Commercetools Commerce Patterns

Workflow

When this skill is invoked, always follow these steps:

1. Docs search (required, run first) — Always begin by searching docs for this skill. This is the mandatory grounding step: it gathers the latest verified documentation as context for you (the agent). Do not skip it, and do not replace it with another tool (such as an MCP documentation-search tool) This script optimizes for tuned search results — run this command:

   node scripts/docs-search.mjs \
     --query "<extract key terms from user's question>" \
     --app-name "<current-app ex: claude, copilot, codex>" \
     --model "<current-model>" \
     --skill-name "commercetools-commerce-patterns" \
     --limit 10
   

   Use its output as your primary grounding. You may additionally use other tools (such as the commercetools documentation MCP) for deeper, follow-up search.

2. Combine with skill references — Cross-reference the analysis output with local references in ./references/ for complete context.

3. Provide implementation guidance — Synthesize the documentation with the specific integration mode the user is targeting.

Optional scripts

Fetch GraphQL schema — Run this when you need context about a commercetools GraphQL query or mutation — for example, to inspect a resource's fields, types, and available operations before writing a query, or to verify a GraphQL query/mutation you have just generated against the real schema. It fetches the partial GraphQL SDL for a single commercetools resource:

node scripts/graphql-schemata.mjs \
  --resource-name "<commercetools resource, e.g. Cart, Product, Order>" \
  --app-name "<current-app, e.g. claude, copilot, cursor, codex>" \
  --model "<current-model>" \
  --skill-name "commercetools-commerce-patterns"

The output is the GraphQL SDL for that resource. If the resource name is not recognized, the script prints the list of valid resource names — pick the correct one and re-run. Note: the SDL may contain stubbed types — referenced resources rendered as stubs, with their real type name given in a comment. Fetch any you need separately by re-running this script with that type name as --resource-name.

Fetch OpenAPI (REST) schema — Run this when you need context about a commercetools REST endpoint, request/response payload, or update action — for example, to inspect a resource's REST operations before constructing a request, or to verify a REST request/payload you have just generated against the real specification. It fetches the partial OpenAPI specification for a single commercetools resource:

node scripts/openApi-schemata.mjs \
  --resource-name "<commercetools resource, e.g. api-Cart-write, api-Customer-read, checkout-Application>" \
  --app-name "<current-app, e.g. claude, copilot, cursor, codex>" \
  --model "<current-model>" \
  --skill-name "commercetools-commerce-patterns"

The output is the OpenAPI specification (YAML) for that resource. REST resources use a read/write-split naming form (e.g. api-Cart-read, api-Cart-write). If the resource name is not recognized, the script prints the list of valid resource names — pick the correct one and re-run. Note: the spec does not include reference-expansion schemas — fetch a referenced resource's schema separately by re-running this script with that resource as --resource-name.

Key Takeaways

Discount stacking follows a strict priority chain. Product Discounts → Cart Discounts → Discount Codes → Direct Discounts. Direct Discounts on a cart block all Discount Codes. Never mix Direct Discounts and Discount Code flows on the same cart.

sortOrder direction: higher value fires first. For both Product Discounts and Cart Discounts, the discount with the highest sortOrder value (closest to 1) is applied first. 0.9 fires before 0.5. For Product Discounts only one applies (no stacking); for Cart Discounts they stack by default unless stackingMode: StopAfterThisDiscount is set.

Product Discounts cannot be used with external pricing. If a project uses an external price source, Product Discounts are not applied. Use Cart Discounts for any promotional discounts when external pricing is active.

Discount Groups bundle multiple cart discounts under one entity. A Discount Group has its own sortOrder and a "Best deal" prioritization mode — only the cart discount from the group that gives the customer the greatest saving is applied. Use Discount Groups to manage large-scale campaigns (e.g., Black Friday) where deactivating dozens of individual discounts at once would otherwise be error-prone.

Customer Group pricing is set on embedded prices, not at the customer level. A buyer's Customer Groups are resolved at cart calculation time — the price with a matching customerGroup on the variant is selected. A Customer can carry multiple Customer Groups (via customerGroupAssignments, up to 500), and price resolution selects the best qualifying price across all assigned groups. For B2B buyers, assign Customer Groups directly to the buyer's customer record or via the Business Unit.

Cart Score is the key to dynamic shipping rates. Set the project's shipping rate input type to "Cart Score" in Merchant Center. Call setShippingRateInput with a Score type and an integer score. CT will look up the rate tier matching that score. The score must be a non-negative integer.

Cart Score is not available in shipping predicates — copy it to a cart custom field. The score is not directly queryable in predicates. Write the underlying value (e.g., distance in km) to a cart custom field. Write your shipping predicate against that custom field.

Price functions turn cart score into a continuous rate. Configure a priceFunction (e.g., (x / 30)) where x is the cart score. CT evaluates the function and sets the resulting amount as the shipping price, enabling rates that scale smoothly without enumerating every possible value.

Use taxMode: ExternalAmount for most PSP/tax service integrations. This mode lets your tax service calculate the exact tax amount per line item and pass it directly to CT, eliminating rounding discrepancies between CT's engine and external tax services (AvaTax, Vertex).

CT records payment state; the PSP does the actual financial transaction. The Payment object is a ledger. Use addTransaction update actions to track each PSP event (Authorization, Charge, Refund, Chargeback). Only set state: "Success" after confirmed PSP confirmation.

interfaceId on a Payment is immutable once set. This field links CT Payment to the PSP's identifier. Record it correctly the first time — there is no update path.

Cart prices are snapshotted at order creation. If a product price changes between cart creation and order creation, the cart holds the old price. Use the recalculate action on the cart to refresh prices before checkout.

