fix(icom): the client pings too — the dropouts' likely root cause

wfview sends a ping (0x07, 0x15 bytes, its own seq and a monotonic
timestamp) every 500 ms on every stream, and so does RS-BA1. OpsLog only
ever REPLIED to the rig's pings — and the loaner IC-7760 stopped serving
CI-V data about a minute into nearly every session while the transport
stayed alive: the rig had concluded nobody was listening. Scope, TX audio
and idle numbering were each eliminated in turn before wfview's source
settled it. Pings now go out on control, CI-V and audio alike.

internal/cat/icomnet.go

@@ -138,6 +138,11 @@ type icomNet struct {
 	vTracked uint16
 	vCivSeq  uint16
 	seqMu    sync.Mutex // guards vTracked/vCivSeq: the command loop AND the pump's quiet-recovery both send
+	// Client-ping sequence counters, one per stream, and the connection's epoch
+	// for the ping timestamps. Owned by their pump goroutines — no locking.
+	civPingSeq  uint16
+	ctrlPingSeq uint16
+	started     time.Time
 	// txCiv counts CI-V command packets sent, and txAtData snapshots it at the
 	// last received CI-V data. Their difference during a silence answers the
 	// question the reconnects cannot: were we still ASKING when the answers
@@ -332,6 +337,7 @@ func (n *icomNet) Close() error {
 func (n *icomNet) ctrlPump() {
 	buf := make([]byte, 4096)
 	lastIdle := time.Now()
+	lastCtrlPing := time.Now()
 	lastToken := time.Now() // token was just granted during dial
 	for {
 		select {
@@ -372,6 +378,11 @@ func (n *icomNet) ctrlPump() {
 		}
 		// Renew well inside the rig's ~2-min token timeout. 30 s (was 45) leaves room
 		// for one lost renewal + its retransmit before the token would lapse.
+		if time.Since(lastCtrlPing) > 500*time.Millisecond {
+			n.ctrlPingSeq++
+			_, _ = n.ctrl.Write(icnPing(n.ctrlPingSeq, n.cID, n.cRemote, uint32(time.Since(n.started).Milliseconds())))
+			lastCtrlPing = time.Now()
+		}
 		if time.Since(lastToken) > 30*time.Second {
 			n.renewToken()
 			lastToken = time.Now()
@@ -416,6 +427,7 @@ func (n *icomNet) civPump() {
 	// and a rig that stopped talking are different repairs, and the 30 s
 	// watchdog that follows cannot tell them apart from where it sits.
 	lastPkt := time.Now()
+	lastPing := time.Now()
 	lastData := time.Now()   // CI-V payload packets (replies + transceive)
 	lastScope := time.Time{} // scope frames within those
 	var lastErr error
@@ -551,6 +563,11 @@ func (n *icomNet) civPump() {
 			n.sendRetransmitReq()
 			lastReq = time.Now()
 		}
+		if time.Since(lastPing) > 500*time.Millisecond {
+			n.civPingSeq++
+			_, _ = n.civ.Write(icnPing(n.civPingSeq, n.vID, n.vRemote, uint32(time.Since(n.started).Milliseconds())))
+			lastPing = time.Now()
+		}
 	}
 }
 
@@ -799,6 +816,7 @@ func dialIcomNet(host, user, pass, compName string, rigAddr byte, cancel <-chan
 		cTracked: cTracked, cAuthSeq: cInner,
 		cToken: token, cTokReq: tokReq,
 		cSentBuf: make(map[uint16][]byte),
+		started:  time.Now(),
 	}
 	n.markRx() // the successful handshake counts as initial rig activity
 	// openClose(open) starts the CI-V data flow. We intentionally DO NOT power the
@@ -1068,6 +1086,25 @@ func icnWakeOnLAN(mac string) error {
 	return err
 }
 
+// icnPing builds a CLIENT ping request (wfview's ping_packet: 0x15 bytes,
+// type 0x07, reply=0, a monotonic time at 0x11). The rig answers each one —
+// and, decisively, treats them as the client's sign of life: wfview sends one
+// every 500 ms on every stream, and OpsLog, which only ever REPLIED to the
+// rig's pings, watched the IC-7760 stop serving CI-V data about a minute into
+// every session. Same socket answered, same transport alive: the rig had
+// simply concluded nobody was listening.
+func icnPing(seq uint16, sentid, rcvdid uint32, ms uint32) []byte {
+	b := make([]byte, 0x15)
+	icnLE.PutUint32(b[0:], 0x15)
+	icnLE.PutUint16(b[4:], 0x07)
+	icnLE.PutUint16(b[6:], seq)
+	icnLE.PutUint32(b[8:], sentid)
+	icnLE.PutUint32(b[12:], rcvdid)
+	b[0x10] = 0x00
+	icnLE.PutUint32(b[0x11:], ms)
+	return b
+}
+
 func icnOpenClose(seq uint16, sentid, rcvdid uint32, civSeq uint16, magic byte) []byte {
 	b := make([]byte, 0x16)
 	icnLE.PutUint32(b[0:], 0x16)