feat(ADM-018): completed feature

work/artifacts/F-017/documenter.md

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+# Documenter — F-017 Pricing module
+
+## Summary
+Documented F-017 pricing behavior in this evidence artifact. Project README updates are not applied during document stage because the active repository guard restricts `project/` product edits to build/implementer state.
+
+## Public API notes
+
+Pricing owns server-side price and VAT truth for product variants. Callers provide variant identity and quantity only; client-supplied prices, tax amounts, discounts, subtotals, or totals are not trusted.
+
+| Route                             | Access     | Result                                      |
+| --------------------------------- | ---------- | ------------------------------------------- |
+| GET /pricing/variants/:variantId  | public     | `200` current server-side variant price     |
+| PUT /pricing/variants/:variantId  | admin only | `200` updated price and history row written |
+| POST /pricing/calculate           | public     | `200` calculated net subtotal, VAT and total |
+
+## Error codes
+- `PRICING_PRICE_NOT_FOUND` — HTTP 404
+- `INVALID_PRICE` — HTTP 422
+
+## Money and VAT rules
+- Money is represented as integer cents only.
+- Currency is fixed to `EUR`.
+- Stored price is `netUnitAmountCents` before VAT.
+- VAT rates:
+  - `general` = 21% (`2100` basis points)
+  - `reduced` = 10% (`1000` basis points)
+- Calculation: `netSubtotal = netUnitAmountCents * quantity`; `vatAmount = round(netSubtotal * vatBps / 10000)`; `total = netSubtotal + vatAmount`.
+
+## Audit/history
+- Current price lives in `pricing_variant_prices`.
+- Every create/update writes an append-only row to `pricing_price_history` with previous and new values.
+- Variant ids are opaque UUIDs; pricing does not import catalog internals or join catalog tables.
+
+## Evidence
+- `work/artifacts/F-017/architect.md`
+- `work/artifacts/F-017/implementer.md`
+- `work/artifacts/F-017/reviewer.json`
+- `work/artifacts/F-017/security.json`
+- `work/artifacts/F-017/qa.json`