event emission on all settlement state changes for indexers

[mikewheeleer]

Summary

Some settlement state changes emit no event, so indexers and off-chain systems can't observe them. Emit a documented event on every state change, with tests.

Why this matters

Silent state changes are invisible to indexers and break downstream systems. Complete, tested events make the contract observable.

Requirements

• Emit a documented event on every settlement state change, with the relevant fields.
• No duplicate or missing emissions.
• Assert topics and payload fields in tests.
• Keep topic symbols within Soroban limits.

Technical guidance

• Capture events immediately after the emitting call in tests.
• Avoid topic collisions across event types.

Edge cases — each must have a test

• each state change -> exactly one event
• payload fields correct
• topic symbols valid and unique
• no duplicate emissions
• read-only calls emit nothing

Acceptance criteria

• All requirements and every edge case above implemented and covered by tests
• New unit and integration tests; existing tests still pass and no regressions
• Structured, typed errors (no leaked internals; stable codes)
• cargo fmt --check, cargo clippy --all-targets -- -D warnings, and cargo test all pass locally
• Code follows the repo's existing conventions; no duplication or dead code
• Short docs/comments explaining the design and any non-obvious decisions
• PR description explains the approach and includes Closes #<issue>

Out of scope

• Event schema versioning
• Indexer implementation

Rewards

Part of the GrantFox OSS / Official Campaign (FWC26) — this task may be rewarded. PR quality is assessed by AI: depth, correctness under edge cases, meaningful tests, and clean design are what earn the reward. Shallow changes (typos, formatting, trivial docs) do not qualify.

[guptakumarranjeet150]

Hi everyone,

I would like to resolve this issue. Here is my proposed execution plan:

• Implementation: Implement event emission on all settlement state changes for indexers with explicit require_auth checks, clean storage layouts, and robust Soroban contract logic.
• Testing & Verification: Add comprehensive unit tests verifying both happy-path invocations and unauthorized revert scenarios.
• Delivery: Ready to ship a thoroughly tested PR within 12–24 hours with passing CI.

I am ready to start immediately—please assign this to me!

[ranjeet150]

Hello @maintainers,

I would love to take this on. My planned approach:

• Implement event emission on all settlement state changes for indexers with explicit require_auth checks, clean storage layouts, and robust Soroban contract logic.
• Add comprehensive unit tests verifying both happy-path invocations and unauthorized revert scenarios.

Ready to deliver a clean, tested PR within 12–24 hours. Please assign!