fix: Host中间件审查修复（本地开发文档/顺序守护测试/ws断连分支/夹具清理）

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

app/platform/host_middleware.py

@@ -52,10 +52,16 @@ def _host_from_scope(scope: Scope) -> str:
 
 async def _close_ws(receive: Receive, send: Send, code: int, reason: str) -> None:
     """以 close 代 accept 拒绝 WS(ASGI 规范序列: 先收到 websocket.connect,
-    再回 websocket.close)。reason 中性,不带租户信息。"""
+    再回 websocket.close)。reason 中性,不带租户信息。
+
+    客户端在握手期间放弃时收到的首个事件是 websocket.disconnect 而非
+    connect——对端已撤,close 送达不了,直接 return。receive 本身抛异常
+    (传输层断)则向上传播,由外层 ServerErrorMiddleware 记日志:拒绝路径
+    无任何已建立状态可留,无需也不应再兜一层。"""
     event = await receive()
-    if event["type"] == "websocket.connect":
-        await send({"type": "websocket.close", "code": code, "reason": reason})
+    if event["type"] == "websocket.disconnect":
+        return
+    await send({"type": "websocket.close", "code": code, "reason": reason})
 
 
 class TenantHostMiddleware: