Shopify Hydrogen

Hydrogen is Shopify's opinionated stack for headless commerce, built on React Router v7. It provides utilities, handlers, and components for building storefronts on top of the Shopify Storefront API.

All exports come from @shopify/hydrogen, which re-exports everything from @shopify/hydrogen-react.

Source: https://github.com/Shopify/hydrogen/tree/main/packages/hydrogen/src

Live Documentation

Run these from this skill's own folder; the paths below are relative to the skill root.

For the most up-to-date Hydrogen API docs, use the search script:

node scripts/search_shopify_docs.mjs "<query>"

This queries Shopify's developer docs (shopify.dev) directly and returns the latest API references, code examples, and guides for Hydrogen.

Examples:

node scripts/search_shopify_docs.mjs "createHydrogenContext"
node scripts/search_shopify_docs.mjs "CartForm actions"
node scripts/search_shopify_docs.mjs "caching strategies"
node scripts/search_shopify_docs.mjs "getSeoMeta"
node scripts/search_shopify_docs.mjs "Pagination component"

For offline/cached reference, see the references/ folder below.

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Key Concepts (Quick Reference)

createHydrogenContext

The single entry point to set up all Hydrogen services in server.ts. Creates and wires together storefront, customerAccount, and cart.

• Required env vars: PUBLIC_STORE_DOMAIN, PUBLIC_STOREFRONT_API_TOKEN, PRIVATE_STOREFRONT_API_TOKEN, PUBLIC_STOREFRONT_ID, PUBLIC_CUSTOMER_ACCOUNT_API_CLIENT_ID, SHOP_ID
• Returns: { storefront, customerAccount, cart }

Caching Strategies

Strategy	maxAge	staleWhileRevalidate	Use for
CacheNone()	—	—	User-specific or real-time data
CacheShort()	1s	9s	Frequently changing data
CacheLong()	1hr	23hr	Stable data (shop info, menus)
CacheCustom({...})	custom	custom	Fine-grained control

Cart Handler

createCartHandler provides all cart operations: get, create, addLines, updateLines, removeLines, updateDiscountCodes, addGiftCardCodes, updateBuyerIdentity, updateNote, setMetafields, and more.

CartForm

Form component for cart mutations. Uses CartForm.ACTIONS enum (LinesAdd, LinesUpdate, LinesRemove, DiscountCodesUpdate, etc.) and submits via React Router's useFetcher.

useOptimisticCart

Applies pending cart mutations locally for instant UI feedback. Requires selectedVariant in LinesAdd inputs.

Pagination

getPaginationVariables(request, { pageBy }) + <Pagination connection={...}> component. GraphQL query must include pageInfo { hasPreviousPage hasNextPage startCursor endCursor }.

SEO

getSeoMeta(...) generates React Router meta arrays. Supports title, titleTemplate, description, url, media, jsonLd, robots, alternates. jsonLd is concatenated across routes.

Sitemaps

getSitemapIndex + getSitemap — two-level sitemap generation. Requires Storefront API 2024-10+.

Content Security Policy

createContentSecurityPolicy({ shop: { checkoutDomain, storeDomain } }) returns { nonce, header, NonceProvider }.

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References

For offline/cached reference when the search script is unavailable:

File	Contents
references/01-setup.md	Full server.ts setup, env vars, session, createHydrogenContext options
references/02-caching.md	Cache strategies, AllCacheOptions type, generateCacheControlHeader
references/03-cart.md	Cart route setup, CartForm examples, useOptimisticCart patterns
references/04-ssr-performance.md	SSR bundle diet (worker inlines dynamic imports — resolveId stub pattern), bundle audit, TTFB measurement methodology