[feat](trx-protocol): add centralised decoder registry

Add DECODER_REGISTRY in trx-protocol::decoders as the single source of
truth for all decoder metadata (activation mode, supported rig modes,
background-decode capability). Replace duplicated resolver functions in
background_decode.rs and sse.rs with shared resolve_bookmark_decoders().
Add GET /decoders endpoint to expose the registry to the frontend.

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

@@ -3241,22 +3241,22 @@ function render(update) {
   const wsprStatus = document.getElementById("wspr-status");
   setModeBoundDecodeStatus(
     aisStatus,
-    ["AIS", "FM", "PKT"],
-    "Select AIS or FM mode to decode",
+    ["AIS"],
+    "Select AIS mode to decode",
     "Connected, listening for packets",
   );
   if (window.updateAisBar) window.updateAisBar();
   setModeBoundDecodeStatus(
     vdesStatus,
-    ["VDES", "FM"],
-    "Select VDES or FM mode to decode",
+    ["VDES"],
+    "Select VDES mode to decode",
     "Connected, listening for bursts",
   );
   if (window.updateVdesBar) window.updateVdesBar();
   setModeBoundDecodeStatus(
     aprsStatus,
-    ["PKT", "FM"],
-    "Select FM mode to decode",
+    ["PKT"],
+    "Select PKT mode to decode",
     "Connected, listening for packets",
   );
   if (window.updateAprsBar) window.updateAprsBar();
@@ -8903,10 +8903,10 @@ function updateDecodeStatus(text) {
   const ft8 = document.getElementById("ft8-status");
   const ft4 = document.getElementById("ft4-status");
   const ft2 = document.getElementById("ft2-status");
-  setModeBoundDecodeStatus(ais, ["AIS", "FM", "PKT"], "Select AIS or FM mode to decode", text);
+  setModeBoundDecodeStatus(ais, ["AIS"], "Select AIS mode to decode", text);
   const vdesText = text === "Connected, listening for packets" ? "Connected, listening for bursts" : text;
-  setModeBoundDecodeStatus(vdes, ["VDES", "FM"], "Select VDES or FM mode to decode", vdesText);
-  setModeBoundDecodeStatus(aprs, ["PKT", "FM"], "Select FM mode to decode", text);
+  setModeBoundDecodeStatus(vdes, ["VDES"], "Select VDES mode to decode", vdesText);
+  setModeBoundDecodeStatus(aprs, ["PKT"], "Select PKT mode to decode", text);
   const cwText = text === "Connected, listening for packets" ? "Connected, listening for CW" : text;
   setModeBoundDecodeStatus(cw, ["CW", "CWR"], "Select CW mode to decode", cwText);
   if (ft8 && ft8.textContent !== "Receiving") ft8.textContent = text;

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

@@ -449,13 +449,14 @@
               <input type="number" id="bm-freq" class="status-input" required min="0" placeholder="e.g. 7074000" />
             </label>
             <label class="bm-label">Mode
-              <input type="text" id="bm-mode" class="status-input" list="bm-mode-list" required placeholder="e.g. USB" />
+              <input type="text" id="bm-mode" class="status-input" list="bm-mode-list" required placeholder="e.g. DIG" />
               <datalist id="bm-mode-list">
                 <option value="LSB">
                 <option value="USB">
                 <option value="AM">
                 <option value="SAM">
                 <option value="FM">
+                <option value="DIG">
                 <option value="CW">
                 <option value="WFM">
               </datalist>
@@ -560,25 +561,25 @@
         <div class="plugin-item">
           <strong>FT8 Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
-            Decodes FT8 messages from RX audio (USB only, toggle required).
+            Decodes FT8 messages from RX audio (DIG/USB only, toggle required).
           </div>
         </div>
         <div class="plugin-item">
           <strong>FT4 Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
-            Decodes FT4 messages from RX audio (USB only, toggle required). 7.5-second slots.
+            Decodes FT4 messages from RX audio (DIG/USB only, toggle required). 7.5-second slots.
           </div>
         </div>
         <div class="plugin-item">
           <strong>FT2 Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
-            Decodes FT2 messages from RX audio (USB only, toggle required). 3.75-second slots.
+            Decodes FT2 messages from RX audio (DIG/USB only, toggle required). 3.75-second slots.
           </div>
         </div>
         <div class="plugin-item">
           <strong>WSPR Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
-            Decodes WSPR messages from RX audio (USB only, toggle required).
+            Decodes WSPR messages from RX audio (DIG/USB only, toggle required).
           </div>
         </div>
         <div class="plugin-item">

