[fix](trx-server): drop in-flight decodes on main retune

Invalidate main-decoder windows whenever the rig's main frequency
changes, including direct SetFreq, scheduler-driven retunes, and
external CAT retunes observed during polling.

The decoder loops now resubscribe their PCM receivers on reset and drop
results that finish after the reset sequence advances, preventing false
decodes from stale pre-retune audio.

Co-Authored-By: OpenAI Codex <noreply@openai.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

src/decoders/trx-wspr/src/protocol.rs

@@ -141,8 +141,8 @@ fn unpack_message(bits: &[u8; NBITS]) -> Option<String> {
         power_code = (power_code << 1) | b as u32;
     }
 
-    // power_code = dBm + 64; valid WSPR levels are 0–60 dBm.
-    let power_dbm = power_code as i32 - 64;
+    // power_code is the raw dBm value; valid WSPR levels are 0–60 dBm.
+    let power_dbm = power_code as i32;
     if !(0..=60).contains(&power_dbm) {
         return None;
     }
@@ -179,7 +179,7 @@ fn unpack_message(bits: &[u8; NBITS]) -> Option<String> {
         CS27[i4] as char,
         CS27[i5] as char,
     )
-    .trim_end()
+    .trim()
     .to_string();
 
     if callsign.len() < 3 || !callsign.chars().any(|c| c.is_alphabetic()) {
@@ -243,10 +243,7 @@ mod tests {
         let c4 = idx27(b'T');
         let c5 = idx27(b' ');
 
-        let n1 = ((c0 * 36 + c1) * 10 + c2) * 27u32.pow(3)
-            + c3 * 27u32.pow(2)
-            + c4 * 27
-            + c5;
+        let n1 = ((c0 * 36 + c1) * 10 + c2) * 27u32.pow(3) + c3 * 27u32.pow(2) + c4 * 27 + c5;
 
         // Grid "FN20": loc1='F'=5 (lon), loc2='N'=13 (lat), loc3='2', loc4='0'
         let loc1 = (b'F' - b'A') as u32; // 5
@@ -255,8 +252,8 @@ mod tests {
         let loc4 = 0u32;
         let m1 = (179 - 10 * loc1 - loc3) * 180 + 10 * loc2 + loc4;
 
-        // Power 37 dBm → power_code = 37 + 64 = 101
-        let power_code = 37u32 + 64;
+        // Power 37 dBm → power_code = 37 (raw dBm value)
+        let power_code = 37u32;
 
         // Pack into 50-bit array
         let mut bits = [0u8; NBITS];

src/trx-server/src/audio.rs

@@ -23,25 +23,23 @@ use trx_ais::AisDecoder;
 use trx_aprs::AprsDecoder;
 use trx_core::audio::{
     parse_vchan_uuid_msg, read_audio_msg, write_audio_msg, write_vchan_audio_frame,
-    write_vchan_uuid_msg, AudioStreamInfo,
-    AUDIO_MSG_AIS_DECODE, AUDIO_MSG_APRS_DECODE, AUDIO_MSG_CW_DECODE, AUDIO_MSG_FT2_DECODE,
-    AUDIO_MSG_FT4_DECODE,
-    AUDIO_MSG_FT8_DECODE, AUDIO_MSG_HF_APRS_DECODE, AUDIO_MSG_HISTORY_COMPRESSED,
-    AUDIO_MSG_RX_FRAME, AUDIO_MSG_STREAM_INFO, AUDIO_MSG_TX_FRAME, AUDIO_MSG_VCHAN_ALLOCATED,
-    AUDIO_MSG_VCHAN_BW, AUDIO_MSG_VCHAN_DESTROYED, AUDIO_MSG_VCHAN_FREQ, AUDIO_MSG_VCHAN_MODE,
-    AUDIO_MSG_VCHAN_REMOVE,
+    write_vchan_uuid_msg, AudioStreamInfo, AUDIO_MSG_AIS_DECODE, AUDIO_MSG_APRS_DECODE,
+    AUDIO_MSG_CW_DECODE, AUDIO_MSG_FT2_DECODE, AUDIO_MSG_FT4_DECODE, AUDIO_MSG_FT8_DECODE,
+    AUDIO_MSG_HF_APRS_DECODE, AUDIO_MSG_HISTORY_COMPRESSED, AUDIO_MSG_RX_FRAME,
+    AUDIO_MSG_STREAM_INFO, AUDIO_MSG_TX_FRAME, AUDIO_MSG_VCHAN_ALLOCATED, AUDIO_MSG_VCHAN_BW,
+    AUDIO_MSG_VCHAN_DESTROYED, AUDIO_MSG_VCHAN_FREQ, AUDIO_MSG_VCHAN_MODE, AUDIO_MSG_VCHAN_REMOVE,
     AUDIO_MSG_VCHAN_SUB, AUDIO_MSG_VCHAN_UNSUB, AUDIO_MSG_VDES_DECODE, AUDIO_MSG_WSPR_DECODE,
 };
-use trx_core::vchan::SharedVChanManager;
-use uuid::Uuid;
 use trx_core::decode::{
     AisMessage, AprsPacket, CwEvent, DecodedMessage, Ft8Message, VdesMessage, WsprMessage,
 };
 use trx_core::rig::state::{RigMode, RigState};
+use trx_core::vchan::SharedVChanManager;
 use trx_cw::CwDecoder;
 use trx_ft8::Ft8Decoder;
 use trx_vdes::VdesDecoder;
 use trx_wspr::WsprDecoder;
+use uuid::Uuid;
 
