diff --git a/cmd/lingma-ipc-proxy/main.go b/cmd/lingma-ipc-proxy/main.go
index 60bb96f..1aa97d4 100644
--- a/cmd/lingma-ipc-proxy/main.go
+++ b/cmd/lingma-ipc-proxy/main.go
@@ -36,6 +36,14 @@ func main() {
 	addr := fmt.Sprintf("%s:%d", cfg.Host, cfg.Port)
 
 	svc := service.New(cfg)
+	warmupCtx, warmupCancel := context.WithTimeout(context.Background(), 10*time.Second)
+	if err := svc.Warmup(warmupCtx); err != nil {
+		log.Printf("warmup failed: %v", err)
+	} else {
+		log.Printf("Lingma IPC warmup completed")
+	}
+	warmupCancel()
+
 	server := httpapi.NewServer(addr, svc)
 
 	log.Printf("lingma-ipc-proxy listening on http://%s", addr)
diff --git a/internal/service/service.go b/internal/service/service.go
index 5f9eb8a..1167206 100644
--- a/internal/service/service.go
+++ b/internal/service/service.go
@@ -88,6 +88,7 @@ type Service struct {
 	client          *lingmaipc.Client
 	pipePath        string
 	stickySessionID string
+	stickyModelID   string
 }
 
 type promptRunResult struct {
@@ -119,6 +120,11 @@ func New(cfg Config) *Service {
 	return &Service{cfg: cfg}
 }
 
+func (s *Service) Warmup(ctx context.Context) error {
+	_, err := s.ensureConnected(ctx)
+	return err
+}
+
 func (s *Service) Close() error {
 	s.mu.Lock()
 	defer s.mu.Unlock()
@@ -137,10 +143,7 @@ func (s *Service) State() State {
 }
 
 func (s *Service) ListModels(ctx context.Context) ([]Model, error) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	ipcClient, err := s.ensureConnectedLocked(ctx)
+	ipcClient, err := s.ensureConnected(ctx)
 	if err != nil {
 		return nil, err
 	}
@@ -158,8 +161,6 @@ func (s *Service) ListModels(ctx context.Context) ([]Model, error) {
 }
 
 func (s *Service) Generate(ctx context.Context, req ChatRequest) (*ChatResult, error) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
 	return s.generateLocked(ctx, req, nil)
 }
 
@@ -168,7 +169,6 @@ func (s *Service) GenerateStream(ctx context.Context, req ChatRequest) (<-chan S
 	done := make(chan StreamResult, 1)
 
 	go func() {
-		s.mu.Lock()
 		result, err := s.generateLocked(ctx, req, func(delta string) {
 			if delta == "" {
 				return
@@ -178,7 +178,6 @@ func (s *Service) GenerateStream(ctx context.Context, req ChatRequest) (<-chan S
 			case <-ctx.Done():
 			}
 		})
-		s.mu.Unlock()
 
 		close(events)
 		done <- StreamResult{Result: result, Err: err}
@@ -196,7 +195,7 @@ func (s *Service) generateLocked(
 	requestCtx, cancel := context.WithTimeout(ctx, s.cfg.Timeout)
 	defer cancel()
 
-	ipcClient, err := s.ensureConnectedLocked(requestCtx)
+	ipcClient, err := s.ensureConnected(requestCtx)
 	if err != nil {
 		return nil, err
 	}
@@ -210,7 +209,7 @@ func (s *Service) generateLocked(
 		return nil, errors.New("empty user message")
 	}
 
-	sessionID, err := s.resolveSessionLocked(requestCtx, ipcClient, effectiveMode)
+	sessionID, err := s.resolveSession(requestCtx, ipcClient, effectiveMode)
 	if err != nil {
 		return nil, err
 	}
@@ -233,30 +232,32 @@ func (s *Service) generateLocked(
 		EnabledMCP:      []any{},
 	})
 
