fix: Flex with multiple slices opened was always showing slice A s-meter.

internal/cat/cat.go

@@ -330,6 +330,7 @@ type FlexMeter struct {
 	Src   string  `json:"src,omitempty"`  // SLC / TX- / RAD / AMP…
 	Name  string  `json:"name,omitempty"` // FWDPWR, SWR, LEVEL, PATEMP…
 	Unit  string  `json:"unit,omitempty"`
+	Slice int     `json:"slice"`          // for SLC meters, the slice index it belongs to; -1 otherwise
 	Value float64 `json:"value"`
 	Lo    float64 `json:"lo"`
 	Hi    float64 `json:"hi"`

internal/cat/flex.go

@@ -140,6 +140,7 @@ type meterInfo struct {
 	src  string // SLC (slice), TX-, COD, RAD, AMP…
 	name string // FWDPWR, SWR, LEVEL, PATEMP, +13.8B…
 	unit string // dbm, dbfs, swr, volts, degc, watts…
+	slc  int    // for src=SLC meters, the slice index (the ".num" field); -1 otherwise
 	lo   float64
 	hi   float64
 }
@@ -641,7 +642,7 @@ func (f *Flex) handleStatus(payload string) {
 				// One meter per token; its fields are '#'-separated:
 				// "<n>.src=…#<n>.num=…#<n>.nam=…#<n>.low=…#<n>.hi=…#<n>.unit=…".
 				num := -1
-				var mi meterInfo
+				mi := meterInfo{slc: -1}
 				for _, sub := range strings.Split(tok, "#") {
 					key, val, ok := splitKV(sub)
 					if !ok {
@@ -661,6 +662,12 @@ func (f *Flex) handleStatus(payload string) {
 						mi.src = val
 					case "nam":
 						mi.name = val
+					case "num":
+						// For a slice (SLC) meter this field is the slice index —
+						// how we tell slice A's S-meter from slice B's.
+						if v, e := strconv.Atoi(strings.TrimSpace(val)); e == nil {
+							mi.slc = v
+						}
 					case "unit", "units":
 						mi.unit = val
 					case "low", "lo":
@@ -675,6 +682,7 @@ func (f *Flex) handleStatus(payload string) {
 				old, seen := f.meterMeta[num]
 				if !seen {
 					newIDs = append(newIDs, num)
+					old.slc = -1
 				}
 				if mi.src != "" {
 					old.src = mi.src
@@ -685,6 +693,9 @@ func (f *Flex) handleStatus(payload string) {
 				if mi.unit != "" {
 					old.unit = mi.unit
 				}
+				if mi.slc >= 0 {
+					old.slc = mi.slc
+				}
 				if mi.lo != 0 {
 					old.lo = mi.lo
 				}
@@ -1079,15 +1090,22 @@ func (f *Flex) SendSpot(s SpotInfo) error {
 	}
 	// De-dupe by callsign: WSJT decodes re-fire every cycle, so a station already
 	// spotted gets its previous spot removed first — one live spot per call,
-	// refreshed, instead of a pile that all expire independently.
+	// refreshed, instead of a pile that all expire independently. NB: capture the
+	// old index under the lock but send OUTSIDE it — f.send() takes f.mu itself,
+	// and Go mutexes aren't reentrant (calling send while locked deadlocks the
+	// whole Flex goroutine → the radio drops OFFLINE).
+	upperCall := strings.ToUpper(s.Callsign)
 	f.mu.Lock()
-	if old, ok := f.spotByCall[strings.ToUpper(s.Callsign)]; ok {
-		delete(f.spotByCall, strings.ToUpper(s.Callsign))
+	old, hadOld := f.spotByCall[upperCall]
+	if hadOld {
+		delete(f.spotByCall, upperCall)
 		delete(f.spotCall, old)
 		delete(f.spotIdx, old)
-		f.send(fmt.Sprintf("spot remove %d", old))
 	}
 	f.mu.Unlock()
+	if hadOld {
+		f.send(fmt.Sprintf("spot remove %d", old))
+	}
 	cmd := fmt.Sprintf("spot add rx_freq=%.6f callsign=%s color=%s source=OpsLog lifetime_seconds=%d trigger_action=Tune timestamp=%d",
 		float64(s.FreqHz)/1e6, call, color, life, time.Now().Unix())
 	if m := flexEncode(s.Mode); m != "" {
@@ -1321,7 +1339,7 @@ func (f *Flex) FlexState() FlexTXState {
 		sort.Ints(ids) // stable order so the UI doesn't reshuffle each poll
 		for _, id := range ids {
 			mi := f.meterMeta[id]
-			st.Meters = append(st.Meters, FlexMeter{ID: id, Src: mi.src, Name: mi.name, Unit: mi.unit, Value: f.meterVal[id], Lo: mi.lo, Hi: mi.hi})
+			st.Meters = append(st.Meters, FlexMeter{ID: id, Src: mi.src, Name: mi.name, Unit: mi.unit, Slice: mi.slc, Value: f.meterVal[id], Lo: mi.lo, Hi: mi.hi})
 		}
 	}
 	return st