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

@@ -322,8 +322,7 @@ function renderAprsHistory() {
 
 function updateAprsBar() {
   if (!aprsBarOverlay) return;
-  const modeVal = (document.getElementById("mode")?.value || "").toUpperCase();
-  const isPkt = modeVal === "PKT" || modeVal === "FM";
+  const isPkt = (document.getElementById("mode")?.value || "").toUpperCase() === "PKT";
   const cutoffMs = Date.now() - APRS_BAR_WINDOW_MS;
   const okFrames = aprsPacketHistory.filter((p) => p.crcOk && p._tsMs >= cutoffMs);
   const frames = collapseAprsDuplicates(okFrames).slice(0, 8);

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

@@ -102,7 +102,7 @@
     if (supported.length > 0) return supported;
     const mode = String(bookmark && bookmark.mode || "").trim().toUpperCase();
     if (mode === "AIS") return ["ais"];
-    if (mode === "PKT" || mode === "FM") return ["aprs"];
+    if (mode === "PKT") return ["aprs"];
     return supported;
   }
 

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

@@ -428,9 +428,9 @@ async function bmApply(bm) {
         await postPath("/set_freq?hz=" + bm.freq_hz);
       }
     })();
-    // Decoder toggles (USB / DIG / FM / PKT modes) — also fire-and-forget.
+    // Decoder toggles (DIG / FM modes) — also fire-and-forget.
     const hasDecoders = Array.isArray(bm.decoders) && bm.decoders.length > 0;
-    const decoderMode = bm.mode === "USB" || bm.mode === "DIG" || bm.mode === "FM" || bm.mode === "PKT";
+    const decoderMode = bm.mode === "DIG" || bm.mode === "FM";
     const decoderPromise = (hasDecoders && decoderMode) ? (async () => {
       const statusResp = await fetch("/status");
       if (statusResp.ok) {

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

@@ -20,6 +20,15 @@ use trx_frontend::FrontendRuntimeContext;
 
 use super::{gzip_bytes, send_command, RemoteQuery};
 
+// ============================================================================
+// Decoder registry
+// ============================================================================
+
+#[get("/decoders")]
+pub async fn decoder_registry() -> impl Responder {
+    HttpResponse::Ok().json(trx_protocol::DECODER_REGISTRY)
+}
+
 // ============================================================================
 // Decode history types and helpers
 // ============================================================================

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

@@ -562,6 +562,7 @@ pub fn configure(cfg: &mut web::ServiceConfig) {
         .service(sse::events)
         .service(sse::spectrum)
         // Decoder endpoints
+        .service(decoder::decoder_registry)
         .service(decoder::decode_history)
         .service(decoder::decode_events)
         .service(decoder::toggle_aprs_decode)

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

@@ -135,30 +135,11 @@ fn sync_scheduler_vchannels(
 }
 
 fn bookmark_decoder_kinds(bookmark: &crate::server::bookmarks::Bookmark) -> Vec<String> {
-    let mut out = Vec::new();
-    for decoder in bookmark
-        .decoders
-        .iter()
-        .map(|item| item.trim().to_ascii_lowercase())
-    {
-        if matches!(
-            decoder.as_str(),
-            "aprs" | "ais" | "ft8" | "ft4" | "ft2" | "wspr" | "hf-aprs"
-        ) && !out.iter().any(|existing| existing == &decoder)
-        {
-            out.push(decoder);
-        }
-    }
-
-    if !out.is_empty() {
-        return out;
-    }
-
-    match bookmark.mode.trim().to_ascii_uppercase().as_str() {
-        "AIS" => vec!["ais".to_string()],
-        "PKT" => vec!["aprs".to_string()],
-        _ => Vec::new(),
-    }
+    trx_protocol::decoders::resolve_bookmark_decoders(
+        &bookmark.decoders,
+        &bookmark.mode,
+        true,
+    )
 }
 
 // ============================================================================

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

@@ -22,7 +22,7 @@ use crate::server::bookmarks::{Bookmark, BookmarkStoreMap};
 use crate::server::scheduler::{SchedulerStatusMap, SharedSchedulerControlManager};
 use crate::server::vchan::{ClientChannel, ClientChannelManager};
 
-const SUPPORTED_DECODER_KINDS: &[&str] = &["aprs", "ais", "ft8", "ft4", "ft2", "wspr", "hf-aprs"];
+use trx_protocol::decoders::resolve_bookmark_decoders;
 const CHANNEL_KIND_NAME: &str = "VirtualBackgroundDecodeChannel";
 const VISIBLE_CHANNEL_KIND_NAME: &str = "VirtualChannel";
 
@@ -233,7 +233,7 @@ impl BackgroundDecodeManager {
                         freq_hz: bookmark.map(|item| item.freq_hz),
                         mode: bookmark.map(|item| item.mode.clone()),
                         decoder_kinds: bookmark
-                            .map(bookmark_supported_decoder_kinds)
+                            .map(bookmark_decoder_kinds)
                             .unwrap_or_default(),
                         state: "inactive".to_string(),
                         channel_kind: None,
@@ -383,7 +383,7 @@ impl BackgroundDecodeManager {
                 continue;
             };
 
