserInfo(ev.UserId, ev.Text ?? $"User#{ev.UserId}", false, ev.ChannelId,
-            false, false, false, false);
+            false, false, false, false, false);
        _users[ev.UserId] = user;
        RefreshChannelTree();
        RefreshUserList();
@@ -663,6 +674,32 @@ public partial class MainForm : Form
    private void BtnMicToggle_Click(object? sender, EventArgs e)
    {
        if (_micStreamId == 0)
+        {
+            var result = _client.JoinVoice();
+            if (result != VcResult.Ok)
+                AddActivity($"Failed to join voice: {result}");
+        }
+        else
+        {
+            StopAuxStream();
+            if (_screenStreamId != 0) StopScreenAudio();
+            _client.SetPushToTalk(false);
+            _client.LeaveVoice();
+        }
+    }
+
+    private void SetVoiceJoinedState(bool joined)
+    {
+        tsbJoinVoice.Text = joined ? "Leave Voice" : "Join Voice";
+        _miJoinVoice.Text = joined ? "Leave &Voice" : "&Join Voice";
+        chkMute.Enabled = joined;
+        chkDeafen.Enabled = joined;
+    }
+
+    private void HandleVoiceState(VoiceCatEvent ev)
+    {
+        bool subscribed = ev.U32a != 0;
+        if (subscribed)
        {
            var (result, streamId) = _client.StartStream(VcStreamKind.Mic, "Microphone");
            if (result == VcResult.Ok)
@@ -680,7 +717,7 @@ public partial class MainForm : Form
                SetVoiceJoinedState(true);
                AddActivity("Joined voice — microphone active");
                _feedback.PlaySound(SoundEvent.VoiceOn);
-                StartAuxStream(); // no-op unless the aux stream is enabled in settings
+                StartAuxStream();
            }
            else
            {
@@ -689,25 +726,12 @@ public partial class MainForm : Form
        }
        else
        {
-            StopAuxStream();
-            _client.SetPushToTalk(false);
-            _client.StopStream(_micStreamId);
-            _micStreamId = 0;
-            pbLevel.Value = 0;
            SetVoiceJoinedState(false);
            AddActivity("Left voice");
            _feedback.PlaySound(SoundEvent.VoiceOff);
        }
    }

-    private void SetVoiceJoinedState(bool joined)
-    {
-        tsbJoinVoice.Text = joined ? "Leave Voice" : "Join Voice";
-        _miJoinVoice.Text = joined ? "Leave &Voice" : "&Join Voice";
-        chkMute.Enabled = joined;
-        chkDeafen.Enabled = joined;
-    }
-
    private void ApplySelfMute() =>
        _client.SetSelfMute(chkMute.Checked, chkDeafen.Checked);

@@ -1122,8 +1146,8 @@ public partial class MainForm : Form

        var editInfo = new ChannelEditInfo(
            channel.Id, channel.ParentId, channel.Name, channel.Topic,
-            channel.PasswordProtected, null, channel.MaxUsers, 0,
-            new AudioConfigInfo(0, false, 48000, 0, 20, 0, true, 0, false, 10, false));
+            channel.PasswordProtected, null, channel.MaxUsers, channel.SortOrder,
+            channel.Audio);

        using var dlg = new ChannelEditDialog(_channels, editInfo);
        if (dlg.ShowDialog(this) != DialogResult.OK || dlg.Result is null) return;
--- a/clients/windows/VoiceCat.Interop/Enums.cs
+++ b/clients/windows/VoiceCat.Interop/Enums.cs
@@ -92,6 +92,8 @@ public enum VcEventType
    GenericResult = 14,
    /// <summary>M5: reply to VoiceCatClient.RequestAccountList — call ListAccounts() to read.</summary>
    AccountList = 15,
+    /// <summary>Voice-plane subscription state. u32a = 1 (subscribed) or 0 (unsubscribed).</summary>
+    VoiceState = 16,
 }

 /// <summary>
--- a/clients/windows/VoiceCat.Interop/Marshaling.cs
+++ b/clients/windows/VoiceCat.Interop/Marshaling.cs
@@ -38,7 +38,9 @@ internal static class Marshaling
                Marshal.PtrToStringUTF8(raw.Name) ?? string.Empty,
                Marshal.PtrToStringUTF8(raw.Topic) ?? string.Empty,
                raw.PasswordProtected != 0,
-                raw.MaxUsers));
+                raw.MaxUsers,
+                raw.SortOrder,
+                ToManaged(in raw.Audio)));
        }
        NativeMethods.vc_free_channel_list(ref native);
        return result;
@@ -59,7 +61,8 @@ internal static class Marshaling
                raw.SelfMicMuted != 0,
                raw.SelfDeafened != 0,
                raw.ServerMuted != 0,
-                raw.ServerDeafened != 0));
+                raw.ServerDeafened != 0,
+                raw.VoiceSubscribed != 0));
        }
        NativeMethods.vc_free_user_list(ref native);
        return result;
--- a/clients/windows/VoiceCat.Interop/Models.cs
+++ b/clients/windows/VoiceCat.Interop/Models.cs
@@ -9,7 +9,9 @@ public sealed record ChannelInfo(
    string Name,
    string Topic,
    bool PasswordProtected,
-    uint MaxUsers);
+    uint MaxUsers,
+    uint SortOrder,
+    AudioConfigInfo Audio);

 public sealed record ChannelEditInfo(
    uint Id,
@@ -30,7 +32,8 @@ public sealed record UserInfo(
    bool SelfMicMuted,
    bool SelfDeafened,
    bool ServerMuted,
-    bool ServerDeafened);
+    bool ServerDeafened,
+    bool VoiceSubscribed);

 public sealed record PermissionsInfo(
    bool CanCreateTempChannel,
--- a/clients/windows/VoiceCat.Interop/NativeMethods.cs
+++ b/clients/windows/VoiceCat.Interop/NativeMethods.cs
@@ -54,6 +54,12 @@ internal static partial class NativeMethods
    [LibraryImport(LibName)]
    internal static partial VcResult vc_leave_channel(nint c);

+    [LibraryImport(LibName)]
+    internal static partial VcResult vc_join_voice(nint c);
+
+    [LibraryImport(LibName)]
+    internal static partial VcResult vc_leave_voice(nint c);
+
    // ── Local media streams ─────────────────────────────────────────────────────────────────
    [LibraryImport(LibName)]
    internal static partial VcResult vc_stream_start(nint c, in VcStreamDescNative desc,
--- a/clients/windows/VoiceCat.Interop/Structs.cs
+++ b/clients/windows/VoiceCat.Interop/Structs.cs
@@ -116,6 +116,8 @@ internal struct VcChannelNative
    public IntPtr Topic;
    public int PasswordProtected;
    public uint MaxUsers;
+    public uint SortOrder;
+    public VcAudioConfigNative Audio;
 }

 [StructLayout(LayoutKind.Sequential)]
@@ -136,6 +138,7 @@ internal struct VcUserNative
    public int SelfDeafened;
    public int ServerMuted;
    public int ServerDeafened;
+    public int VoiceSubscribed;
 }

 [StructLayout(LayoutKind.Sequential)]
--- a/clients/windows/VoiceCat.Interop/VoiceCatClient.cs
+++ b/clients/windows/VoiceCat.Interop/VoiceCatClient.cs
@@ -152,6 +152,12 @@ public sealed class VoiceCatClient : IDisposable
    public VcResult LeaveChannel() =>
        NativeMethods.vc_leave_channel(_handle.DangerousGetHandle());