 use crate::config::AudioConfig;
 use trx_decode_log::DecoderLoggers;
@@ -1053,6 +1051,8 @@ pub async fn run_aprs_decoder(
                             last_reset_seq = reset_seq;
                             decoder.reset();
                             info!("APRS decoder reset (seq={})", last_reset_seq);
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
                         }
 
                         // Downmix to mono if stereo
@@ -1070,6 +1070,14 @@ pub async fn run_aprs_decoder(
 
                         was_active = true;
                         let packets = tokio::task::block_in_place(|| decoder.process_samples(&mono));
+                        let latest_reset_seq = state_rx.borrow().aprs_decode_reset_seq;
+                        if latest_reset_seq != reset_seq {
+                            last_reset_seq = latest_reset_seq;
+                            decoder.reset();
+                            info!("APRS decoder reset (seq={})", last_reset_seq);
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
+                        }
                         for mut pkt in packets {
                             if let Some(logger) = decode_logs.as_ref() {
                                 logger.log_aprs(&pkt);
@@ -1124,7 +1132,10 @@ pub async fn run_hf_aprs_decoder(
     decode_logs: Option<Arc<DecoderLoggers>>,
     histories: Arc<DecoderHistories>,
 ) {
-    info!("HF APRS decoder started ({}Hz, {} ch)", sample_rate, channels);
+    info!(
+        "HF APRS decoder started ({}Hz, {} ch)",
+        sample_rate, channels
+    );
     let mut decoder = AprsDecoder::new_hf(sample_rate);
     let mut was_active = false;
     let mut last_reset_seq: u64 = 0;
@@ -1162,6 +1173,8 @@ pub async fn run_hf_aprs_decoder(
                             last_reset_seq = reset_seq;
                             decoder.reset();
                             info!("HF APRS decoder reset (seq={})", last_reset_seq);
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
                         }
 
                         let mut mono = downmix_if_needed(frame, channels);
@@ -1169,6 +1182,14 @@ pub async fn run_hf_aprs_decoder(
 
                         was_active = true;
                         let packets = tokio::task::block_in_place(|| decoder.process_samples(&mono));
+                        let latest_reset_seq = state_rx.borrow().hf_aprs_decode_reset_seq;
+                        if latest_reset_seq != reset_seq {
+                            last_reset_seq = latest_reset_seq;
+                            decoder.reset();
+                            info!("HF APRS decoder reset (seq={})", last_reset_seq);
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
+                        }
                         for mut pkt in packets {
                             if let Some(logger) = decode_logs.as_ref() {
                                 logger.log_aprs(&pkt);
@@ -1241,10 +1262,7 @@ pub async fn run_ais_decoder(
     let mut decoder_a = AisDecoder::new(sample_rate);
     let mut decoder_b = AisDecoder::new(sample_rate);
     let mut was_active = false;
-    let mut active = matches!(
-        state_rx.borrow().status.mode,
-        RigMode::AIS
-    );
+    let mut active = matches!(state_rx.borrow().status.mode, RigMode::AIS);
 
