Turn on Remix v3_singleFetch future flag

[wizardlyhel]

WHY are these changes introduced?

Turn on Remix v3_singleFetch future flag

Upgrade steps

Remix single fetch migration quick guide: https://remix.run/docs/en/main/start/future-flags#v3_singlefetch
Remix single fetch migration guide: https://remix.run/docs/en/main/guides/single-fetch

1. In your vite.config.ts, add the single fetch future flag.

   +  declare module "@remix-run/server-runtime" {
   +    interface Future {
   +     v3_singleFetch: true;
   +    }
   +  }
   
     export default defineConfig({
       plugins: [
         hydrogen(),
         oxygen(),
         remix({
           presets: [hydrogen.preset()],
           future: {
             v3_fetcherPersist: true,
             v3_relativeSplatPath: true,
             v3_throwAbortReason: true,
             v3_lazyRouteDiscovery: true,
   +         v3_singleFetch: true,
           },
         }),
         tsconfigPaths(),
       ],

2. In your entry.server.tsx, add nonce to the <RemixServer>.

   const body = await renderToReadableStream(
     <NonceProvider>
       <RemixServer
         context={remixContext}
         url={request.url}
   +     nonce={nonce}
       />
     </NonceProvider>,

3. Deprecate json and defer import usage from @shopify/remix-oxygen

   Remove json()/defer() in favor of raw objects.

   Single Fetch supports JSON objects and Promises out of the box, so you can return the raw data from your loader/action functions:

   - import {json} from "@shopify/remix-oxygen";
   
     export async function loader({}: LoaderFunctionArgs) {
       let tasks = await fetchTasks();
   -   return json(tasks);
   +   return tasks;
     }

   - import {defer} from "@shopify/remix-oxygen";
   
     export async function loader({}: LoaderFunctionArgs) {
       let lazyStuff = fetchLazyStuff();
       let tasks = await fetchTasks();
   -   return defer({ tasks, lazyStuff });
   +   return { tasks, lazyStuff };
     }

   If you were using the second parameter of json/defer to set a custom status or headers on your response, you can continue doing so via the new data API:

   -  import {json} from "@shopify/remix-oxygen";
   +  import {data} from "@shopify/remix-oxygen";
   
     export async function loader({}: LoaderFunctionArgs) {
       let tasks = await fetchTasks();
   -    return json(tasks, {
   +    return data(tasks, {
         headers: {
           "Cache-Control": "public, max-age=604800"
         }
       });
     }

WHAT is this pull request doing?

For all templates, remove json(), and defer() Remix response functions and use data() Remix response function when required

HOW to test your changes?

Make sure all templates are working properly without errors across all functions. Make sure:

• Customers can login with customer account
• All template examples are working
• Oxygen deploys are working

Post-merge steps

Checklist

• I've read the Contributing Guidelines
• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've added a changeset if this PR contains user-facing or noteworthy changes
• I've added tests to cover my changes
• I've added or updated the documentation

[shopify]

Oxygen deployed a preview of your hl-single-fetch branch. Details:

Storefront	Status	Preview link	Deployment details	Last update (UTC)
custom-cart-method	✅ Successful (Logs)	Preview deployment	Inspect deployment	January 15, 202510:19 PM
metaobjects	✅ Successful (Logs)	Preview deployment	Inspect deployment	January 15, 202510:19 PM
classic-remix	✅ Successful (Logs)	Preview deployment	Inspect deployment	January 15, 202510:19 PM
third-party-queries-caching	✅ Successful (Logs)	Preview deployment	Inspect deployment	January 15, 202510:19 PM
Skeleton (skeleton.hydrogen.shop)	✅ Successful (Logs)	Preview deployment	Inspect deployment	January 15, 202510:19 PM

Learn more about Hydrogen's GitHub integration.

[github-actions]

We detected some changes in packages/*/package.json or packages/*/src, and there are no updates in the .changeset.
If the changes are user-facing and should cause a version bump, run npm run changeset add to track your changes and include them in the next release CHANGELOG.
If you are making simple updates to examples or documentation, you do not need to add a changeset.

[rbshop]

Is this new behaviour covered in any of our tests?

[wizardlyhel]

oh good catch - I'll get a test in

[wizardlyhel]

tests added