# Extension recipe Use this order when adding a new shared backend-facing capability: 1. Decide the behavior is no longer storefront-specific. 2. Add or reuse the backend-facing types. 3. Add query-key helpers through `createQueryKey()`. 4. Add the Medusa service and forward `AbortSignal`. 5. Add hooks or helper functions that match existing package patterns. 6. Wire the new surface into `createMedusaStorefrontPreset`. 7. Add regression tests in `libs/storefront-data/tests`. 8. Only then consume the new surface from apps. ## Shared extension checks - Keep imports direct. Do not add a barrel file. - Reuse shared helpers instead of burying generic logic inside one domain. - Treat tests as part of the public contract. - Prefer extending the preset surface over asking apps to assemble low-level factories. - If the behavior is still only one-storefront-specific, stop and keep it local.