Reject self-referential transfers explicitly

[arisu6804]

Summary

Reject self-referential transfers explicitly.

Context

Tracking issue for the RemitFlow smart contract. Open to contributors.

Acceptance criteria

• Implement the change described above
• Add or update automated tests
• Update the relevant documentation

[Emmanueljr-stack]

Hi! I'd like to work on this issue. I have experience contributing to Soroban/Stellar smart contracts and implementing comprehensive Rust test suites. I'll keep the change focused by explicitly rejecting self-referential transfers, add/update automated tests covering success and failure cases, and update the relevant documentation while maintaining backward compatibility. I'll ensure the implementation follows the project's existing coding style and that all tests pass before submitting the PR. I'd appreciate being assigned this issue. Thanks!

[Emmanueljr-stack]

I'd like to take this issue. I have experience working with Soroban smart contracts, implementing permission and validation logic, and writing thorough Rust tests. I'll add an explicit guard against self-referential transfers, ensure deterministic error handling, update and extend the test suite to cover the new behaviour and edge cases, and document the change clearly. I'll keep the implementation focused, follow the existing contract conventions, and make sure all checks and tests pass before submitting the PR. I'd appreciate being assigned this task. Thank you!

[grantfox-oss]

🦊 GrantFox — @Emmanueljr-stack 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 #89)
2. Your PR will be reviewed by the RemitFlow maintainers

Good luck! Track your progress on GrantFox.

[arisu6804]

This one's yours too, @Emmanueljr-stack! Rejecting self-referential transfers is a good correctness fix.

Questions or just want to say hi? Our contributor group: https://t.me/+8DgYV9HrNaA1Yjg1

[Emmanueljr-stack]

Looked into this — create_transfer already rejects self-referential transfers explicitly via the SameParty error (see src/lib.rs), confirmed it was added in commit 64f6172 feat(contract): reject self-transfers in create_transfer. It's covered by test_create_transfer_rejects_self_transfer in src/test.rs, and documented in docs/error-reference.md. Looks like this was already resolved by a prior merge — safe to close unless there's a different transfer path you'd like this extended to.