     loop {
         if !active {
@@ -1338,10 +1356,7 @@ pub async fn run_vdes_decoder(
     info!("VDES decoder started ({}Hz complex baseband)", sample_rate);
     let mut decoder = VdesDecoder::new(sample_rate);
     let mut was_active = false;
-    let mut active = matches!(
-        state_rx.borrow().status.mode,
-        RigMode::VDES
-    );
+    let mut active = matches!(state_rx.borrow().status.mode, RigMode::VDES);
 
     loop {
         if !active {
@@ -1486,6 +1501,8 @@ pub async fn run_cw_decoder(
                             last_reset_seq = reset_seq;
                             decoder.reset();
                             info!("CW decoder reset (seq={})", last_reset_seq);
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
                         }
                         if !process_enabled {
                             if was_active {
@@ -1509,6 +1526,14 @@ pub async fn run_cw_decoder(
                         };
                         was_active = true;
                         let events = tokio::task::block_in_place(|| decoder.process_samples(&mono));
+                        let latest_reset_seq = state_rx.borrow().cw_decode_reset_seq;
+                        if latest_reset_seq != reset_seq {
+                            last_reset_seq = latest_reset_seq;
+                            decoder.reset();
+                            info!("CW decoder reset (seq={})", last_reset_seq);
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
+                        }
                         for evt in events {
                             if let Some(logger) = decode_logs.as_ref() {
                                 logger.log_cw(&evt);
@@ -1686,6 +1711,8 @@ pub async fn run_ft8_decoder(
                             last_reset_seq = reset_seq;
                             decoder.reset();
                             ft8_buf.clear();
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
                         }
 
                         let mut mono = downmix_mono(frame, channels);
@@ -1702,6 +1729,14 @@ pub async fn run_ft8_decoder(
                                 decoder.process_block(&block);
                                 decoder.decode_if_ready(100)
                             });
+                            let latest_reset_seq = state_rx.borrow().ft8_decode_reset_seq;
+                            if latest_reset_seq != reset_seq {
+                                last_reset_seq = latest_reset_seq;
+                                decoder.reset();
+                                ft8_buf.clear();
+                                pcm_rx = pcm_rx.resubscribe();
+                                continue;
+                            }
                             if !results.is_empty() {
                                 for res in results {
                                     let ts_ms = match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH) {
@@ -1831,6 +1866,8 @@ pub async fn run_ft4_decoder(
                             last_reset_seq = reset_seq;
                             decoder.reset();
                             ft4_buf.clear();
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
                         }
 
                         let mut mono = downmix_mono(frame, channels);
@@ -1847,6 +1884,14 @@ pub async fn run_ft4_decoder(
                                 decoder.process_block(&block);
                                 decoder.decode_if_ready(100)
                             });
+                            let latest_reset_seq = state_rx.borrow().ft4_decode_reset_seq;
+                            if latest_reset_seq != reset_seq {
+                                last_reset_seq = latest_reset_seq;
+                                decoder.reset();
+                                ft4_buf.clear();
+                                pcm_rx = pcm_rx.resubscribe();
+                                continue;
+                            }
                             if !results.is_empty() {
                                 for res in results {
                                     let ts_ms = match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH) {
@@ -1965,6 +2010,8 @@ pub async fn run_ft2_decoder(
                             ft2_buf.clear();
                             pending_decode_samples = 0;
                             recent_decodes.clear();
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
                         }
 