+    public VcResult JoinVoice() =>
+        NativeMethods.vc_join_voice(_handle.DangerousGetHandle());
+
+    public VcResult LeaveVoice() =>
+        NativeMethods.vc_leave_voice(_handle.DangerousGetHandle());
+
    public List<ChannelInfo> ListChannels()
    {
        NativeMethods.vc_list_channels(_handle.DangerousGetHandle(), out var native);
--- a/core/include/voicecat.h
+++ b/core/include/voicecat.h
@@ -145,6 +145,10 @@ typedef enum vc_event_type {
                                       vc_delete_channel/vc_create_account/vc_reset_password/
                                       vc_delete_account. */
    VC_EVENT_ACCOUNT_LIST = 15,    /* Reply to vc_list_accounts. */
+    VC_EVENT_VOICE_STATE = 16,    /* u32a = subscribed(0/1). Reply to vc_join_voice()/
+                                       vc_leave_voice(), and also emitted when the server
+                                       changes your voice-subscription state. The user list
+                                       (vc_user) carries per-user voice_subscribed. */
 } vc_event_type;

 /* TOFU server-identity classification (M4) — see VC_EVENT_SERVER_IDENTITY and
@@ -292,6 +296,10 @@ typedef struct vc_channel {
    const char* topic;
    int         password_protected; /* bool */
    uint32_t    max_users;          /* 0 = unlimited */
+    uint32_t    sort_order;         /* channel sort order */
+    /* Authoritative channel Opus params (docs/voice.md §3). Populated from the Channel proto
+     * so the edit dialog can read back the current config without a separate round-trip. */
+    vc_audio_config audio;
 } vc_channel;

 typedef struct vc_channel_list {
@@ -308,6 +316,7 @@ typedef struct vc_user {
    int         self_deafened;  /* bool */
    int         server_muted;   /* bool */
    int         server_deafened; /* bool */
+    int         voice_subscribed; /* bool — true when on the voice plane */
 } vc_user;

 typedef struct vc_user_list {
@@ -366,6 +375,16 @@ VC_API vc_result vc_join_channel(vc_client* c, uint32_t channel_id,
                                 const char* password /* nullable */);
 VC_API vc_result vc_leave_channel(vc_client* c);

+/* ── Voice-plane subscription ─────────────────────────────────────────────── */
+/* Joining voice subscribes to the voice plane: the server starts relaying voice frames
+ * to you, and the core wires up remote-stream decoders so you hear other users. Leaving
+ * voice unsubscribes: the server stops relaying voice to you, the core tears down all
+ * remote decoders (playback stops), and any active local mic/screen/aux streams are
+ * stopped. Text chat is unaffected either way. Result arrives as VC_EVENT_VOICE_STATE
+ * (u32a = 1 for subscribed, 0 for unsubscribed). */
+VC_API vc_result vc_join_voice(vc_client* c);
+VC_API vc_result vc_leave_voice(vc_client* c);
+
 /* ── Local media streams (mic / screen audio / aux) ───────────────────────── */
 VC_API vc_result vc_stream_start(vc_client* c, const vc_stream_desc* desc,
                                 uint32_t* out_stream_id);
--- a/core/proto/voicecat.proto
+++ b/core/proto/voicecat.proto
@@ -44,6 +44,9 @@ message Envelope {
    StreamStop           stream_stop            = 42;
    StreamStateUpdate    stream_state           = 43;
    UdpBinding           udp_binding            = 44;
+    SubscribeVoiceRequest   subscribe_voice     = 45;
+    UnsubscribeVoiceRequest unsubscribe_voice   = 46;
+    VoiceSubscriptionResult voice_subscription_result = 47;

    // Text (50–59)
    TextMessage          text_message           = 50;
@@ -120,6 +123,7 @@ message User {
  bool   server_muted = 7;
  repeated StreamInfo streams = 8;
  bool   server_deafened = 9;  // M5: server-imposed deafen
+  bool   voice_subscribed = 10; // true when the user is on the voice plane (hears + can send)
 }

 message Permissions {
@@ -216,6 +220,14 @@ message StreamStop          { uint32 stream_id = 1; }
 message StreamStateUpdate   { uint32 user_id = 1; uint32 stream_id = 2; bool muted = 3; bool talking = 4; }
 message UdpBinding          { bytes udp_token = 1; bool ack = 2; }

+// Voice-plane subscription. Joining voice = you can hear and send voice in your channel;
+// leaving voice = the server stops relaying voice frames to you and you stop receiving.
+// Text chat is unaffected. The server toggles a per-session flag checked by the SFU relay's
+// recipient filter (docs/protocol.md §5). Result arrives as voice_subscription_result.
+message SubscribeVoiceRequest   {}
+message UnsubscribeVoiceRequest {}
+message VoiceSubscriptionResult { bool ok = 1; string error = 2; bool subscribed = 3; }
+
 // ── Text (ephemeral — server does not persist history, docs/protocol.md §5) ──────
 message TextMessage {
  TextScope scope = 1;
--- a/core/src/core/client.cpp
+++ b/core/src/core/client.cpp
@@ -500,6 +500,9 @@ void vc_client::handle_envelope(const voicecat::v1::Envelope& env) {
        case voicecat::v1::Envelope::kStreamAnnounceResult:
            handle_stream_announce_result(env.request_id(), env.stream_announce_result());
            break;
+        case voicecat::v1::Envelope::kVoiceSubscriptionResult:
+            handle_voice_subscription_result(env.voice_subscription_result());
+            break;
        case voicecat::v1::Envelope::kPong: {
            // Correlate the echoed nonce to measure RTT (docs/protocol.md §7).
            uint64_t nonce = env.pong().nonce();
@@ -618,10 +621,44 @@ void vc_client::handle_server_state(const voicecat::v1::ServerStateSnapshot& sna
 }

 void vc_client::handle_channel_event(const voicecat::v1::ChannelEvent& ce) {
+    bool audio_changed = false;
+    uint32_t updated_channel_id = 0;
    {
        std::lock_guard<std::mutex> lk(session_model_mu_);
+
+        // Detect audio-config changes on our current channel BEFORE apply_channel_event
+        // overwrites the stored config. Encoders/decoders are frozen at StreamAnnounceResult
+        // time (docs/voice.md §3), so a channel audio change requires restarting active
+        // local streams to pick up the new params.
+        if (ce.kind() == voicecat::v1::ChannelEvent::UPDATED) {
+            updated_channel_id = ce.channel().id();
+            const auto* self_user = session_model_.find_user(self_user_id_);
+            if (self_user && self_user->channel_id == updated_channel_id) {
+                const auto* old_ch = session_model_.find_channel(updated_channel_id);
+                const auto& na = ce.channel().audio();
+                if (old_ch) {
+                    audio_changed =
+                        old_ch->audio_sample_rate          != (na.sample_rate() ? na.sample_rate() : 48000) ||
+                        old_ch->audio_frame_ms             != (na.frame_ms() ? na.frame_ms() : 20) ||
+                        old_ch->audio_mode                 != static_cast<uint32_t>(na.mode()) ||
+                        old_ch->audio_bitrate_bps          != na.bitrate_bps() ||
+                        old_ch->audio_application          != static_cast<uint32_t>(na.application()) ||
+                        old_ch->audio_fec                  != na.fec() ||
+                        old_ch->audio_expected_packet_loss != na.expected_packet_loss() ||
+                        old_ch->audio_dtx                  != na.dtx() ||
+                        old_ch->audio_complexity           != (na.complexity() ? na.complexity() : 10) ||
+                        old_ch->audio_dred                 != na.dred();
+                }
+            }
+        }
+
        session_model_.apply_channel_event(ce);
    }
+
+    if (audio_changed) {
+        restart_active_streams_for_channel(updated_channel_id);
+    }
+
    // Same "go look" signal vc_list_channels' callers already poll on after the initial
    // snapshot — see voicecat.h's VC_EVENT_CHANNEL_LIST doc comment.
    vc_event ev{};
@@ -1215,6 +1252,10 @@ void vc_client::ensure_audio_running() {

