Vyuh Workflow Engine

Business Process Orchestration

A powerful, extensible workflow engine for Dart and Flutter applications. Build complex business processes, approval flows, and stateful automations with a clean, composable API.

Why Workflow Engine?

Visual Process Modeling

Define executable workflows with a fluent builder or load persisted workflow definitions from storage.

Human-in-the-Loop

Built-in support for user tasks, approvals, and signal-based interactions.

Persistent State

Storage repositories persist definitions, instances, user tasks, and append-only workflow events.

Fully Extensible

Type registries for custom task executors, conditions, signals, and more.

Getting Started

InstallationAdd to your Dart or Flutter project

Quick StartBuild your first workflow

ArchitectureUnderstand the engine design

Core Concepts

• Workflow — The blueprint for your business process
• Workflow Instance — A running execution of a workflow
• Workflow Descriptor — Register executors with the engine
• Tokens — Track execution position through the graph
• Data Flow — How data moves through your workflow
• Type Registries — Extend the engine with custom executors

Node Types

Node	Purpose
Start/End	Entry and exit points
Task	Automated tasks
User Task	Human interactions
Signal Wait	Wait for external events
Gateways	Branching and merging

Patterns & Examples

Control FlowBranching, looping, and parallel executionApprovalsCanonical CDX approval template and domain dispatchError HandlingCompensation and retry strategiesCDX IntegrationTemplates, Supabase, feature inboxes, protocol, and editor wiringSimple ApprovalBasic approval workflow exampleParallel TasksConcurrent task execution

Quick Example

final context = RegistryTypeResolver(
  descriptors: [DefaultWorkflowDescriptor()],
);

final engine = WorkflowEngine(
  context: context,
  storage: InMemoryStorage(),
  executionMode: ExecutionMode.production,
);
await engine.initialize();

// Define a simple approval workflow
final workflow = WorkflowBuilder('expense-approval', 'Expense Approval')
    .start('begin')
    .task('validate-expense', execute: (ctx) async {
      return {'valid': true};
    })
    .userTask('manager-review',
        signal: 'approval_decision',
        schemaType: 'userTask.approval',
        assignToRole: 'managers',
        storeAs: 'approvalResult')
    .oneOf('decision', [
      Branch.whenTrue('approvalResult.approved', then: 'process-payment'),
      Branch.otherwise(then: 'notify-rejection'),
    ])
    .task('process-payment', execute: (ctx) async {
      return {'processed': true};
    })
    .end('completed')
    .from('decision').to('notify-rejection')
    .task('notify-rejection', execute: (ctx) async {
      return {'notified': true};
    })
    .end('rejected')
    .build();

// Register and start the workflow
engine.registerWorkflow(workflow);
final instance = await engine.startWorkflow(
  workflowCode: workflow.code,
  input: {'amount': 500, 'description': 'Conference travel'},
);

For production CDX approvals, prefer the canonical ApprovalTemplate from cdx_workflow_templates and load its stored approval definition at boot. See Approval Workflows and CDX Integration.