Why does my live API contract only break in ways my CI pipeline cannot see?

Consumer-driven contract testing catches breaking changes before merge, but it pins contracts at PR time and has no mechanism to detect semantic drift that accumulates in a live service after deployment. Teams add undocumented fields in production hotfixes, change error shapes to unblock an incident, or relax validation without touching the OpenAPI spec. The World Quality Report 2025 names undetected API schema drift a top-three cause of production incidents in distributed systems, and estimates roughly 70 percent of API failures in production passed all CI checks. No current tool continuously monitors real production traffic against a published contract and surfaces violations as they accumulate rather than at merge time.