 void vc_client::sync_remote_streams(const voicecat::v1::User& user) {
    if (user.id() == self_user_id_) return;
+    // Don't wire up remote decoders when not on the voice plane — the server isn't relaying
+    // voice to us, and decoders would sit idle consuming memory. resync_remote_streams()
+    // wires them up on voice join.
+    if (!voice_subscribed_.load(std::memory_order_acquire)) return;

    std::vector<uint32_t> current_ssrcs;
    for (const auto& si : user.streams()) current_ssrcs.push_back(si.ssrc());
@@ -1285,6 +1326,7 @@ vc_result vc_client::stream_start(const vc_stream_desc& desc, uint32_t* out_stre
        ls.stream_id    = sid;
        ls.pending      = true;
        ls.external_feed = (desc.external_feed != 0);
+        ls.label        = desc.label ? desc.label : "";
        if (out_stream_id) *out_stream_id = sid;

        req_id = next_req_id_++;
@@ -1441,6 +1483,141 @@ vc_client::LocalStream* vc_client::find_local_stream_by_id(uint32_t stream_id) {
    return nullptr;
 }

+void vc_client::restart_active_streams_for_channel(uint32_t channel_id) {
+    // Collect active stream info under the lock, then stop→start outside the lock (stream_stop
+    // and stream_start both acquire local_streams_mu_). capture_device_id and capture_channels
+    // survive the restart: stream_stop doesn't clear them, and stream_start reuses the existing
+    // LocalStream entry (auto& ls = local_streams_[kind]) without resetting them.
+    struct ActiveStreamInfo {
+        int         kind;
+        std::string label;
+        int         external_feed;
+        uint32_t    stream_id;
+    };
+    std::vector<ActiveStreamInfo> active;
+    {
+        std::lock_guard lk(local_streams_mu_);
+        for (auto& [kind, ls] : local_streams_) {
+            if (!ls.active.load(std::memory_order_acquire)) continue;
+            active.push_back({kind, ls.label, ls.external_feed ? 1 : 0, ls.stream_id});
+        }
+    }
+
+    for (const auto& info : active) {
+        stream_stop(info.stream_id);
+        vc_stream_desc desc{};
+        desc.kind          = static_cast<vc_stream_kind>(info.kind);
+        desc.device_id     = nullptr;  // default — capture_device_id is retained on the LocalStream
+        desc.label         = info.label.c_str();
+        desc.external_feed = info.external_feed;
+        uint32_t new_sid = 0;
+        stream_start(desc, &new_sid);
+    }
+}
+
+// ── Voice-plane subscription ──────────────────────────────────────────────────
+
+vc_result vc_client::join_voice() {
+    if (state_net_.load(std::memory_order_acquire) != VC_STATE_CONNECTED) return VC_ERR_NOT_CONNECTED;
+    voicecat::v1::Envelope req;
+    req.set_request_id(next_req_id_++);
+    req.mutable_subscribe_voice();
+    queue_envelope(req);
+    return VC_OK;
+}
+
+vc_result vc_client::leave_voice() {
+    if (state_net_.load(std::memory_order_acquire) != VC_STATE_CONNECTED) return VC_ERR_NOT_CONNECTED;
+    voicecat::v1::Envelope req;
+    req.set_request_id(next_req_id_++);
+    req.mutable_unsubscribe_voice();
+    queue_envelope(req);
+    return VC_OK;
+}
+
+void vc_client::handle_voice_subscription_result(
+        const voicecat::v1::VoiceSubscriptionResult& msg) {
+    bool subscribed = msg.subscribed();
+    voice_subscribed_.store(subscribed, std::memory_order_release);
+
+    if (subscribed) {
+        // Wire up remote-stream decoders for all users already in the session model.
+        // While we were unsubscribed, sync_remote_streams was gated off, so no decoders
+        // exist — resync from the current session state.
+        resync_remote_streams();
+    } else {
+        // Stop all active local streams (emits VC_EVENT_STREAM_STOPPED for each) and tear
+        // down every remote decoder so playback ceases. The server has already stopped
+        // relaying voice to us.
+        stop_all_local_streams();
+        clear_all_remote_streams();
+    }
+
+    vc_event ev{};
+    ev.type = VC_EVENT_VOICE_STATE;
+    ev.u32a = subscribed ? 1 : 0;
+    emit(ev);
+}
+
+void vc_client::resync_remote_streams() {
+    bool any_added = false;
+    {
+        std::lock_guard<std::mutex> sm_lk(session_model_mu_);
+        std::lock_guard rs_lk(remote_streams_mu_);
+        for (const auto& u : session_model_.users()) {
+            if (u.id == self_user_id_) continue;
+            for (const auto& s : u.streams) {
+                if (remote_streams_.count(s.ssrc)) continue;
+                remote_streams_[s.ssrc] = {u.id, s.stream_id};
+
+                voicecat::v1::AudioConfig audio;
+                audio.set_sample_rate(s.sample_rate);
+                audio.set_frame_ms(s.frame_ms);
+                audio.set_mode(static_cast<voicecat::v1::ChannelMode>(s.mode));
+                audio.set_bitrate_bps(s.bitrate_bps);
+                audio.set_application(static_cast<voicecat::v1::OpusApplication>(s.application));
+                audio.set_fec(s.fec);
+                audio.set_expected_packet_loss(s.expected_packet_loss);
+                audio.set_dtx(s.dtx);
+                audio.set_complexity(s.complexity);
+                audio.set_dred(s.dred);
+
+                voicecat::codec::OpusParams p = opus_params_from_audio_config(audio);
+                bool is_voice = (s.kind == static_cast<int>(voicecat::v1::STREAM_MIC));
+                audio_engine_.init_recv_stream(s.ssrc, p, u.id, s.stream_id, is_voice);
+                bool muted = self_deafened_.load(std::memory_order_acquire) ||
+                             server_deafened_.load(std::memory_order_acquire);
+                audio_engine_.set_stream_mute(s.ssrc, muted);
+                any_added = true;
+            }
+        }
+    }
+    if (any_added) ensure_audio_running();
+}
+
+void vc_client::clear_all_remote_streams() {
+    std::lock_guard lk(remote_streams_mu_);
+    for (auto& [ssrc, info] : remote_streams_) {
+        audio_engine_.remove_stream(ssrc);
+    }
+    remote_streams_.clear();
+}
+
+void vc_client::stop_all_local_streams() {
+    std::vector<uint32_t> active_ids;
+    {
+        std::lock_guard lk(local_streams_mu_);
+        for (auto& [kind, ls] : local_streams_) {
+            if (ls.active.load(std::memory_order_acquire)) {
+                active_ids.push_back(ls.stream_id);
+            }
+        }
+    }
+    for (uint32_t sid : active_ids) {
+        stream_stop(sid);
+    }
+}
+
 vc_result vc_client::set_input_device(uint32_t stream_id, const char* device_id) {
    int kind = -1;
    {
@@ -1734,6 +1911,19 @@ vc_result vc_client::list_channels(vc_channel_list* out) {
        items[i].topic              = topic;
        items[i].password_protected = ch.password_protected ? 1 : 0;
        items[i].max_users          = ch.max_users;
+        items[i].sort_order         = ch.sort_order;
+        auto& ac = items[i].audio;
+        ac.codec                = 0;  // OPUS
+        ac.mode                 = ch.audio_mode;
+        ac.sample_rate          = ch.audio_sample_rate;
+        ac.bitrate_bps          = ch.audio_bitrate_bps;
+        ac.frame_ms             = ch.audio_frame_ms;
+        ac.application          = ch.audio_application;
+        ac.fec                  = ch.audio_fec ? 1 : 0;
+        ac.expected_packet_loss = ch.audio_expected_packet_loss;
+        ac.dtx                  = ch.audio_dtx ? 1 : 0;
+        ac.complexity           = ch.audio_complexity;
+        ac.dred                 = ch.audio_dred ? 1 : 0;
    }
    out->items = items;
    out->count = channels.size();
@@ -1756,6 +1946,7 @@ vc_result vc_client::list_users(vc_user_list* out) {
        items[i].self_deafened   = u.self_deafened ? 1 : 0;
        items[i].server_muted    = u.server_muted ? 1 : 0;
        items[i].server_deafened = u.server_deafened ? 1 : 0;
+        items[i].voice_subscribed = u.voice_subscribed ? 1 : 0;
    }
    out->items = items;
    out->count = users.size();
@@ -2036,6 +2227,8 @@ vc_result vc_client::authenticate_guest(const char*)        { return VC_ERR_NOT_
 vc_result vc_client::authenticate_user(const char*, const char*) { return VC_ERR_NOT_IMPLEMENTED; }
 vc_result vc_client::join_channel(uint32_t, const char*)   { return VC_ERR_NOT_IMPLEMENTED; }
 vc_result vc_client::leave_channel()                        { return VC_ERR_NOT_IMPLEMENTED; }
+vc_result vc_client::join_voice()                           { return VC_ERR_NOT_IMPLEMENTED; }
+vc_result vc_client::leave_voice()                          { return VC_ERR_NOT_IMPLEMENTED; }
 vc_result vc_client::stream_start(const vc_stream_desc&, uint32_t*) { return VC_ERR_NOT_IMPLEMENTED; }
 vc_result vc_client::stream_stop(uint32_t)                 { return VC_ERR_NOT_IMPLEMENTED; }
 vc_result vc_client::set_input_device(uint32_t, const char*) { return VC_ERR_NOT_IMPLEMENTED; }
--- a/core/src/core/client.h
+++ b/core/src/core/client.h
@@ -46,6 +46,9 @@ struct vc_client {
    vc_result join_channel(uint32_t channel_id, const char* password);
    vc_result leave_channel();

