stageflow-framework 0.1.2

StageFlow: Pipeline framework for stages

StageFlow

StageFlow is a lightweight framework for describing and running JSON pipelines with nodes, stages, and schema validation.

Features

• Node types: stage, condition, parallel, map, subpipeline, terminal.
• Custom stages (async run) with documented arguments/config/outputs.
• Input waiting (wait_input), event history, session snapshots.
• Built-in stages for dict/list/string/logic utilities.
• Pipeline JSON Schema (stage enum injected on the fly) and HTML doc generator.

Installation

python -m venv .venv
source .venv/bin/activate  # Windows: .venv\Scripts\activate
pip install stageflow-framework
# or for local dev:
# pip install -e .

Requires Python 3.10+.

Quickstart

1. Register your stage:

from stageflow.core.stage import BaseStage, register_stage

@register_stage("HelloStage")
class HelloStage(BaseStage):
    """
    description: "Custom stage example"
    arguments:
      name: string
    outputs:
      greeting: string
    """
    async def run(self):
        name = self.get_arguments().get("name", "world")
        self.set_outputs({"greeting": f"Hello, {name}!"})

2. Describe a pipeline in JSON:

pipeline_dict = {
    "entry": "start",
    "nodes": [
        {
            "id": "start",
            "type": "stage",
            "stage": "HelloStage",
            "arguments": {"name": "user_name"},
            "outputs": {"greeting": "greeting"},
            "next": "finish",
        },
        {
            "id": "finish",
            "type": "terminal",
            "result": {"status": "ok"},
            "artifacts": ["greeting"],
        },
    ],
}

3. Run:

import asyncio
from stageflow.core.pipeline import Pipeline
from stageflow.core.session import Session
from stageflow.core.context import Context

async def main():
    pipe = Pipeline.from_dict(pipeline_dict)
    session = Session(id="demo", pipeline=pipe, context=Context(payload={"user_name": "Alice"}))
    result = await session.run()
    print(result.result)        # {'status': 'ok'}
    print(result.artifacts)     # {'greeting': 'Hello, Alice!'}

asyncio.run(main())

Docs and schema generation

• Programmatic:

from stageflow.docs.html import generate_docs_assets

html_page, pipeline_schema, stages_json = generate_docs_assets()
# html_page — ready-to-serve HTML
# pipeline_schema — dict with JSON Schema (stage enum injected)
# stages_json — raw JSON with stage specs

• CLI (prints JSON payload with html, pipeline_schema, stages_json to stdout):

python scripts/generate_docs_html.py > docs_assets.json

If needed, persist the html from the JSON payload yourself.

Tests

python -m unittest

Node types overview

• stage: Executes a registered Stage. Fields: stage (name), config/arguments/outputs mappings, next, optional fallback.
• condition: List of {if, then} branches (JsonLogic conditions), optional else.
• parallel: Runs several children; policy = all|any, cancel_on_error flag, optional next.
• map: Iterates over items path, runs body node for each item (sequential/parallel), collects mapped outputs.
• subpipeline: Invokes nested pipeline by id, with inputs mapping, artifact_outputs, optional result_output, next.
• terminal: Ends execution, returns result and selects artifacts.

Node types in detail

• Stage node
  • Required: id, type="stage", stage (registered stage name).
  • Data flow: arguments map context paths -> stage inputs; outputs map stage return keys -> context paths.
  • Control flow: next points to following node; optional fallback node is used on stage exceptions.
  • Stage class declares skipable, allowed_events, allowed_inputs, timeout, retries.
• Condition node
  • Required: id, type="condition", non-empty conditions list.
  • Each condition: { "if": <JsonLogic>, "then": "<node id>" }; first matched branch wins.
  • Optional else target if no branch matches.
• Parallel node
  • Required: id, type="parallel", non-empty children (node ids).
  • policy: all (default) waits all children; any completes on first success.
  • cancel_on_error: whether to cancel siblings on failure.
  • next: node id to continue after parallel finishes.
• Map node
  • Required: id, type="map", items (context path with iterable), body (node id).
  • mode: sequential (default) or parallel for body executions.
  • output_map: map of body outputs -> target context paths for aggregated results.
  • item_path/index_path: where to inject current item/index into context for body runs.
  • cancel_on_error: abort remaining iterations on error.
  • next: node id after all iterations finish.
• Subpipeline node
  • Required: id, type="subpipeline", subpipeline_id (key in subpipelines dict of pipeline).
  • inputs: context mapping passed into subpipeline root context.
  • artifact_outputs: map subpipeline artifacts -> parent context paths.
  • result_output: path in parent context to store subpipeline result.
  • next: next node in parent pipeline.
• Terminal node
  • Required: id, type="terminal".
  • result: arbitrary object returned as final result.
  • artifacts: list of context paths that will be returned as artifacts map.

Built-in stages

• Vars: SetValueStage, CopyValueStage, IncrementStage, MergeDictStage.
• Dicts: PickKeysStage, DropKeysStage.
• Lists: AppendListStage, ExtendListStage, FilterListStage, UniqueListStage, PopListStage.
• Strings: ConcatStage, TemplateStage.
• Logic: AssertStage, FailStage, LogStage, SleepStage.

Each stage docstring describes arguments/config/outputs; they are also available via generate_docs_assets() / stages_json.

Useful refs

• stageflow/core — core (pipeline, session, nodes, context).
• stageflow/builtins — built-in stages.
• stageflow/docs — schema/HTML generation helpers.
• scripts/ — helpers (docs generator wrapper).
• tests/ — unit tests.