Engineering Team Cuts SQLite Database Size by 54% With Zero Downtime

A development team reduced their OpenCode session database from 8.7GB to 3.8GB after it accumulated 1.26 million event rows, mostly redundant state updates that were causing sessions to freeze and queries to exceed two seconds. An initial deletion attempt using 250,000-row chunks caused lock collisions due to checkpoint contention, prompting a revised approach with smaller 25,000-row chunks and no intermediate checkpoints. The team also identified and fixed a bug where rowid reuse caused the deletion loop to exit prematurely, requiring six full passes to stabilize the table. Three AI agents — Scout, Spec Critic, and Verifier — were used to map the codebase, define acceptance criteria, and independently validate results against a pre-prune backup. The final outcome saw event rows drop by 65% and WAL size shrink by 96%, with zero loss of session, message, or part data.