+    vc_result join_voice();
+    vc_result leave_voice();
+
    vc_result stream_start(const vc_stream_desc& desc, uint32_t* out_stream_id);
    vc_result stream_stop(uint32_t stream_id);
    vc_result set_input_device(uint32_t stream_id, const char* device_id);
@@ -161,6 +164,11 @@ struct vc_client {
    uint64_t server_session_id_{0};
    std::atomic<uint64_t> next_req_id_{1};

+    // Voice-plane subscription state. When false, the server does not relay voice frames to
+    // us, and we do not wire up remote-stream decoders (sync_remote_streams is gated on this).
+    // Toggled by vc_join_voice / vc_leave_voice; confirmed via VoiceSubscriptionResult.
+    std::atomic<bool> voice_subscribed_{false};
+
    // Keepalive: client sends a Ping every ~15s (docs/protocol.md §7) so the server's
    // last_seen stays fresh and the reaper doesn't drop us. Pong echoes the nonce, which
    // we correlate to measure RTT. The read loop's 50ms TLS timeout means it spins fast
@@ -265,6 +273,11 @@ struct vc_client {
        // time and checked in handle_stream_announce_result / stream_stop.
        bool external_feed = false;

+        // Stream label (from vc_stream_desc.label at stream_start time). Retained so the
+        // channel-update stream restart (restart_active_streams_for_channel) can re-announce
+        // with the same label without the caller's involvement.
+        std::string label;
+
        // Reframe buffer: the AudioEngine clock is fixed at 48 kHz / 20 ms, so capture/feed
        // always delivers 960-sample frames — but the channel's frame_ms (docs/voice.md §3)
        // can be 2.5…60 ms, so the encoder needs frame_samples per call (480 @10ms, 1920 @40ms,
@@ -344,12 +357,27 @@ struct vc_client {
    void handle_server_state(const voicecat::v1::ServerStateSnapshot& snap);
    void handle_user_event(const voicecat::v1::UserEvent& ue);
    void handle_channel_event(const voicecat::v1::ChannelEvent& ce);
+    // Called from handle_channel_event when the current channel's audio config changed:
+    // stop→start every active local stream so the new Opus params take effect (encoders are
+    // frozen at StreamAnnounceResult time — docs/voice.md §3). capture_device_id and
+    // capture_channels survive the restart (stream_stop doesn't clear them; stream_start
+    // reuses the existing LocalStream entry). The server reads the updated channel config
+    // on re-announce and returns new effective_audio; peers' sync_remote_streams wire up
+    // fresh decoders at the new ssrc.
+    void restart_active_streams_for_channel(uint32_t channel_id);
    void handle_join_channel_result(const voicecat::v1::JoinChannelResult& msg);
    void handle_text_message(const voicecat::v1::TextMessage& msg);
    void handle_disconnect(const voicecat::v1::Disconnect& msg);
    void handle_udp_binding_ack(const voicecat::v1::UdpBinding& msg);
    void handle_stream_announce_result(uint64_t req_id,
                                       const voicecat::v1::StreamAnnounceResult& msg);
+    void handle_voice_subscription_result(const voicecat::v1::VoiceSubscriptionResult& msg);
+    // Wire up remote-stream decoders for all users in the session model (used on voice join).
+    void resync_remote_streams();
+    // Tear down all remote-stream decoders and clear remote_streams_ (used on voice leave).
+    void clear_all_remote_streams();
+    // Stop every active local stream (used on voice leave — emits STREAM_STOPPED for each).
+    void stop_all_local_streams();

    // ── M2: UDP / media helpers ──────────────────────────────────────────────────
    // Kicks off TCP UdpBinding request; called once after a successful AuthResult.
--- a/core/src/session/session.cpp
+++ b/core/src/session/session.cpp
@@ -26,6 +26,20 @@ std::pair<const User*, const Stream*> SessionModel::find_user_by_ssrc(uint32_t s
 #ifdef VOICECAT_HAS_NET

 namespace {
+
+void copy_channel_audio(Channel& ch, const voicecat::v1::AudioConfig& a) {
+    ch.audio_sample_rate          = a.sample_rate() ? a.sample_rate() : 48000;
+    ch.audio_frame_ms             = a.frame_ms() ? a.frame_ms() : 20;
+    ch.audio_mode                 = static_cast<uint32_t>(a.mode());
+    ch.audio_bitrate_bps          = a.bitrate_bps();
+    ch.audio_application          = static_cast<uint32_t>(a.application());
+    ch.audio_fec                  = a.fec();
+    ch.audio_expected_packet_loss = a.expected_packet_loss();
+    ch.audio_dtx                  = a.dtx();
+    ch.audio_complexity           = a.complexity();
+    ch.audio_dred                 = a.dred();
+}
+
 std::vector<Stream> copy_streams(
    const google::protobuf::RepeatedPtrField<voicecat::v1::StreamInfo>& src) {
    std::vector<Stream> out;
@@ -62,6 +76,8 @@ void SessionModel::apply_snapshot(const voicecat::v1::ServerStateSnapshot& snap)
        ch.topic              = pb.topic();
        ch.password_protected = pb.password_protected();
        ch.max_users          = pb.max_users();
+        ch.sort_order         = static_cast<uint32_t>(pb.order());
+        copy_channel_audio(ch, pb.audio());
        channels_.push_back(std::move(ch));
    }

