Show agent liveness, stuck/zombie detection and parse errors in admin

internal/server/server.go

@@ -67,6 +67,7 @@ func New(dataDir string, spa fs.FS) (*Server, error) {
 		s.store.Close()
 		return nil, fmt.Errorf("recover sessions: %w", err)
 	}
+	go s.agents.Watch()
 
 	return s, nil
 }
@@ -393,6 +394,12 @@ func (s *Server) GetStatus(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	health, err := s.agents.Health(r.Context())
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err)
+		return
+	}
+
 	dbBytes := int64(0)
 	for _, suffix := range []string{"", "-wal", "-shm"} {
 		fi, err := os.Stat(s.store.Path() + suffix)
@@ -413,6 +420,11 @@ func (s *Server) GetStatus(w http.ResponseWriter, r *http.Request) {
 		QueuedTurns:  usage.Queued,
 		Caps:         usage.Caps,
 		RateLimits:   usage.RateLimits,
+
+		AgentProcesses:    health.Processes,
+		Zombies:           health.Zombies,
+		StuckAfterSeconds: int(agents.StuckAfter / time.Second),
+		ProtocolErrors:    s.agents.ProtocolErrors(),
 	})
 }