[feat](trx-frontend-http): hide decoder tabs not present in server registry

After fetching /decoders, hide sub-tab buttons, panels, overview
descriptions, about-status rows, and settings clear-history buttons
for decoders the server doesn't advertise. This makes feature-gated
decoders like FT2 fully invisible in the UI when disabled.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

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

@@ -18,12 +18,50 @@ window.onDecoderRegistryReady = function (fn) {
       window.decoderRegistry = decoderRegistry;
       for (const fn of _decoderRegistryReadyCallbacks) fn();
       _decoderRegistryReadyCallbacks.length = 0;
+      hideUnsupportedDecoderTabs();
     }
   } catch (e) {
     console.error("Failed to fetch decoder registry:", e);
   }
 })();
 
+/** Hide decoder sub-tabs, panels, about rows, and settings buttons
+ *  for decoders not present in the server's registry. */
+function hideUnsupportedDecoderTabs() {
+  const knownIds = new Set(decoderRegistry.map(function (d) { return d.id; }));
+  // Sub-tabs that are not decoders and should always be visible.
+  const alwaysShow = new Set(["overview", "rds", "sat"]);
+  document.querySelectorAll("#tab-digital-modes > .sub-tab-bar > .sub-tab[data-subtab]").forEach(function (btn) {
+    const id = btn.dataset.subtab;
+    if (alwaysShow.has(id) || knownIds.has(id)) return;
+    btn.style.display = "none";
+    var panel = document.getElementById("subtab-" + id);
+    if (panel) panel.style.display = "none";
+  });
+  // About-tab decoder status rows: <td>LABEL</td><td id="about-dec-ID">
+  document.querySelectorAll('[id^="about-dec-"]').forEach(function (el) {
+    var id = el.id.replace("about-dec-", "");
+    if (!alwaysShow.has(id) && !knownIds.has(id)) {
+      var row = el.closest("tr");
+      if (row) row.style.display = "none";
+    }
+  });
+  // Settings clear-history buttons
+  document.querySelectorAll('[id^="settings-clear-"][id$="-history"]').forEach(function (el) {
+    var m = el.id.match(/^settings-clear-(.+)-history$/);
+    if (m && !alwaysShow.has(m[1]) && !knownIds.has(m[1])) {
+      el.style.display = "none";
+    }
+  });
+  // Overview decoder descriptions
+  document.querySelectorAll("#subtab-overview .plugin-item[data-decoder]").forEach(function (el) {
+    var id = el.dataset.decoder;
+    if (!alwaysShow.has(id) && !knownIds.has(id)) {
+      el.style.display = "none";
+    }
+  });
+}
+
 // --- Persistent settings (localStorage) ---
 const STORAGE_PREFIX = "trx_";
 function saveSetting(key, value) {

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

@@ -539,61 +539,61 @@
         <button class="sub-tab" data-subtab="sat">SAT</button>
       </div>
       <div id="subtab-overview" class="sub-tab-panel">
-        <div class="plugin-item">
+        <div class="plugin-item" data-decoder="ais">
           <strong>AIS Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
             Decodes dual-channel AIS traffic from RX audio using 9.6 kbit/s GMSK and HDLC.
           </div>
         </div>
-        <div class="plugin-item">
+        <div class="plugin-item" data-decoder="vdes">
           <strong>VDES Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
             Decodes single-channel 100 kHz VDES bursts from SDR IQ using the dedicated VDES path.
           </div>
         </div>
-        <div class="plugin-item">
+        <div class="plugin-item" data-decoder="aprs">
           <strong>APRS Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
             Decodes APRS packets from RX audio using Bell 202 AFSK (1200 baud).
           </div>
         </div>
-        <div class="plugin-item">
+        <div class="plugin-item" data-decoder="cw">
           <strong>CW Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
             Decodes CW (Morse code) from RX audio.
           </div>
         </div>
-        <div class="plugin-item">
+        <div class="plugin-item" data-decoder="ft8">
           <strong>FT8 Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
             Decodes FT8 messages from RX audio (DIG/USB only, toggle required).
           </div>
         </div>
-        <div class="plugin-item">
+        <div class="plugin-item" data-decoder="ft4">
           <strong>FT4 Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
             Decodes FT4 messages from RX audio (DIG/USB only, toggle required). 7.5-second slots.
           </div>
         </div>
-        <div class="plugin-item">
+        <div class="plugin-item" data-decoder="ft2">
           <strong>FT2 Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
             Decodes FT2 messages from RX audio (DIG/USB only, toggle required). 3.75-second slots.
           </div>
         </div>
-        <div class="plugin-item">
+        <div class="plugin-item" data-decoder="wspr">
           <strong>WSPR Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
             Decodes WSPR messages from RX audio (DIG/USB only, toggle required).
           </div>
         </div>
-        <div class="plugin-item">
+        <div class="plugin-item" data-decoder="rds">
           <strong>RDS Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
             Decodes Radio Data System (RDS) metadata from WFM broadcasts (57 kHz subcarrier).
           </div>
         </div>
-        <div class="plugin-item">
+        <div class="plugin-item" data-decoder="lrpt">
           <strong>Weather Satellite Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
             Decodes Meteor-M LRPT (137 MHz QPSK) weather satellite imagery.