Workflow: nodes, routes, and partial state updates

Use a single node definition that actually participates in execution to show order, branches, error destinations, and end conditions together.

When entryNodeId is omitted, the first node is used; the entry must set startsRound. Every node needs a description and at least one route. Conditions are evaluated in array order, and routes without when are normally placed last; jumping to a target and ending with complete are mutually exclusive.

Core checks for duplicate nodes, invalid references, unreachable nodes, and loops that bypass round boundaries at construction time. A node can be a plain object or a class implementing the WorkflowNode structure; Core fixes the callback and its original receiver. describe returns a projection of the definition without the current state or handler implementations.

Progressive examples for the same business case

A single node completes the greeting

Beginner · Node.js

TypeScript

import { AgentCoreEngine, defineWorkflow, route } from '@jangts/agent-core/engine';

type State = { name: string; answer?: string };
const workflow = defineWorkflow<State, string>({
  id: 'greeting',
  nodes: [{
    id: 'greet', description: '根据本次姓名生成问候', startsRound: true,
    run: state => ({ answer: '你好，' + state.name }),
    routes: [route.deliver('answer')],
  }],
});
console.log(workflow.entryNodeId);
console.log(workflow.describe());

JavaScript

import { AgentCoreEngine, defineWorkflow, route } from '@jangts/agent-core/engine';
const workflow = defineWorkflow({
    id: 'greeting',
    nodes: [{
            id: 'greet', description: '根据本次姓名生成问候', startsRound: true,
            run: state => ({ answer: '你好，' + state.name }),
            routes: [route.deliver('answer')],
        }],
});
console.log(workflow.entryNodeId);
console.log(workflow.describe());

Add a validation stage without changing state or the run call

Configuration · Node.js

TypeScript

import { AgentCoreEngine, defineWorkflow, route } from '@jangts/agent-core/engine';
type State = { name: string; answer?: string; error?: string };
const workflow = defineWorkflow<State, string>({
  id: 'greeting',
  nodes: [
    { id: 'check', description: '检查姓名', startsRound: true,
      run: state => ({ error: state.name.trim() ? undefined : '姓名不能为空' }),
      routes: [route.toIfError('failure'), route.to('greet')] },
    { id: 'greet', description: '生成问候', provides: ['answer'],
      run: state => ({ answer: '你好，' + state.name }), routes: [route.deliver('answer')] },
    { id: 'failure', description: '返回校验提示', requires: ['error'], routes: [route.deliver('error')] },
  ],
});
console.log(await new AgentCoreEngine({ workflow }).run({ name: 'Ivan' }));

JavaScript

import { AgentCoreEngine, defineWorkflow, route } from '@jangts/agent-core/engine';
const workflow = defineWorkflow({
    id: 'greeting',
    nodes: [
        { id: 'check', description: '检查姓名', startsRound: true,
            run: state => ({ error: state.name.trim() ? undefined : '姓名不能为空' }),
            routes: [route.toIfError('failure'), route.to('greet')] },
        { id: 'greet', description: '生成问候', provides: ['answer'],
            run: state => ({ answer: '你好，' + state.name }), routes: [route.deliver('answer')] },
        { id: 'failure', description: '返回校验提示', requires: ['error'], routes: [route.deliver('error')] },
    ],
});
console.log(await new AgentCoreEngine({ workflow }).run({ name: 'Ivan' }));

The same node contract can be implemented by a class

Extension · Node.js

TypeScript

import { AgentCoreEngine, defineWorkflow, route } from '@jangts/agent-core/engine';
type State = { name: string; answer?: string };
class GreetingNode {
  readonly id = 'greet';
  readonly description = '根据姓名生成问候';
  readonly startsRound = true;
  readonly routes = [route.deliver('answer')];
  #prefix = '你好，';
  run(state: Readonly<State>) { return { answer: this.#prefix + state.name }; }
}
const workflow = defineWorkflow<State, string>({ id: 'greeting', nodes: [new GreetingNode()] });
console.log(await new AgentCoreEngine({ workflow }).run({ name: 'Ivan' }));

JavaScript

import { AgentCoreEngine, defineWorkflow, route } from '@jangts/agent-core/engine';
class GreetingNode {
    id = 'greet';
    description = '根据姓名生成问候';
    startsRound = true;
    routes = [route.deliver('answer')];
    #prefix = '你好，';
    run(state) { return { answer: this.#prefix + state.name }; }
}
const workflow = defineWorkflow({ id: 'greeting', nodes: [new GreetingNode()] });
console.log(await new AgentCoreEngine({ workflow }).run({ name: 'Ivan' }));

Policies & implementations

• Reference, reachability, and bounded-loop validation