-	if strings.TrimSpace(req.Model) != "" {
+	modelID := strings.TrimSpace(req.Model)
+	if modelID != "" && s.shouldSetModel(sessionID, effectiveMode, modelID) {
 		if err := ipcClient.Request(requestCtx, "session/set_model", map[string]any{
 			"sessionId": sessionID,
-			"modelId":   strings.TrimSpace(req.Model),
+			"modelId":   modelID,
 			"timestamp": time.Now().UnixMilli(),
 			"_meta":     meta,
 		}, nil); err != nil {
 			if effectiveMode == SessionModeReuse {
-				s.stickySessionID = ""
+				s.invalidateStickySession()
 			}
 			return nil, err
 		}
+		s.rememberStickyModel(sessionID, modelID)
 	}
 
 	runResult, err := s.runPromptLocked(requestCtx, ipcClient, sessionID, prompt, requestID, meta, onDelta)
 	if err != nil {
 		if effectiveMode == SessionModeReuse {
-			s.stickySessionID = ""
+			s.invalidateStickySession()
 		}
 		return nil, err
 	}
 	if runResult.TimedOut || strings.TrimSpace(runResult.AssistantText) == "" {
 		if effectiveMode == SessionModeReuse {
-			s.stickySessionID = ""
+			s.invalidateStickySession()
 		}
 	}
 	if runResult.TimedOut && strings.TrimSpace(runResult.AssistantText) == "" {
@@ -292,20 +293,20 @@ func (s *Service) buildChatResult(
 		StopReason:       nestedString(runResult.PromptResult, "stopReason"),
 		UsedTokens:       int(nestedInt64(runResult.ContextUsage, "usedTokens")),
 		LimitTokens:      int(nestedInt64(runResult.ContextUsage, "limitTokens")),
-		PipePath:         s.pipePath,
+		PipePath:         s.currentPipePath(),
 		EffectiveSession: effectiveMode,
 	}
 }
 
+func (s *Service) ensureConnected(ctx context.Context) (*lingmaipc.Client, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.ensureConnectedLocked(ctx)
+}
+
 func (s *Service) ensureConnectedLocked(ctx context.Context) (*lingmaipc.Client, error) {
 	if s.client != nil {
-		pingCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
-		defer cancel()
-		var pong any
-		if err := s.client.Request(pingCtx, "ping", map[string]any{}, &pong); err == nil {
-			return s.client, nil
-		}
-		_ = s.closeClientLocked()
+		return s.client, nil
 	}
 
 	pipePath, err := lingmaipc.ResolvePipePath(s.cfg.Pipe)
@@ -333,16 +334,63 @@ func (s *Service) ensureConnectedLocked(ctx context.Context) (*lingmaipc.Client,
 func (s *Service) closeClientLocked() error {
 	if s.client == nil {
 		s.pipePath = ""
-		s.stickySessionID = ""
+		s.clearStickyLocked()
 		return nil
 	}
 	client := s.client
 	s.client = nil
 	s.pipePath = ""
-	s.stickySessionID = ""
+	s.clearStickyLocked()
 	return client.Close()
 }
 
+func (s *Service) resolveSession(ctx context.Context, client *lingmaipc.Client, mode SessionMode) (string, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.resolveSessionLocked(ctx, client, mode)
+}
+
+func (s *Service) invalidateStickySession() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.clearStickyLocked()
+}
+
+func (s *Service) rememberStickyModel(sessionID string, modelID string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if strings.TrimSpace(s.stickySessionID) == strings.TrimSpace(sessionID) {
+		s.stickyModelID = strings.TrimSpace(modelID)
+	}
+}
+
+func (s *Service) shouldSetModel(sessionID string, mode SessionMode, modelID string) bool {
+	if strings.TrimSpace(modelID) == "" {
+		return false
+	}
+	if mode != SessionModeReuse {
+		return true
+	}
+
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if strings.TrimSpace(s.stickySessionID) != strings.TrimSpace(sessionID) {
+		return true
+	}
+	return strings.TrimSpace(s.stickyModelID) != strings.TrimSpace(modelID)
+}
+
+func (s *Service) clearStickyLocked() {
+	s.stickySessionID = ""
+	s.stickyModelID = ""
+}
+
+func (s *Service) currentPipePath() string {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.pipePath
+}
+
 func (s *Service) resolveSessionLocked(ctx context.Context, client *lingmaipc.Client, mode SessionMode) (string, error) {
 	if mode == SessionModeReuse && strings.TrimSpace(s.stickySessionID) != "" {
 		return s.stickySessionID, nil
@@ -371,6 +419,7 @@ func (s *Service) resolveSessionLocked(ctx context.Context, client *lingmaipc.Cl
 
 	if mode == SessionModeReuse {
 		s.stickySessionID = sessionID
+		s.stickyModelID = ""
 	}
 	return sessionID, nil
 }