[FUZZ] Differential fuzzing failed on push run 30468210569 (main@81a7b9c60b567c3152ca59a2f86aad843bb8f034)

[github-actions]

Summary

Failing Test

• EVM (Foundry)
• Soroban (Proptest)
• Cross-validation

Test name: testFuzz_... or prop_...

Reproduction

Counterexample

[FAIL. Reason: ...]
  Counterexample: calldata=0x...
  args=[...]

proptest-regressions/fuzz/<test_name>.txt

Reproduce Locally

# Solidity
cd contracts/evm
forge test --match-test <test_name> --fuzz-seed <SEED>

# Rust
cd contracts/soroban/settlement
cargo test fuzz -- <test_name> --nocapture

Failing Payload

0x...

Analysis

Expected Behavior

Actual Behavior

Divergence Type

• Round-trip mismatch (encode → decode != original)
• Asymmetric rejection (one side accepts, other rejects)
• Incorrect error (wrong revert reason)
• Length mismatch
• Field corruption
• Other: ___________

Impact Assessment

Severity

• Critical — can cause fund loss
• High — breaks cross-chain settlement
• Medium — causes rejection of valid messages
• Low — edge case, unlikely in practice

Affected Message Types

• FillConfirmed
• CancelIntent
• FillInstruction (future)
• Other: ___________

Exploitability

Root Cause

Location:

• Solidity: contracts/evm/src/PerihelionEscrow.sol:L???
• Rust: contracts/soroban/settlement/src/messages.rs:L???

Issue:

Fix

Proposed Solution

Regression Test

• Add failing case to fixed golden vectors (neg/*.hex)
• Commit proptest regression file
• Add explicit unit test covering this case

Checklist

• Reproduced locally
• Impact assessed
• Root cause identified
• Fix implemented
• Regression test added
• Both codecs pass differential fuzz after fix
• Golden vectors updated if needed