pacta-contract

The isolated core contract for Pacta: the durable lifecycle vocabulary, the colorless lifecycle kernel, and the sans-I/O step-driver kernel.

This crate defines the types the workspace is built on — Pact, Claim, Retainer, Timestamp, and Outcome / Settlement — and the Registry lifecycle trait, with time injected at its seam so the core reads no ambient clock.

A backend implements three primitives — a native claim selection, a lease_millis accessor, and an atomic apply(retainer, transition) transition port — and inherits heartbeat, fulfill, breach, and release as default methods over apply. The transition semantics live once in the colorless lifecycle module (State, the on_X transition decisions, the is_claimable predicate, and the lease arithmetic), which both bindings compose over so they cannot drift. That lifecycle module plus the Transition port type is the backend-author surface.

Behind the async feature it also ships AsyncRegistry — the same five-op contract made asynchronous, a second binding over the same transition port (native async fn in traits, Send-agnostic at its futures) — and the optional apply_via_cas compare-and-set helper. A backend type in either binding need not be Send or Sync, so a single-threaded backend may stay local; callers that share a backend across threads add those bounds themselves. The pure Transition closure remains Send + Sync independently. A sync-only consumer that does not enable async compiles none of it.

It also holds the advanced-tier kernel: a pure step-driver state machine that decides the lifecycle through Directive / Notice, performs no I/O, and exposes no async fn, so it commits to no runtime shape. (The kernel step-driver is distinct from the lifecycle kernel: the facade re-exports lifecycle but excludes kernel.)

It depends only on serde and uuid. Most consumers should depend on the pacta facade instead; depend on pacta-contract directly to implement a Registry backend or to build a custom runtime over the step-driver kernel.

Part of Pacta.

License

Licensed under either of Apache-2.0 or MIT, at your option.