@@ -76,6 +92,7 @@ void SessionModel::apply_snapshot(const voicecat::v1::ServerStateSnapshot& snap)
        u.self_deafened   = pb.self_deafened();
        u.server_muted    = pb.server_muted();
        u.server_deafened = pb.server_deafened();
+        u.voice_subscribed = pb.voice_subscribed();
        u.streams         = copy_streams(pb.streams());
        users_.push_back(std::move(u));
    }
@@ -95,6 +112,7 @@ void SessionModel::apply_user_event(const voicecat::v1::UserEvent& ev) {
        u.self_deafened   = pb.self_deafened();
        u.server_muted    = pb.server_muted();
        u.server_deafened = pb.server_deafened();
+        u.voice_subscribed = pb.voice_subscribed();
        u.streams         = copy_streams(pb.streams());

        auto it = std::find_if(users_.begin(), users_.end(),
@@ -122,6 +140,8 @@ void SessionModel::apply_channel_event(const voicecat::v1::ChannelEvent& ev) {
        ch.topic              = pb.topic();
        ch.password_protected = pb.password_protected();
        ch.max_users          = pb.max_users();
+        ch.sort_order         = static_cast<uint32_t>(pb.order());
+        copy_channel_audio(ch, pb.audio());

        auto it = std::find_if(channels_.begin(), channels_.end(),
                               [&](const Channel& x) { return x.id == ch.id; });
--- a/core/src/session/session.h
+++ b/core/src/session/session.h
@@ -25,6 +25,21 @@ struct Channel {
    std::string topic;
    bool        password_protected{false};
    uint32_t    max_users{0};
+    uint32_t    sort_order{0};
+    // Authoritative channel AudioConfig (docs/voice.md §3) — mirrors
+    // voicecat::v1::AudioConfig field-for-field, same flat shape as Stream below. Populated
+    // from ServerStateSnapshot / ChannelEvent so the channel-edit dialog can read back the
+    // current config (the vc_channel read struct now carries these too).
+    uint32_t    audio_sample_rate{48000};
+    uint32_t    audio_frame_ms{20};
+    uint32_t    audio_mode{0};              // 0 = mono, 1 = stereo
+    uint32_t    audio_bitrate_bps{0};
+    uint32_t    audio_application{0};       // 0=VOIP, 1=AUDIO, 2=LOWDELAY
+    bool        audio_fec{false};
+    uint32_t    audio_expected_packet_loss{0};
+    bool        audio_dtx{false};
+    uint32_t    audio_complexity{0};
+    bool        audio_dred{false};
 };

 struct Stream {
@@ -57,6 +72,7 @@ struct User {
    bool                self_deafened{false};
    bool                server_muted{false};
    bool                server_deafened{false};
+    bool                voice_subscribed{false};
    std::vector<Stream> streams;
 };

--- a/core/src/voicecat.cpp
+++ b/core/src/voicecat.cpp
@@ -82,6 +82,16 @@ vc_result vc_leave_channel(vc_client* c) {
    return c->leave_channel();
 }

+vc_result vc_join_voice(vc_client* c) {
+    if (c == nullptr) return VC_ERR_INVALID_ARG;
+    return c->join_voice();
+}
+
+vc_result vc_leave_voice(vc_client* c) {
+    if (c == nullptr) return VC_ERR_INVALID_ARG;
+    return c->leave_voice();
+}
+
 vc_result vc_stream_start(vc_client* c, const vc_stream_desc* desc, uint32_t* out_stream_id) {
    if (c == nullptr || desc == nullptr) return VC_ERR_INVALID_ARG;
    return c->stream_start(*desc, out_stream_id);
--- a/docs/protocol.md
+++ b/docs/protocol.md
@@ -82,6 +82,9 @@ message Envelope {
    StreamStop        stream_stop         = 42;
    StreamStateUpdate stream_state        = 43;   // talking/muted indicator
    UdpBinding        udp_binding         = 44;   // token to bind the UDP 5-tuple
+    SubscribeVoiceRequest   subscribe_voice     = 45;   // join the voice plane
+    UnsubscribeVoiceRequest unsubscribe_voice   = 46;   // leave the voice plane
+    VoiceSubscriptionResult voice_subscription_result = 47; // ack with subscribed flag

    // ── Text ──────────────────────────────────────────────
    TextMessage       text_message        = 50;
--- a/server/src/conn_session.cpp
+++ b/server/src/conn_session.cpp
@@ -111,6 +111,14 @@ void ConnSession::on_frame(std::vector<uint8_t> frame) {
            if (st == State::Authenticated)
                handle_stream_stop(env.stream_stop());
            break;
+        case voicecat::v1::Envelope::kSubscribeVoice:
+            if (st == State::Authenticated)
+                handle_subscribe_voice(env.request_id());
+            break;
+        case voicecat::v1::Envelope::kUnsubscribeVoice:
+            if (st == State::Authenticated)
+                handle_unsubscribe_voice(env.request_id());
+            break;

        // ── M5 moderation / admin ─────────────────────────────────────────────
        case voicecat::v1::Envelope::kKick:
@@ -521,6 +529,14 @@ void ConnSession::handle_udp_binding(uint64_t req_id, const voicecat::v1::UdpBin

 void ConnSession::handle_stream_announce(uint64_t req_id,
                                          const voicecat::v1::StreamAnnounce& msg) {
+    if (!voice_subscribed_.load(std::memory_order_acquire)) {
+        auto env = make_env(req_id);
+        auto* res = env.mutable_stream_announce_result();
+        res->set_ok(false);
+        res->set_error("not subscribed to voice — call vc_join_voice first");
+        send_envelope(env);
+        return;
+    }
    uint32_t ssrc = registry_->assign_ssrc(session_id_);
    uint32_t stream_id = next_stream_id_++;

@@ -595,6 +611,66 @@ void ConnSession::handle_stream_stop(const voicecat::v1::StreamStop& msg) {
    }
 }

