Supervisor probes before spawning: an external server on the port is used, never fought or killed

internal/supervise/supervise_test.go

@@ -57,8 +57,10 @@ func TestHelperProcess(t *testing.T) {
 
 func newHelper(t *testing.T, name string) *Process {
 	t.Helper()
+	// The probe always fails: nothing external serves the port, so
+	// EnsureRunning spawns the helper child.
 	p, err := New(name, `"`+os.Args[0]+`" -test.run=TestHelperProcess`, "",
-		func(context.Context) error { return nil }, 5*time.Second, slog.Default())
+		func(context.Context) error { return errors.New("nothing there") }, 5*time.Second, slog.Default())
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -103,6 +105,38 @@ func TestEnsureRunningAndStop(t *testing.T) {
 	waitStopped(t, p, 5*time.Second)
 }
 
+func TestEnsureRunningPrefersExternalServer(t *testing.T) {
+	// The port is already served (e.g. the ComfyUI desktop app): no child
+	// is spawned, the supervisor reports ready, and Stop is a no-op.
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer srv.Close()
+	probe := func(ctx context.Context) error {
+		req, _ := http.NewRequestWithContext(ctx, http.MethodGet, srv.URL, nil)
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			return err
+		}
+		resp.Body.Close()
+		return nil
+	}
+	p, err := New("external", `"`+os.Args[0]+`"`, "", probe, 5*time.Second, slog.Default())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := p.EnsureRunning(); err != nil {
+		t.Fatal(err)
+	}
+	if p.Running() {
+		t.Fatal("spawned a child even though the port is already served")
+	}
+	if !p.Ready() {
+		t.Fatal("external server should count as ready")
+	}
+	p.Stop() // must not touch the external server
+}
+
 func TestWaitReady(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusOK)