The system was buckling under growth and the old design had run out of room — every fix bought weeks rather than quarters, and the next step up in traffic would have broken it outright. I owned the redesign end to end: the tradeoffs, the migration path, and a rollout that kept old and new live until the cutover was boring.

Added backpressure and at-least-once delivery with reconciliation; row loss under peak load went to zero.

Batch jobs ran overnight, so by the time anyone saw a failure the window had closed and the day already started behind. I moved the critical paths to streaming, made retries safe to repeat, and turned a nightly gamble into something that just quietly kept up.

Decomposed the monolith behind a strangler proxy into 9 services — no maintenance window needed.

Costs were climbing faster than usage and nobody owned the number, so every team assumed someone else was watching it. I took the problem, instrumented spend down to the service level, and worked through the biggest offenders one at a time until the trend line bent and stayed bent.

Added SLO-based alerting and rewrote the top runbooks; paging volume fell 15% in a quarter.

Deploys were a held-breath event only a couple of people knew how to do safely, so releases bunched up and got riskier the longer we waited. I made shipping boring — automated the pipeline, put the guardrails in code, and handed the whole team a button they could trust at 5pm on a Friday.

Rewrote the three noisiest services and their alerts; overnight pages dropped 15% and stayed down.