fix: persistent event loop in _run_async prevents 'Event loop is closed' (#2190)

Cherry-picked from PR #2146 by @crazywriter1. Fixes #2104.

asyncio.run() creates and closes a fresh event loop each call. Cached
httpx/AsyncOpenAI clients bound to the dead loop crash on GC with
'Event loop is closed'. This hit vision_analyze on first use in CLI.

Two-layer fix:
- model_tools._run_async(): replace asyncio.run() with persistent
  loop via _get_tool_loop() + run_until_complete()
- auxiliary_client._get_cached_client(): track which loop created
  each async client, discard stale entries if loop is closed

6 regression tests covering loop lifecycle, reuse, and full vision
dispatch chain.

Co-authored-by: Test <test@test.com>

agent/auxiliary_client.py

@@ -1191,7 +1191,17 @@ def _get_cached_client(
     cache_key = (provider, async_mode, base_url or "", api_key or "")
     with _client_cache_lock:
         if cache_key in _client_cache:
-            cached_client, cached_default = _client_cache[cache_key]
+            cached_client, cached_default, cached_loop = _client_cache[cache_key]
+            if async_mode:
+                # Async clients are bound to the event loop that created them.
+                # A cached async client whose loop has been closed will raise
+                # "Event loop is closed" when httpx tries to clean up its
+                # transport.  Discard the stale client and create a fresh one.
+                if cached_loop is not None and cached_loop.is_closed():
+                    del _client_cache[cache_key]
+                else:
+                    return cached_client, model or cached_default
+            else:
                 return cached_client, model or cached_default
     # Build outside the lock
     client, default_model = resolve_provider_client(
@@ -1202,11 +1212,20 @@ def _get_cached_client(
         explicit_api_key=api_key,
     )
     if client is not None:
+        # For async clients, remember which loop they were created on so we
+        # can detect stale entries later.
+        bound_loop = None
+        if async_mode:
+            try:
+                import asyncio as _aio
+                bound_loop = _aio.get_event_loop()
+            except RuntimeError:
+                pass
         with _client_cache_lock:
             if cache_key not in _client_cache:
-                _client_cache[cache_key] = (client, default_model)
+                _client_cache[cache_key] = (client, default_model, bound_loop)
             else:
-                client, default_model = _client_cache[cache_key]
+                client, default_model, _ = _client_cache[cache_key]
     return client, model or default_model
 
 

model_tools.py

@@ -24,6 +24,7 @@ import json
 import asyncio
 import os
 import logging
+import threading
 from typing import Dict, Any, List, Optional, Tuple
 
 from tools.registry import registry
@@ -36,6 +37,25 @@ logger = logging.getLogger(__name__)
 # Async Bridging  (single source of truth -- used by registry.dispatch too)
 # =============================================================================
 
+_tool_loop = None          # persistent loop for the main (CLI) thread
+_tool_loop_lock = threading.Lock()
+
+
+def _get_tool_loop():
+    """Return a long-lived event loop for running async tool handlers.
+
+    Using a persistent loop (instead of asyncio.run() which creates and
+    *closes* a fresh loop every time) prevents "Event loop is closed"
+    errors that occur when cached httpx/AsyncOpenAI clients attempt to
+    close their transport on a dead loop during garbage collection.
+    """
+    global _tool_loop
+    with _tool_loop_lock:
+        if _tool_loop is None or _tool_loop.is_closed():
+            _tool_loop = asyncio.new_event_loop()
+        return _tool_loop
+
+
 def _run_async(coro):
     """Run an async coroutine from a sync context.
 
@@ -44,6 +64,10 @@ def _run_async(coro):
     disposable thread so asyncio.run() can create its own loop without
     conflicting.
 
