Maciej: he killed production once. During a REST→GraphQL migration behind a feature flag at 10% traffic, he over-sanitized parameters in both branches and accidentally stripped the entire WHERE clause of an external-service query, effectively loading the whole joined database into memory until infra reverted his deploy. Stephen: can't remember anything he did more than two years ago, but the whole SQLite-performance talk he stepped through represents his most complex recent work, with a lot cut on view-layer and SQLite driver exploration. Caio: during Brazil's 2022 elections project, their Rails API connected to a WhatsApp channel and called a Python ML Lambda synchronously; under load they saw DB connection pool contention with zero DB activity because Rails opened transactions that held connections open during the blocking external HTTP call. Fix: release DB connections around external calls.