                         let mut mono = downmix_mono(frame, channels);
@@ -1984,6 +2031,16 @@ pub async fn run_ft2_decoder(
                             let results = tokio::task::block_in_place(|| {
                                 decode_ft2_window(&mut decoder, &ft2_buf, 100)
                             });
+                            let latest_reset_seq = state_rx.borrow().ft2_decode_reset_seq;
+                            if latest_reset_seq != reset_seq {
+                                last_reset_seq = latest_reset_seq;
+                                decoder.reset();
+                                ft2_buf.clear();
+                                pending_decode_samples = 0;
+                                recent_decodes.clear();
+                                pcm_rx = pcm_rx.resubscribe();
+                                continue;
+                            }
                             if !results.is_empty() {
                                 for res in results {
                                     let ts_ms = match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH) {
@@ -2109,13 +2166,33 @@ pub async fn run_wspr_decoder(
                             Err(_) => 0,
                         };
                         let slot = now / slot_len_s;
+                        let reset_seq = {
+                            let state = state_rx.borrow();
+                            state.wspr_decode_reset_seq
+                        };
+                        if reset_seq != last_reset_seq {
+                            last_reset_seq = reset_seq;
+                            slot_buf.clear();
+                            last_slot = slot;
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
+                        }
                         if last_slot == -1 {
                             last_slot = slot;
                         } else if slot != last_slot {
                             let base_freq = state_rx.borrow().status.freq.hz;
-                            match tokio::task::block_in_place(|| {
+                            let decode_results = tokio::task::block_in_place(|| {
                                 decoder.decode_slot(&slot_buf, Some(base_freq))
-                            }) {
+                            });
+                            let latest_reset_seq = state_rx.borrow().wspr_decode_reset_seq;
+                            if latest_reset_seq != reset_seq {
+                                last_reset_seq = latest_reset_seq;
+                                slot_buf.clear();
+                                last_slot = slot;
+                                pcm_rx = pcm_rx.resubscribe();
+                                continue;
+                            }
+                            match decode_results {
                                 Ok(results) => {
                                     for res in results {
                                         let ts_ms = match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH) {
@@ -2141,15 +2218,13 @@ pub async fn run_wspr_decoder(
                             slot_buf.clear();
                             last_slot = slot;
                         }
-
-                        let reset_seq = {
-                            let state = state_rx.borrow();
-                            state.wspr_decode_reset_seq
-                        };
-                        if reset_seq != last_reset_seq {
-                            last_reset_seq = reset_seq;
+                        let latest_reset_seq = state_rx.borrow().wspr_decode_reset_seq;
+                        if latest_reset_seq != last_reset_seq {
+                            last_reset_seq = latest_reset_seq;
                             slot_buf.clear();
                             last_slot = slot;
+                            pcm_rx = pcm_rx.resubscribe();
+                            continue;
                         }
 
                         let mut mono = downmix_mono(frame, channels);
@@ -2348,8 +2423,7 @@ async fn run_background_ft8_decoder(
     loop {
         match pcm_rx.recv().await {
             Ok(frame) => {
-                let now = match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH)
-                {
+                let now = match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH) {
                     Ok(dur) => dur.as_secs() as i64,
                     Err(_) => 0,
                 };
@@ -2427,8 +2501,7 @@ async fn run_background_ft4_decoder(
         match pcm_rx.recv().await {
             Ok(frame) => {
                 let now_ms =
-                    match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH)
-                {
+                    match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH) {
                         Ok(dur) => dur.as_millis() as i64,
                         Err(_) => 0,
                     };
@@ -2540,11 +2613,7 @@ async fn run_background_ft2_decoder(
                             },
                             message: res.text,
                         };
-                        if !should_emit_ft2_decode(
-                            &mut recent_decodes,
-                            &msg.message,
-                            msg.freq_hz,
-                        ) {
+                        if !should_emit_ft2_decode(&mut recent_decodes, &msg.message, msg.freq_hz) {
                             continue;
                         }
                         let _ = decode_tx.send(DecodedMessage::Ft2(msg));
@@ -2584,8 +2653,7 @@ async fn run_background_wspr_decoder(
     loop {
         match pcm_rx.recv().await {
             Ok(frame) => {
-                let now = match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH)
-                {
+                let now = match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH) {
                     Ok(dur) => dur.as_secs() as i64,
                     Err(_) => 0,
                 };
@@ -2755,15 +2823,51 @@ async fn handle_audio_client(
             };
         }
 