+    For the common CLI path (no running loop), we use a persistent event
+    loop so that cached async clients (httpx / AsyncOpenAI) remain bound
+    to a live loop and don't trigger "Event loop is closed" on GC.
+
     This is the single source of truth for sync->async bridging in tool
     handlers. The RL paths (agent_loop.py, tool_context.py) also provide
     outer thread-pool wrapping as defense-in-depth, but each handler is
@@ -59,7 +83,9 @@ def _run_async(coro):
         with concurrent.futures.ThreadPoolExecutor(max_workers=1) as pool:
             future = pool.submit(asyncio.run, coro)
             return future.result(timeout=300)
-    return asyncio.run(coro)
+
+    tool_loop = _get_tool_loop()
+    return tool_loop.run_until_complete(coro)
 
 
 # =============================================================================

tests/test_model_tools_async_bridge.py

@@ -0,0 +1,211 @@
+"""Regression tests for the _run_async() event-loop lifecycle.
+
+These tests verify the fix for GitHub issue #2104:
+  "Event loop is closed" after vision_analyze used as first call in session.
+
+Root cause: asyncio.run() creates and *closes* a fresh event loop on every
+call.  Cached httpx/AsyncOpenAI clients that were bound to the now-dead loop
+would crash with RuntimeError("Event loop is closed") when garbage-collected.
+
+The fix replaces asyncio.run() with a persistent event loop in _run_async().
+"""
+
+import asyncio
+import json
+import threading
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+async def _get_current_loop():
+    """Return the running event loop from inside a coroutine."""
+    return asyncio.get_event_loop()
+
+
+async def _create_and_return_transport():
+    """Simulate an async client creating a transport on the current loop.
+
+    Returns a simple asyncio.Future bound to the running loop so we can
+    later check whether the loop is still alive.
+    """
+    loop = asyncio.get_event_loop()
+    fut = loop.create_future()
+    fut.set_result("ok")
+    return loop, fut
+
+
+# ---------------------------------------------------------------------------
+# Tests
+# ---------------------------------------------------------------------------
+
+class TestRunAsyncLoopLifecycle:
+    """Verify _run_async() keeps the event loop alive after returning."""
+
+    def test_loop_not_closed_after_run_async(self):
+        """The loop used by _run_async must still be open after the call."""
+        from model_tools import _run_async
+
+        loop = _run_async(_get_current_loop())
+
+        assert not loop.is_closed(), (
+            "_run_async() closed the event loop — cached async clients will "
+            "crash with 'Event loop is closed' on GC (issue #2104)"
+        )
+
+    def test_same_loop_reused_across_calls(self):
+        """Consecutive _run_async calls should reuse the same loop."""
+        from model_tools import _run_async
+
+        loop1 = _run_async(_get_current_loop())
+        loop2 = _run_async(_get_current_loop())
+
+        assert loop1 is loop2, (
+            "_run_async() created a new loop on the second call — cached "
+            "async clients from the first call would be orphaned"
+        )
+
+    def test_cached_transport_survives_between_calls(self):
+        """A transport/future created in call 1 must be valid in call 2."""
+        from model_tools import _run_async
+
+        loop, fut = _run_async(_create_and_return_transport())
+
+        assert not loop.is_closed()
+        assert fut.result() == "ok"
+
+        loop2 = _run_async(_get_current_loop())
+        assert loop2 is loop, "Loop changed between calls"
+        assert not loop.is_closed(), "Loop closed before second call"
+
+
+class TestRunAsyncWithRunningLoop:
+    """When a loop is already running, _run_async falls back to a thread."""
+
+    @pytest.mark.asyncio
+    async def test_run_async_from_async_context(self):
+        """_run_async should still work when called from inside an
+        already-running event loop (gateway / Atropos path)."""
+        from model_tools import _run_async
+
+        async def _simple():
+            return 42
+
+        result = await asyncio.get_event_loop().run_in_executor(
+            None, _run_async, _simple()
+        )
+        assert result == 42
+
+
