Shopware 6 Store API vs Admin API: Can an Admin API Client Take Over an In-Progress Customer Cart?

Integration boundary

We are designing a headless integration against Shopware 6 that uses the two supported HTTP components: the sales-channel-scoped Store API (authenticated with the sw-access-key header) for storefront browsing and cart operations, and the Admin API (OAuth2 over /api/oauth/token) for a backend service that needs to inspect and adjust orders.

The unresolved decision

Our storefront creates customer carts through the Store API, where cart state is bound to a sales-channel context token. The backend service would like to read or modify that same in-progress cart through the Admin API, for example to apply a service-side discount or pre-fill line items before checkout. It is unclear to us whether cart state can cross this boundary at all, or whether the Admin API client must re-create the cart contents independently, duplicating business logic such as price calculation and promotion handling.

We also need to decide which API should own catalog reads, since both support criteria-based querying, but the Store API applies sales-channel visibility rules that the Admin API bypasses.

Questions

• Is there a supported way for an Admin API client to access or mutate a cart that was created under a Store API context token, or is re-creating the state the only option?
• For catalog reads shared by both clients, is it acceptable to use the Admin API server-side while keeping the Store API for anything customer-facing?
• Does cart/context-token behavior differ between Shopware 6 minor versions or editions in a way we should verify before committing to this design?