-        push_history!(histories.snapshot_ais_history(), DecodedMessage::Ais, AUDIO_MSG_AIS_DECODE);
-        push_history!(histories.snapshot_vdes_history(), DecodedMessage::Vdes, AUDIO_MSG_VDES_DECODE);
-        push_history!(histories.snapshot_aprs_history(), DecodedMessage::Aprs, AUDIO_MSG_APRS_DECODE);
-        push_history!(histories.snapshot_hf_aprs_history(), DecodedMessage::HfAprs, AUDIO_MSG_HF_APRS_DECODE);
-        push_history!(histories.snapshot_ft8_history(), DecodedMessage::Ft8, AUDIO_MSG_FT8_DECODE);
-        push_history!(histories.snapshot_ft4_history(), DecodedMessage::Ft4, AUDIO_MSG_FT4_DECODE);
-        push_history!(histories.snapshot_ft2_history(), DecodedMessage::Ft2, AUDIO_MSG_FT2_DECODE);
-        push_history!(histories.snapshot_wspr_history(), DecodedMessage::Wspr, AUDIO_MSG_WSPR_DECODE);
-        push_history!(histories.snapshot_cw_history(), DecodedMessage::Cw, AUDIO_MSG_CW_DECODE);
+        push_history!(
+            histories.snapshot_ais_history(),
+            DecodedMessage::Ais,
+            AUDIO_MSG_AIS_DECODE
+        );
+        push_history!(
+            histories.snapshot_vdes_history(),
+            DecodedMessage::Vdes,
+            AUDIO_MSG_VDES_DECODE
+        );
+        push_history!(
+            histories.snapshot_aprs_history(),
+            DecodedMessage::Aprs,
+            AUDIO_MSG_APRS_DECODE
+        );
+        push_history!(
+            histories.snapshot_hf_aprs_history(),
+            DecodedMessage::HfAprs,
+            AUDIO_MSG_HF_APRS_DECODE
+        );
+        push_history!(
+            histories.snapshot_ft8_history(),
+            DecodedMessage::Ft8,
+            AUDIO_MSG_FT8_DECODE
+        );
+        push_history!(
+            histories.snapshot_ft4_history(),
+            DecodedMessage::Ft4,
+            AUDIO_MSG_FT4_DECODE
+        );
+        push_history!(
+            histories.snapshot_ft2_history(),
+            DecodedMessage::Ft2,
+            AUDIO_MSG_FT2_DECODE
+        );
+        push_history!(
+            histories.snapshot_wspr_history(),
+            DecodedMessage::Wspr,
+            AUDIO_MSG_WSPR_DECODE
+        );
+        push_history!(
+            histories.snapshot_cw_history(),
+            DecodedMessage::Cw,
+            AUDIO_MSG_CW_DECODE
+        );
 
