fix(icom): re-open the CI-V flow when the rig goes quiet mid-session

The IC-7760 recurrently stops answering CI-V a few minutes into a network
session while the transport keeps chatting — pings answered, session alive,
commands unanswered — and the only recovery was the 30 s watchdog's full
teardown. At 10 s of CI-V silence the pump now says 'open' again on the
existing stream, which is all it should take if the rig quietly closed the
data flow; the watchdog remains as the backstop. The send counters gain a
mutex since the pump now transmits too.

changelog.json

@@ -18,7 +18,8 @@
       "MY_RIG follows the radio actually connected: the entry form now asks the active radio first, before the per-band default — an IC-7760 on the air no longer logs as the Flex the band plan names.",
       "QSO recorder: a manual take on a network Icom records the network RX stream, not the “From radio” sound card (which captured another radio’s DAX on a mixed station).",
       "Icom network audio: duplicate and late-retransmitted packets no longer reach the recorder — recordings came out longer than the QSO, slowed and stuttering, while the speakers played fine.",
-      "Icom network audio: it now starts with the app — launching OpsLog connected with audio silently off, and the option had to be unticked and re-saved to hear anything."
+      "Icom network audio: it now starts with the app — launching OpsLog connected with audio silently off, and the option had to be unticked and re-saved to hear anything.",
+      "Icom network: when the rig goes quiet on CI-V while the session stays up (seen on the IC-7760), the CI-V flow is re-opened on the spot — recovery in seconds instead of the 35-second full reconnect."
     ],
     "fr": [
       "Console Elecraft : le S-mètre est calibré sur un vrai K3 — S9 et les +dB correspondent désormais à l’affichage de la radio (il lisait environ deux points S trop bas).",
@@ -36,7 +37,8 @@
       "MY_RIG suit la radio réellement connectée : le formulaire interroge d’abord la radio active, avant le défaut par bande — un IC-7760 à l’antenne ne se logue plus comme le Flex prévu par le plan de bande.",
       "Enregistreur de QSO : une prise manuelle sur un Icom réseau enregistre le flux RX réseau, pas la carte son « From Radio » (qui capturait le DAX d’une autre radio sur une station mixte).",
       "Audio réseau Icom : les paquets dupliqués ou retransmis en retard n’atteignent plus l’enregistreur — les enregistrements sortaient plus longs que le QSO, ralentis et hachés, alors que les haut-parleurs jouaient bien.",
-      "Audio réseau Icom : il démarre maintenant avec l’application — au lancement, la connexion se faisait audio coupé, et il fallait décocher/recocher l’option pour entendre quelque chose."
+      "Audio réseau Icom : il démarre maintenant avec l’application — au lancement, la connexion se faisait audio coupé, et il fallait décocher/recocher l’option pour entendre quelque chose.",
+      "Réseau Icom : quand la radio se tait sur le CI-V alors que la session tient (constaté sur l’IC-7760), le flux CI-V est rouvert immédiatement — récupération en quelques secondes au lieu des 35 secondes de reconnexion complète."
     ]
   },
   {

internal/cat/icomnet.go

@@ -97,6 +97,7 @@ type icomNet struct {
 	// CAT goroutine) and during dial — never by the pump — so no lock is needed.
 	vTracked uint16
 	vCivSeq  uint16
+	seqMu    sync.Mutex // guards vTracked/vCivSeq: the command loop AND the pump's quiet-recovery both send
 
 	rx      chan []byte // CI-V byte chunks from civPump → Read (control replies)
 	scopeRx chan []byte // scope (0x27) frames, kept off rx so the panadapter
@@ -227,10 +228,12 @@ func (n *icomNet) Write(p []byte) (int, error) {
 	if icnTrace {
 		debugLog.Printf("icom net TX: % X", p)
 	}
-	seq := n.vTracked
+	n.seqMu.Lock()
-	pkt := icnCivData(seq, n.vID, n.vRemote, n.vCivSeq, p)
+	seq, civSeq := n.vTracked, n.vCivSeq
 	n.vTracked++
 	n.vCivSeq++
+	n.seqMu.Unlock()
+	pkt := icnCivData(seq, n.vID, n.vRemote, civSeq, p)
 	n.sentMu.Lock()
 	n.sentBuf[seq] = pkt
 	delete(n.sentBuf, seq-1024) // keep the buffer bounded (~last 1024 packets) so
@@ -441,6 +444,22 @@ func (n *icomNet) civPump() {
 			}
 			debugLog.Printf("icom net: no CI-V DATA for 10 s (transport last heard %s ago; last scope frame %s ago; last socket error: %v; missing-seq backlog: %d)",
 				time.Since(lastPkt).Round(time.Second), scopeAge, lastErr, len(n.rxMissing))
+			// And try the gentle repair before the 30 s watchdog tears the whole
+			// session down: if the rig quietly closed the CI-V data flow (the
+			// transport is still chatting, so the session itself stands), saying
+			// "open" again on the same stream is all it should take. Harmless
+			// when the cause is elsewhere — the watchdog still fires at 30 s.
+			n.seqMu.Lock()
+			seq, civSeq := n.vTracked, n.vCivSeq
+			n.vTracked++
+			n.vCivSeq++
+			n.seqMu.Unlock()
+			ocPkt := icnOpenClose(seq, n.vID, n.vRemote, civSeq, 0x04)
+			n.sentMu.Lock()
+			n.sentBuf[seq] = ocPkt
+			n.sentMu.Unlock()
+			_, _ = n.civ.Write(ocPkt)
+			debugLog.Printf("icom net: re-sent the CI-V open on the existing stream")
 		}
 		if time.Since(lastIdle) > 150*time.Millisecond {
 			_, _ = n.civ.Write(icnCtrl(0x00, 0, n.vID, n.vRemote))