WooCommerce Store API

The Store API is the public REST surface used by Woo blocks (Cart, Checkout, Mini-Cart) and external integrations. It lives under /wc/store/v1/* and has its own conventions distinct from the older /wc/v3/* admin REST API.

When to use this skill

• Adding a new route under /wc/store/v1/.
• Modifying an existing route's response shape, status codes, or argument schema.
• Designing the schema for a new resource the frontend will consume.
• Wiring a block (or iAPI store) to a Store API endpoint.

This skill complements woocommerce-backend-dev (general PHP conventions) and woocommerce-performance (cache priming patterns). Read those first for general conventions; this skill covers Store-API-specific decisions.

Topics

• authentication.md — permission_callback styles, nonce enforcement via AbstractCartRoute, when to extend which abstract.
• rest-conventions.md — Path/body/query separation, collection vs item vs action routes, status codes, idempotency.
• schema-design.md — Schema as public contract, field discipline, response-shape alignment.
• variation-handling.md — Server-authoritative variation reconciliation.
• performance.md — Where to apply cache priming in Store API responses. Cross-links to woocommerce-performance for the underlying patterns.

Key principles

• Schemas are the public contract. What the schema declares must be what the route returns. Don't bolt fields onto a response after the schema produced it.
• Pick the right abstract. Routes that mutate per-user state via cookies must extend AbstractCartRoute (which enforces nonces) or implement equivalent CSRF protection. AbstractRoute alone is for read-only or own-auth routes.
• GET is safe. No side effects, no body. Auto-create-on-read is allowed only as in-memory materialisation; persist on the first explicit write.
• Server is authoritative on identity. Don't trust client-supplied attribute payloads for variations; derive them from the variation product.
• Don't ship dead fields. Schema properties that have only one possible value forever, or that mirror data already exposed elsewhere, are public-API surface that's easier to add later than to retract.

Reference files

• Authentication.php — global Store API auth filter; deliberately bypasses WP's cookie-nonce check.
• AbstractCartRoute.php — nonce enforcement, cart-session loading, Nonce/Cart-Token response headers.
• AbstractRoute.php — base class for routes that don't need cart-session/nonce machinery.
• AbstractSchema.php — prepare_html_response(), prepare_money_response(), response-formatting helpers.
• CartItems.php — canonical example of collection-style POST/DELETE routes.
• CartController.php — variation reconciliation reference (parse_variation_data()).