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SKU.md platform publishing guide: Shopify, WooCommerce, BigCommerce, SHOPLINE
Compare strict root publication and compatibility paths across four commerce platforms, with official sources and recheck boundaries.
Platform labels do not determine whether a SKU.md deployment is strict. Conformance depends on the response at the merchant’s exact same-origin /sku.md URL. Platform features only determine which routes may be possible.
SKU.md is merchant-hosted product discovery and stable product knowledge: agents can find products, understand sourced facts, and know where to recheck live commerce. It is not a new checkout protocol.
Strict publication and compatibility presentation
Strict root publication requires direct HTTP 200, text/markdown, exact canonical and accepted bytes, a valid document graph, predictable cache replacement, and correct failures. Compatibility presentation may expose discovery or readable content while missing root-path or media-type control.
| Platform path | What official capabilities support | SKU.md assessment |
|---|---|---|
| Shopify theme | Shopify documents theme-owned agents.md/llms templates |
Compatible discovery; no proof of arbitrary /sku.md Markdown |
| Shopify App Proxy | One configurable route under allowed prefixes | Cannot promise the root path |
| WooCommerce route | WordPress Rewrite API can register a root route | Strict candidate after live verification |
| BigCommerce Stencil | Custom templates bind to existing page types | Compatible discovery, not arbitrary root Markdown |
| BigCommerce headless/edge | Merchant-controlled same-origin application or edge | Strict candidate after live verification |
| SHOPLINE hosted store | File Library plus documented llms.txt 301 workaround |
Compatibility only; redirect is not direct 200 |
Shopify: documented agent files are not SKU.md adoption
Shopify documents /agents.md, /llms.txt, and /llms-full.txt template behavior for its own store resources. That evidence is specific to those paths. A theme can link to SKU.md, and an alternate product template can present text, but hosted theme output does not establish exact root text/markdown delivery.
An App Proxy is restricted to allowed prefixes such as /apps; merchants can customize its prefix and subpath. A merchant-controlled Hydrogen or custom headless storefront can implement /sku.md, but it becomes strict only after the deployed response is tested.
WooCommerce and BigCommerce: route control differs
WooCommerce on WordPress can register ^sku\.md/?$ and serve a pre-generated file from template_redirect. The route should not rebuild knowledge on each request, and rewrite rules should be flushed only at activation or deactivation. Web server, plugin, and same-origin edge routes all require the same online proof.
BigCommerce Stencil custom templates apply to existing brand, category, product, and page types; that does not demonstrate an arbitrary root resource. A merchant-controlled headless application or same-origin edge can own the route. BigCommerce remains authoritative for current catalog, price, inventory, cart, and checkout.
What the SHOPLINE 301 pattern tells us
SHOPLINE’s LLMS.txt guide says root upload is unavailable and recommends a File Library upload plus 301 redirect for that file. Its File Library formats list .txt but not .md.
Those facts do not prove strict /sku.md, correct Markdown MIME, or official SKU.md support. A merchant-controlled headless, proxy, or edge route remains a strict candidate only after direct same-origin validation.
Recheck before every publication
Platform capabilities change. Before using this table, reopen each localized platform guide and its official citations, check route and file restrictions, then test the real store. Do not promote a dated capability snapshot into a permanent platform guarantee.
| Recheck | Evidence required |
|---|---|
| Platform capability | Current first-party documentation |
| SKU.md delivery | Real status, redirect, MIME, bytes, canonical, graph, cache, 404 |
| Adoption claim | Explicit platform statement naming SKU.md |
Current v1 three-platform series
For current implementation guidance, use the platform-specific v1 articles:
Further reading
Read Publish your first SKU.md for the platform-neutral contract and What is SKU.md? for its scope.