Concepts
The mental model behind goal-driven orchestration: how Steps connect through Attributes, how a Flow advances through state, the lifecycle of each Step, and the event-sourced architecture that keeps it all deterministic.
How the engine turns a set of Goal Steps into an execution plan, runs steps in parallel where dependencies allow, and advances the Flow only on committed state so retries are deterministic.
Steps are the units of work, sync HTTP, async HTTP, in-engine scripts, or sub-flows. Each declares its inputs, outputs, and lifecycle, and the engine wires them together by attribute name.
A Flow is one execution run driven by a set of Goal Steps. Covers the lifecycle (active, terminal, deactivated), how state advances, and how Flows compose through sub-flow Steps.
Attributes are how Steps share data. Covers the five roles (required, optional, const, meta, output), the five collection policies (first, last, some, all, none), and Collection Deadlines for optional inputs.
A Raft-replicated, event-sourced engine running across a cluster of nodes. Two stores (engine and flow), one execution model, no runtime mutation of plans.
All state in Argyll lives in append-only event logs organized by aggregate. Every state change is an event, and projections are derived deterministically. Includes the full event-type catalog.