Sale prices are validated to be less than base prices

A sale price equal to or greater than the base price (salePrice >= basePrice) is a deceptive pricing display: the customer sees a crossed-out "original" price that is lower than or equal to the "sale" price. The FTC Act prohibits deceptive pricing, and several state consumer protection statutes specifically require that a reference price must reflect a genuine prior offer. CWE-20 (Improper Input Validation) covers this at the technical layer — the API accepts a logically invalid price relationship with no rejection. Even without legal exposure, a visible sale price of $60 crossed out next to a regular price of $50 destroys customer trust immediately.

Add a validation guard in src/app/api/products/route.ts that rejects product updates where salePrice >= basePrice.

if (salePrice !== undefined && salePrice >= basePrice) {
  return Response.json(
    { error: 'Sale price must be strictly less than base price' },
    { status: 400 }
  )
}

Also add a database-level check constraint if your Postgres version supports it:

ALTER TABLE products
  ADD CONSTRAINT sale_price_less_than_base
  CHECK (sale_price IS NULL OR sale_price < price);

• ID: ecommerce-catalog.variant-pricing.sale-price-valid

• Severity: medium

• What to look for: Count all sale price or discount price fields in the product and variant schemas (salePrice, discountedPrice, compareAtPrice). Enumerate all product update paths in src/app/api/products/ that accept sale price values. For each path, check whether validation exists to ensure salePrice < basePrice.

• Pass criteria: If sale prices exist in the schema, at least 1 validation path ensures salePrice < basePrice and rejects or errors when the constraint is violated. Count all product update paths and report: "X of Y update paths validate sale price < base price."

• Fail criteria: Products can be created or updated with salePrice >= basePrice, or no validation prevents this logical error in any code path.

• Skip (N/A) when: The project has no sale price functionality — confirmed by finding no salePrice, discountedPrice, or compareAtPrice fields in the schema.

• Cross-reference: For pricing display on promotional pages, the Marketing Content Quality audit covers promotional accuracy.

• Cross-reference: For sale price compliance in app stores, the App Store IAP & Subscriptions audit covers pricing rule enforcement.

• Cross-reference: For consumer protection around sale pricing, the FTC Consumer Protection audit covers deceptive pricing practices.

• Detail on fail: "No validation in src/app/api/products/route.ts — 3 products have salePrice greater than or equal to basePrice (e.g., base=$50, sale=$60 in prisma/seed.ts)"

• Remediation: Add validation in src/app/api/products/route.ts when updating product prices:

  if (salePrice && salePrice >= basePrice) {
    throw new Error('Sale price must be less than base price')
  }