[feat](trx-rs): add settings tab and virtual audio plan

Move Scheduler under a new Settings tab in the HTTP frontend.
Add the virtual-channel audio implementation plan document.

Co-authored-by: OpenAI Codex <codex@openai.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

VIRTAUDIO.md

@@ -0,0 +1,188 @@
+# Virtual-Channel Audio — Implementation Plan
+
+## Goal
+
+Each virtual channel (SDR DSP slice) has its own Opus audio stream.  When the
+browser switches to a non-primary virtual channel the `/audio` WebSocket should
+deliver audio demodulated at that channel's frequency and mode, not the primary
+channel's audio.
+
+---
+
+## Current Architecture (baseline)
+
+```
+SoapySDR HW
+  └─ SdrPipeline (slot 0: primary, slot 1..N: virtual)
+       pcm_tx[0]  pcm_tx[1] ... pcm_tx[N]   (broadcast::Sender<Vec<f32>>)
+
+trx-server/src/main.rs
+  subscribe_pcm(slot 0) → Opus encode → rx_audio_tx (broadcast::Sender<Bytes>)
+
+trx-server/src/audio.rs  handle_audio_client()
+  writes  [0x00] StreamInfo
+          [0x0a] history blob
+  loop:   [0x01] RX frame  ← only primary channel
+
+trx-client/src/audio_client.rs
+  reads all frames → rx_audio_tx.send(bytes)   (single broadcast)
+
+FrontendRuntimeContext.audio_rx  (single broadcast::Sender<Bytes>)
+
+audio.rs / audio_ws()
+  subscribes to audio_rx → WebSocket to browser
+```
+
+Only slot 0 (primary) is ever encoded/transmitted.  All sessions hear the same
+audio.
+
+---
+
+## Planned Architecture
+
+```
+SdrPipeline  pcm_tx[0..N]
+     │
+trx-server/src/audio.rs   (extended handle_audio_client)
+  ┌── per-rig VChanAudioMixer ──────────────────────────────────┐
+  │  tracks (server_uuid → OpusEncoder + broadcast::Sender<Bytes>) │
+  │  listens for VCHAN_SUB/VCHAN_UNSUB from client              │
+  │  Opus-encodes each channel's PCM independently              │
+  └─────────────────────────────────────────────────────────────┘
+     │ wire frames:
+     │  [0x01] RX_FRAME          (primary channel, unchanged)
+     │  [0x0b] RX_FRAME_CH  [16 B UUID][N B Opus]   ← NEW
+     │  [0x0c] VCHAN_ALLOCATED  [16 B UUID]           ← NEW
+     │  client→server:
+     │  [0x0d] VCHAN_SUB    [16 B UUID]   subscribe to channel
+     │  [0x0e] VCHAN_UNSUB  [16 B UUID]   unsubscribe
+
+trx-client/src/audio_client.rs
+  demux 0x0b frames by UUID → per-channel broadcast::Sender<Bytes>
+  on 0x0c (allocated): publish UUID to per-channel map
+
+FrontendRuntimeContext
+  audio_rx: Option<broadcast::Sender<Bytes>>       (primary, unchanged)
+  vchan_audio: Arc<RwLock<HashMap<Uuid, broadcast::Sender<Bytes>>>>  ← NEW
+
+ClientChannelManager  (trx-frontend-http/src/vchan.rs)
+  allocate(): after creating local entry, sends VCHAN_SUB via new
+              vchan_audio_tx: mpsc::Sender<VChanAudioCmd>             ← NEW
+  delete_channel(): sends VCHAN_UNSUB
+  expose: subscribe_audio(channel_id) → Option<broadcast::Receiver<Bytes>>
+
+audio_ws()  (trx-frontend-http/src/audio.rs)
+  accepts ?channel_id=<uuid> query param
+  if present → lookup context.vchan_audio[uuid] → subscribe
+  else        → context.audio_rx (primary, current behaviour)
+```
+
+---
+
+## Wire Protocol Additions (trx-core/src/audio.rs)
+
+```
+AUDIO_MSG_RX_FRAME_CH    = 0x0b
+AUDIO_MSG_VCHAN_ALLOCATED = 0x0c
+AUDIO_MSG_VCHAN_SUB      = 0x0d
+AUDIO_MSG_VCHAN_UNSUB    = 0x0e
+```
+
+Frame layout for `RX_FRAME_CH`:
+```
+[0x0b] [4 B BE length = 16 + opus_len] [16 B UUID bytes] [opus_len B Opus]
+```
+
+Frame layout for `VCHAN_ALLOCATED`, `VCHAN_SUB`, `VCHAN_UNSUB`:
+```
+[type] [4 B BE length = 16] [16 B UUID bytes]
+```
+
+---
+
+## Layer-by-Layer Changes
+
+### 1. `trx-core/src/audio.rs`
+- Add four new `AUDIO_MSG_*` constants.
+- Add helper `read_vchan_frame(reader) -> (Uuid, Bytes)` and
+  `write_vchan_frame(writer, msg_type, uuid, payload)`.
+
