Writing(03)
Notes fromproduction
Case studies from systems I’ve shipped. Every number is verified against the codebase before it’s published.
(03)Case study · AI at scaleA Postgres table is my job queueAdmission control for LLM generation at Velric: optimistic locks across six instances, a 40-generation global cap, load shedding at depth 200, and the stale-job sweeper that saves the throughput.Aug 2026(02)Case study · PaymentsA ledger that refuses to lieBuilding fiat-crypto rails at Sendcoins: double-entry enforced by a database trigger, idempotency as an explicit contract, and the advisory lock that ended a gas-race bug.Aug 2026(01)Case study · AI + PaymentsRunning a real booking flow inside WhatsAppHow IléHQ takes a guest from a first hello to a paid booking: a hostile webhook runtime, an 11-state booking machine, 38 tools, and money the model never decides.Aug 2026