chore: import upstream snapshot with attribution

agent/async_utils.py

@@ -0,0 +1,68 @@
+"""Async/sync bridging helpers.
+
+The codebase has ~30 sites that schedule a coroutine onto an event loop from a
+worker thread via :func:`asyncio.run_coroutine_threadsafe`.  That function can
+raise :class:`RuntimeError` (e.g. the loop was closed during a shutdown race),
+and when it does the coroutine object is never awaited and never closed —
+which triggers a ``"coroutine '<name>' was never awaited"`` RuntimeWarning and
+leaks the coroutine's frame until GC.
+
+:func:`safe_schedule_threadsafe` wraps the call, closes the coroutine on
+scheduling failure, and returns ``None`` (instead of a half-formed future) so
+callers can branch cleanly:
+
+    fut = safe_schedule_threadsafe(coro, loop)
+    if fut is None:
+        return  # or fallback behavior
+    fut.result(timeout=5)
+
+The helper deliberately does NOT also handle ``future.result()`` failures —
+that is a separate concern.  Once the loop has accepted the coroutine, its
+lifecycle belongs to the loop, not the scheduling thread.
+"""
+from __future__ import annotations
+
+import asyncio
+import logging
+from concurrent.futures import Future
+from typing import Any, Coroutine, Optional
+
+
+_DEFAULT_LOGGER = logging.getLogger(__name__)
+
+
+def safe_schedule_threadsafe(
+    coro: Coroutine[Any, Any, Any],
+    loop: Optional[asyncio.AbstractEventLoop],
+    *,
+    logger: Optional[logging.Logger] = None,
+    log_message: str = "Failed to schedule coroutine on loop",
+    log_level: int = logging.DEBUG,
+) -> Optional[Future]:
+    """Schedule ``coro`` on ``loop`` from a sync context, leak-safe.
+
+    Returns the :class:`concurrent.futures.Future` on success, or ``None`` if
+    the loop is missing or :func:`asyncio.run_coroutine_threadsafe` raised
+    (e.g. the loop was closed during a shutdown race).  In all failure paths
+    the coroutine is :meth:`close`-d so it does not trigger
+    ``"coroutine was never awaited"`` warnings or leak its frame.
+
+    Callers retain full control over what to do with the returned future
+    (call ``.result(timeout=...)``, attach ``add_done_callback``, ignore it
+    fire-and-forget, etc.).
+    """
+    log = logger if logger is not None else _DEFAULT_LOGGER
+
+    if loop is None:
+        if asyncio.iscoroutine(coro):
+            coro.close()
+        log.log(log_level, "%s: loop is None", log_message)
+        return None
+
+    try:
+        return asyncio.run_coroutine_threadsafe(coro, loop)
+    except Exception as exc:
+        if asyncio.iscoroutine(coro):
+            coro.close()
+        log.log(log_level, "%s: %s", log_message, exc)
+        return None