tari-project / tari / 33493219414

77%

Build Type

push

github

Committed by web-flow

Commit Message

feat(sidechain)!: add a protocol version to the sidechain block header (#7983)

## Description

Adds a `protocol_version: u32` field to `SidechainBlockHeader` and makes
`calculate_hash` select its hash preimage schema from that field.

## Motivation and Context

The Ootle sidechain resolves its protocol version from a per-network
activation schedule (epoch → version). That table lives on the
sidechain, so today a block gives an L1 verifier no way to tell which
schema it was hashed under — the verifier has to already know the
schedule, and a node running a stale schedule silently hashes a
post-fork block under the superseded schema and diverges instead of
stopping.

Making the header self-describing moves that decision into the block
itself. `tari_sidechain` can hash any block it is handed with no
knowledge of the activation schedule at all, which keeps this crate free
of a table it would otherwise have to track across every sidechain fork.

The window matters: once validator registration is decentralised, the
header format is L1 consensus and changing it costs an L1 coordination
round. The Ootle side is already taking a protocol bump, so this is the
cheap moment to add it.

### Hashing

- Version 0 keeps the existing `BlockHeaderHashFieldsV1` preimage, which
carries no version. Every block ID committed so far stays reproducible —
the existing fixtures are unmodified by this PR and still validate.
- From version 1 the preimage is the new `BlockHeaderHashFieldsV2`,
which commits to `protocol_version` itself. Committing the version
explicitly (rather than relying on the variant discriminant) is what
keeps it non-malleable when a fork bumps the version without changing
the header shape — two such versions would otherwise share a preimage
and a block ID.

`BlockHeaderHashFields` variant indices are consensus-bound and
append-only.

### Compatibility

Version 0 is what a header decodes to when the field is absent, so no
reset is needed to adopt this:

- **s... (continued)

Coverage Stats

28 of 30 new or added lines in 2 files covered. (93.33%)

329 existing lines in 13 files now uncovered.

79343 of 123873 relevant lines covered (64.05%)

216087.18 hits per line