+void ConnSession::handle_subscribe_voice(uint64_t req_id) {
+    voice_subscribed_.store(true, std::memory_order_release);
+    registry_->set_user_voice_subscribed(user_id_.load(), true);
+
+    // Reply with the result.
+    auto env = make_env(req_id);
+    auto* res = env.mutable_voice_subscription_result();
+    res->set_ok(true);
+    res->set_subscribed(true);
+    send_envelope(env);
+
+    // Broadcast the updated user proto so peers see voice_subscribed = true.
+    if (auto updated_user = registry_->user_snapshot_user(user_id_.load())) {
+        auto bcast = make_env();
+        auto* ue = bcast.mutable_user_event();
+        ue->set_kind(voicecat::v1::UserEvent::UPDATED);
+        *ue->mutable_user() = *updated_user;
+        registry_->broadcast(bcast, /*exclude*/ 0);
+    }
+}
+
+void ConnSession::handle_unsubscribe_voice(uint64_t req_id) {
+    voice_subscribed_.store(false, std::memory_order_release);
+
+    // Clear all the user's streams so peers stop receiving from them. Each clear broadcasts
+    // a UserEvent::UPDATED; we collect the ids first to avoid mutating announced_stream_ids_
+    // while iterating.
+    auto stream_ids = announced_stream_ids_;
+    for (uint32_t sid : stream_ids) {
+        auto it = std::find(announced_stream_ids_.begin(), announced_stream_ids_.end(), sid);
+        if (it != announced_stream_ids_.end()) announced_stream_ids_.erase(it);
+        auto updated = registry_->clear_user_stream(user_id_.load(), sid);
+        if (updated) {
+            auto bcast = make_env();
+            auto* ue = bcast.mutable_user_event();
+            ue->set_kind(voicecat::v1::UserEvent::UPDATED);
+            *ue->mutable_user() = *updated;
+            registry_->broadcast(bcast, /*exclude*/ 0);
+        }
+    }
+
+    registry_->set_user_voice_subscribed(user_id_.load(), false);
+
+    // Reply with the result.
+    auto env = make_env(req_id);
+    auto* res = env.mutable_voice_subscription_result();
+    res->set_ok(true);
+    res->set_subscribed(false);
+    send_envelope(env);
+
+    // Broadcast the updated user proto so peers see voice_subscribed = false.
+    if (auto updated_user = registry_->user_snapshot_user(user_id_.load())) {
+        auto bcast = make_env();
+        auto* ue = bcast.mutable_user_event();
+        ue->set_kind(voicecat::v1::UserEvent::UPDATED);
+        *ue->mutable_user() = *updated_user;
+        registry_->broadcast(bcast, /*exclude*/ 0);
+    }
+}
+
 // ── M5 handlers ──────────────────────────────────────────────────────────────

 void ConnSession::handle_kick_request(uint64_t req_id, const voicecat::v1::KickRequest& msg) {
--- a/server/src/conn_session.h
+++ b/server/src/conn_session.h
@@ -82,6 +82,7 @@ class ConnSession : public std::enable_shared_from_this<ConnSession> {
    State    state()      const { return state_.load(); }
    uint64_t session_id() const { return session_id_; }
    uint32_t user_id()    const { return user_id_; }
+    bool     voice_subscribed() const { return voice_subscribed_.load(std::memory_order_acquire); }

    // Keepalive: bump last_seen to "now" on any inbound activity (TCP frame or UDP voice
    // frame). The server's reaper sweeps sessions whose last_seen is older than the
@@ -105,6 +106,8 @@ class ConnSession : public std::enable_shared_from_this<ConnSession> {
    void handle_stream_announce(uint64_t req_id, const voicecat::v1::StreamAnnounce& msg);
    void handle_stream_stop(const voicecat::v1::StreamStop& msg);
    void handle_leave_channel();
+    void handle_subscribe_voice(uint64_t req_id);
+    void handle_unsubscribe_voice(uint64_t req_id);

    // M5 handlers
    void handle_kick_request(uint64_t req_id, const voicecat::v1::KickRequest& msg);
@@ -172,6 +175,11 @@ class ConnSession : public std::enable_shared_from_this<ConnSession> {

    // M5: permissions granted at auth time (server-side authority).
    voicecat::v1::Permissions permissions_;
+
+    // Voice-plane subscription. When false, the SFU relay excludes this session from the
+    // recipient set (find_channel_sessions), and handle_stream_announce rejects new streams.
+    // Toggled by SubscribeVoiceRequest / UnsubscribeVoiceRequest.
+    std::atomic<bool> voice_subscribed_{false};
 };

 }  // namespace voicecat::server
--- a/server/src/media_relay.cpp
+++ b/server/src/media_relay.cpp
@@ -81,6 +81,12 @@ void MediaRelay::on_udp_frame(const uint8_t* data, size_t len,
        auto sender_session = registry_->find_by_udp_endpoint(sender);
        if (!sender_session) { note_drop("unmapped-endpoint"); return; }

+        // Defense in depth: don't relay voice from sessions not on the voice plane.
+        // handle_stream_announce already rejects announces from non-subscribers, so a
+        // non-subscribed session shouldn't have any active streams — but this catches any
+        // edge case (e.g. a stream announced just before unsubscribing).
+        if (!sender_session->voice_subscribed()) { note_drop("not-subscribed"); return; }
+
        auto* recv_crypto = sender_session->recv_crypto();
        if (!recv_crypto) { note_drop("no-recv-crypto"); return; }

--- a/server/src/session_registry.cpp
+++ b/server/src/session_registry.cpp
@@ -145,6 +145,13 @@ bool SessionRegistry::set_user_channel(uint32_t user_id, uint32_t channel_id) {
    return true;
 }

+void SessionRegistry::set_user_voice_subscribed(uint32_t user_id, bool subscribed) {
+    std::unique_lock lk(mu_);
+    auto it = users_.find(user_id);
+    if (it == users_.end()) return;
+    it->second.proto.set_voice_subscribed(subscribed);
+}
+
 std::vector<voicecat::v1::Channel> SessionRegistry::channel_snapshot() const {
    std::shared_lock lk(mu_);
    std::vector<voicecat::v1::Channel> result;
@@ -492,7 +499,11 @@ std::vector<std::shared_ptr<ConnSession>> SessionRegistry::find_channel_sessions
        if (entry.session_id == exclude_session_id) continue;
        auto sit = sessions_.find(entry.session_id);
        if (sit == sessions_.end()) continue;
-        if (auto sess = sit->second.lock()) result.push_back(sess);
+        if (auto sess = sit->second.lock()) {
+            // Only relay voice to sessions that are on the voice plane.
+            if (!sess->voice_subscribed()) continue;
+            result.push_back(sess);
+        }
    }
    return result;
 }
--- a/server/src/session_registry.h
+++ b/server/src/session_registry.h
@@ -75,6 +75,9 @@ class SessionRegistry {
    // Move a user to a channel. Returns false if channel doesn't exist.
    bool set_user_channel(uint32_t user_id, uint32_t channel_id);

+    // Set the user's voice-plane subscription flag on their proto (broadcast-ready).
+    void set_user_voice_subscribed(uint32_t user_id, bool subscribed);
+
    // Snapshot for ServerStateSnapshot message.
    std::vector<voicecat::v1::Channel> channel_snapshot() const;
    std::vector<voicecat::v1::User>    user_snapshot() const;
--- a/tests/test_channel_samplerate.cpp
+++ b/tests/test_channel_samplerate.cpp
@@ -46,6 +46,7 @@ struct EventStore {
    bool      channel_list_received{false};
    bool      generic_result_received{false};
    bool      generic_ok{false};
+    bool      voice_subscribed{false};
    std::vector<std::pair<uint32_t, uint32_t>> streams_started;  // (user_id, stream_id)
    vc_client* client{nullptr};
    const char* label{nullptr};
@@ -61,6 +62,7 @@ static void on_event(void* user, const vc_event* ev) {
            s->self_user_id = ev->user_id;
            break;
        case VC_EVENT_CHANNEL_LIST:    s->channel_list_received = true; break;
+        case VC_EVENT_VOICE_STATE:   s->voice_subscribed = (ev->u32a == 1); break;
        case VC_EVENT_GENERIC_RESULT:
            s->generic_result_received = true;
            s->generic_ok              = (ev->result == VC_OK);
@@ -90,6 +92,8 @@ static bool connect_guest(vc_client*& client, const char* name, const char* labe
    if (vc_authenticate_guest(client, name) != VC_OK) return false;
    if (!wait_for(ev, [](EventStore& s) { return s.auth_ok; }, 8000)) return false;
    if (!wait_for(ev, [](EventStore& s) { return s.channel_list_received; }, 3000)) return false;
+    if (vc_join_voice(client) != VC_OK) return false;
+    if (!wait_for(ev, [](EventStore& s) { return s.voice_subscribed; }, 5000)) return false;
    return true;
 }

