Quick Start

1npm install @loop-engine/sdk

1"cmt">// @no-typecheck
2import { aggregateId, transitionId } from '@loop-engine/core'
3import { LoopBuilder, createLoopSystem } from '@loop-engine/sdk'
4 
5const approval = LoopBuilder
6  .create('expense.approval', 'finance')
7  .description('Expense report approval')
8  .state('SUBMITTED')
9  .state('UNDER_REVIEW')
10  .state('APPROVED', { isTerminal: true })
11  .state('REJECTED', { isTerminal: true })
12  .initialState('SUBMITTED')
13  .transition({
14    id: 'start_review',
15    from: 'SUBMITTED',
16    to: 'UNDER_REVIEW',
17    actors: ['automation']
18  })
19  .transition({
20    id: 'approve',
21    from: 'UNDER_REVIEW',
22    to: 'APPROVED',
23    actors: ['human']
24  })
25  .transition({
26    id: 'reject',
27    from: 'UNDER_REVIEW',
28    to: 'REJECTED',
29    actors: ['human']
30  })
31  .outcome({
32    id: 'expense_approved',
33    description: 'Expense report approved',
34    valueUnit: 'expense_approved',
35    businessMetrics: [
36      { id: 'm_expense_approved', label: 'Expense report approved', unit: 'count' }
37    ]
38  })
39  .build()
40 
41const { engine, eventBus } = await createLoopSystem({ loops: [approval] })
42eventBus.subscribe(async (event) => console.log(event.type))
43 
44await engine.start({
45  loopId: 'expense.approval',
46  aggregateId: aggregateId('EXP-2026-001'),
47  actor: { type: 'automation', id: 'system:intake', serviceId: 'intake' }
48})
49 
50await engine.transition({
51  aggregateId: aggregateId('EXP-2026-001'),
52  transitionId: transitionId('start_review'),
53  actor: { type: 'automation', id: 'system:router', serviceId: 'router' }
54})
55 
56await engine.transition({
57  aggregateId: aggregateId('EXP-2026-001'),
58  transitionId: transitionId('approve'),
59  actor: { type: 'human', id: 'manager@acme.com', userId: 'manager-1', displayName: 'Manager' },
60  evidence: { comment: 'Approved for Q1 budget' }
61})
62 
63const state = await engine.getState(aggregateId('EXP-2026-001'))
64console.log(state?.currentState) "cmt">// APPROVED
65console.log(state?.status)       "cmt">// completed