Checkout Enforcement

Checkout enforcement is the practice of evaluating a cart against rules while the buyer is still in checkout, and stopping or changing it before the order is placed. On Shopify, the main surfaces are native discount settings (usage limits, one-use-per-customer, combination rules), Shopify Functions for discounts, delivery and payment customization, and the Cart and Checkout Validation Function, which can return a validation error that keeps the buyer from completing checkout until the problem is fixed. Enforcement actions inside checkout typically take three forms: hard stops (a validation error shown to the buyer), modifications (a discount not applied, a shipping or payment option hidden), and soft nudges (a message suggesting a change). The approach is strongest for rules that can be decided from data already in the cart: quantity limits, address or region restrictions, B2B minimums, and which discount types may combine. Its limits are structural. Logic runs inside Shopify's checkout under strict resource limits, and for most function types it cannot call external systems during execution, so data such as live ERP cost has to be staged in advance (for example in metafields) and can go stale. Every rule is customer-facing, so an overly strict rule costs conversion directly. And rules generally have to be written and maintained as code. The alternative control point is after the order is placed and before it ships. That is where Agentis works: within 60 seconds of each order, it computes true net margin from live store data, NetSuite COGS, freight, fees, and FX, and flags the order or automatically holds it before fulfillment under merchant-approved rules, logging each decision to the Evidence Ledger. Agentis does not use checkout enforcement and cannot stop a checkout; the two approaches are complementary. Use checkout rules for constraints the cart can answer on its own, and a post-order margin check for decisions that need real cost data.