+### 2. `trx-server/src/audio.rs`  (`handle_audio_client`)
+- Accept `vchan_manager: Option<SharedVChanManager>` from `RigHandle`.
+- Spawn a `VChanAudioMixer` task:
+  - Holds `HashMap<Uuid, (JoinHandle, broadcast::Sender<Bytes>)>`.
+  - On `VCHAN_SUB { uuid }`: call `vchan_manager.subscribe_pcm(uuid)`, spawn
+    Opus-encode task, write `VCHAN_ALLOCATED { uuid }` to client.
+  - On `VCHAN_UNSUB { uuid }`: abort encode task, remove from map.
+  - On PCM ready: Opus-encode, write `RX_FRAME_CH { uuid, opus }`.
+- Add the `vchan_manager` parameter to `run_audio_listener()` and pass it
+  through from `main.rs`.
+
+### 3. `trx-server/src/main.rs`
+- Pass `rig_handle.vchan_manager.clone()` to `run_audio_listener()`.
+
+### 4. `trx-client/src/audio_client.rs`
+- Add `vchan_audio_tx: mpsc::Sender<VChanAudioEvent>` parameter
+  (where `VChanAudioEvent = Allocated(Uuid, broadcast::Sender<Bytes>) | Frame(Uuid, Bytes)`).
+- On `RX_FRAME_CH { uuid, opus }`: forward to per-channel sender (create if
+  first frame for that uuid).
+- On `VCHAN_ALLOCATED { uuid }`: signal that the channel is ready.
+
+### 5. `trx-client/src/main.rs`
+- Create `vchan_audio: Arc<RwLock<HashMap<Uuid, broadcast::Sender<Bytes>>>>`
+  shared between audio_client task and FrontendRuntimeContext.
+- Add an `mpsc::Sender<VChanAudioCmd>` that lets the HTTP frontend request
+  SUB/UNSUB over the audio TCP; pass it into `run_audio_client()`.
+
+### 6. `trx-client/trx-frontend/src/lib.rs`  (`FrontendRuntimeContext`)
+- Add:
+  ```rust
+  pub vchan_audio: Arc<RwLock<HashMap<Uuid, broadcast::Sender<Bytes>>>>,
+  pub vchan_audio_cmd: Option<mpsc::Sender<VChanAudioCmd>>,
+  ```
+- Initialise both to empty/None in `new()`.
+
+### 7. `trx-client/trx-frontend/trx-frontend-http/src/vchan.rs`  (`ClientChannelManager`)
+- `allocate()`: after inserting the local record, if `vchan_audio_cmd` is
+  available, send `VChanAudioCmd::Subscribe(uuid)`.
+- `delete_channel()`: send `VChanAudioCmd::Unsubscribe(uuid)`.
+- `subscribe_audio(channel_id, context) -> Option<broadcast::Receiver<Bytes>>`:
+  look up `context.vchan_audio.read()[channel_id].subscribe()`.
+
+### 8. `trx-client/trx-frontend/trx-frontend-http/src/audio.rs`  (`audio_ws`)
+- Parse optional `channel_id: Option<Uuid>` from query string.
+- If `Some(uuid)`:
+  - Look up `context.vchan_audio.read()[uuid]` → `broadcast::Sender<Bytes>`.
+  - Subscribe, forward Opus frames exactly as today but from that sender.
+- Else: current primary-channel path unchanged.
+
+### 9. `assets/web/plugins/vchan.js`
+- `vchanSubscribe()` and `vchanAllocate()` call `vchanReconnectAudio()`.
+- `vchanReconnectAudio()`:
+  - If on virtual channel: `reconnectAudioWs(vchanActiveId)` (pass channel UUID).
+  - If on primary: `reconnectAudioWs(null)`.
+- `reconnectAudioWs(channelId)` (new in `app.js` or `vchan.js`):
+  - Close existing `audioWs`.
+  - Reopen `new WebSocket('/audio' + (channelId ? '?channel_id=' + channelId : ''))`.
+
+---
+
+## Out of Scope (non-SDR rigs)
+
+Non-SDR rigs (`vchan_manager === None`) are unaffected.  The new message types
+are only exchanged when the server-side vchan manager is present.  Primary-
+channel audio behaviour is 100% backwards-compatible.
+
+---
+
+## Implementation Order
+
+1. `trx-core/src/audio.rs` — add constants and frame helpers  *(no breakage)*
+2. `trx-server/src/audio.rs` — `VChanAudioMixer` + new frame handling
+3. `trx-server/src/main.rs` — plumb vchan_manager through
+4. `trx-client/src/audio_client.rs` — demux RX_FRAME_CH
+5. `trx-client/src/main.rs` — shared vchan_audio map + cmd channel
+6. `trx-frontend/src/lib.rs` — new FrontendRuntimeContext fields
+7. `trx-frontend-http/src/vchan.rs` — SUB/UNSUB on allocate/delete
+8. `trx-frontend-http/src/audio.rs` — channel_id query param routing
+9. `vchan.js` — reconnect WebSocket on channel switch

