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compute_additions_root

dig_block

Function compute_additions_root 

Source 
pub fn compute_additions_root(additions: &[Coin]) -> Bytes32
Expand description

additions_root (header field, SPEC §3.4) — Merkle-set root over created coins grouped by puzzle_hash.

Normative: HSH-004 and Chia block_body_validation (additions handling ~158–175).
Algorithm: Walk additions in slice order; bucket coin IDs by Coin::puzzle_hash. Emit two 32-byte leaves per group, in first-seen puzzle_hash order: [puzzle_hash, hash_coin_ids(ids…)], then chia_consensus::merkle_set::compute_merkle_set_root with DIG empty-set semantics (EMPTY_ROOT when there are no additions).

Why IndexMap instead of HashMap: HSH-004’s pseudocode uses a map for grouping; Chia’s Python uses dict insertion order when flattening groups. Rust’s HashMap iteration order is nondeterministic, which would make roots non-reproducible. IndexMap matches insertion-order semantics and the existing crate::L2Block::compute_additions_root behavior exercised by BLK-004 tests.

hash_coin_ids: sorts multiple IDs descending by bytes, concatenates, SHA-256 — see the crate-internal hash_coin_ids helper and Chia coin.py.

Callers: crate::L2Block::compute_additions_root delegates here after collecting SpendBundle::additions-derived Coins so validation and tooling share one definition.