backend phase 11

product/data-model/06-payments-ledger-and-refunds.md

@@ -118,3 +118,19 @@ This is the most-changed domain. The previous model **inferred** money state fro
 | `issued_at` | DATETIME2 | |
 
 **Relations:** 1:1 → `bookings`; N:1 → `partner_centers` (when issuer).
+
+### As built (backend-phase-11)
+- **`refunds.refund_channel` canonical code is `manual`** (not `manual_bank`) for the out-of-band bank refund —
+  the two are the same channel; `manual` is the value stored and served. Set: `psp_card` | `bnpl_revert` | `manual`.
+- **`refunds.ticket_id`** ships as a **nullable column with no FK** (the `tickets` table arrives in b15); the
+  "ticket required" rule is gated by the `refund_ticket_required` config flag (default off).
+  **`nurse_clawbacks.original_payout_id` / `recovered_in_payout_id`** and **`invoices.partner_center_id`** are
+  likewise nullable, FK-less join points that b13 / b15 fill.
+- **`invoices.vat_irr = round(platform_commission_irr × vat_rate)`**, integer-only, on the commission line only; a
+  `vat_rate = 0` exemption yields `vat_irr = 0`.
+- **`invoices.invoice_number`** is drawn from a single-row **counter table** (`invoice_number_sequences`), locked
+  and committed with the invoice insert — gap-free, unique, portable across SQL Server / SQLite (no DB sequence),
+  never random/timestamp-derived. One issued invoice per booking (idempotent).
+- The refund posts the balanced reversal via the b10 ledger helper; the **`refund_payable ↔ escrow_held` clearing**
+  posts immediately for a succeeded card refund and is deferred to reconciliation for a `processing` BNPL/manual
+  refund. Card and BNPL post the **same** reversal legs.