--- a/tests/test_channel_user_list_abi.cpp
+++ b/tests/test_channel_user_list_abi.cpp
@@ -59,6 +59,7 @@ struct EventStore {
    bool     channel_list_received{false};
    std::vector<StreamEvent> stream_events;
    std::vector<JoinResult>  join_results;
+    bool     voice_subscribed{false};

    const char* label{nullptr};
    vc_client*  client{nullptr};
@@ -78,6 +79,9 @@ static void on_event(void* user, const vc_event* ev) {
        case VC_EVENT_CHANNEL_LIST:
            s->channel_list_received = true;
            break;
+        case VC_EVENT_VOICE_STATE:
+            s->voice_subscribed = (ev->u32a == 1);
+            break;
        case VC_EVENT_STREAM_STARTED:
            s->stream_events.push_back({true, ev->user_id, ev->stream_id});
            break;
@@ -195,6 +199,9 @@ static void test_live_channel_user_list() {
    CHECK(wait_for(evA, [](EventStore& s) { return s.auth_ok; }, 8000));
    CHECK(wait_for(evA, [](EventStore& s) { return s.channel_list_received; }, 3000));

+    CHECK(vc_join_voice(clientA) == VC_OK);
+    CHECK(wait_for(evA, [](EventStore& s) { return s.voice_subscribed; }, 5000));
+
    EventStore evB;
    evB.label = "B";
    vc_callbacks cbB{on_event, nullptr, &evB};
@@ -207,6 +214,9 @@ static void test_live_channel_user_list() {
    CHECK(wait_for(evB, [](EventStore& s) { return s.auth_ok; }, 8000));
    CHECK(wait_for(evB, [](EventStore& s) { return s.channel_list_received; }, 3000));

+    CHECK(vc_join_voice(clientB) == VC_OK);
+    CHECK(wait_for(evB, [](EventStore& s) { return s.voice_subscribed; }, 5000));
+
    uint32_t a_uid = 0, b_uid = 0;
    { std::lock_guard lk(evA.mu); a_uid = evA.self_user_id; }
    { std::lock_guard lk(evB.mu); b_uid = evB.self_user_id; }
--- a/tests/test_dred_toggle.cpp
+++ b/tests/test_dred_toggle.cpp
@@ -35,6 +35,7 @@ struct EventStore {
    bool      channel_list_received{false};
    bool      generic_result_received{false};
    bool      generic_ok{false};
+    bool      voice_subscribed{false};
    std::vector<std::pair<uint32_t,uint32_t>> streams_started;  // (user_id, stream_id)
    vc_client* client{nullptr};
    const char* label{nullptr};
@@ -54,6 +55,9 @@ static void on_event(void* user, const vc_event* ev) {
        case VC_EVENT_CHANNEL_LIST:
            s->channel_list_received = true;
            break;
+        case VC_EVENT_VOICE_STATE:
+            s->voice_subscribed = (ev->u32a == 1);
+            break;
        case VC_EVENT_GENERIC_RESULT:
            s->generic_result_received = true;
            s->generic_ok              = (ev->result == VC_OK);
@@ -199,6 +203,9 @@ int main() {
    CHECK(wait_for(evGuest, [](EventStore& s){ return s.auth_ok; }, 8000));
    CHECK(wait_for(evGuest, [](EventStore& s){ return s.channel_list_received; }, 3000));

+    CHECK(vc_join_voice(guest) == VC_OK);
+    CHECK(wait_for(evGuest, [](EventStore& s){ return s.voice_subscribed; }, 5000));
+
    // Move the guest into the DRED channel.
    uint32_t guest_uid = 0;
    { std::lock_guard lk(evGuest.mu); guest_uid = evGuest.self_user_id; }
--- a/tests/test_external_pcm.cpp
+++ b/tests/test_external_pcm.cpp
@@ -47,6 +47,7 @@ struct EventStore {
    uint32_t  self_user_id{0};
    bool      channel_list_received{false};
    bool      join_ok{false};
+    bool      voice_subscribed{false};
    std::vector<std::pair<uint32_t, uint32_t>> streams_started;  // (user_id, stream_id)
    vc_client* client{nullptr};
    const char* label{nullptr};
@@ -66,6 +67,9 @@ static void on_event(void* user, const vc_event* ev) {
        case VC_EVENT_CHANNEL_LIST:
            s->channel_list_received = true;
            break;
+        case VC_EVENT_VOICE_STATE:
+            s->voice_subscribed = (ev->u32a == 1);
+            break;
        case VC_EVENT_JOIN_RESULT:
            s->join_ok = (ev->result == VC_OK);
            break;
@@ -96,6 +100,8 @@ static bool connect_guest(vc_client*& client, const char* name, const char* labe
    if (vc_authenticate_guest(client, name) != VC_OK) return false;
    if (!wait_for(ev, [](EventStore& s) { return s.auth_ok; }, 8000)) return false;
    if (!wait_for(ev, [](EventStore& s) { return s.channel_list_received; }, 3000)) return false;
+    if (vc_join_voice(client) != VC_OK) return false;
+    if (!wait_for(ev, [](EventStore& s) { return s.voice_subscribed; }, 5000)) return false;
    return true;
 }

--- a/tests/test_frame_ms_reframe.cpp
+++ b/tests/test_frame_ms_reframe.cpp
@@ -51,6 +51,7 @@ struct EventStore {
    bool      channel_list_received{false};
    bool      generic_result_received{false};
    bool      generic_ok{false};
+    bool      voice_subscribed{false};
    std::vector<std::pair<uint32_t, uint32_t>> streams_started;  // (user_id, stream_id)
    vc_client* client{nullptr};
    const char* label{nullptr};
@@ -66,6 +67,7 @@ static void on_event(void* user, const vc_event* ev) {
            s->self_user_id = ev->user_id;
            break;
        case VC_EVENT_CHANNEL_LIST:    s->channel_list_received = true; break;
+        case VC_EVENT_VOICE_STATE:   s->voice_subscribed = (ev->u32a == 1); break;
        case VC_EVENT_GENERIC_RESULT:
            s->generic_result_received = true;
            s->generic_ok              = (ev->result == VC_OK);
@@ -95,6 +97,8 @@ static bool connect_guest(vc_client*& client, const char* name, const char* labe
    if (vc_authenticate_guest(client, name) != VC_OK) return false;
    if (!wait_for(ev, [](EventStore& s) { return s.auth_ok; }, 8000)) return false;
    if (!wait_for(ev, [](EventStore& s) { return s.channel_list_received; }, 3000)) return false;
+    if (vc_join_voice(client) != VC_OK) return false;
+    if (!wait_for(ev, [](EventStore& s) { return s.voice_subscribed; }, 5000)) return false;
    return true;
 }

