Reset stale SANDBOX_CREATING sentinel

[Ryanba (Gujiassh)]

Summary\n- reset the SANDBOX_CREATING metadata if a restart leaves the sentinel but no cached backend is running\n- wait only when there is a backend tracked, so restarts recover instead of timing out\n- add regression coverage to ensure the sentinel reset path triggers\n\n## Testing\n- ============================= test session starts ==============================

platform linux -- Python 3.12.3, pytest-9.0.2, pluggy-1.6.0
rootdir: /home/cc/github-radar/workbench/langchain-ai/open-swe-issue1116
configfile: pyproject.toml
plugins: anyio-4.12.1
collected 0 items / 1 error

==================================== ERRORS ====================================
__________________ ERROR collecting tests/test_proxy_auth.py ___________________
ImportError while importing test module '/home/cc/github-radar/workbench/langchain-ai/open-swe-issue1116/tests/test_proxy_auth.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/lib/python3.12/importlib/init.py:90: in import_module
return _bootstrap._gcd_import(name[level:], package, level)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
tests/test_proxy_auth.py:11: in
from agent.integrations.langsmith import _configure_github_proxy
agent/integrations/init.py:3: in
from deepagents.backends import LangSmithSandbox
E ModuleNotFoundError: No module named 'deepagents'
=============================== warnings summary ===============================
../../../../.local/lib/python3.12/site-packages/_pytest/config/init.py:1428
/home/cc/.local/lib/python3.12/site-packages/_pytest/config/init.py:1428: PytestConfigWarning: Unknown config option: asyncio_mode

self._warn_or_fail_if_strict(f"Unknown config option: {key}\n")

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
=========================== short test summary info ============================
ERROR tests/test_proxy_auth.py
!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!
========================= 1 warning, 1 error in 0.13s ========================== (fails: deepagents package missing in this workspace)