feat: emit peer_status (ICE state + candidate type) from daemon

Hooks pc.OnConnectionStateChange in WireDataChannel to emit peer_status
events. On connected, calls pc.GetStats() to find the nominated candidate
pair and report candidateType (host/srflx/relay) and remote address.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/mesh/peer.go

@@ -5,6 +5,7 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"encoding/json"
+	"fmt"
 	"log"
 	"strings"
 	"sync"
@@ -94,6 +95,17 @@ func WireDataChannel(
 		m.RemovePeer(peerID)
 		pc.Close()
 	})
+
+	pc.OnConnectionStateChange(func(state webrtc.PeerConnectionState) {
+		m.Emit(proto.IpcMessage{
+			Type:      proto.EvtPeerStatus,
+			PeerID:    &peerID,
+			ConnState: state.String(),
+		})
+		if state == webrtc.PeerConnectionStateConnected {
+			go emitICEStats(pc, peerID, m)
+		}
+	})
 }
 
 // WireCandidateTrickle seals and forwards each ICE candidate via the anchor as it arrives.
@@ -257,6 +269,42 @@ func dispatchPeerMessage(msg proto.PeerMessage, from proto.PeerID, m *Mesh) {
 	}
 }
 
+// emitICEStats reads the active (nominated) ICE candidate pair from pion's stats
+// and emits a peer_status event with the candidate type and remote address.
+func emitICEStats(pc *webrtc.PeerConnection, peerID proto.PeerID, m *Mesh) {
+	stats := pc.GetStats()
+	candidateType := "unknown"
+	remoteAddress := ""
+
+	// Find the nominated candidate pair and its remote candidate.
+	for _, s := range stats {
+		pair, ok := s.(webrtc.ICECandidatePairStats)
+		if !ok || !pair.Nominated {
+			continue
+		}
+		// Look up remote candidate by its ID.
+		if rc, ok2 := stats[pair.RemoteCandidateID]; ok2 {
+			remote, ok3 := rc.(webrtc.ICECandidateStats)
+			if ok3 {
+				candidateType = remote.CandidateType.String()
+				if remote.Port > 0 {
+					remoteAddress = fmt.Sprintf("%s:%d", remote.IP, remote.Port)
+				} else {
+					remoteAddress = remote.IP
+				}
+			}
+		}
+		break
+	}
+
+	m.Emit(proto.IpcMessage{
+		Type:          proto.EvtPeerStatus,
+		PeerID:        &peerID,
+		CandidateType: candidateType,
+		RemoteAddress: remoteAddress,
+	})
+}
+
 // midOrRandom returns mid if non-empty, otherwise generates a random 16-byte hex string.
 // Ensures every stored message has a unique mid even from peers that don't send one.
 func midOrRandom(mid string) string {

internal/proto/proto.go

@@ -228,6 +228,7 @@ const (
 	EvtPeerConnected    IpcMsgType = "peer_connected"
 	EvtPeerDisconnected IpcMsgType = "peer_disconnected"
 	EvtSessionReady     IpcMsgType = "session_ready"   // DataChannel open + hello verified
+	EvtPeerStatus       IpcMsgType = "peer_status"     // ICE connection state + candidate type
 	EvtIncomingFile     IpcMsgType = "incoming_file"
 	EvtFileProgress     IpcMsgType = "file_progress"
 	EvtStateSnapshot    IpcMsgType = "state_snapshot"
@@ -294,4 +295,8 @@ type IpcMessage struct {
 	// export_identity / import_identity
 	Passphrase     string       `json:"passphrase,omitempty"` // import only; never echoed back
 	Backup         string       `json:"backup,omitempty"`     // JSON backup blob
+	// peer_status — ICE connection quality
+	ConnState     string `json:"conn_state,omitempty"`     // pion PeerConnectionState string
+	CandidateType string `json:"candidate_type,omitempty"` // host | srflx | relay | unknown
+	RemoteAddress string `json:"remote_address,omitempty"` // remote IP:port of active candidate pair
 }