Crate choir_oplog 

Append-only operation log: the L1 wire format and the log-backend seam.

One-way-door rules (DECISIONS.md) enforced here:

• every persisted entry carries format_version
• hashes are self-describing (codec byte + digest), so the hash function can change under the same envelope (D6)
• witnesses exists from day 1 and stays empty (D67), so the append-only → witnessed swap (D16) is additive, not a migration

Examples

use choir_oplog::{MemLog, OpEntry, OpLog, FORMAT_VERSION};

let mut log = MemLog::new();
let genesis = OpEntry {
    format_version: FORMAT_VERSION,
    parent: None,
    seq: 0,
    channel: "agent-1".into(),
    payload: b"first op".to_vec(),
    witnesses: Vec::new(),
    author_sig: None,
};
let head = log.append(genesis).unwrap();
assert_eq!(log.head(), Some(head));
assert_eq!(log.len(), 1);

Where this sits

docs/architecture.md is the map of the whole workspace. This crate is L1, the op log’s wire format and the seam every log backend implements.

It builds on choir_hash.

Modules

repair

Inspecting and repairing a log file that a daemon is not holding.

scheme

Signature scheme identifiers for Witness::scheme (D39).

Structs

ContentHash

Self-describing content address (multihash-style envelope).

FileLog

Second implementation (seam rule: feature-poor is fine, broken is not): JSON-lines file, append-only, rebuilt head on open.

MemLog

Primary in-memory implementation (also the dev/test runtime).

OpEntry

One operation in the log. Payload semantics live above this layer.

Witness

A cosignature: a witness cosignature (never populated here, D67) or, in OpEntry::author_sig, the author’s own. Present in the format from the first persisted byte so adding witnessing never rewrites history.

Enums

LogError

Failure modes of an OpLog backend.

Constants

FORMAT_VERSION

Current wire-format version. Bump on any incompatible change; additive changes keep the version (DECISIONS.md).

Traits

OpLog

The log-backend seam (D16). Conformance suite: tests/it/conformance.rs, run against every implementation.

Functions

signing_hash

Hash over an author’s submission content — see OpEntry::signing_hash. Standalone so clients can sign before the sequencer has built the entry.