Contract tests between internal services

Integrations that only pass in a «near-production» environment delay feedback and hide breakages late in the sprint. Contracts capture consumer expectations and verify the provider meets them — often without running every service.

The typical flow: the client defines request/response examples; the provider validates in CI. Compatibility breaks fail the right build with a readable diff.

This complements — not replaces — unit tests and some critical e2e. A healthy middle ground is: contracts for stable boundaries; e2e for journeys that represent revenue or risk.

Start with one pair of services that already caused regressions. Automate, document the process in the team README, then expand.