feat(open-chat): 新增 /api/open/chat 开放问答接口

- 无需登录(/api/open/ 加入 auth 白名单 + CSRF 豁免),供外部系统直接调用本项目智能体做问答
- 可指定模型(model_name)与智能体(agent_name 中文名称,扫描 agents/*/config.yaml 解析为运行 id);GET /api/open/agents 列出可选名称
- 只返回最终结果(answer = 最后一段 markdown),不含中间过程/工具调用
- 可靠关闭思考:thinking_enabled=false 时下发 thinking_force_disabled,经 create_chat_model(force_disable_thinking=True) 强制注入 enable_thinking=false(及 GLM thinking.type=disabled),覆盖只声明 supports_thinking 的内网 vLLM/Qwen 模型(与生成标题关思考一致)
- 一次性问答设 is_scheduled_run 跳过自动起标题

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

offline-backend-20260512/backend/packages/harness/deerflow/agents/lead_agent/agent.py

@@ -412,6 +412,11 @@ def _make_lead_agent(config: RunnableConfig, *, app_config: AppConfig):
     resolved_app_config = app_config
 
     thinking_enabled = cfg.get("thinking_enabled", True)
+    # Hard "thinking off" switch for internal vLLM/Qwen models whose config only
+    # declares `supports_thinking: true` (no disable shape) — passes through to
+    # create_chat_model(force_disable_thinking=...) so enable_thinking=false is
+    # actually injected. Default off → no behavior change for normal chats.
+    thinking_force_disabled = bool(cfg.get("thinking_force_disabled", False))
     reasoning_effort = cfg.get("reasoning_effort", None)
     requested_model_name: str | None = cfg.get("model_name") or cfg.get("model")
     is_plan_mode = cfg.get("is_plan_mode", False)
@@ -501,7 +506,7 @@ def _make_lead_agent(config: RunnableConfig, *, app_config: AppConfig):
         from deerflow.agents.middlewares.writing_setup_round_cap_middleware import WritingSetupRoundCapMiddleware
 
         return create_agent(
-            model=create_chat_model(name=model_name, thinking_enabled=thinking_enabled, app_config=resolved_app_config),
+            model=create_chat_model(name=model_name, thinking_enabled=thinking_enabled, force_disable_thinking=thinking_force_disabled, app_config=resolved_app_config),
             tools=[setup_writing, ask_clarification_tool],
             middleware=[
                 *_build_middlewares(config, model_name=model_name, app_config=resolved_app_config),
@@ -514,7 +519,7 @@ def _make_lead_agent(config: RunnableConfig, *, app_config: AppConfig):
     if is_bootstrap:
         # Special bootstrap agent with minimal prompt for initial custom agent creation flow
         return create_agent(
-            model=create_chat_model(name=model_name, thinking_enabled=thinking_enabled, app_config=resolved_app_config),
+            model=create_chat_model(name=model_name, thinking_enabled=thinking_enabled, force_disable_thinking=thinking_force_disabled, app_config=resolved_app_config),
             tools=get_available_tools(
                 model_name=model_name,
                 subagent_enabled=subagent_enabled,
@@ -593,7 +598,7 @@ def _make_lead_agent(config: RunnableConfig, *, app_config: AppConfig):
         )
 
     return create_agent(
-        model=create_chat_model(name=model_name, thinking_enabled=thinking_enabled, reasoning_effort=reasoning_effort, app_config=resolved_app_config),
+        model=create_chat_model(name=model_name, thinking_enabled=thinking_enabled, reasoning_effort=reasoning_effort, force_disable_thinking=thinking_force_disabled, app_config=resolved_app_config),
         tools=default_tools,
         middleware=_build_middlewares(config, model_name=model_name, agent_name=agent_id, app_config=resolved_app_config),
         system_prompt=system_prompt,