feat(mcp): 增强MCP服务器异常处理和错误描述

- 添加_iter_leaf_exceptions函数用于处理嵌套异常组
- 实现_describe_mcp_exception函数提供详细的MCP服务器错误信息
- 改进connect_mcp_servers中的错误处理，使用更精确的错误描述
- 在日志记录中包含更具体的错误详情

feat(outlook): 优化Outlook集成异常处理

- 添加_iter_leaf_exceptions函数用于异常处理
- 创建_coerce_outlook_mcp_exception函数统一异常转换
- 改进_call_outlook_mcp_tool中的异常捕获和处理
- 对认证令牌获取和MCP调用添加专门的超时和HTTP错误处理

feat(web): 改进Web会话定时任务结果记录

- 实现_record_cron_result_for_web_session函数
- 为Web模式下的独立定时任务执行结果提供持久化存储
- 支持将定时任务响应消息添加到目标会话中
- 确保前端可以显示定时任务执行结果

app-instance/backend/nanobot/web/outlook.py

@@ -31,6 +31,38 @@ class OutlookIntegrationError(RuntimeError):
     """Raised when the Outlook integration backend is unavailable or misconfigured."""
 
 
+def _iter_leaf_exceptions(exc: BaseException) -> list[BaseException]:
+    if isinstance(exc, BaseExceptionGroup):
+        leaves: list[BaseException] = []
+        for sub_exc in exc.exceptions:
+            leaves.extend(_iter_leaf_exceptions(sub_exc))
+        return leaves
+    return [exc]
+
+
+def _coerce_outlook_mcp_exception(exc: BaseException, *, url: str) -> OutlookIntegrationError:
+    if isinstance(exc, OutlookIntegrationError):
+        return exc
+
+    leaves = _iter_leaf_exceptions(exc)
+    for leaf in leaves:
+        if isinstance(leaf, httpx.TimeoutException):
+            return OutlookIntegrationError(f"Outlook MCP 请求超时：{url}")
+        if isinstance(leaf, httpx.ConnectError):
+            return OutlookIntegrationError(f"Outlook MCP 无法连接：{url}")
+        if isinstance(leaf, httpx.HTTPStatusError):
+            return OutlookIntegrationError(f"Outlook MCP 返回 HTTP {leaf.response.status_code}：{url}")
+        if isinstance(leaf, httpx.HTTPError):
+            detail = str(leaf).strip() or leaf.__class__.__name__
+            return OutlookIntegrationError(f"Outlook MCP 网络错误：{detail}")
+
+    detail_source = leaves[0] if leaves else exc
+    detail = str(detail_source).strip() or detail_source.__class__.__name__
+    return OutlookIntegrationError(
+        f"Outlook MCP 调用失败：{detail_source.__class__.__name__}: {detail}"
+    )
+
+
 @dataclass(frozen=True)
 class OutlookDefaults:
     """Default values exposed to the web setup form."""
@@ -187,32 +219,43 @@ async def _call_outlook_mcp_tool(
     from mcp import ClientSession, types
     from mcp.client.streamable_http import streamable_http_client
 
+    url = _outlook_mcp_url(config)
     backend_id = _require_backend_identity(config)
     client = _authz_client(config)
-    token_response = await client.issue_token(
-        client_id=config.backend_identity.client_id,
-        client_secret=config.backend_identity.client_secret,
-        audience=f"mcp:{OUTLOOK_SERVER_ID}",
-        scopes=scopes or ["list_tools", f"tool:{tool_name}"],
-    )
+    try:
+        token_response = await client.issue_token(
+            client_id=config.backend_identity.client_id,
+            client_secret=config.backend_identity.client_secret,
+            audience=f"mcp:{OUTLOOK_SERVER_ID}",
+            scopes=scopes or ["list_tools", f"tool:{tool_name}"],
+        )
+    except httpx.TimeoutException as exc:
+        raise OutlookIntegrationError("AuthZ token 请求超时。") from exc
+    except httpx.HTTPError as exc:
+        detail = str(exc).strip() or exc.__class__.__name__
+        raise OutlookIntegrationError(f"AuthZ token 获取失败：{detail}") from exc
+
     access_token = str(token_response.get("access_token") or "").strip()
     if not access_token:
         raise OutlookIntegrationError("Failed to obtain an Outlook MCP access token.")
 
-    async with AsyncExitStack() as stack:
-        http_client = await stack.enter_async_context(
-            httpx.AsyncClient(
-                headers={"Authorization": f"Bearer {access_token}"},
-                follow_redirects=True,
-                trust_env=False,
+    try:
+        async with AsyncExitStack() as stack:
+            http_client = await stack.enter_async_context(
+                httpx.AsyncClient(
+                    headers={"Authorization": f"Bearer {access_token}"},
+                    follow_redirects=True,
+                    trust_env=False,
+                )
             )
-        )
-        read, write, _ = await stack.enter_async_context(
-            streamable_http_client(_outlook_mcp_url(config), http_client=http_client)
-        )
-        session = await stack.enter_async_context(ClientSession(read, write))
-        await session.initialize()
-        result = await session.call_tool(tool_name, arguments=arguments)
+            read, write, _ = await stack.enter_async_context(
+                streamable_http_client(url, http_client=http_client)
+            )
+            session = await stack.enter_async_context(ClientSession(read, write))
+            await session.initialize()
+            result = await session.call_tool(tool_name, arguments=arguments)
+    except Exception as exc:  # noqa: BLE001
+        raise _coerce_outlook_mcp_exception(exc, url=url) from exc
 
     parts: list[str] = []
     for block in result.content: