Fix error before M7

README.md

@@ -158,7 +158,7 @@ sport-store/
 │
 ├── docs/
 │   ├── architecture.md  Boundaries, conventions, risks — read this first
-│   └── adr/             18 decision records
+│   └── adr/             19 decision records
 │
 ├── docker-compose.yml   Backing services; `--profile full` runs everything
 ├── turbo.json  pnpm-workspace.yaml  package.json
@@ -272,7 +272,7 @@ Everything below was run, not assumed:
   `pnpm format:check` clean
 - 7 migrations, 35 tables; seed loads 36 permissions, 6 roles, 3 brands, 8 categories,
   3 collections, 12 products, **155 variants**, 64 uploaded images and 3 dev accounts
-- **57 tests** — RBAC guards, password hashing, translation fallback, `Accept-Language`, the
+- **60 tests** — RBAC guards, password hashing, translation fallback, `Accept-Language`, the
   variant matrix planner, the HTTP client's fetch receiver and retry recursion, the inventory
   list's variant-driven projection, the two admin-schema defects that caused silent data loss, and
   order-number round-tripping
@@ -303,6 +303,12 @@ through Chrome with the console and network panel open:
   media library upload driven from the browser (presign → PUT to MinIO → register, 400×500 PNG
   landed at 10,962 bytes with a date-partitioned UUID key); inventory adjustment from the table
   wrote a ledger entry and the storefront went `OUT_OF_STOCK` → `IN_STOCK` on the next request
+- **Checkout is idempotent:** a request without an `Idempotency-Key` is refused; the same key
+  twice returns the _same_ order rather than a second one; two simultaneous requests with one key
+  yield one order and one clear refusal — total order count grows by exactly one in every case
+- **Order status and fulfilment agree:** `FULFILLED` and `COMPLETED` now set `fulfillmentStatus`,
+  so the "FULFILLED / UNFULFILLED" contradiction can no longer occur; two historical rows were
+  backfilled
 - **Search (M6):** `nocturne` and `running jacket` match exactly; `ao chay bo` finds _Áo Chạy Bộ
   Aero_ without diacritics; `nocturn`, `jaket` and `runing` survive their typos; `velocity`
   matches by brand, `crimson` by colourway, `VEL-NOC` by SKU; `zzzzqqq` correctly finds nothing.