--- a/tests/test_m2_voice.cpp
+++ b/tests/test_m2_voice.cpp
@@ -291,6 +291,23 @@ struct TestClient {
        return true;
    }

+    bool do_subscribe_voice() {
+        {
+            v1::Envelope env;
+            env.set_request_id(3);
+            env.mutable_subscribe_voice();
+            if (!tcp_send_envelope(*tls, env)) return false;
+        }
+        for (int i = 0; i < 20; ++i) {
+            v1::Envelope env;
+            if (!tcp_recv_envelope(*tls, codec, env)) return false;
+            if (env.has_voice_subscription_result()) {
+                return env.voice_subscription_result().subscribed();
+            }
+        }
+        return false;
+    }
+
    bool do_stream_announce() {
        // Send StreamAnnounce.
        {
@@ -396,6 +413,7 @@ int main() {
    CHECK(A.do_hello_and_auth("SenderBob"));
    CHECK(A.server_udp_port == udp_port.load());
    CHECK(A.do_udp_binding());
+    CHECK(A.do_subscribe_voice());
    CHECK(A.do_stream_announce());
    CHECK(A.stream_ok);
    std::printf("m2_voice: A ssrc=%u local_udp=%u\n", A.assigned_ssrc, A.udp_local_port);
@@ -408,6 +426,7 @@ int main() {
    CHECK(B.do_hello_and_auth("ReceiverAlice"));
    CHECK(B.server_udp_port == udp_port.load());
    CHECK(B.do_udp_binding());
+    CHECK(B.do_subscribe_voice());
    // B doesn't need to announce a stream to receive relayed frames

    if (g_failures > 0) {
--- a/tests/test_m3_multistream.cpp
+++ b/tests/test_m3_multistream.cpp
@@ -59,6 +59,7 @@ struct EventStore {
    bool      channel_list_received{false};
    std::vector<StreamEvent> stream_events;
    std::vector<TalkEvent>   talk_events;
+    bool      voice_subscribed{false};
    bool      disconnected{false};

    const char* label{nullptr};
@@ -85,6 +86,9 @@ static void on_event(void* user, const vc_event* ev) {
        case VC_EVENT_CHANNEL_LIST:
            s->channel_list_received = true;
            break;
+        case VC_EVENT_VOICE_STATE:
+            s->voice_subscribed = (ev->u32a == 1);
+            break;
        case VC_EVENT_STREAM_STARTED:
            s->stream_events.push_back({true, ev->user_id, ev->stream_id});
            break;
@@ -191,6 +195,9 @@ int main() {
    CHECK(wait_for(evA, [](EventStore& s) { return s.auth_ok; }, 8000));
    CHECK(wait_for(evA, [](EventStore& s) { return s.channel_list_received; }, 3000));

+    CHECK(vc_join_voice(clientA) == VC_OK);
+    CHECK(wait_for(evA, [](EventStore& s) { return s.voice_subscribed; }, 5000));
+
    // ── Client B: guest "M3-B" ────────────────────────────────────────────────
    EventStore evB;
    evB.label = "clientB";
@@ -205,6 +212,9 @@ int main() {
    CHECK(wait_for(evB, [](EventStore& s) { return s.auth_ok; }, 8000));
    CHECK(wait_for(evB, [](EventStore& s) { return s.channel_list_received; }, 3000));

+    CHECK(vc_join_voice(clientB) == VC_OK);
+    CHECK(wait_for(evB, [](EventStore& s) { return s.voice_subscribed; }, 5000));
+
    uint32_t a_uid = 0;
    { std::lock_guard lk(evA.mu); a_uid = evA.self_user_id; }

--- a/tests/test_vad_ptt_devices.cpp
+++ b/tests/test_vad_ptt_devices.cpp
@@ -59,6 +59,7 @@ struct EventStore {
    bool     channel_list_received{false};
    bool     saw_stream_started{false};
    std::vector<TalkEvent> talk_events;
+    bool     voice_subscribed{false};
    bool     disconnected{false};

    const char* label{nullptr};
@@ -83,6 +84,9 @@ static void on_event(void* user, const vc_event* ev) {
        case VC_EVENT_CHANNEL_LIST:
            s->channel_list_received = true;
            break;
+        case VC_EVENT_VOICE_STATE:
+            s->voice_subscribed = (ev->u32a == 1);
+            break;
        case VC_EVENT_STREAM_STARTED:
            s->saw_stream_started = true;
            break;
@@ -490,6 +494,9 @@ static void test_vad_and_ptt_gate() {
    CHECK(wait_for(evA, [](EventStore& s) { return s.auth_ok; }, 8000));
    CHECK(wait_for(evA, [](EventStore& s) { return s.channel_list_received; }, 3000));

+    CHECK(vc_join_voice(clientA) == VC_OK);
+    CHECK(wait_for(evA, [](EventStore& s) { return s.voice_subscribed; }, 5000));
+
    EventStore evB;
    evB.label = "B";
    vc_callbacks cbB{on_event, nullptr, &evB};
@@ -502,6 +509,9 @@ static void test_vad_and_ptt_gate() {
    CHECK(wait_for(evB, [](EventStore& s) { return s.auth_ok; }, 8000));
    CHECK(wait_for(evB, [](EventStore& s) { return s.channel_list_received; }, 3000));

+    CHECK(vc_join_voice(clientB) == VC_OK);
+    CHECK(wait_for(evB, [](EventStore& s) { return s.voice_subscribed; }, 5000));
+
    uint32_t a_uid = 0;
    { std::lock_guard lk(evA.mu); a_uid = evA.self_user_id; }

--- a/tests/test_voice_client_abi.cpp
+++ b/tests/test_voice_client_abi.cpp
@@ -40,6 +40,7 @@ struct EventStore {
    uint32_t  self_user_id{0};
    bool      channel_list_received{false};
    std::vector<StreamEvent> stream_events;
+    bool      voice_subscribed{false};

    const char* label{nullptr};
    bool        disconnected{false};
@@ -66,6 +67,9 @@ static void on_event(void* user, const vc_event* ev) {
        case VC_EVENT_CHANNEL_LIST:
            s->channel_list_received = true;
            break;
+        case VC_EVENT_VOICE_STATE:
+            s->voice_subscribed = (ev->u32a == 1);
+            break;
        case VC_EVENT_STREAM_STARTED:
            s->stream_events.push_back({true, ev->user_id, ev->stream_id});
            break;
@@ -159,6 +163,9 @@ int main() {
    CHECK(wait_for(evA, [](EventStore& s) { return s.auth_ok; }, 8000));
    CHECK(wait_for(evA, [](EventStore& s) { return s.channel_list_received; }, 3000));

+    CHECK(vc_join_voice(clientA) == VC_OK);
+    CHECK(wait_for(evA, [](EventStore& s) { return s.voice_subscribed; }, 5000));
+
    // ── Client B: guest "VoiceB" ───────────────────────────────────────────────
    EventStore evB;
    evB.label = "clientB";
@@ -173,6 +180,9 @@ int main() {
    CHECK(wait_for(evB, [](EventStore& s) { return s.auth_ok; }, 8000));
    CHECK(wait_for(evB, [](EventStore& s) { return s.channel_list_received; }, 3000));

+    CHECK(vc_join_voice(clientB) == VC_OK);
+    CHECK(wait_for(evB, [](EventStore& s) { return s.voice_subscribed; }, 5000));
+
    uint32_t a_uid = 0;
    { std::lock_guard lk(evA.mu); a_uid = evA.self_user_id; }