Third-Party API Deprecation & Migration Readiness Review

The likely issue is a contract mismatch around third-party API deprecations, endpoint/version retirement, client libraries, authentication changes, rate limits, data contracts, feature parity, observability, migration sequencing, rollback, vendor timelines, and owner evidence. I would first define the invariant: A third-party API retirement is ready only when every used contract has a verified replacement or accepted exception, with timing, rollback, ownership, and observability evidence that does not depend on the deprecated path remaining available. Then I would trace the smallest owning boundary, apply or propose a bounded repair/review step, and add deterministic normal, boundary, failure and replay tests. The workflow preserves existing authorization, privacy, security policy, public interfaces, user-visible behavior, and documented operational ownership. If repository/workspace files are available, findings can be mapped to exact paths and focused local validation; with partial evidence, the result stays an explicit diagnosis/evidence map with assumptions and no invented execution claims.