PR_DESCRIPTION_REENTRANCY.md

Reentrancy Module Audit And Documentation

Summary

Audits the hello-world contract reentrancy guard against Soroban's synchronous cross-contract execution model, versions the temporary lock key, and adds focused tests plus contract-crate documentation.

Changes

• documented src/reentrancy.rs with explicit guarantees, limits, and security notes,
• replaced the string temporary-storage key with a versioned ReentrancyDataKey::LockV1,
• added tests for lock acquisition/release, callback-driven re-entry rejection, and entrypoint error mapping,
• added stellar-lend/contracts/hello-world/REENTRANCY.md,
• linked crate documentation back to the reentrancy audit notes.

Security Notes

• The guard protects only same-transaction nested entry on the same contract instance.
• It is defense in depth; authorization, pause switches, and collateral checks remain mandatory.
• Token contracts are treated as untrusted and may attempt callback-based re-entry during transfer or transfer_from.
• borrow_asset keeps the guard in place for production token transfers; tests verify lock rejection at the entrypoint because the token transfer branch is compiled out in unit tests.

Test Output

Run:

cargo test -p hello-world test_reentrancy --lib

Summary:

All reentrancy tests passed locally.