Max statements one interactive write transaction may issue before the round-trip guard fires. Every statement inside a withTransaction holds the single primary write connection open for another edge→primary round-trip, so a chatty interactive transaction is what the primary aborts as "Transaction timed-out". A plain batch (executeBatch) is one round-trip regardless of how many statements it carries and is never counted — the whole point is to push chatty writes onto it. Set above the largest legitimate interactive transaction; anything that grows with input size (a big attendee merge, a per-leg ledger post) must prepare its reads outside the lock and apply its writes as one batch instead. The current high-water mark is recreateTable on attendee_answers: 8 DROP TRIGGER + 5 rebuild + 6 CREATE INDEX + 8 CREATE TRIGGER = 27 statements; the threshold sits above that.