The merged webhook session-close fix (#57370, salvaging #57322) wrapped
handle_message in a try/finally — but BasePlatformAdapter.handle_message
is fire-and-forget: it spawns _process_message_background and returns
before the agent run starts. The finally-close therefore ran BEFORE
get_or_create_session created the session row, found no session_id, and
silently no-op'd — the ghost-session leak persisted on the real path.
(The shipped test masked this by stubbing handle_message with a fake
that created the row synchronously.)
Move the close to an on_processing_complete override — the lifecycle
hook the base class fires at the TRUE end of the run, on the success,
failure, and cancellation paths alike. Empirically verified through the
real fire-and-forget pipeline: before, ended_at stayed NULL; after,
ended_at is set with end_reason=webhook_complete and the row is
prunable.
Tests now stub only the runner-side _message_handler (the seam the live
gateway injects) so handle_message / _process_message_background /
on_processing_complete all run for real; adds an AsyncSessionDB-facade
coverage test for the coroutine-await branch.
64ed99a6e6