Add heartbeat ping/pong to detect disconnects

Windows client sends ping every 10s.
Linux server responds with pong.
If write fails, client detects disconnect and reconnects.

2 files changed, 28 insertions, 0 deletions

diff --git a/cmd_linux.go b/cmd_linux.go
index 5d5e10a..4239d1d 100644
--- a/cmd_linux.go
+++ b/cmd_linux.go
@@ -155,6 +155,13 @@ func handleClient(conn net.Conn, stack *GitignoreStack) {
 					msg.Path, remoteManifest, *dryRun,
 				)
 			}
+
+		case "ping":
+			logDebug("ping from client")
+			pong := &ProtocolMessage{Type: "pong"}
+			pongData, _ := EncodeMessage(pong)
+			pongData = append(pongData, '\n')
+			conn.Write(pongData)
 		}
 	}
 
diff --git a/cmd_windows.go b/cmd_windows.go
index 4d7df37..da26684 100644
--- a/cmd_windows.go
+++ b/cmd_windows.go
@@ -93,6 +93,27 @@ func run() {
 
 		logInfo("watcher: monitoring for changes ...")
 
+		// Heartbeat goroutine to detect disconnects
+		go func() {
+			ticker := time.NewTicker(10 * time.Second)
+			defer ticker.Stop()
+			for {
+				select {
+				case <-ctx.Done():
+					return
+				case <-ticker.C:
+					msg := &ProtocolMessage{Type: "ping"}
+					data, _ := EncodeMessage(msg)
+					data = append(data, '\n')
+					if _, err := conn.Write(data); err != nil {
+						logErrorf("heartbeat failed: %v", err)
+						conn.Close()
+						return
+					}
+				}
+			}
+		}()
+
 		if !watchLoop(ctx, conn, watcher, manifest, stack) {
 			conn.Close()
 			continue