fix(toolstream): remove stale socket file on restart

When the process exits abnormally the Unix socket file is left behind,
causing the next startup to fail with 'socket path already exists'.
Probe for a live listener before refusing: if Dial fails the file is
stale and gets removed so the new process can bind successfully.

Author: huhong-web

internal/toolstream/transport/uds.go

@@ -30,10 +30,18 @@ func (l *udsListener) Close() error {
 	return l.Listener.Close()
 }
 
-// ListenUDS binds a Unix socket at path; returns an error if path already exists.
+// ListenUDS binds a Unix socket at path. If the socket file already exists it
+// probes for a live listener; when none is found the stale file is removed so
+// the new process can start successfully.
 func ListenUDS(path string) (net.Listener, error) {
 	if _, err := os.Stat(path); err == nil {
-		return nil, fmt.Errorf("transport: socket path already exists: %s", path)
+		conn, dialErr := net.Dial("unix", path)
+		if dialErr != nil {
+			_ = os.Remove(path)
+		} else {
+			_ = conn.Close()
+			return nil, fmt.Errorf("transport: socket path already in use: %s", path)
+		}
 	}
 
 	l, err := net.Listen("unix", path)