Add archival pruning entrypoint with sorted-by-resolution cursor to EventArchive

[greatest0fallt1me]

Description

event_archive.rs::EventArchive exposes prune_archive(env, admin, count) but the order of pruning is undefined. Make pruning deterministic by resolution timestamp ascending and expose a paginated cursor for very large archives.

Requirements and Context

• Track resolution-timestamp index keyed by (timestamp, market_id)
• Iterate ascending and stop after count
• Return a PruneCursor clients can pass back for paging
• Must be secure, tested, and documented
• Should be efficient and easy to review

Suggested Execution

1. Fork the repo and create a branch

   git checkout -b feat/event-archive-pruning-cursor

2. Implement changes
   • contracts/predictify-hybrid/src/event_archive.rs
   • contracts/predictify-hybrid/src/lib.rs (prune_archive signature gains cursor)
3. Test and commit
   • cargo test -p predictify-hybrid event_archive -- --nocapture
   • Cover edge cases: empty archive, single entry, count > archive size
   • Include test output and notes in the PR

Example commit message

feat: deterministic archive pruning with paginated PruneCursor

Acceptance Criteria

• Order is by resolution timestamp ascending
• Cursor roundtrip tested
• Admin auth enforced via require_auth
• No unwrap() in iteration

Guidelines

• Use Soroban Map/Vec indexing; avoid format! keys
• Minimum 95% coverage
• Clear documentation and inline comments
• Timeframe: 96 hours

[Kami-no-san]

@Kami-no-san has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi team,

I’d love to take on this issue. Making the archival pruning deterministic and adding cursor-based pagination is a great optimization for handling large archives safely.

I will implement:

Deterministic Sorting: Indexing by (timestamp, market_id) to ensure pruning processes sequentially by resolution timestamp ascending.

Pagination & Safety: Exposing the PruneCursor for paginated processing, removing any risky unwrap() statements within the iteration, and strictly enforcing require_auth for the admin entrypoint.

Robust Testing: Full test coverage including empty archives, single entries, and count > archive_size, validating successful cursor roundtrips.

Could you please assign this to me? Thanks!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Kami-no-san to this issue.

[codenerde]

@codenerde has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Good morning Mr Baskar, please entrust this projects to me sir. I can deliver promptly.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @codenerde to this issue.

[grantfox-oss]

🦊 GrantFox — @Kami-no-san has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #614)
2. Your PR will be reviewed by the Predictify-org maintainers

Good luck! Track your progress on GrantFox.

[drips-wave]

Congratulations, @Kami-no-san! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @Kami-no-san: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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