Add contract events for TTL extension and protocol fee recipient updates with shared event assertion helper

[Chucks1093]

Summary

Two admin and lifecycle operations — storage TTL extension and protocol fee recipient updates — emit no observable events, leaving indexers with no signal unless they poll storage directly. Both events should be added together with a shared test assertion helper that makes event verification consistent across all future event tests.

Scope

• Emit a contract event on TTL extension with fields: creator_id, extended_at_ledger, new_expiry_ledger
• Emit a contract event on set_protocol_fee_recipient with fields: old_recipient, new_recipient, updated_at_ledger
• Each event must use a distinct topic so indexers can filter without scanning all events
• Add assert_event(env, contract_id, topic, expected_fields) test helper — extracts events from transaction result meta, filters by topic, compares fields with a clear mismatch message
• Use the helper in tests for both new events

Acceptance Criteria

• TTL extension event emitted with correct fields on every extension call
• Fee recipient event emitted with correct fields on every admin update
• Each event has a distinct topic
• assert_event helper filters by topic and contract correctly
• Field mismatch produces a clear assertion message
• Both new event tests use the shared helper

ETA: 12 hours

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Coordinate on Telegram

[DingiDinigi]

I'm an experienced Rust/Web3 developer with hands-on Soroban/smart-contract experience, including work with contract events, storage TTL management, and admin-controlled lifecycle functions. I've reviewed the TTL extension and set_protocol_fee_recipient paths — both are silent right now, which blurs indexer visibility into state changes that matter for downstream systems.

I'll add distinct-topic contract events for both operations with the specified fields, build the shared assert_event helper to extract and filter events from transaction meta with clear mismatch messaging, and wire both new event tests through it so future event tests have one consistent pattern to follow instead of duplicating assertion logic.

I can deliver within the 12-hour window, with full test output included in the PR description.

[JamesVictor-O]

Hello! I’d love to take on this issue. I’ve reviewed the requirements and have a clear path forward for the implementation. I estimate I can have a PR ready within about 3 hours of being assigned. Could you please assign this to me?

[grantfox-oss]

🦊 GrantFox — @JamesVictor-O has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #573)
2. Your PR will be reviewed by the accesslayerorg maintainers

Good luck! Track your progress on GrantFox.