diff --git a/server/chat_flow_helpers.py b/server/chat_flow_helpers.py
index c5b09e7..57a926a 100644
--- a/server/chat_flow_helpers.py
+++ b/server/chat_flow_helpers.py
@@ -65,18 +65,18 @@ async def _generate_title_async(
         return None
 
     client = DeepSeekClient(thinking_mode=False, web_mode=True)
-    title_base = _env_optional("AGENT_TITLE_API_BASE_URL")
-    title_key = _env_optional("AGENT_TITLE_API_KEY")
-    title_model = _env_optional("AGENT_TITLE_MODEL_ID")
-    if title_base:
-        client.fast_api_config["base_url"] = title_base
-        client.api_base_url = title_base
-    if title_key:
-        client.fast_api_config["api_key"] = title_key
-        client.api_key = title_key
-    if title_model:
-        client.fast_api_config["model_id"] = title_model
-        client.model_id = title_model
+    # 对话标题生成使用独立模型配置（支持 config 默认值 + .env 覆盖）
+    title_base = _env_optional("AGENT_TITLE_API_BASE_URL") or TITLE_API_BASE_URL
+    title_key = _env_optional("AGENT_TITLE_API_KEY") or TITLE_API_KEY
+    title_model = _env_optional("AGENT_TITLE_MODEL_ID") or TITLE_MODEL_ID
+    client.fast_api_config = {
+        "base_url": title_base,
+        "api_key": title_key,
+        "model_id": title_model,
+    }
+    client.api_base_url = title_base
+    client.api_key = title_key
+    client.model_id = title_model
     _title_debug_log("start_generate_title", user_message_preview=str(user_message)[:200], user_message_len=len(str(user_message)))
     _title_debug_log(
         "title_api_config",