Output Root

The output root is a Merkle root over computation results. HDP follows the OpenZeppelin StandardMerkleTree approach with double-hashed leaves.

Key properties

• Leaves are hashed twice with Keccak.
• The tree is built over unordered leaves.
• Results are endian-adjusted for Solidity compatibility.

What gets hashed

The leaf list is derived from the Cairo module return data (retdata). The output root commits to the module's results, not the full execution trace.

Implementation

See compute_merkle_root in src/utils/merkle.cairo.