useBuyerJourneyIntercept hook deprecated; migrate to validation Functions

Starting in version 2026-07, the useBuyerJourneyIntercept hook on checkout UI extensions, and the block_progress capability it depends on, are deprecated. Existing extensions will continue to work on current and prior API versions, but this API will be removed in a future version, so you should plan to migrate.

If you currently use useBuyerJourneyIntercept to enforce merchant business rules, migrate to a cart and checkout validation Function. These Functions run server-side and apply your rules consistently across all checkout surfaces, including express wallets and agentic checkout.

If you use useBuyerJourneyIntercept to reject discount codes, migrate that logic to the discount Function API, which now supports rejecting discount codes with a custom message.

The following are deprecated:

• useBuyerJourneyIntercept (Preact hook) in checkout UI extensions
• The block_progress capability in the extension’s shopify.extension.toml configuration file