fix: suppress 3.14 DeprecationWarning in uvicorn thread + Windows Proactor GC warning

Two separate CI failures, both exposed by moving from subprocess to in-thread:

Python 3.14 (hang → 10m timeout):
  pyproject.toml's filterwarnings=error is inherited by the server thread.
  On 3.14, uvicorn's config.load() calls asyncio.iscoroutinefunction which
  is deprecated, so the warning-turned-error kills the thread before it
  starts serving. Because we pre-bind the socket, the kernel listen queue
  still accepts connections — clients see ReadTimeout (~5m) instead of
  ConnectError. Fixed by catch_warnings inside the thread (thread-local
  since 3.12).

Windows Proactor (flaky unraisable warning):
  force_exit skips graceful drain, so the Proactor's overlapped AcceptEx
  on the listening socket may not finish cancellation before the event
  loop is torn down. GC finds it pending during a later unrelated test.
  Previously hidden by subprocess isolation. Suppressed at module level —
  this is Windows asyncio internals, not a real leak.

Author: maxisbey

tests/shared/test_streamable_http.py

@@ -63,6 +63,13 @@
 )
 from tests.test_helpers import run_uvicorn_in_thread
 
+# When the in-thread uvicorn server force-exits, the Proactor's overlapped
+# AcceptEx on the listening socket may not finish cancellation before the
+# event loop is torn down; GC later finds it pending and pytest's unraisable
+# collector surfaces it during an unrelated test. Previously hidden by
+# subprocess isolation. This is Windows asyncio internals, not a real leak.
+pytestmark = pytest.mark.filterwarnings("ignore::pytest.PytestUnraisableExceptionWarning")
+
 # Test constants
 SERVER_NAME = "test_streamable_http_server"
 TEST_SESSION_ID = "test-session-id-12345"

tests/test_helpers.py

@@ -3,6 +3,7 @@
 import socket
 import threading
 import time
+import warnings
 from collections.abc import Generator
 from contextlib import contextmanager
 from typing import Any
@@ -74,7 +75,19 @@ def run_uvicorn_in_thread(app: Any, **config_kwargs: Any) -> Generator[str, None
 
     config = uvicorn.Config(app=app, **config_kwargs)
     server = uvicorn.Server(config=config)
-    thread = threading.Thread(target=server.run, args=([sock],), daemon=True)
+
+    def _run() -> None:
+        # pyproject.toml sets filterwarnings=error, which is inherited by this
+        # thread. On Python 3.14 uvicorn's config.load() triggers the
+        # asyncio.iscoroutinefunction DeprecationWarning, killing the thread
+        # before it starts serving — the pre-bound socket keeps accepting
+        # connections into the kernel queue, so clients see ReadTimeout rather
+        # than ConnectError. catch_warnings is thread-local since 3.12.
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            server.run(sockets=[sock])
+
+    thread = threading.Thread(target=_run, daemon=True)
     thread.start()
 
     try: