This is super cool! I like your method for handling the claiming of queue items. I always end up wishing SQLite had something like Postgres' LISTEN/NOTIFY/SKIP

This is super cool! I like your method for handling the claiming of queue items. I always end up wishing SQLite had something like Postgres' LISTEN/NOTIFY/SKIP LOCKED but your UPDATE solution is nice and low tech and fitting for SQLite, in a good way!