SqliteStorage.commit(batches) reads the check state of all batches up front,
checks each batch in memory against what the earlier ones left (same
prefix-stop refusals, no savepoints), and writes the accepted batches per
table: small rows as one JSON array parameter (json_each), rows with much
text bound column by column within 100 parameters. A group commit over a
remote SQLite takes a few round trips instead of about eight per batch;
local groups are faster too. Randomized differential test against
MemoryStorage, raw-table and statement-count guards.
