Module chain 

Proof-event chain and merkle-tree helpers.

Matches tools/tf-types-ts/src/core/chain.ts byte-for-byte via conformance/chain-vectors.yaml.

• event_hash(event) → sha256:<hex> over the canonical JSON of the event with its signature field removed. This is the bytes a signer actually signs; putting the signature inside the event would make the hash self-referential.
• verify_chain(events) → asserts every events[i].parent_hash equals event_hash(events[i-1]) for i > 0 (the first event has no parent).
• merkle_root(events) → sha256 over pair-wise concatenated hashes, duplicating the last leaf at each odd level (Bitcoin convention).
• chain_hash(events) → rolling sha256(prev || event_hash) seeded with 32 zero bytes.

Enums

ChainError

Functions

canonical_of

Minimal serialization helper used by tests that need to serialize an arbitrary Serialize value to canonical JSON.

chain_hash

Rolling chain hash: seeded with 32 zero bytes, then for each event the hash is sha256(prev || sha256_bytes_of_event).

event_hash

The sha256:<hex> hash of an event’s signed payload.

event_signed_payload

Canonical JSON of an event with its signature stripped.

merkle_root

Merkle root over the event hashes. Empty trees return a sentinel zero hash; single-event trees return that event’s hash; otherwise pair-wise hash up, duplicating the last leaf when a level has an odd number of nodes.

verify_chain

Verify a chain of events. events[0] may have no parent_hash; every subsequent event must declare parent_hash == event_hash(events[i-1]).