pacta-executor

Pacta-native execution abstractions: the Executor role and its Middleware composition seam, plus the reified composition mechanism.

Executor handles a claimed pact and reports an Outcome; Execution is its input; Middleware decorates an executor into an executor — the Tower Service / Layer shape narrowed to the lifecycle, with no orchestration baked in. Orchestration such as retry, timeout, and rate limiting is deliberately deferred: it composes onto this seam as Middleware, it is not built in.

Policy is the one user-obligation trait shipped for such a Middleware to consume: Policy::decide(attempts, &error) governs only infrastructure-failure disposition — Verdict::Continue to keep letting a claim lapse and be reclaimed, Verdict::Concede to settle it as a terminal breach instead. It has no bearing on a clean business Outcome, which the shipped Driver always settles as terminal. The concrete, publicly shippable Middleware that consumes a Policy stays sibling- or consumer-owned and does not ship from this crate.

Composition is reified as three values: Identity (the no-op middleware — the empty stack and neutral element), Stack<Inner, Outer> (the closure property as a holdable value that is itself a Middleware), and Composition (a blind assembler that accumulates Stack over Identity through a single generic then, exposing no named policy method). The order is documented and proven by an enter/exit trace: the first middleware added is outermost — entered first and exited last — and the executor is innermost.

Part of Pacta; most consumers depend on the pacta facade rather than this crate directly.

License

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