Step-based Workflow System

Synapse SDK provides a step-based workflow system for complex actions that need:

• Multi-phase execution with progress tracking
• Automatic rollback on failure
• State sharing between steps
• Conditional step execution

Core Components

Component	Purpose
BaseStep	Abstract step definition
StepResult	Step execution result
StepRegistry	Ordered step registration
Orchestrator	Step execution with rollback
BaseStepContext	State sharing between steps

Quick Start

from dataclasses import dataclass, field
from synapse_sdk.plugins.steps import (
    BaseStep,
    StepResult,
    StepRegistry,
    Orchestrator,
    BaseStepContext,
)
from synapse_sdk.plugins.context import RuntimeContext

# 1. Define context for state sharing
@dataclass
class ProcessContext(BaseStepContext):
    data: list = field(default_factory=list)
    processed: int = 0

# 2. Define steps
class LoadStep(BaseStep[ProcessContext]):
    @property
    def name(self) -> str:
        return 'load'

    @property
    def progress_weight(self) -> float:
        return 0.3

    def execute(self, ctx: ProcessContext) -> StepResult:
        ctx.data = load_data()
        return StepResult(success=True, data={'count': len(ctx.data)})

class ProcessStep(BaseStep[ProcessContext]):
    @property
    def name(self) -> str:
        return 'process'

    @property
    def progress_weight(self) -> float:
        return 0.7

    def execute(self, ctx: ProcessContext) -> StepResult:
        for item in ctx.data:
            process(item)
            ctx.processed += 1
            ctx.set_progress(ctx.processed, len(ctx.data))
        return StepResult(success=True)

# 3. Register and run
registry = StepRegistry[ProcessContext]()
registry.register(LoadStep())
registry.register(ProcessStep())

context = ProcessContext(runtime_ctx=runtime_ctx)
orchestrator = Orchestrator(registry, context)
result = orchestrator.execute()

Using with Specialized Actions

Override setup_steps() in specialized actions:

from synapse_sdk.plugins.actions.train import BaseTrainAction, TrainContext
from synapse_sdk.plugins.steps import StepRegistry

class MyTrainAction(BaseTrainAction[TrainParams]):
    def setup_steps(self, registry: StepRegistry[TrainContext]) -> None:
        registry.register(LoadDatasetStep())
        registry.register(TrainStep())
        registry.register(UploadModelStep())

Workflow Features

Automatic Progress Tracking

Progress is calculated based on step weights:

# Total weight = 0.2 + 0.6 + 0.2 = 1.0
LoadStep()    # progress_weight = 0.2 -> 0-20%
TrainStep()   # progress_weight = 0.6 -> 20-80%
UploadStep()  # progress_weight = 0.2 -> 80-100%

Automatic Rollback

On failure, executed steps are rolled back in reverse order:

class UploadStep(BaseStep[UploadContext]):
    def execute(self, ctx: UploadContext) -> StepResult:
        ctx.uploaded_files = upload_files()
        return StepResult(success=True)

    def rollback(self, ctx: UploadContext, result: StepResult) -> None:
        for file in ctx.uploaded_files:
            delete_file(file)

Conditional Execution

Skip steps based on context:

class OptionalStep(BaseStep[MyContext]):
    def can_skip(self, ctx: MyContext) -> bool:
        return not ctx.params.get('enable_validation', True)

Detailed References

• references/step-classes.md - BaseStep, StepResult, StepRegistry
• references/orchestrator.md - Orchestrator usage
• references/contexts.md - BaseStepContext and specialized contexts