Business Units are the core B2B entity — all B2B operations run through them. All B2B operations use the as-associate API chain (construction and scope in references/as-associate-api.md). Never use project-level cart/order APIs for B2B user-facing operations.

The quote lifecycle has four entities: QuoteRequest → StagedQuote → Quote → Order. A buyer creates a QuoteRequest; a sales rep creates a StagedQuote (working draft with negotiated prices); the Quote is the finalized offer; if accepted, the buyer converts it to an Order. Each step has its own state machine.

POST /orders vs POST /recurring-orders produce fundamentally different results. Calling POST /orders on a cart with recurring line items creates both a regular order (immediate) and a recurring order. Calling POST /recurring-orders creates only the recurring order. Use /orders for "subscribe and ship now" flow; use /recurring-orders for future-dated subscriptions.

Cart discount recurringOrderScope controls whether a discount repeats. Set "NonRecurringOrdersOnly" for one-time welcome promotions. Set "AnyOrder" for standing loyalty discounts that should apply on every recurrence cycle.

Reference Index

Pricing & Promotions

Shipping & Fulfillment

Payments & Tax

B2B Order Flows

Recurring Orders

Catalog & Import

Priority Tiers

CRITICAL

• Direct Discounts block Discount Codes. Never add a Direct Discount to a cart if the checkout flow expects users to enter discount codes.
• sortOrder: higher value fires first — for both Product Discounts and Cart Discounts. 0.9 is applied before 0.5. This is a common misconception that causes incorrect promotion behavior.
• Product Discounts do not work with external pricing. If the project uses an external price source, switch all promotional discounts to Cart Discounts.
• triggerPattern SKU predicates are ANDed across entries. A single CountOnLineItemUnits entry can only match one SKU — add separate entries per bundle component.
• Score must be set before shipping rate lookup. setShippingRateInput must be called before checkout and before shipping rate totals are calculated. Calling it after order creation has no effect.
• Shipping predicate failures are silent. If a predicate syntax error exists, CT may silently return no methods or all methods. Always test predicate behavior explicitly with GET /shipping-methods?cartId=<id>.
• All B2B writes MUST use the as-associate API chain. Project-level apiRoot.carts().* does not enforce B2B permissions. This is a security requirement, not just a convention.
• An Associate must have CreateMyCarts permission to add items to a cart as-associate. Missing permissions result in a 403.
• POST /orders creates both a regular order and recurring orders from a mixed cart. Design the order confirmation flow to handle multiple order IDs.
• A RecurrencePolicy cannot be deleted while in use. Remove all line item and cart references before attempting deletion.
• Never set a Payment transaction to Success before PSP confirmation. Optimistic success marking creates reconciliation failures.
• interfaceId on a Payment cannot be changed once set. Record the PSP transaction identifier correctly on the first write.
• Import API has no ordering guarantee. Poll the first operation's status before submitting the second.
• productDraftImport is destructive. Any field not included in the draft is deleted.
• Version conflicts (409 ConcurrentModification) require retry with the latest version. Do NOT use the version from the failed request.

HIGH

• Customer Group pricing requires the customer to be logged in and have a customerGroup set. Anonymous carts get the default price.
• HighPrecisionMoney must be consistent across all prices in a cart. Mixing centPrecision and highPrecision prices in the same cart/order causes calculation errors.
• Discount Code maxApplications is global across all customers. Use maxApplicationsPerCustomer for per-customer limits — they are separate fields.
• Cart Score is not available in shipping predicates. Copy the distance or weight value to a cart custom field before writing predicates against it.
• Per-warehouse predicates need the warehouse key in a cart custom field. The cart's assigned supply channel is not directly queryable in a shipping predicate.
• StagedQuotes hold negotiated line item prices. When converting a StagedQuote to a Quote, prices from the StagedQuote are locked in.
• Approval Rules are evaluated at Order creation, not Cart creation. Design the cart-to-order UX to set buyer expectations about the approval wait.
• priceSelectionMode must be set intentionally per use case. "Fixed" provides price guarantee; "Dynamic" always applies current catalog pricing.
• recurringOrderScope on cart discounts defaults to applying on all orders. Explicitly set "NonRecurringOrdersOnly" for introductory discounts.
• Nested attributes are not searchable and cannot target discount predicates. Use flat attribute types for any attribute that must appear in search filters or predicates.
• Batch size for Import API is max 20 operations per request. Always chunk.
• Changing a ProductType attribute constraint after data exists requires a migration. Plan attribute constraints during initial design.

MEDIUM

• isActive on a Cart Discount is a soft toggle. Use this for scheduled campaigns rather than creating/deleting discounts.
• Use stackingMode: StopAfterThisDiscount to make a specific discount exclusive. Cart discounts stack by default.
• Price rounding is configurable via priceRoundingMode (on Cart/Order/Quote and as a Project default). Modes: HalfEven (banker's rounding — the default), HalfUp, HalfDown. Only HalfDown rounds .5 in the customer's favor; align the mode with your ERP/tax system and budget margin accordingly for high-volume campaigns.
• For unsupported discount scenarios, the pattern is an API Extension on cart/order that calculates and injects a Direct Discount or custom line item.
• lineItemGrossTotal(categories.key = (...)) >= "X.XX USD" is the pattern for category spend thresholds. The currency string must be included in the value.
• Price functions are evaluated server-side at rate lookup time. Do not try to replicate the function in your frontend.
• Quote negotiation supports multiple rounds. Track negotiation rounds via custom fields on QuoteRequest if your business requires round history.
• Customer Group assignment on the buyer's customer record is the simplest B2B pricing pattern. All their carts inherit the group pricing automatically.
• Order confirmation UX must handle multiple order IDs. A single cart checkout with recurring items at different frequencies produces N+1 orders.
• Standalone prices via Import API support validFrom/validUntil for time-limited pricing without product republication.