Your First Loop

1SUBMITTED -> UNDER_REVIEW -> APPROVED
2                        \-> REJECTED

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    guards: [
25      {
26        id: 'approval_obtained',
27        severity: 'hard',
28        evaluatedBy: 'runtime',
29        description: 'Approval must be present',
30        failureMessage: 'Approval not obtained'
31      }
32    ]
33  })
34  .transition({
35    id: 'reject',
36    from: 'UNDER_REVIEW',
37    to: 'REJECTED',
38    actors: ['human']
39  })
40  .outcome({
41    id: 'expense_approved',
42    description: 'Expense report approved',
43    valueUnit: 'expense_approved',
44    businessMetrics: [
45      { id: 'm_expense_approved', label: 'Expense report approved', unit: 'count' }
46    ]
47  })
48  .build()
49 
50const aggregate = aggregateId('EXP-2026-001')
51const { engine } = await createLoopSystem({ loops: [approval] })
52 
53await engine.start({
54  loopId: 'expense.approval',
55  aggregateId: aggregate,
56  actor: { type: 'system', id: 'system:intake' }, "cmt">// StartOptions.actor
57  metadata: { source: 'expense_form' } "cmt">// optional application correlation (neutral keys only)
58})
59 
60const reviewResult = await engine.transition({
61  aggregateId: aggregate,
62  transitionId: transitionId('start_review'),
63  actor: { type: 'automation', id: 'system:router' }
64})
65 
66const approveResult = await engine.transition({
67  aggregateId: aggregate,
68  transitionId: transitionId('approve'),
69  actor: { type: 'human', id: 'manager@acme.com' },
70  evidence: { approved: true, comment: 'Within policy' }
71})