[fix](trx-client): preserve vchan commands under scheduler churn

Use an unbounded virtual-channel command queue so background decode and scheduler transitions do not silently drop subscribe or remove commands.\n\nCo-authored-by: OpenAI Codex <codex@openai.com>

Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/src/lib.rs

@@ -252,7 +252,7 @@ pub struct FrontendRuntimeContext {
     /// Channel to send `VChanAudioCmd` to the audio-client task, which in turn
     /// forwards `VCHAN_SUB` / `VCHAN_UNSUB` frames over the audio TCP connection.
     /// `None` when no audio connection is active.
-    pub vchan_audio_cmd: Arc<Mutex<Option<mpsc::Sender<VChanAudioCmd>>>>,
+    pub vchan_audio_cmd: Arc<Mutex<Option<mpsc::UnboundedSender<VChanAudioCmd>>>>,
     /// Broadcast sender that fires whenever the server destroys a virtual
     /// channel (e.g. out-of-bandwidth after center-frequency retune).
     /// The HTTP frontend subscribes to clean up `ClientChannelManager`.

src/trx-client/trx-frontend/trx-frontend-http/src/background_decode.rs

@@ -238,7 +238,7 @@ impl BackgroundDecodeManager {
     fn send_audio_cmd(&self, cmd: VChanAudioCmd) {
         if let Ok(guard) = self.context.vchan_audio_cmd.lock() {
             if let Some(tx) = guard.as_ref() {
-                let _ = tx.try_send(cmd);
+                let _ = tx.send(cmd);
             }
         }
     }

src/trx-client/trx-frontend/trx-frontend-http/src/vchan.rs

@@ -97,7 +97,7 @@ pub struct ClientChannelManager {
     pub change_tx: broadcast::Sender<String>,
     pub max_channels: usize,
     /// Optional sender to the audio-client task for virtual-channel audio commands.
-    pub audio_cmd: std::sync::Mutex<Option<tokio::sync::mpsc::Sender<VChanAudioCmd>>>,
+    pub audio_cmd: std::sync::Mutex<Option<tokio::sync::mpsc::UnboundedSender<VChanAudioCmd>>>,
 }
 
 impl ClientChannelManager {
@@ -114,14 +114,14 @@ impl ClientChannelManager {
 
     /// Wire the audio-command sender so the manager can dispatch
     /// `VChanAudioCmd` messages when channels are allocated/deleted/changed.
-    pub fn set_audio_cmd(&self, tx: tokio::sync::mpsc::Sender<VChanAudioCmd>) {
+    pub fn set_audio_cmd(&self, tx: tokio::sync::mpsc::UnboundedSender<VChanAudioCmd>) {
         *self.audio_cmd.lock().unwrap() = Some(tx);
     }
 
     /// Fire-and-forget: send a `VChanAudioCmd` to the audio-client task.
     fn send_audio_cmd(&self, cmd: VChanAudioCmd) {
         if let Some(tx) = self.audio_cmd.lock().unwrap().as_ref() {
-            let _ = tx.try_send(cmd);
+            let _ = tx.send(cmd);
         }
     }