Bug Description

tools/homeassistant_tool.py reuses persistent event loops for some sync call paths, but _run_async() still falls back to a disposable-thread + asyncio.run(coro) path when called from inside an already-running event loop.

In long-running Hermes processes, that per-call create-and-destroy loop behavior can leave aiohttp cleanup tied to dead loops and risks Unclosed client session / Unclosed connector warnings.

Steps to Reproduce

1. Start from current main.
2. Call tools/homeassistant_tool.py:_run_async() from within an already-running event loop.
3. Exercise a Home Assistant tool path that creates and cleans up an async HTTP client/session.
4. Observe that this branch still creates a fresh event loop via asyncio.run() for each call instead of using a persistent loop.

Expected Behavior

When _run_async() is called from inside a running event loop, the Home Assistant tool should use a persistent async bridge loop so async client cleanup stays bound to a live event loop.

Actual Behavior

The async-context branch creates a disposable thread and runs asyncio.run(coro) per invocation, which creates and immediately closes a fresh event loop for that call.

Environment

• OS: Ubuntu 24.04
• Version/Commit: current main before PR fix(tools): reuse persistent loop in Home Assistant async bridge #13422
• Python version: 3.12
• Browser (if applicable): N/A

Error Output

Observed risk/symptom in long-running processes:

ERROR asyncio: Unclosed client session
ERROR asyncio: Unclosed connector

Relevant problematic pattern:

if loop and loop.is_running():
    import concurrent.futures
    with concurrent.futures.ThreadPoolExecutor(max_workers=1) as pool:
        future = pool.submit(asyncio.run, coro)
        return future.result(timeout=30)

Additional Context

This issue is narrowly scoped to tools/homeassistant_tool.py.

It is related to async resource lifecycle management and the same general class of sync-to-async bridging problems seen elsewhere in Hermes, but I did not find an existing open issue that cleanly covers this exact Home Assistant tool path.

A proposed fix is in PR #13422:
#13422