# Atlas API deprecation-header inventory and migration alerts > Source-anchored research for Atlas API deprecation-header inventory and migration alerts. Run status: COMPLETED. Parent: [MongoDB Atlas Infrastructure as Code](https://llms-explorer.com/tree/mongodb-atlas-infrastructure-as-code/) · 3 facets · 7 facts · page: https://llms-explorer.com/tree/atlas-api-deprecation-header-inventory-and-migration-alerts/ ## Problems, failure modes and limitations - Deprecation and Sunset information is optional. Record an absent header as unobserved; absence alone cannot establish continued support or justify clearing an earlier migration warning. (medium confidence) — [source](https://www.rfc-editor.org/rfc/rfc9745.html) · [also](https://www.rfc-editor.org/rfc/rfc8594.html) - RFC 8594 treats a past Sunset timestamp as risk of unavailability at any time. Use parsed Sunset for advance migration alerts, but do not treat its timestamp as an availability guarantee. (low confidence) — [source](https://www.rfc-editor.org/rfc/rfc8594.html) ## Comparisons and alternatives - Deprecation indicates a migration concern without itself changing resource behavior; Sunset indicates expected unavailability. Keep the two alert meanings separate rather than treating deprecation as an immediate outage. (medium confidence) — [source](https://www.rfc-editor.org/rfc/rfc9745.html) · [also](https://www.rfc-editor.org/rfc/rfc8594.html) - RFC 9745 requires Sunset not to precede Deprecation. If parsed dates violate that ordering, flag conflicting lifecycle evidence and seek provider clarification rather than silently choosing one. (low confidence) — [source](https://www.rfc-editor.org/rfc/rfc9745.html) ## Facts and statements - RFC 8594 scopes Sunset to the returning resource, and RFC 9745 scopes Deprecation to the resource identified by the response. Both permit broader scope and say it will usually be documented; they do not require documentation in every case. Atlas versions individual resources. Avoid assuming one endpoint/version observation governs all endpoints sharing a media-type date. (medium confidence) — [source](https://www.mongodb.com/docs/atlas/api/versioned-api-overview.md) · [also](https://www.rfc-editor.org/rfc/rfc8594.html) · [also](https://www.rfc-editor.org/rfc/rfc9745.html) - The Atlas documentation example uses an HTTP-date Deprecation value; RFC 9745 requires a Structured Field Date such as @1688169599. Preserve the format distinction; any legacy-date parsing fallback is a client compatibility policy, not RFC conformance. (medium confidence) — [source](https://www.mongodb.com/docs/atlas/api/versioned-api-overview.md) · [also](https://www.rfc-editor.org/rfc/rfc9745.html) - Zalando explicitly recommends that clients monitor Deprecation/Sunset response headers and that client owners build alerts to align migration tasks with service owners. This independent guidance supports client-side alerting, not an Atlas-managed alert feature. (low confidence) — [source](https://github.com/zalando/restful-api-guidelines/blob/main/chapters/deprecation.adoc)