fix: ON AIR badge correct at launch + faster to appear

At launch nothing is in memory yet, so the badge showed offline even with a
recent QSO. liveLastQSOTime is now authoritative: it takes the most recent of
the in-memory stamp AND the DB (this operator's last QSO — covers a contact
from the shared logbook or one logged before launch), used by both the
published status and the badge. The badge polls the backend every 5 s (down
from 15) and on each qso:logged, so it shows on air within a few seconds and
flips online instantly on a new contact.

frontend/src/App.tsx

@@ -1096,23 +1096,17 @@ export default function App() {
   // offline. Only shown when live-status publishing is enabled (Settings→General).
   const [liveStatusOn, setLiveStatusOn] = useState(false);
   const [onAir, setOnAir] = useState(false);
-  const lastQsoAtRef = useRef(0);
   useEffect(() => { if (!showSettings) GetLiveStatusEnabled().then((v) => setLiveStatusOn(!!v)).catch(() => {}); }, [showSettings]);
   useEffect(() => {
-    const LIVE_WINDOW = 5 * 60 * 1000; // 5 min, matches the backend
-    const evalOnAir = () => setOnAir(liveStatusOn && lastQsoAtRef.current > 0 && (Date.now() - lastQsoAtRef.current) < LIVE_WINDOW);
-    const off = EventsOn('qso:logged', () => { lastQsoAtRef.current = Date.now(); evalOnAir(); });
-    // Seed from the DB at launch so a QSO logged just before starting OpsLog still
-    // counts (otherwise the badge showed offline until the next contact).
-    LiveLastQSOAgeSec().then((sec: number) => {
-      if (typeof sec === 'number' && sec >= 0) {
-        const at = Date.now() - sec * 1000;
-        if (at > lastQsoAtRef.current) lastQsoAtRef.current = at;
-        evalOnAir();
-      }
-    }).catch(() => {});
-    evalOnAir();
-    const id = window.setInterval(evalOnAir, 10 * 1000); // flip to offline within ~10s of the window elapsing
+    // Read the ON-AIR state straight from the backend (single source of truth:
+    // liveLastQSOAt, stamped on every log and seeded from the DB at launch). Poll
+    // it + refresh on each logged QSO — no fragile frontend timestamp to drift.
+    const refresh = () => LiveLastQSOAgeSec()
+      .then((sec: number) => setOnAir(liveStatusOn && typeof sec === 'number' && sec >= 0 && sec < 300))
+      .catch(() => {});
+    refresh();
+    const off = EventsOn('qso:logged', refresh);
+    const id = window.setInterval(refresh, 5 * 1000); // responsive without hammering (cheap 400-row scan)
     return () => { off(); window.clearInterval(id); };
   }, [liveStatusOn]);
   // QSO-rate meter (10/60 min) in the header — opt-in via Settings→General.

livestatus.go

@@ -87,12 +87,29 @@ func (a *App) seedLiveLastQSO() {
 	}
 }
 
-// LiveLastQSOAgeSec returns seconds since this operator's last logged QSO, or -1 if
-// none is known — the UI uses it to seed the "on air" badge at launch.
-func (a *App) LiveLastQSOAgeSec() int {
+// liveLastQSOTime is the authoritative "last contact" instant for this operator:
+// the most recent of the in-memory stamp (this session's local logs, updated
+// instantly) AND the DB (a contact that arrived via the SHARED logbook from another
+// station, or one logged before launch). Used by both the published status and the
+// UI badge so on-air/offline is right in every multi-op case.
+func (a *App) liveLastQSOTime() time.Time {
 	a.liveActMu.Lock()
 	last := a.liveLastQSOAt
 	a.liveActMu.Unlock()
+	if a.qso != nil {
+		if op, _ := a.liveStatusOperator(); op != "" {
+			if t, ok := a.qso.LastQSOTime(a.ctx, op); ok && t.After(last) {
+				last = t
+			}
+		}
+	}
+	return last
+}
+
+// LiveLastQSOAgeSec returns seconds since this operator's last logged QSO, or -1 if
+// none is known — the UI polls it for the "on air" badge.
+func (a *App) LiveLastQSOAgeSec() int {
+	last := a.liveLastQSOTime()
 	if last.IsZero() {
 		return -1
 	}
@@ -182,8 +199,8 @@ func (a *App) publishLiveStatus() {
 	if mode == "" {
 		mode = a.liveMode
 	}
-	lastQSO := a.liveLastQSOAt
 	a.liveActMu.Unlock()
+	lastQSO := a.liveLastQSOTime() // authoritative (in-memory OR shared DB)
 	// Online = a new contact was logged within the window. An operator who leaves
 	// the log open but stops working shows offline after `liveOnlineWindow`; the
 	// next QSO flips them back on. never-logged (zero time) → offline.