fix(inference): chat 每次调用新建 httpx client，修复同步门禁 Event loop is closed

_AI_USAGE_LOG.md

@@ -107,3 +107,4 @@
 | 2026-08-13 23:11 | Agent 实现 | 接通真实 LLM 引擎工厂（P5-T10 门禁接线）：新增 inference/factory.py，orchestrator/qa_loop 接入，脚本校验适配，补工厂测试 | src/genesis/inference/factory.py; src/genesis/writer/orchestrator.py; src/genesis/qa/qa_loop.py; scripts/run_phase5_slice.py; tests/test_inference_factory.py | hy3-free |
 | 2026-08-13 23:20 | 测试验证 | P5-T10 引擎工厂接线：补 engine=None 委托工厂测试（orchestrator/qa_loop），全量 296 passed / 99.04% | tests/test_phase5_writer_orchestrator.py; tests/test_phase5_qa_loop.py | hy3-free |
 | 2026-08-13 23:35 | 测试验证 | P5-T10 门禁诊断：修复 WriterGenerationError 吞掉底层 LLM 错误（如 401 详情），补透传测试 | src/genesis/writer/writer_agent.py; tests/test_phase5_writer_agent.py | hy3-free |
+| 2026-08-13 23:50 | Agent 实现 | 修复 HttpLLMClient 在同步门禁中多次 asyncio.run 复用已关闭事件循环致 Event loop is closed：chat 改为每次调用新建 client（保留 async with 协议）| src/genesis/inference/client.py | hy3-free |

src/genesis/inference/client.py

@@ -50,6 +50,7 @@ class HttpLLMClient:
         self._api_key = api_key
         self._timeout_sec = timeout_sec
         self._retry_backoff = retry_backoff
+        self._transport = transport
         self._client = httpx.AsyncClient(timeout=timeout_sec, transport=transport)
 
     async def __aenter__(self) -> HttpLLMClient:
@@ -79,13 +80,17 @@ class HttpLLMClient:
             "Content-Type": "application/json",
         }
 
+        # 每次调用新建 httpx.AsyncClient，绑定到当前事件循环。
+        # 兼容「同步门禁中多次 asyncio.run 驱动 async chat_structured」场景，
+        # 避免复用 __init__ 中创建的 client 因首个循环关闭而报 Event loop is closed。
+        async with httpx.AsyncClient(timeout=self._timeout_sec, transport=self._transport) as client:
             attempts = 1 + len(self._retry_backoff)
             last_error: Exception | None = None
             for attempt in range(attempts):
                 if attempt > 0:
                     await asyncio.sleep(self._retry_backoff[attempt - 1])
                 try:
-                resp = await self._client.post(url, json=payload, headers=headers)
+                    resp = await client.post(url, json=payload, headers=headers)
                 except httpx.TimeoutException as exc:
                     last_error = exc
                     continue