CreateInvoice

1# CreateInvoice.intent
2# The canonical mission: notes, guarantees, never-rules, targets, and verification.
3
4mission CreateInvoice
5
6note pm:
7  One placed order should become one invoice, even if checkout retries.
8
9note beginner:
10  This mission is about safe invoice creation, not charging the card.
11
12goal
13  Generate an invoice from approved orders
14
15why
16  Customers need accurate invoices that are auditable and never duplicated.
17
18requires
19  Customer
20  ApprovedOrders
21
22input
23  customer: Customer
24  orders: List<Order>
25  idempotencyKey: IdempotencyKey
26    note beginner:
27      A retry key. The same key returns the same invoice instead of creating another.
28    note qa:
29      Send the same order twice with the same idempotency key and expect one invoice.
30
31output
32  invoice: Invoice
33
34guarantees
35  invoice.total is never negative
36  duplicate invoices are not created
37  every invoice is auditable
38
39guarantee duplicate invoices are not created
40  because duplicate billing damages customer trust
41  note risk:
42    Duplicate billing creates refunds, support tickets, finance cleanup, and lost trust.
43  verify duplicate prevention test
44
45never
46  create invoice for unapproved order
47  expose payment token in logs
48
49never expose payment token in logs
50  because logs may be visible to support and observability tools
51  note security:
52    Payment tokens must not appear in logs, events, debug output, proof artifacts, or AI context.
53  verify security scan
54
55target
56  TypeScript
57  DotNet
58  OpenAPI
59  Tests
60  Markdown
61  Mermaid
62
63style
64  CleanArchitecture
65  CQRS
66
67verify
68  unit tests
69  duplicate prevention test
70  audit trail test
71  security scan