Quick Start

1npm install @loop-engine/sdk

1import { LoopBuilder } from '@loop-engine/sdk'
2 
3const approval = LoopBuilder
4  .create('expense.approval', 'finance')
5  .description('Expense report approval')
6  .state('SUBMITTED')
7  .state('UNDER_REVIEW')
8  .state('APPROVED', { isTerminal: true })
9  .state('REJECTED', { isTerminal: true })
10  .initialState('SUBMITTED')
11  .transition({
12    id: 'start_review',
13    from: 'SUBMITTED',
14    to: 'UNDER_REVIEW',
15    actors: ['automation']
16  })
17  .transition({
18    id: 'approve',
19    from: 'UNDER_REVIEW',
20    to: 'APPROVED',
21    actors: ['human']
22  })
23  .transition({
24    id: 'reject',
25    from: 'UNDER_REVIEW',
26    to: 'REJECTED',
27    actors: ['human']
28  })
29  .outcome({
30    id: 'expense_approved',
31    description: 'Expense report approved',
32    valueUnit: 'expense_approved'
33  })
34  .build()

1import { aggregateId, transitionId } from '@loop-engine/core'
2import { createLoopSystem } from '@loop-engine/sdk'
3 
4const { engine, eventBus } = createLoopSystem({ loops: [approval] })
5eventBus.subscribe(async (event) => console.log(event.type))
6 
7await engine.start({
8  loopId: 'expense.approval',
9  aggregateId: aggregateId('EXP-2026-001'),
10  actor: { type: 'automation', id: 'system:intake', serviceId: 'intake' }
11})
12 
13await engine.transition({
14  aggregateId: aggregateId('EXP-2026-001'),
15  transitionId: transitionId('start_review'),
16  actor: { type: 'automation', id: 'system:router', serviceId: 'router' }
17})
18 
19await engine.transition({
20  aggregateId: aggregateId('EXP-2026-001'),
21  transitionId: transitionId('approve'),
22  actor: { type: 'human', id: 'manager@acme.com', userId: 'manager-1', displayName: 'Manager' },
23  evidence: { comment: 'Approved for Q1 budget' }
24})
25 
26const state = await engine.getState(aggregateId('EXP-2026-001'))
27console.log(state?.currentState) "cmt">// APPROVED
28console.log(state?.status)       "cmt">// CLOSED