Missing up migrations applied during "down"

I had a situation with switching branches where the latest migration in the DB was "newer" than 2 migration files that had not yet been applied.

When running a "Down" migration, I noticed the "Up" code for both migrations was unintentionally applied and even worse they weren't recorded in the migrations table.

I tracked it down to the PlanMigration() function where it adds the results of ToCatchup(), regardless of the migration direction.

Obviously there a few issues with this. 1. They are up migrations when applying down. 2. The "catchup" migrations aren't considered in the check against the "max" parameter (which is 1 in my case). 3. The up migrations aren't recorded in the DB at all, leaving us in a broken state.

I'm not fluent in Go quite yet, otherwise I'd make a PR... but maybe the "catchup" logic should be ignored altogether for Down migrations.

Start by reading PlanMigration() and ToCatchup(), then trace how migration direction and the max parameter are handled. Reproduce the branch-switching case with a down migration and verify that unapplied catch-up migrations are not applied or omitted from migration tracking, while the requested down migration still behaves correctly.