---

name: flow-authoring description: "Guides authoring, checking, running, resuming, and debugging local Metaflow FlowSpec workflows with parameters, configs, files, foreach, and decorators." disable-model-invocation: true metadata: disco-role: operating license: Apache 2.0

Flow Authoring

Use this sub-skill when the task is to create or debug a Metaflow flow script, inspect the flow graph, run locally, resume, or reason about FlowSpec, @step, self.next, parameters, configs, IncludeFile, foreach, or local step decorators.

Quick Route

• Read references/workflows.md for the standard local authoring and CLI loop.
• Read references/parameters-and-configs.md for Parameter, JSONType, Config, config_expr, and IncludeFile behavior.
• Read references/advanced-flow-patterns.md for foreach, joins, merge_artifacts, resume, and local decorators.
• Read references/troubleshooting.md for reserved parameter names, invalid graph transitions, username failures, and file/config issues.
• Run or adapt scripts/hello_flow.py when you need a self-contained starter flow with parameters and foreach.

Minimal Flow Pattern

from metaflow import FlowSpec, Parameter, step

class ExampleFlow(FlowSpec):
    count = Parameter("count", default=3, type=int)

    @step
    def start(self):
        self.values = list(range(self.count))
        self.next(self.work, foreach="values")

    @step
    def work(self):
        self.result = self.input * 2
        self.next(self.join)

    @step
    def join(self, inputs):
        self.results = [task.result for task in inputs]
        self.next(self.end)

    @step
    def end(self):
        print(self.results)

if __name__ == "__main__":
    ExampleFlow()

Use python flow.py --no-pylint check before run when lint dependencies are not installed. Use python flow.py version for the package version.

Boundaries

• For Runner, NBRunner, or programmatic execution, route to ../runner-and-programmatic/SKILL.md.
• For reading finished runs, artifacts, tags, logs, metadata providers, or S3 datatools, route to ../client-and-data/SKILL.md.
• For Cards and current.card, route to ../cards-and-observability/SKILL.md.
• For AWS Batch, Kubernetes, Argo, Step Functions, Airflow, schedules, triggers, secrets, or projects, route to ../deployment-orchestration/SKILL.md.
• For @pypi, @conda, --environment, or package suffixes, route to ../dependency-environments/SKILL.md.