A DBOS step runs async SQLAlchemy on the launch loop

[czpython]

DBOS submits async steps to the event loop it captured at launch(). This is the contract async database work will stand on, so a regression test now pins it: an AsyncSession write inside DBOS.run_step_async succeeds on the loop that was running at launch.

Teardown restores the DBOS registry to its pre-launch state — destroy() leaves it pointing at the dead launched instance, which breaks the next module that registers scheduled units. Also drops a stale _OWN_DATABASE_MODULES entry for a module that no longer exists.

🤖 Generated with Claude Code

[czpython]

Closing by owner decision: the loop-topology assumption is proven (test passed locally and in CI); we take the finding forward without a standing test and handle any dispatch change at deploy time.