Create a POS UI extension with the Shopify CLI and choose the post-purchase extension point.
Set the target to `pos.purchase.post.block.render` in the extension's configuration.
Implement the React/JS component using POS UI extension components to display content on the post-purchase screen.
Run the extension in development against a POS device or simulator, then deploy with `shopify app deploy`.
Known gotchas
The correct extension target is `pos.purchase.post.block.render`; targets such as `pos.checkout.post-purchase.render` do not exist for POS UI extensions.
POS UI extension targets are distinct from web checkout UI extension targets — do not reuse checkout extension target names in a POS extension.
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp