fix(agent): stricter max_tokens calculation for response length control

- Reduce tokensPerChar from 2 to 1.8 for more accurate Chinese token estimation
- Use min() instead of max() to enforce upper limits on token counts
- CHAT: max 200 tokens (was min 256)
- SIMPLE_QUERY: max 600 tokens (was min 512)
- CLARIFICATION: max 300 tokens (was min 256)
- CONFIRMATION: max 400 tokens (was min 384)
- DEEP_CONSULTATION: 800-1600 tokens (was 1024-4096)
- ACTION_NEEDED: 500-1000 tokens (was 768-2048)

This should result in more concise AI responses that better match
the intent classifier's suggested length limits.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/services/conversation-service/src/infrastructure/claude/claude-agent.service.ts

@@ -85,29 +85,29 @@ export class ClaudeAgentService implements OnModuleInit {
 
   /**
    * Calculate max tokens based on intent classification
-   * 中文平均每字符约 1.5 tokens，加上一定余量
+   * 严格控制回复长度，中文约 1.5 tokens/字符
    */
   private calculateMaxTokens(intent: IntentResult): number {
-    // 字符数转 tokens（中文约 1.5 tokens/字符，取 2 以留余量）
-    const tokensPerChar = 2;
-    const baseTokens = intent.maxResponseLength * tokensPerChar;
+    // 中文约 1.5 tokens/字符，稍加余量取 1.8
+    const tokensPerChar = 1.8;
+    const baseTokens = Math.round(intent.maxResponseLength * tokensPerChar);
 
-    // 根据意图类型调整
+    // 根据意图类型调整，严格限制上限
     switch (intent.type) {
       case IntentType.CHAT:
-        return Math.max(256, baseTokens); // 闲聊最少 256 tokens
+        return Math.min(200, baseTokens); // 闲聊严格限制 200 tokens
       case IntentType.SIMPLE_QUERY:
-        return Math.max(512, baseTokens); // 简单查询最少 512 tokens
+        return Math.min(600, baseTokens); // 简单查询限制 600 tokens (~300字)
       case IntentType.CLARIFICATION:
-        return Math.max(256, baseTokens); // 澄清最少 256 tokens
+        return Math.min(300, baseTokens); // 澄清限制 300 tokens
       case IntentType.CONFIRMATION:
-        return Math.max(384, baseTokens); // 确认最少 384 tokens
+        return Math.min(400, baseTokens); // 确认限制 400 tokens
       case IntentType.DEEP_CONSULTATION:
-        return Math.min(4096, Math.max(1024, baseTokens)); // 深度咨询 1024-4096
+        return Math.min(1600, Math.max(800, baseTokens)); // 深度咨询 800-1600
       case IntentType.ACTION_NEEDED:
-        return Math.min(2048, Math.max(768, baseTokens)); // 需要行动 768-2048
+        return Math.min(1000, Math.max(500, baseTokens)); // 需要行动 500-1000
       default:
-        return 2048; // 默认 2048
+        return 1024; // 默认 1024
     }
   }