new-arnold-pipeline-template

New Arnold Pipeline Template

Copy arnold_pipelines/_template/ to a new package under arnold_pipelines/, rename it (remove the leading underscore), and replace the skeleton native declarations with real pipeline logic.

This template is native-first. Every package built from it uses @pipeline, @phase, @decision, parallel, compile_pipeline, and project_graph to declare a native program and project it into a Pipeline shell that the runtime executes directly.

Contract

• build_pipeline() -> arnold.pipeline.Pipeline returning a projected shell with a non-null native_program.
• Module-level metadata: name, description, driver, entrypoint, arnold_api_version, capabilities.
• driver must be ("native", "<kind>") (e.g. ("native", "project+validate")).
• supported_modes must include "native" (e.g. ("native",)).
• Optional: default_profile, recommended_profiles.

New packages must be native-first. Do not add _legacy.py, graph fallback builders, compatibility namespaces, shim packages, or temporary wrapper modules for new work — those patterns are explicitly disallowed.

Dispatch Substrate, Not Final Composition

The native_program attached to the projected Pipeline is a dispatch substrate. It describes how the runtime lowers and executes pipeline topology, but it does not define the final visible compositional semantics (panel synthesis, join delegation, parallel merge strategy, subpipeline ownership, or Capsule projection). Those compositional concerns are deferred to later Megaplan layers above the dispatch boundary.

Package authors should treat native_program as the execution-level contract: a non-null program proves the package is native-runnable, but the exact shape of how composition is rendered for end users, agents, or Capsules is not finalised at this layer.

Example

from arnold.pipeline import Pipeline, StepResult, compile_pipeline, phase, pipeline, project_graph


@phase(name="draft")
def draft(ctx: object) -> StepResult:
    return StepResult(outputs={"draft": "TODO"}, next="publish")


@phase(name="publish")
def publish(ctx: object) -> StepResult:
    return StepResult(outputs={"final_artifact": "TODO"}, next="halt")


@pipeline(name="my-pipeline", description="draft → publish")
def my_pipeline_native(ctx: object) -> Any:
    state = yield draft(ctx)
    state = yield publish(ctx)
    return state


def build_pipeline() -> Pipeline:
    native = compile_pipeline(my_pipeline_native)
    return project_graph(native, key_mode="phase")