+# ---------------------------------------------------------------------------
+# Integration: full vision_analyze dispatch chain
+# ---------------------------------------------------------------------------
+
+def _mock_vision_response():
+    """Build a fake LLM response matching async_call_llm's return shape."""
+    message = SimpleNamespace(content="A cat sitting on a chair.")
+    choice = SimpleNamespace(index=0, message=message, finish_reason="stop")
+    return SimpleNamespace(choices=[choice], model="test/vision", usage=None)
+
+
+class TestVisionDispatchLoopSafety:
+    """Simulate the full registry.dispatch('vision_analyze') chain and
+    verify the event loop stays alive afterwards — the exact scenario
+    from issue #2104."""
+
+    def test_vision_dispatch_keeps_loop_alive(self, tmp_path):
+        """After dispatching vision_analyze via the registry, the event
+        loop must remain open so cached async clients don't crash on GC."""
+        from model_tools import _run_async, _get_tool_loop
+        from tools.registry import registry
+
+        fake_response = _mock_vision_response()
+
+        with (
+            patch(
+                "tools.vision_tools.async_call_llm",
+                new_callable=AsyncMock,
+                return_value=fake_response,
+            ),
+            patch(
+                "tools.vision_tools._download_image",
+                new_callable=AsyncMock,
+                side_effect=lambda url, dest, **kw: _write_fake_image(dest),
+            ),
+            patch(
+                "tools.vision_tools._validate_image_url",
+                return_value=True,
+            ),
+            patch(
+                "tools.vision_tools._image_to_base64_data_url",
+                return_value="data:image/jpeg;base64,abc",
+            ),
+        ):
+            result_json = registry.dispatch(
+                "vision_analyze",
+                {"image_url": "https://example.com/cat.png", "question": "What is this?"},
+            )
+
+        result = json.loads(result_json)
+        assert result.get("success") is True, f"dispatch failed: {result}"
+        assert "cat" in result.get("analysis", "").lower()
+
+        loop = _get_tool_loop()
+        assert not loop.is_closed(), (
+            "Event loop closed after vision_analyze dispatch — cached async "
+            "clients will crash with 'Event loop is closed' (issue #2104)"
+        )
+
+    def test_two_consecutive_vision_dispatches(self, tmp_path):
+        """Two back-to-back vision_analyze dispatches must both succeed
+        and share the same loop (simulates 'first call fails, second
+        works' from the issue report)."""
+        from model_tools import _get_tool_loop
+        from tools.registry import registry
+
+        fake_response = _mock_vision_response()
+
+        with (
+            patch(
+                "tools.vision_tools.async_call_llm",
+                new_callable=AsyncMock,
+                return_value=fake_response,
+            ),
+            patch(
+                "tools.vision_tools._download_image",
+                new_callable=AsyncMock,
+                side_effect=lambda url, dest, **kw: _write_fake_image(dest),
+            ),
+            patch(
+                "tools.vision_tools._validate_image_url",
+                return_value=True,
+            ),
+            patch(
+                "tools.vision_tools._image_to_base64_data_url",
+                return_value="data:image/jpeg;base64,abc",
+            ),
+        ):
+            args = {"image_url": "https://example.com/cat.png", "question": "Describe"}
+
+            r1 = json.loads(registry.dispatch("vision_analyze", args))
+            loop_after_first = _get_tool_loop()
+
+            r2 = json.loads(registry.dispatch("vision_analyze", args))
+            loop_after_second = _get_tool_loop()
+
+        assert r1.get("success") is True
+        assert r2.get("success") is True
+        assert loop_after_first is loop_after_second, "Loop changed between dispatches"
+        assert not loop_after_second.is_closed()
+
+
+def _write_fake_image(dest):
+    """Write minimal bytes so vision_analyze_tool thinks download succeeded."""
+    dest.parent.mkdir(parents=True, exist_ok=True)
+    dest.write_bytes(b"\xff\xd8\xff" + b"\x00" * 16)
+    return dest