We extracted one high-churn billing endpoint behind a strangler facade. Dual-writes ran for two weeks while we compared totals nightly. A feature flag controlled read traffic so we could roll back instantly. The hardest part was matching edge-case rounding in legacy invoices. Cutover finished with no customer-facing downtime and a smaller blast radius. We kept the facade until three more endpoints followed the same path.
We needed locks so queue workers did not process the same job twice. Redis SET NX was faster under load and easy to expire automatically. Postgres advisory locks were simpler operationally for our small team. Failover behavior mattered more than raw latency in our case. We chose Postgres first, then moved hot paths to Redis later. Pick the lock store you can operate confidently at 3am.
Curious how teams balance generated clients and hand-written SDKs. OpenAPI docs help humans, but drift still sneaks into multi-repo setups. Generated clients catch breaking changes in CI before they hit prod. They can also create noisy diffs when schemas change often. Plain fetch wrappers stay flexible but hide contract mismatches. What has actually reduced production bugs on your teams?