fetch_scope_targets() runs a SELECT that autobegins the session transaction
(SQLAlchemy 2.0), so the following `async with db.begin()` raised
"A transaction is already begun on this Session" → 500 on both
/plugins/host_agent/deploy and /provision.
Mint registrations directly into the autobegun transaction, build the
inventory while the ORM objects are still live, then await db.commit().
Escaped CI because unit tests use a mock db_sessionmaker; no integration
test exercises these routes (follow-up noted in Scribe issue #884).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
bvandeusen
cfe6b4c25f