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API versioning and sunset headers: exposing deprecation signals through CORS-safe responses
Sunset and Deprecation headers inform clients; ensure they appear on error bodies too, not only 200 OK.
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api-designversioningcors
Client ecosystems
Mobile SDKs may ignore browser CORS but still benefit from the same sunset schedule communicated server-side.
Coordinate header names with OpenAPI descriptions so codegen tools surface warnings.
Breaking changes
When removing paths, return 410 with CORS headers so SPAs can show in-app banners instead of opaque failures.
Track adoption via metrics per API key before flipping default versions.