Every multi-statement migration and its matching schema_version insert
now execute on the same sqlx Transaction. A failure anywhere — a bad
statement, the version insert, or the commit itself — rolls the
database back to its previous state, so the next startup replays the
migration against a clean schema rather than a half-mutated one.
Extracted run_migrations_slice(pool, migrations) as the single apply
path. run_migrations delegates to it with MIGRATIONS; the test helper
run_migrations_up_to now filters MIGRATIONS by target and delegates to
the same code, eliminating the duplicated loop that previously lived
in the test module.
Regression test multi_statement_migration_rolls_back_on_failure
injects a poisoned v9 migration (valid CREATE followed by a bogus
function call) and asserts neither the partial schema change nor the
schema_version row persists after the failure.
SQLite DDL participates in transactions, so this is sufficient. Any
future migration that needs an implicitly-committing statement
(VACUUM / REINDEX / ATTACH — none today) must be its own
non-transactional migration; that's a reviewer responsibility.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>