fix(dify-agent): keep tmux server alive without sessions (#39943)

dify-agent-runtime/internal/server/tmux.go

@@ -21,7 +21,11 @@ func NewTmuxController(config *Config) *TmuxController {
 
 // StartServer ensures the tmux server is running.
 func (t *TmuxController) StartServer() error {
-	_, err := t.runTmux("start-server")
+	_, err := t.runTmux(
+		"start-server",
+		";",
+		"set-option", "-g", "exit-empty", "off",
+	)
 	return err
 }
 

dify-agent-runtime/internal/server/tmux_test.go

@@ -1,9 +1,91 @@
 package server
 
 import (
+	"os/exec"
+	"strings"
 	"testing"
 )
 
+func newTestTmuxController(t *testing.T) *TmuxController {
+	t.Helper()
+
+	if _, err := exec.LookPath("tmux"); err != nil {
+		t.Skip("tmux is not installed")
+	}
+
+	config := DefaultConfig()
+	config.RuntimeDir = t.TempDir()
+	controller := NewTmuxController(config)
+	t.Cleanup(func() {
+		_, _ = controller.runTmuxNoCheck("kill-server")
+	})
+
+	return controller
+}
+
+func assertTmuxServerRunning(t *testing.T, controller *TmuxController) {
+	t.Helper()
+
+	exitEmpty, err := controller.runTmux("show-options", "-gv", "exit-empty")
+	if err != nil {
+		t.Fatalf("tmux server is not running: %v", err)
+	}
+	if got := strings.TrimSpace(exitEmpty); got != "off" {
+		t.Fatalf("exit-empty = %q, want %q", got, "off")
+	}
+}
+
+func TestStartServerKeepsTmuxServerRunningWithoutSessions(t *testing.T) {
+	controller := newTestTmuxController(t)
+
+	if err := controller.StartServer(); err != nil {
+		t.Fatalf("StartServer() error = %v", err)
+	}
+
+	assertTmuxServerRunning(t, controller)
+
+	sessions, err := controller.ListSessions()
+	if err != nil {
+		t.Fatalf("ListSessions() error = %v", err)
+	}
+	if len(sessions) != 0 {
+		t.Fatalf("ListSessions() = %v, want no sessions", sessions)
+	}
+}
+
+func TestTmuxServerRemainsRunningAfterLastSessionIsDeleted(t *testing.T) {
+	controller := newTestTmuxController(t)
+
+	if err := controller.StartServer(); err != nil {
+		t.Fatalf("StartServer() error = %v", err)
+	}
+
+	const jobID = "last-session"
+	sessionName := JobSessionName(jobID)
+	if _, err := controller.runTmux("new-session", "-d", "-s", sessionName); err != nil {
+		t.Fatalf("create tmux session: %v", err)
+	}
+
+	sessions, err := controller.ListSessions()
+	if err != nil {
+		t.Fatalf("ListSessions() before cleanup error = %v", err)
+	}
+	if !sessions[sessionName] {
+		t.Fatalf("ListSessions() = %v, want session %q", sessions, sessionName)
+	}
+
+	controller.CleanupSession(jobID)
+	assertTmuxServerRunning(t, controller)
+
+	sessions, err = controller.ListSessions()
+	if err != nil {
+		t.Fatalf("ListSessions() after cleanup error = %v", err)
+	}
+	if len(sessions) != 0 {
+		t.Fatalf("ListSessions() after cleanup = %v, want no sessions", sessions)
+	}
+}
+
 func TestShellQuote(t *testing.T) {
 	tests := []struct {
 		input    string