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Shopify Builds>Primitives>Theme app extension blocks

Theme app extension blocks

Definition

App blocks are interface an app ships as part of a theme app extension. A merchant adds one to a section from the theme editor, and the app owns its markup, its assets and its settings from then on. The theme decides only where blocks are allowed, by accepting the @app block type in a section's schema.

Documented at shopify.dev, theme app extensions.

How We've Used It

Every product page we rebuild ends up as a block list, and the question that decides its shape is which blocks a merchant can add that we don't control. So our product sections accept @app blocks beside our own, and pin them by position rather than by selector, because a selector into someone else's markup breaks on their next release. A subscription widget, a review mount, a back-in-stock button: all of them become things a merchandiser places. One storefront goes further and runs a section whose only block type is @app, built to host a Shopify form and restyle it through the custom properties and the shadow root the app exposes.

Builds Using It

5 further gated builds use it; their pages follow.

Related Entities

Builds

A second product template whose add-to-bag switches between one cart line and several

`main-product-bundle.liquid` is a fork of the theme's product section in which one Liquid conditional wraps the buy form in either a standard `<product-form>` or a `<bundle-product-form>`, depending on which bundle metafield the product carries.

Nudestix

Deferred LyveCom shoppable-video mounting on the product page

An integration layer that loads LyveCom's widget script once per page and mounts each carousel only when its container is about to enter the viewport — so a paid shoppable-video app stays off the product page's first paint, and a theme-editor reload doesn't mount it twice.

LUS Brands

Rebuilt 2026 PDP section with merchandiser-composable blocks and per-product ATC color

A custom product section for LUS Brands that declares 26 block types beyond Dawn's set, resolves title and subtitle copy per variant, and paints the add-to-cart button from a product metafield.

LUS Brands

Configurable PDP block system on the Palo Alto theme (Recharge widget placement, size charts, siblings, quick view)

Merchandiser-orderable buy-box blocks on Three Ships' licensed theme, with the subscription app block captured and re-emitted inside the buy box, plus metafield-driven size charts, a product-family switcher and a sticky add-to-cart bar.

Three Ships

Metafield-driven PDP content system: auto-built accordions, need-to-know strip and campaign widgets

A layered content resolver on the Nudestix product page: legacy description HTML parsed into accordions at render time, three of them overridden per shade from metafields, with icon strips, badges and campaign widgets assembled from 29 metafield keys around them.

Nudestix

Themed host section for Shopify Forms app blocks

A section whose only block type is `@app`, wrapping any app block in the theme's width, padding and background scaffolding — and, when a merchandiser switches it on, writing the `--forms-heading-*` and `--forms-body-*` custom properties that Shopify's Forms embed reads for its own typography.

Three Ships

DOM and shadow-DOM remediation layer for Yotpo, Rebuy and Recharge widgets

Corrections applied to markup the theme didn't write: `MutationObserver` routines that re-level a review widget's headings, demote headings inside a cart drawer, re-anchor a subscription add-to-cart control, and append a stylesheet inside a subscription widget's shadow root — every one re-entrant, so the fix converges instead of looping.

Three Ships