         (blob, count)
     };
@@ -2773,10 +2877,7 @@ async fn handle_audio_client(
         // well (~10-20x) so this dramatically reduces both transfer size and
         // the time the client spends waiting for data.
         let compressed = {
-            let mut enc = GzEncoder::new(
-                Vec::with_capacity(blob.len() / 8),
-                Compression::fast(),
-            );
+            let mut enc = GzEncoder::new(Vec::with_capacity(blob.len() / 8), Compression::fast());
             enc.write_all(&blob)
                 .and_then(|_| enc.finish())
                 .unwrap_or(blob.clone())
@@ -3160,9 +3261,7 @@ async fn handle_audio_client(
                     // Payload: JSON { "uuid": "...", "freq_hz": N, "mode": "..." }
                     match serde_json::from_slice::<serde_json::Value>(&payload) {
                         Ok(v) => {
-                            let uuid = v["uuid"]
-                                .as_str()
-                                .and_then(|s| s.parse::<Uuid>().ok());
+                            let uuid = v["uuid"].as_str().and_then(|s| s.parse::<Uuid>().ok());
                             let freq_hz = v["freq_hz"].as_u64();
                             let mode_str = v["mode"].as_str().unwrap_or("USB");
                             let hidden = v["hidden"].as_bool().unwrap_or(false);
@@ -3184,9 +3283,16 @@ async fn handle_audio_client(
                                 };
                                 match ensure_result {
                                     Ok(pcm_rx) => {
-                                        if let Some(bandwidth_hz) = bandwidth_hz.filter(|bw| *bw > 0) {
-                                            if let Err(e) = mgr.set_channel_bandwidth(uuid, bandwidth_hz) {
-                                                warn!("Audio vchan SUB bandwidth apply failed: {}", e);
+                                        if let Some(bandwidth_hz) =
+                                            bandwidth_hz.filter(|bw| *bw > 0)
+                                        {
+                                            if let Err(e) =
+                                                mgr.set_channel_bandwidth(uuid, bandwidth_hz)
+                                            {
+                                                warn!(
+                                                    "Audio vchan SUB bandwidth apply failed: {}",
+                                                    e
+                                                );
                                             }
                                         }
                                         let _ = vchan_cmd_tx
@@ -3194,7 +3300,8 @@ async fn handle_audio_client(
                                                 uuid,
                                                 pcm_rx,
                                                 send_audio: !hidden,
-                                                background_decode: (!decoder_kinds.is_empty()).then_some(BackgroundDecodeSpec {
+                                                background_decode: (!decoder_kinds.is_empty())
+                                                    .then_some(BackgroundDecodeSpec {
                                                         base_freq_hz: freq_hz,
                                                         decoder_kinds,
                                                     }),
@@ -3211,14 +3318,12 @@ async fn handle_audio_client(
                     }
                 }
             }
-            Ok((AUDIO_MSG_VCHAN_UNSUB, payload)) => {
-                match parse_vchan_uuid_msg(&payload) {
+            Ok((AUDIO_MSG_VCHAN_UNSUB, payload)) => match parse_vchan_uuid_msg(&payload) {
                 Ok(uuid) => {
                     let _ = vchan_cmd_tx.send(VChanCmd::Unsubscribe(uuid)).await;
                 }
                 Err(e) => warn!("Audio vchan UNSUB: bad payload: {}", e),
-                }
-            }
+            },
             Ok((AUDIO_MSG_VCHAN_FREQ, payload)) => {
                 if let Some(ref mgr) = vchan_manager {
                     if let Ok(v) = serde_json::from_slice::<serde_json::Value>(&payload) {
@@ -3236,7 +3341,8 @@ async fn handle_audio_client(
             Ok((AUDIO_MSG_VCHAN_MODE, payload)) => {
                 if let Some(ref mgr) = vchan_manager {
                     if let Ok(v) = serde_json::from_slice::<serde_json::Value>(&payload) {
-                        if let Some(uuid) = v["uuid"].as_str().and_then(|s| s.parse::<Uuid>().ok()) {
+                        if let Some(uuid) = v["uuid"].as_str().and_then(|s| s.parse::<Uuid>().ok())
+                        {
                             let mode = trx_protocol::codec::parse_mode(
                                 v["mode"].as_str().unwrap_or("USB"),
                             );
@@ -3280,7 +3386,10 @@ async fn handle_audio_client(
                 }
             }
             Ok((msg_type, _)) => {
-                warn!("Audio: unexpected message type {:#04x} from {}", msg_type, peer);
+                warn!(
+                    "Audio: unexpected message type {:#04x} from {}",
+                    msg_type, peer
+                );
             }
             Err(_) => break,
         }

src/trx-server/src/rig_task.rs

@@ -671,7 +671,9 @@ async fn process_command(
             // Apply state updates based on command result
             match cmd_result {
                 CommandResult::FreqUpdated(freq) => {
+                    let prev_freq_hz = ctx.state.status.freq.hz;
                     ctx.state.apply_freq(freq);
+                    invalidate_main_decoder_windows_on_freq_change(ctx.state, prev_freq_hz);
                     *ctx.poll_pause_until = Some(Instant::now() + Duration::from_millis(200));
                 }
                 CommandResult::ModeUpdated(mode) => {
@@ -786,7 +788,9 @@ async fn refresh_state_from_cat(rig: &mut Box<dyn RigCat>, state: &mut RigState)
     let (freq, mode, vfo) = rig.get_status().await?;
     state.filter = rig.filter_state();
     state.control.enabled = Some(true);
+    let prev_freq_hz = state.status.freq.hz;
     state.apply_freq(freq);
+    invalidate_main_decoder_windows_on_freq_change(state, prev_freq_hz);
     state.apply_mode(mode);
     state.status.vfo = vfo;
 
