feat(F-057): completed feature

work/artifacts/F-057/reviewer.json

@@ -0,0 +1,16 @@
+{
+  "feature_id": "F-057",
+  "agent": "reviewer",
+  "verdict": "APPROVED",
+  "summary": "Minimal and surgical change. CheckoutClient now maps CartContext items to the items array required by the /api/checkout body schema. No API changes, no contract drift, no new dependencies. TypeScript build clean.",
+  "evidence": [
+    "git diff project/frontend/src/components/checkout/CheckoutClient.tsx — only one block added (items mapping)",
+    "npx tsc --noEmit (project/frontend) — exit 0",
+    "./scripts/verify.sh — exit 0",
+    "Before: curl POST without items → 400 INVALID_CART 'El carrito está vacío.'",
+    "After: curl POST with items[] → advances past items validation (401 from backend because of fake session, expected)",
+    "After: curl POST without items still → 400 INVALID_CART (route handler guard still works)",
+    "No new dependencies, no schema migrations, no contract changes"
+  ],
+  "timestamp": "2026-08-19T13:35:00Z"
+}