Skip to content
Reference

Reference

Status: Pre-release. The spec is in flux and no compatibility guarantees apply until v0.1 is cut.

For learning material (introduction, tutorials, cookbook), see the Guide. For design reasoning and non-goals, see Rationale.

In this document

  • Concepts — orientation. Informative: a minimal Flow, the execution loop, and the model’s vocabulary, each concept pointing to its owning section. Defines the term “the data plane”.
  • The data model — foundation. The RFC 8259 value model, the single number type, and the temporal format profile.
  • The definition format — foundation. The definition as a JSON document: well-formedness, schema documents, and comment.
  • Expressions — foundation. The {{ ... }} embedding, the CEL conformance profile, and the binding namespaces.
  • The Call interface and Result — spine. The first-class call object: target (provider | flow), input, with, and the onSuccess/onFailure arms; and the Result it yields (success value and the failure envelope). Defined here, before its consumers. Consumed by the Call and Gather actions.
  • The Flow object — spine. The one Flow object and all its keys; where it appears (root, named flows, inline); the vars model; Step-name scoping; parameter validation.
  • Steps and step mechanics — spine. What a Step is; shared fields (input/output, assign); the Step lifecycle; catch and failure matching (against the envelope defined in The Call interface and Result).
  • Middleware mechanics — spine. The phase model (onEntry/onSuccess/onFailure/onAlways), composition and ordering, the contract, and how middleware wraps each Call a Step dispatches (Step-level) or a Step-graph (Flow-level).
  • Execution model — The completion contract, the frame lifecycle, and cancellation.
  • Execution context — The runtime data exposed to expressions: frames, frame/Step metadata, and the failure context.
  • Step actions — The Step actions, each with its complete field set. Call and Gather consume the Call interface.
  • Providers — The extension catalogs: the provider model, Call providers, and middleware providers (the spec-defined middleware catalog plus the platform-extensible mechanism).
  • Data flow — synthesis. Informative: how data moves end to end, across Steps, the middleware stack, subflow and Gather boundaries, and the failure path, composing the owning sections’ rules.
  • Conformance — appendix. The conformance profiles and claims, and the consolidated requirements index.
  • Failure code reference — appendix. Every spec-defined failure code in one table.
  • Glossary — appendix. Informative: working definitions of the specification’s terms, each pointing to its owning section.