[feat](trx-frontend-http): add Plugins tab showing registered frontends

Add GET /frontends API endpoint returning registered frontend names as
JSON. Add Plugins tab to the web UI that fetches and displays the list.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

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

@@ -615,6 +615,18 @@ document.querySelector(".tab-bar").addEventListener("click", (e) => {
 
 connect();
 
+// --- Plugins tab ---
+fetch("/frontends").then(r => r.json()).then(names => {
+  const list = document.getElementById("plugins-list");
+  if (!Array.isArray(names) || names.length === 0) {
+    list.innerHTML = '<div class="plugin-item" style="color:var(--text-muted);">No frontends registered</div>';
+    return;
+  }
+  list.innerHTML = names.map(n => `<div class="plugin-item">${n}</div>`).join("");
+}).catch(err => {
+  console.error("Failed to fetch frontends", err);
+});
+
 // --- Signal measurement ---
 const sigMeasureBtn = document.getElementById("sig-measure-btn");
 const sigClearBtn = document.getElementById("sig-clear-btn");

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

@@ -19,6 +19,7 @@
     </div>
     <div class="tab-bar">
       <button class="tab active" data-tab="main">Main</button>
+      <button class="tab" data-tab="plugins">Plugins</button>
       <button class="tab" data-tab="about">About</button>
     </div>
     <div id="tab-main" class="tab-panel">
@@ -116,6 +117,9 @@
     </div>
     </div>
     </div>
+    <div id="tab-plugins" class="tab-panel" style="display:none;">
+      <div id="plugins-list"></div>
+    </div>
     <div id="tab-about" class="tab-panel" style="display:none;">
       <table class="about-table">
         <tr><td>Server</td><td id="about-server-ver">--</td></tr>

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

@@ -157,6 +157,8 @@ small { color: var(--text-muted); }
 .about-table td { padding: 0.5rem 0.6rem; border-bottom: 1px solid var(--border); }
 .about-table tr:last-child td { border-bottom: none; }
 .about-table td:first-child { color: var(--text-muted); width: 40%; }
+.plugin-item { padding: 0.5rem 0.6rem; border-bottom: 1px solid var(--border); color: var(--text); }
+.plugin-item:last-child { border-bottom: none; }
 .footer { display: flex; justify-content: space-between; align-items: baseline; margin-top: 1.1rem; }
 .full-row { grid-column: 1 / -1; }
 .copyright { color: var(--text-muted); font-size: 0.75rem; opacity: 0.7; }

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

@@ -26,6 +26,12 @@ const FAVICON_BYTES: &[u8] = include_bytes!(concat!(
 const LOGO_BYTES: &[u8] =
     include_bytes!(concat!(env!("CARGO_MANIFEST_DIR"), "/assets/trx-logo.png"));
 
+#[get("/frontends")]
+pub async fn frontends_api() -> Result<impl Responder, Error> {
+    let names = trx_frontend::registered_frontends();
+    Ok(HttpResponse::Ok().json(names))
+}
+
 #[get("/status")]
 pub async fn status_api(
     state: web::Data<watch::Receiver<RigState>>,
@@ -229,6 +235,7 @@ pub async fn set_tx_limit(
 
 pub fn configure(cfg: &mut web::ServiceConfig) {
     cfg.service(index)
+        .service(frontends_api)
         .service(status_api)
         .service(events)
         .service(toggle_power)
@@ -322,9 +329,17 @@ async fn wait_for_view(mut rx: watch::Receiver<RigState>) -> Result<RigSnapshot,
         return Ok(view);
     }
 
-    while rx.changed().await.is_ok() {
-        if let Some(view) = rx.borrow().snapshot() {
-            return Ok(view);
+    // Wait up to 5 seconds for a valid snapshot; fall back to a placeholder
+    // so the SSE stream starts immediately and the browser isn't left hanging.
+    let deadline = time::Instant::now() + Duration::from_secs(5);
+    loop {
+        match time::timeout_at(deadline, rx.changed()).await {
+            Ok(Ok(())) => {
+                if let Some(view) = rx.borrow().snapshot() {
+                    return Ok(view);
+                }
+            }
+            _ => break,
         }
     }