[feat](trx-frontend-http): intercept freq/mode changes for virtual channels

When on a non-primary (virtual) channel, redirect freq and mode changes
to the channel metadata API instead of the server:

- vchan.js: add vchanIsOnVirtual(), vchanSetChannelFreq/Mode(); expose
  window.vchanInterceptMode() hook; wrap window.setRigFrequency so all
  callers (jog, freq input, bookmarks, spectrum click) are automatically
  redirected without modification
- app.js: check vchanInterceptMode() in applyModeFromPicker() before
  posting /set_mode
- bookmarks.js: check vchanInterceptMode() for mode in bmApply();
  setRigFrequency() redirect is automatic via the vchan.js wrapper;
  bandwidth and decoder toggles still apply regardless of channel

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

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

@@ -3119,6 +3119,10 @@ async function applyModeFromPicker() {
   modeEl.disabled = true;
   showHint("Setting mode…");
   try {
+    if (typeof vchanInterceptMode === "function" && await vchanInterceptMode(mode)) {
+      showHint("Channel mode set", 1500);
+      return;
+    }
     await postPath(`/set_mode?mode=${encodeURIComponent(mode)}`);
     showHint("Mode set", 1500);
     if (mode.toUpperCase() === "WFM") {

src/trx-client/trx-frontend/trx-frontend-http/assets/web/plugins/bookmarks.js

@@ -277,7 +277,11 @@ async function bmDelete(id) {
 
 async function bmApply(bm) {
   try {
+    const onVirtual = typeof vchanInterceptMode === "function"
+      && await vchanInterceptMode(bm.mode);
+    if (!onVirtual) {
       await postPath("/set_mode?mode=" + encodeURIComponent(bm.mode));
+    }
     if (typeof modeEl !== "undefined" && modeEl) {
       modeEl.value = String(bm.mode || "").toUpperCase();
     }
@@ -290,12 +294,14 @@ async function bmApply(bm) {
         syncBandwidthInput(bm.bandwidth_hz);
       }
     }
+    // setRigFrequency is wrapped by vchan.js to redirect to the channel API
+    // when on a virtual channel, so this call works correctly in both cases.
     if (typeof setRigFrequency === "function") {
       await setRigFrequency(bm.freq_hz);
     } else {
       await postPath("/set_freq?hz=" + bm.freq_hz);
     }
-    // Toggle decoders when in DIG mode
+    // Toggle decoders when in DIG mode.
     if (bm.mode === "DIG" && Array.isArray(bm.decoders)) {
       const statusResp = await fetch("/status");
       if (statusResp.ok) {

src/trx-client/trx-frontend/trx-frontend-http/assets/web/plugins/vchan.js

@@ -168,3 +168,70 @@ function vchanApplyCapabilities(caps) {
   if (!row) return;
   row.style.display = (caps && caps.filter_controls) ? "" : "none";
 }
+
+// ---------------------------------------------------------------------------
+// Freq / mode interception
+// ---------------------------------------------------------------------------
+
+// Returns true when the active channel is a non-primary (virtual) channel.
+function vchanIsOnVirtual() {
+  if (!vchanActiveId || vchanChannels.length === 0) return false;
+  return vchanActiveId !== vchanChannels[0].id;
+}
+
+async function vchanSetChannelFreq(freqHz) {
+  if (!vchanRigId || !vchanActiveId) return;
+  try {
+    const resp = await fetch(
+      `/channels/${encodeURIComponent(vchanRigId)}/${encodeURIComponent(vchanActiveId)}/freq`,
+      {
+        method: "PUT",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ freq_hz: Math.round(freqHz) }),
+      }
+    );
+    if (!resp.ok) console.warn("vchan: set freq failed", resp.status);
+  } catch (e) {
+    console.error("vchan: set freq error", e);
+  }
+}
+
+async function vchanSetChannelMode(mode) {
+  if (!vchanRigId || !vchanActiveId) return;
+  try {
+    const resp = await fetch(
+      `/channels/${encodeURIComponent(vchanRigId)}/${encodeURIComponent(vchanActiveId)}/mode`,
+      {
+        method: "PUT",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ mode }),
+      }
+    );
+    if (!resp.ok) console.warn("vchan: set mode failed", resp.status);
+  } catch (e) {
+    console.error("vchan: set mode error", e);
+  }
+}
+
+// Called by app.js (applyModeFromPicker) and bookmarks.js (bmApply) before
+// sending /set_mode to the server.  Returns true if the change was handled
+// by the virtual channel (caller should skip the server request).
+window.vchanInterceptMode = async function(mode) {
+  if (!vchanIsOnVirtual()) return false;
+  await vchanSetChannelMode(mode);
+  return true;
+};
+
+// Wrap setRigFrequency (defined in app.js, loaded before this file) so that
+// frequency changes are redirected to the active virtual channel instead of
+// the server when on a non-primary channel.
+(function() {
+  const _orig = window.setRigFrequency;
+  window.setRigFrequency = async function(freqHz) {
+    if (vchanIsOnVirtual()) {
+      await vchanSetChannelFreq(freqHz);
+      return;
+    }
+    if (typeof _orig === "function") return _orig(freqHz);
+  };
+})();