diff --git a/src/modules/rag-chat/rag-chat.service.ts b/src/modules/rag-chat/rag-chat.service.ts
index 1026ab4..25cb486 100644
--- a/src/modules/rag-chat/rag-chat.service.ts
+++ b/src/modules/rag-chat/rag-chat.service.ts
@@ -53,6 +53,7 @@ export class RagChatService {
 
     // Retrieve knowledge base context
     const context = await this.loadContext(session.knowledgeBaseId);
+    this.logger.log(`RAG context: isEmpty=${context.isEmpty}, textLen=${context.text.length}, citations=${context.citations.length}, aiGateway=${!!this.aiGateway}`);
 
     // Generate AI response
     let reply: string;
@@ -60,6 +61,7 @@ export class RagChatService {
 
     if (this.aiGateway && context.text) {
       try {
+        this.logger.log(`Calling AI Gateway with ${context.text.length} chars context`);
         const messages = [
           { role: 'system' as const, content: this.buildSystemPrompt(context.text) },
           { role: 'user' as const, content },
@@ -73,13 +75,15 @@ export class RagChatService {
           messages,
           maxTokens: 2048,
         });
+        this.logger.log(`AI Gateway response: parsed=${!!resp.parsed}, rawLen=${resp.rawText?.length ?? 0}`);
         reply = resp.parsed?.answer ?? String(resp.parsed?.content ?? '抱歉，AI 暂时无法生成回答。');
         citations = context.citations;
       } catch (err: any) {
-        this.logger.error('AI Gateway failed, falling back', err?.message);
+        this.logger.error(`AI Gateway FAILED: ${err?.message}`, err?.stack?.substring(0, 300));
         reply = this.fallbackReply(context.isEmpty);
       }
     } else {
+      this.logger.warn(`Falling back: aiGateway=${!!this.aiGateway}, hasText=${!!context.text}`);
       reply = this.fallbackReply(context.isEmpty);
     }