diff --git a/backend/ai-core/internal/background/thinker.go b/backend/ai-core/internal/background/thinker.go
index 2a2ca3c..b0de429 100644
--- a/backend/ai-core/internal/background/thinker.go
+++ b/backend/ai-core/internal/background/thinker.go
@@ -1080,8 +1080,8 @@ func (t *Thinker) HasPendingThoughts() bool {
 // 强制执行最小间隔，防止并发调用或 bug 导致 LLM 配额被快速消耗。
 func (t *Thinker) performThink(triggerReason string) {
 	t.muLock()
-	defer t.muUnlock()
 	gapSinceLast := time.Since(t.lastThinkTimeAtomic())
+	t.muUnlock()
 	minGap := t.minThinkGap
 	if minGap <= 0 {
 		minGap = 5 * time.Second // 默认最小间隔 5 秒
@@ -1101,15 +1101,14 @@ func (t *Thinker) performThink(triggerReason string) {
 	ctx, cancel := context.WithTimeout(context.Background(), 120*time.Second)
 	defer cancel()
 	t.muLock()
-	defer t.muUnlock()
 	t.thinkCancel = cancel
-
+	t.muUnlock()
 
 	// 0. 让步于前台——如果用户最近有活动（非post_chat），跳过本次思考。
 	if triggerReason != "post_chat" {
 		t.muLock()
-		defer t.muUnlock()
 		sinceLastUser := time.Since(t.lastUserTime())
+		t.muUnlock()
 
 		if sinceLastUser < 10*time.Second {
 			log.Printf("[后台思考] 用户 %v 前有活动，让步于前台回复，跳过思考", sinceLastUser.Round(time.Second))
@@ -1122,8 +1121,8 @@ func (t *Thinker) performThink(triggerReason string) {
 	// 0. 让步于前台——如果用户最近有活动（非post_chat），跳过本次思考。
 	if triggerReason != "post_chat" {
 		t.muLock()
-		defer t.muUnlock()
 		sinceLastUser := time.Since(t.lastUserTime())
+		t.muUnlock()
 
 		if sinceLastUser < 10*time.Second {
 			log.Printf("[后台思考] 用户 %v 前有活动，让步于前台回复，跳过思考", sinceLastUser.Round(time.Second))