-            let decoder_kinds = bookmark_supported_decoder_kinds(bookmark);
+            let decoder_kinds = bookmark_decoder_kinds(bookmark);
             let mut status = BackgroundDecodeBookmarkStatus {
                 bookmark_id: bookmark.id.clone(),
                 bookmark_name: Some(bookmark.name.clone()),
@@ -609,30 +609,8 @@ fn dedup_ids(ids: &[String]) -> Vec<String> {
     out
 }
 
-fn supported_decoder_kinds(decoders: &[String]) -> Vec<String> {
-    let mut out = Vec::new();
-    for decoder in decoders {
-        let decoder = decoder.trim().to_ascii_lowercase();
-        if SUPPORTED_DECODER_KINDS.contains(&decoder.as_str())
-            && !out.iter().any(|existing| existing == &decoder)
-        {
-            out.push(decoder);
-        }
-    }
-    out
-}
-
-fn bookmark_supported_decoder_kinds(bookmark: &Bookmark) -> Vec<String> {
-    let explicit = supported_decoder_kinds(&bookmark.decoders);
-    if !explicit.is_empty() {
-        return explicit;
-    }
-
-    match bookmark.mode.trim().to_ascii_uppercase().as_str() {
-        "AIS" => vec!["ais".to_string()],
-        "PKT" | "FM" => vec!["aprs".to_string()],
-        _ => Vec::new(),
-    }
+fn bookmark_decoder_kinds(bookmark: &Bookmark) -> Vec<String> {
+    resolve_bookmark_decoders(&bookmark.decoders, &bookmark.mode, true)
 }
 
 fn channel_matches_bookmark(channel: &ClientChannel, bookmark: &Bookmark) -> bool {

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

@@ -966,8 +966,7 @@ async fn apply_scheduler_decoders(
     bookmark: &crate::server::bookmarks::Bookmark,
     extra_bookmarks: &[crate::server::bookmarks::Bookmark],
 ) {
-    let mut want_aprs = bookmark.mode.trim().eq_ignore_ascii_case("PKT")
-        || bookmark.mode.trim().eq_ignore_ascii_case("FM");
+    let mut want_aprs = bookmark.mode.trim().eq_ignore_ascii_case("PKT");
     let mut want_hf_aprs = false;
     let mut want_ft8 = false;
     let mut want_ft4 = false;

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

@@ -723,7 +723,7 @@ mod tests {
 
         mgr.init_rig(rig_id, 14_074_000, "USB");
         let channel = mgr
-            .allocate(session_id, rig_id, 14_075_000, "USB")
+            .allocate(session_id, rig_id, 14_075_000, "DIG")
             .expect("allocate vchan");
 
         assert_eq!(mgr.channels(rig_id).len(), 2);
@@ -747,7 +747,7 @@ mod tests {
             &[(
                 "bm-ft8".to_string(),
                 14_074_000,
-                "USB".to_string(),
+                "DIG".to_string(),
                 3_000,
                 vec!["ft8".to_string()],
             )],
@@ -756,7 +756,7 @@ mod tests {
         let channels = mgr.channels(rig_id);
         assert_eq!(channels.len(), 2);
         assert_eq!(channels[1].freq_hz, 14_074_000);
-        assert_eq!(channels[1].mode, "USB");
+        assert_eq!(channels[1].mode, "DIG");
         assert_eq!(channels[1].bandwidth_hz, 3_000);
         assert_eq!(channels[1].subscribers, 0);
         assert!(channels[1].permanent);
@@ -770,14 +770,14 @@ mod tests {
 
         mgr.init_rig(rig_id, 14_074_000, "USB");
         let _channel = mgr
-            .allocate(session_id, rig_id, 14_075_000, "USB")
+            .allocate(session_id, rig_id, 14_075_000, "DIG")
             .expect("allocate vchan");
         mgr.sync_scheduler_channels(
             rig_id,
             &[(
                 "bm-ft8".to_string(),
                 14_074_000,
-                "USB".to_string(),
+                "DIG".to_string(),
                 3_000,
                 vec!["ft8".to_string()],
             )],
@@ -787,7 +787,7 @@ mod tests {
 
         let channels = mgr.channels(rig_id);
         assert_eq!(channels.len(), 2);
-        assert_eq!(channels[1].mode, "USB");
+        assert_eq!(channels[1].mode, "DIG");
         assert_eq!(channels[1].subscribers, 0);
     }
 
@@ -803,7 +803,7 @@ mod tests {
             &[(
                 "bm-aprs".to_string(),
                 144_800_000,
-                "FM".to_string(),
+                "PKT".to_string(),
                 12_500,
                 vec!["aprs".to_string()],
             )],