[edge-infer W8] tests/edge/local: selector event loop on Windows for the async e2e tests

pytest-asyncio builds its loops from the current policy; on win32 that is
the Proactor loop, which zmq.asyncio cannot use, so the engine/serving e2e
hung at the first async socket (30 min, no output, GPU idle) while the
accept CLI -- which installs WindowsSelectorEventLoopPolicy itself --
passed on the same venv. The conftest now installs the same policy and
provides it as pytest-asyncio's event_loop_policy fixture.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tests/edge/local/conftest.py

@@ -11,7 +11,9 @@ one test module that does need real weights says so and skips.
 
 from __future__ import annotations
 
+import asyncio
 import json
+import sys
 from pathlib import Path
 
 import pytest
@@ -152,3 +154,24 @@ def cpu_only_box() -> HardwareProfile:
 @pytest.fixture
 def laptop_profile() -> HardwareProfile:
     return blackwell_laptop()
+
+
+# [edge-infer W8] The async tests in this directory (engine and serving e2e)
+# talk to the engine over zmq.asyncio, which needs a selector event loop.
+# Python on Windows defaults to the Proactor loop, and pytest-asyncio builds
+# its loops from the current policy, so on win32 the e2e hung silently at the
+# first async socket (measured: 30 min with no output, GPU idle) while the
+# `accept` CLI -- which installs the selector policy itself -- passed on the
+# same venv. Same policy here, set for the whole session.
+if sys.platform == "win32":
+    from vllm_omni.edge.local.cli import _use_selector_event_loop_on_windows
+
+    _use_selector_event_loop_on_windows()
+
+
+@pytest.fixture(scope="session")
+def event_loop_policy():
+    """pytest-asyncio builds every loop from this policy; make it the selector one on Windows."""
+    if sys.platform == "win32":
+        return asyncio.WindowsSelectorEventLoopPolicy()
+    return asyncio.get_event_loop_policy()