> Historical note from the supplied ZIP. Current findings: `142-REQUIREMENT-AUDIT.md` and `CONSOLIDATED-VERIFICATION.md`.

# Variant checkout integration
- Product detail loads active variants and product gallery; selection required when variants exist.
- Cart uses product+variant composite keys and validates variant ownership and stock.
- Checkout locks product and variant records, saves order_items.variant_id, and decrements variant stock within transaction.
- Customer cancellation restores variant stock for variant lines.
- Run migrations after overlay installation. Existing session carts using numeric keys must be emptied.
- Known limitations: other admin/warehouse order transitions and RTO workflows require separate variant-aware reconciliation; creator price overrides are product-wide; MySQL/CI4 end-to-end verification not performed.