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footprintjs

footprintjs

Build → Run → Observe. Every pipeline self-documents as it runs.
Quick Start Interactive Playground

Why footprintjs?

Section titled “Why footprintjs?”

Self-documenting pipelines

Every stage writes its own narrative as it runs — no post-processing, no log parsing. chart.recorder(narrative()).run() tells you exactly what happened and why.

Typed from the start

Define your state as a TypeScript interface. TypedScope<T> gives you full type inference inside every stage — no casts, no getValue() as string.

Decision evidence capture

decide() and select() auto-capture which values matched which rules. Narrative: “creditScore 750 gt 700 ✓ → chose approved.”

Composable by design

Subflows compose like functions. getSubtreeSnapshot() gives you time-travel debugging at any depth. Works with MCP and OpenAPI out of the box.

How it works

Section titled “How it works”

The 3-step pattern

Section titled “The 3-step pattern”
import { flowChart, decide, narrative } from 'footprintjs';


// 1. Define your state
interface OrderState {
  orderId: string;
  total: number;
  tier?: string;
  status?: string;
}


// 2. Build your flowchart
const chart = flowChart<OrderState>('Validate', async (scope) => {
  scope.tier = scope.total > 100 ? 'premium' : 'standard';
}, 'validate')
  .addDeciderFunction('Route', (scope) => {
    return decide(scope, [
      { when: { tier: { eq: 'premium' } }, then: 'express', label: 'Premium order' },
    ], 'standard');
  }, 'route')
  .addFunctionBranch('express', 'ExpressShip', async (scope) => {
    scope.status = 'express-shipping';
  })
  .addFunctionBranch('standard', 'StandardShip', async (scope) => {
    scope.status = 'standard-shipping';
  })
  .setDefault('standard')
  .end()
  .build();


// 3. Run and observe
const rec = narrative();
await chart.recorder(rec).run({ input: { orderId: 'ORD-001', total: 149 } });


console.log(rec.lines().join('\n'));
// Stage 1: The process began with Validate.
// Stage 2: Next, it moved on to Route.
// [Condition]: It evaluated Rule 0 "Premium order": tier "premium" eq "premium" ✓, and chose express.
// Stage 3: Next, it moved on to ExpressShip.