v1 state

Record

Record is v1's shape: Score widened to int64 and scaled by 1000, plus a new Active flag that migrated records get set to true.

records

init.2

migrate

migrate converts a v0 record into a v1 one. Kept separate from Get so the conversion is testable without a write.

Get

Get returns a record, migrating it from v0 on first touch. Crossing, because the migration writes. That is the cost of the pattern: the cheapest possible read is now a transaction.

Peek

Peek is the read-only half: it never migrates, so a record that has not been touched yet reads as its v0 self converted on the fly and NOT stored.

Migrated

Migrated is how many records have actually moved over.

Pending

Pending is how many v0 records have never been touched. It is only a bound: v0 keeps every record it ever had, migrated or not.

Render