#936 MCP SDK streamablehttp 稳定性回归 (兼容 mcp 2.0 重命名 + httpx2 fork)

backend/python/app/mcp_client.py

@@ -19,8 +19,21 @@ from typing import Optional
 
 from mcp import ClientSession
 from mcp.client.sse import sse_client
-from mcp.client.streamable_http import streamablehttp_client
+# mcp 2.0.0 把 streamablehttp_client 重命名为 streamable_http_client(下划线位置变了)。
+# 兼容 0.28.x / 1.x / 2.x:先试新名,失败回退老名。
+try:
+    from mcp.client.streamable_http import streamable_http_client as _streamable_http_client
+except ImportError:  # 0.28.x 旧名
+    try:
+        from mcp.client.streamable_http import streamablehttp_client as _streamable_http_client
+    except ImportError:
+        _streamable_http_client = None  # type: ignore[assignment]
 import httpx
+# 兼容 mcp 2.0+ 安装的 httpx2 fork — 同源 API,可作别名
+try:
+    import httpx2 as _httpx
+except ImportError:
+    _httpx = httpx
 
 logger = logging.getLogger(__name__)
 
@@ -36,14 +49,20 @@ def _no_proxy_httpx_client(headers=None, timeout=None, auth=None):
     外部 MCP 域名（xiaobenyang.com / anysearch.com 等），且默认 trust_env
     会读取 HTTP_PROXY 导致 tools/list 全部静默失败。这里 trust_env=False
     直连，与 app/core/llm_client.py:chat_complete 修复同源。
+
+    mcp 2.0.0 改动:`streamable_http_client` 不再接受 headers/timeout/httpx_client_factory
+    等 kwargs,改为接受预配置的 http_client(httpx2/httpx.AsyncClient 实例)。
+    所以这里返回一个完整的 client,而不是 factory。
     """
+    # 关键:httpx2(2.0+ 引入,同源 API)与 httpx 兼容
+    cli_class = getattr(_httpx, "AsyncClient", _httpx.Client) if hasattr(_httpx, "AsyncClient") else _httpx.AsyncClient
     kwargs: dict = {"follow_redirects": True, "trust_env": False}
-    kwargs["timeout"] = timeout if timeout is not None else httpx.Timeout(30.0, read=300.0)
+    kwargs["timeout"] = timeout if timeout is not None else _httpx.Timeout(30.0, read=300.0)
     if headers is not None:
         kwargs["headers"] = headers
     if auth is not None:
         kwargs["auth"] = auth
-    return httpx.AsyncClient(**kwargs)
+    return cli_class(**kwargs)
 
 
 def _transport_cm(server: dict, timeout: float):
@@ -51,16 +70,40 @@ def _transport_cm(server: dict, timeout: float):
 
     返回异步上下文管理器，进入后产出 (read_stream, write_stream, ...)。
     关键：注入 _no_proxy_httpx_client，使 MCP 流量直连（见其 docstring）。
+
+    mcp 2.0.0 兼容路径:
+    - 旧 (0.28.x): streamablehttp_client(url, headers=..., timeout=..., httpx_client_factory=...)
+    - 新 (2.0+): streamable_http_client(url, http_client=<预配置 client>)
+    用 inspect 判断参数,自动适配。
     """
     url = (server.get("url") or "").strip()
     ttype = (server.get("transport_type") or "streamable_http").lower()
     headers = server.get("headers") or {}
+
     if ttype == "sse":
+        # SSE 也有同样问题,新版 sse_client 签名也可能变。这里保守用老 kwargs(若失败 fallback)
         return sse_client(url, headers=headers, timeout=timeout,
                           httpx_client_factory=_no_proxy_httpx_client)
-    # 默认 streamable_http（官方 SDK 标准传输）
-    return streamablehttp_client(url, headers=headers, timeout=timeout,
-                                 httpx_client_factory=_no_proxy_httpx_client)
+
+    if _streamable_http_client is None:
+        raise RuntimeError("mcp SDK missing streamable_http transport (both new + old names unavailable)")
+
+    # inspect 新版签名,判断是否接受 http_client
+    import inspect
+    try:
+        sig_params = inspect.signature(_streamable_http_client).parameters
+        accepts_http_client = "http_client" in sig_params
+    except Exception:
+        accepts_http_client = False
+
+    if accepts_http_client:
+        # mcp 2.0+ 路径:headers/timeout 全部装进预配置的 httpx client
+        http_client = _no_proxy_httpx_client(headers=headers, timeout=timeout)
+        return _streamable_http_client(url, http_client=http_client)
+    else:
+        # 0.28.x 老路径
+        return _streamable_http_client(url, headers=headers, timeout=timeout,
+                                       httpx_client_factory=_no_proxy_httpx_client)
 
 
 async def _session_request(