feat(event): add invoice.issued and invoice.paid event contracts

event/event.go

@@ -61,6 +61,13 @@ const (
 	// Payload is an order.Created (platform/order). See docs/inventory-shape.md
 	// and docs/fulfillment-stance.md.
 	OrderCreated Type = "order.created"
+	// InvoiceIssued is emitted when an order is invoiced (pay-later placement or
+	// manual invoice issuance). Payload is an order.InvoiceIssued (platform/order).
+	InvoiceIssued Type = "invoice.issued"
+	// InvoicePaid is emitted when an invoiced order payment status crosses to paid.
+	// Payload is an order.InvoicePaid (platform/order).
+	InvoicePaid Type = "invoice.paid"
+
 
 	// Analytics (tracking). Replaces the integer enum 0–6 that finder and
 	// slask-tracking use on the `tracking` topic today. Producer: slask-finder

order/order.go

@@ -58,3 +58,41 @@ func Decode(raw []byte) (Created, error) {
 	err := json.Unmarshal(raw, &c)
 	return c, err
 }
+
+// InvoiceIssued is the payload of an event.InvoiceIssued envelope.
+type InvoiceIssued struct {
+	OrderID       string `json:"order_id"`
+	InvoiceNumber string `json:"invoice_number"`
+	CompanyID     string `json:"company_id,omitempty"`
+	CustomerEmail string `json:"customer_email,omitempty"`
+	AmountIncVat  int64  `json:"amount_inc_vat"`
+	DueDate       string `json:"due_date"`
+	OCRReference  string `json:"ocr_reference"`
+	IssuedAtMs    int64  `json:"issued_at_ms"`
+}
+
+func (i InvoiceIssued) Encode() ([]byte, error) { return json.Marshal(i) }
+
+func DecodeInvoiceIssued(raw []byte) (InvoiceIssued, error) {
+	var i InvoiceIssued
+	err := json.Unmarshal(raw, &i)
+	return i, err
+}
+
+// InvoicePaid is the payload of an event.InvoicePaid envelope.
+type InvoicePaid struct {
+	OrderID       string `json:"order_id"`
+	InvoiceNumber string `json:"invoice_number"`
+	CompanyID     string `json:"company_id,omitempty"`
+	AmountPaid    int64  `json:"amount_paid"`
+	PaidAtMs      int64  `json:"paid_at_ms"`
+}
+
+func (i InvoicePaid) Encode() ([]byte, error) { return json.Marshal(i) }
+
+func DecodeInvoicePaid(raw []byte) (InvoicePaid, error) {
+	var i InvoicePaid
+	err := json.Unmarshal(raw, &i)
+	return i, err
+}
+

order/order_test.go

@@ -28,3 +28,49 @@ func TestCreatedRoundTrip(t *testing.T) {
 		t.Errorf("line[0] mismatch: %+v", out.Lines[0])
 	}
 }
+
+func TestInvoiceIssuedRoundTrip(t *testing.T) {
+	in := InvoiceIssued{
+		OrderID:       "ord-1",
+		InvoiceNumber: "INV-000001",
+		CompanyID:     "comp-1",
+		CustomerEmail: "a@b.c",
+		AmountIncVat:  14995,
+		DueDate:       "2026-09-15",
+		OCRReference:  "00000139",
+		IssuedAtMs:    1234567890,
+	}
+	raw, err := in.Encode()
+	if err != nil {
+		t.Fatalf("encode: %v", err)
+	}
+	out, err := DecodeInvoiceIssued(raw)
+	if err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	if out.InvoiceNumber != in.InvoiceNumber || out.OCRReference != in.OCRReference || out.AmountIncVat != in.AmountIncVat {
+		t.Fatalf("round-trip mismatch: got %+v, want %+v", out, in)
+	}
+}
+
+func TestInvoicePaidRoundTrip(t *testing.T) {
+	in := InvoicePaid{
+		OrderID:       "ord-1",
+		InvoiceNumber: "INV-000001",
+		CompanyID:     "comp-1",
+		AmountPaid:    14995,
+		PaidAtMs:      1234567990,
+	}
+	raw, err := in.Encode()
+	if err != nil {
+		t.Fatalf("encode: %v", err)
+	}
+	out, err := DecodeInvoicePaid(raw)
+	if err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	if out.InvoiceNumber != in.InvoiceNumber || out.AmountPaid != in.AmountPaid {
+		t.Fatalf("round-trip mismatch: got %+v, want %+v", out, in)
+	}
+}
+