Design an optimistic UI state reconciler for fractional token swaps with automatic rollback on RPC failure

[Damola-Sodiq]

Description

Build a sophisticated optimistic mutation layer in React Query that updates token balances instantly upon wallet signature, handling complex rollbacks if the network rejects the transaction.

Architecture & Context

Waiting for blockchain finality destroys the UX of trading fractional assets. The UI must predict the outcome of the trade, update the local cache immediately, and invisibly reconcile the true state once the block closes.

Technical Requirements

• Intercept tRPC/React Query onMutate hooks to snapshot the previous cache state.
• Apply the exact fractional math locally to predict the new user balances.
• Implement onError handlers to cleanly restore the snapshot if the Soroban RPC returns a tx_failed status.

Acceptance Criteria

• Token balances update to the millisecond the user signs the transaction.
• Failed transactions gracefully and invisibly revert the UI to the prior true state.
• Concurrent overlapping optimistic mutations resolve accurately.

[benzy018]

Hi maintainer, I would like to work on this issue, please assign it to me

[grantfox-oss]

🦊 GrantFox — @benzy018 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 #470)
2. Your PR will be reviewed by the Sahara-Pay maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@benzy018's PR #505 was approved and merged by @Damola-Sodiq.

🏆 @benzy018: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (366 total points). Track your full progress on GrantFox.

👏 Great work, @benzy018! Keep contributing to Sahara-Pay.