Update

tests/conftest.py

@@ -41,32 +41,50 @@ os.environ["DEVPLACE_RANKING_TTL"] = "0"
 os.environ["DEVPLACE_MARKET_SATURATION_TTL"] = "0"
 
 
+_ASYNC_LOOP = None
+_ASYNC_LOOP_LOCK = threading.Lock()
+
+
+def _async_loop():
+    # One shared background loop thread for the whole session, not one thread
+    # per run_async() call: dataset's NullPool caches one SQLite connection per
+    # OS thread ID forever (see the root CLAUDE.md NullPool note), so a fresh
+    # throwaway thread per call - this helper is invoked 270+ times across the
+    # suite - permanently claimed one file descriptor apiece for the rest of
+    # the session and could exhaust the process's open-file limit on a long run.
+    global _ASYNC_LOOP
+    with _ASYNC_LOOP_LOCK:
+        if _ASYNC_LOOP is None:
+            loop = asyncio.new_event_loop()
+            threading.Thread(
+                target=loop.run_forever, name="run-async-loop", daemon=True
+            ).start()
+            _ASYNC_LOOP = loop
+        return _ASYNC_LOOP
+
+
 def run_async(coro):
-    """Run a coroutine from sync test code on a dedicated thread and fresh loop."""
-    result_box = []
-    exc_box = []
+    """Run a coroutine from sync test code on the shared background loop."""
+
+    async def _wrapped():
+        from devplacepy.database import refresh_snapshot
 
-    def _run():
         try:
-            result_box.append(asyncio.run(coro))
-        except BaseException as e:
-            exc_box.append(e)
+            return await coro
         finally:
-            from devplacepy.database import refresh_snapshot
-
             refresh_snapshot()
 
-    t = threading.Thread(target=_run, daemon=True)
-    t.start()
-    t.join(timeout=30)
-    from devplacepy.database import refresh_snapshot
+    future = asyncio.run_coroutine_threadsafe(_wrapped(), _async_loop())
+    try:
+        return future.result(timeout=30)
+    except TimeoutError:
+        raise TimeoutError(
+            "run_async timed out waiting for coroutine to complete"
+        ) from None
+    finally:
+        from devplacepy.database import refresh_snapshot
 
-    refresh_snapshot()
-    if exc_box:
-        raise exc_box[0]
-    if result_box:
-        return result_box[0]
-    raise TimeoutError("run_async timed out waiting for coroutine to complete")
+        refresh_snapshot()
 
 
 @pytest.fixture(autouse=True)