Add key deprecation event indexing and successor key resolution API

[Chucks1093]

Summary

Index deprecation events from the contract and expose an endpoint returning deprecation status, reason, date, and successor key details for any deprecated key.

Scope

• GET /keys/:keyId/deprecation — status, reason, deprecated_at, successor key summary
• Deprecation events indexed from contract event stream
• Successor key details fetched and embedded in response
• Deprecated keys flagged in existing key list and search endpoints
• In-app notification triggered on deprecation event for key holders

Acceptance Criteria

• Deprecation endpoint returns correct status and all fields
• Successor key details embedded when successor is designated
• Key list and search endpoints include deprecated flag
• In-app notification created for all holders on deprecation
• Events indexed without duplication on re-indexing

ETA

12 hours

[Justkoredx]

@Justkoredx has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hello, I’ve reviewed the scope and I’m ready to contribute. I’d appreciate being assigned this issue.

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[T-kesh]

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Please assign me

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[sarah-obasi-analytics]

@sarah-obasi-analytics has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

hello maintainer, i'd love to work on this issue! please assign me

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[Samuel-21-eng]

@Samuel-21-eng has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

I can work on this

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[shinorh247]

@shinorh247 has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hi maintainer I would like to work on this issue

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[preciousolajide09]

@preciousolajide09 has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

This is a great project, i would love to be a part of, i have studied this issue description, its requirements and criteria and i understood them. I shall deliver on this qualitatively with a detailed and comprehensive PR within the specified TAT

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[drips-wave]

Congratulations, @sarah-obasi-analytics! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on September 30, 2026.

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