Address CodeRabbit feedback

- Fix potential None session_id in span attributes
- Add return type annotation to _get_parent_trace_context
- Fix type checker issue with ClientFactoryT await pattern

🤖 Generated with Claude Code

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/servers/telemetry.mdx

@@ -244,9 +244,11 @@ def trace_exporter() -> Generator[InMemorySpanExporter, None, None]:
     exporter = InMemorySpanExporter()
     provider = TracerProvider()
     provider.add_span_processor(SimpleSpanProcessor(exporter))
+    original_provider = trace.get_tracer_provider()
     trace.set_tracer_provider(provider)
     yield exporter
     exporter.clear()
+    trace.set_tracer_provider(original_provider)
 
 async def test_tool_creates_span(trace_exporter: InMemorySpanExporter) -> None:
     mcp = FastMCP("test")

src/fastmcp/server/providers/proxy.py

@@ -120,11 +120,11 @@ class ProxyTool(Tool):
             span.set_attribute("fastmcp.provider.type", "ProxyProvider")
             client = await self._get_client()
             async with client:
-                context = get_context()
+                ctx = context or get_context()
                 # Build meta dict from request context
                 meta: dict[str, Any] | None = None
-                if hasattr(context, "request_context"):
-                    req_ctx = context.request_context
+                if hasattr(ctx, "request_context"):
+                    req_ctx = ctx.request_context
                     # Start with existing meta if present
                     if hasattr(req_ctx, "meta") and req_ctx.meta:
                         meta = dict(req_ctx.meta)

src/fastmcp/server/telemetry.py

@@ -4,6 +4,7 @@ from collections.abc import Generator
 from contextlib import contextmanager
 
 from mcp.server.lowlevel.server import request_ctx
+from opentelemetry.context import Context
 from opentelemetry.trace import Span, SpanKind, Status, StatusCode
 
 from fastmcp.telemetry import extract_trace_context, get_tracer
@@ -33,14 +34,14 @@ def get_session_span_attributes() -> dict[str, str]:
     attrs: dict[str, str] = {}
     try:
         ctx = get_context()
-        if ctx.request_context is not None:
+        if ctx.request_context is not None and ctx.session_id is not None:
             attrs["fastmcp.session.id"] = ctx.session_id
     except RuntimeError:
         pass
     return attrs
 
 
-def _get_parent_trace_context():
+def _get_parent_trace_context() -> Context | None:
     """Get parent trace context from request meta for distributed tracing."""
     try:
         req_ctx = request_ctx.get()

tests/server/providers/proxy/test_proxy_server.py

@@ -214,7 +214,9 @@ async def test_proxy_with_async_client_factory():
     proxy = FastMCPProxy(client_factory=async_factory)
     assert isinstance(proxy, FastMCPProxy)
     assert inspect.iscoroutinefunction(proxy.client_factory)
-    client = await proxy.client_factory()
+    client = proxy.client_factory()
+    if inspect.isawaitable(client):
+        client = await client
     assert isinstance(client, Client)
     assert isinstance(client.transport, StreamableHttpTransport)
     assert client.transport.url == "http://example.com/mcp/"