0001 called Base.metadata.create_all(), building the schema from the
current models, so on a fresh PostgreSQL 0002 collided on
datasets.raw_sha256 and `alembic upgrade head` could never run from zero.
0001 is now an explicit, frozen baseline: the seven base tables exactly as
the real history created them, before 0002/0006 extended them. Databases
already past 0001 never re-run it. Proof: a fresh `upgrade head` produces a
schema identical (pg_dump --schema-only) to the long-lived dev database.
0019 repairs a latent bug found by that comparison: 0006 used
server_default="now()" as a string, which PostgreSQL froze at the instant
the column was created, so every Agent and Job got the same created_at.
It also adds three indexes the models declare but no migration created.
central/tests/test_migration_baseline.py guards (via AST) against
migrations importing the models or using string timestamp defaults.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