src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js

@@ -3523,7 +3523,7 @@ if (spectrumBwSweetBtn) {
 }
 
 // --- Tab navigation ---
-const TAB_ORDER = ["main", "bookmarks", "decoders", "map", "scheduler", "about"];
+const TAB_ORDER = ["main", "bookmarks", "decoders", "map", "settings", "about"];
 
 function navigateToTab(name) {
   if (authEnabled && !authRole && name !== "main") return;
@@ -5613,7 +5613,7 @@ window.ft8MapAddLocator = function(message, grids, type = "ft8", station = null,
   applyMapFilter();
 };
 
-// --- Sub-tab navigation (Decoders tab) ---
+// --- Sub-tab navigation ---
 document.querySelectorAll(".sub-tab-bar").forEach((bar) => {
   bar.addEventListener("click", (e) => {
     const btn = e.target.closest(".sub-tab[data-subtab]");

src/trx-client/trx-frontend/trx-frontend-http/assets/web/index.html

@@ -46,9 +46,9 @@
             <svg class="tab-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="M8 2a4 4 0 0 1 4 4c0 3-4 8-4 8S4 9 4 6a4 4 0 0 1 4-4z"/><circle cx="8" cy="6" r="1.2" fill="currentColor" stroke="none"/></svg>
             <span class="tab-label">Map</span>
           </button>
-          <button class="tab" data-tab="scheduler">
+          <button class="tab" data-tab="settings">
-            <svg class="tab-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><circle cx="8" cy="8" r="6"/><path d="M8 5v3l2 2"/></svg>
+            <svg class="tab-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="1.4" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><circle cx="8" cy="8" r="2.1"/><path d="M8 1.8v1.4"/><path d="M8 12.8v1.4"/><path d="M14.2 8h-1.4"/><path d="M3.2 8H1.8"/><path d="M12.4 3.6l-1 1"/><path d="M4.6 11.4l-1 1"/><path d="M12.4 12.4l-1-1"/><path d="M4.6 4.6l-1-1"/></svg>
-            <span class="tab-label">Scheduler</span>
+            <span class="tab-label">Settings</span>
           </button>
           <button class="tab" data-tab="about">
             <svg class="tab-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" aria-hidden="true"><circle cx="8" cy="8" r="6"/><path d="M8 7v5"/><circle cx="8" cy="5" r="0.5" fill="currentColor" stroke="none"/></svg>
@@ -671,7 +671,11 @@
         <div id="aprs-map"></div>
       </div>
     </div>
-    <div id="tab-scheduler" class="tab-panel" style="display:none;">
+    <div id="tab-settings" class="tab-panel" style="display:none;">
+      <div class="sub-tab-bar">
+        <button class="sub-tab active" data-subtab="settings-scheduler">Scheduler</button>
+      </div>
+      <div id="subtab-settings-scheduler" class="sub-tab-panel">
         <div id="scheduler-panel" class="sch-panel">
           <div class="sch-toast" id="scheduler-toast" style="display:none;"></div>
           <div class="sch-row">
@@ -775,6 +779,7 @@
           </div>
         </div>
       </div>
+    </div>
     <div id="tab-about" class="tab-panel" style="display:none;">
       <div id="auth-badge" style="display:none; margin-bottom: 1rem; padding: 0.5rem; background: var(--bg-secondary); border-radius: 0.25rem; color: var(--text-muted); font-size: 0.85rem;">Authenticated as: <strong id="auth-role-badge">--</strong></div>
       <table class="about-table">

src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css

@@ -1983,7 +1983,7 @@ button:focus-visible, input:focus-visible, select:focus-visible {
     bottom: calc(0.55rem + env(safe-area-inset-bottom));
     z-index: 30;
     display: grid;
-    grid-template-columns: repeat(5, minmax(0, 1fr));
+    grid-template-columns: repeat(6, minmax(0, 1fr));
     gap: 0.25rem;
     padding: 0.38rem;
     border: 1px solid color-mix(in srgb, var(--border-light) 82%, transparent);