@@ -923,9 +927,7 @@ fn map_signal_strength(mode: &RigMode, raw: u8) -> i32 {
     // FT-817 returns 0-15 for signal strength
     // Map to approximate dBm / S-units
     match mode {
-        RigMode::FM | RigMode::WFM | RigMode::AIS | RigMode::VDES => {
-            -120 + (raw as i32 * 6)
-        }
+        RigMode::FM | RigMode::WFM | RigMode::AIS | RigMode::VDES => -120 + (raw as i32 * 6),
         _ => -127 + (raw as i32 * 6),
     }
 }
@@ -937,6 +939,19 @@ fn snapshot_from(state: &RigState) -> RigResult<RigSnapshot> {
         .ok_or_else(|| RigError::invalid_state("Rig info unavailable"))
 }
 
+fn invalidate_main_decoder_windows_on_freq_change(state: &mut RigState, prev_freq_hz: u64) {
+    if state.status.freq.hz == prev_freq_hz {
+        return;
+    }
+    state.aprs_decode_reset_seq += 1;
+    state.hf_aprs_decode_reset_seq += 1;
+    state.cw_decode_reset_seq += 1;
+    state.ft8_decode_reset_seq += 1;
+    state.ft4_decode_reset_seq += 1;
+    state.ft2_decode_reset_seq += 1;
+    state.wspr_decode_reset_seq += 1;
+}
+
 fn sync_machine_state(machine: &mut RigStateMachine, state: &RigState) {
     let desired = desired_machine_state(state);
     match (machine.state().clone(), &desired) {
@@ -1069,3 +1084,50 @@ fn tx_meter_parts(tx: Option<&RigTxStatus>) -> (Option<u8>, Option<u8>, Option<f
     tx.map(|tx| (tx.power, tx.limit, tx.swr, tx.alc))
         .unwrap_or((None, None, None, None))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn freq_change_invalidates_all_main_decoder_windows() {
+        let mut state = RigState::new_uninitialized();
+        let prev_freq_hz = state.status.freq.hz;
+        state.apply_freq(Freq {
+            hz: prev_freq_hz + 2_700,
+        });
+
+        invalidate_main_decoder_windows_on_freq_change(&mut state, prev_freq_hz);
+
+        assert_eq!(state.aprs_decode_reset_seq, 1);
+        assert_eq!(state.hf_aprs_decode_reset_seq, 1);
+        assert_eq!(state.cw_decode_reset_seq, 1);
+        assert_eq!(state.ft8_decode_reset_seq, 1);
+        assert_eq!(state.ft4_decode_reset_seq, 1);
+        assert_eq!(state.ft2_decode_reset_seq, 1);
+        assert_eq!(state.wspr_decode_reset_seq, 1);
+    }
+
+    #[test]
+    fn unchanged_freq_keeps_decoder_windows_intact() {
+        let mut state = RigState::new_uninitialized();
+        state.aprs_decode_reset_seq = 2;
+        state.hf_aprs_decode_reset_seq = 3;
+        state.cw_decode_reset_seq = 4;
+        state.ft8_decode_reset_seq = 5;
+        state.ft4_decode_reset_seq = 6;
+        state.ft2_decode_reset_seq = 7;
+        state.wspr_decode_reset_seq = 8;
+        let prev_freq_hz = state.status.freq.hz;
+
+        invalidate_main_decoder_windows_on_freq_change(&mut state, prev_freq_hz);
+
+        assert_eq!(state.aprs_decode_reset_seq, 2);
+        assert_eq!(state.hf_aprs_decode_reset_seq, 3);
+        assert_eq!(state.cw_decode_reset_seq, 4);
+        assert_eq!(state.ft8_decode_reset_seq, 5);
+        assert_eq!(state.ft4_decode_reset_seq, 6);
+        assert_eq!(state.ft2_decode_reset_seq, 7);
+        assert_eq!(state.wspr_decode_reset_seq, 8);
+    }
+}