Design a zero-copy state deserialization routine for hot-path fractional balance lookups

[Damola-Sodiq]

Description

Refactor the contract to read fractional token balances directly from raw WASM byte slices, skipping expensive Rust struct allocations.

Architecture & Context

For high-frequency queries like balance checks, deserializing host environment data into full Rust structs consumes massive amounts of CPU instructions. Zero-copy deserialization allows the contract to extract exactly the needed bytes directly from memory, drastically lowering gas fees.

Technical Requirements

• Intercept the raw byte payload from the Soroban host environment.
• Implement pointer arithmetic and offset reading in Rust to extract the i128 balance.
• Ensure all unsafe memory boundaries are heavily documented and proven safe.

Acceptance Criteria

• Hot-path queries execute in a fraction of the original instruction count.
• No heap memory allocations occur during a balance lookup.
• Fuzz tests ensure out-of-bounds byte reads are impossible.

[Digitalasu]

Hi Maintainer, I'd like to work on this issue. I have experience with similar tasks and can begin working on it right away.

[grantfox-oss]

🦊 GrantFox — @Digitalasu 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 #477)
2. Your PR will be reviewed by the Sahara-Pay maintainers

Good luck! Track your progress on GrantFox.