Add typed JSON output to Hydrogen project and account commands

[gonzaloriestra]

WHY are these changes introduced?

Project creation, storefront linking and account commands need finite results for automation.

WHAT is this pull request doing?

Add domain schemas, --json and schema help to init, link, list, login, logout and unlink. Separate onboarding execution from final presentation, report partial setup failures, and preserve the shared fatal-error path during asynchronous cleanup. Results omit authentication tokens.

Without --json, the existing terminal presentation remains. Example JSON result:

shopify hydrogen unlink --json

{"unlinked":false,"storefront":null}

HOW to test your changes?

pnpm --filter @shopify/cli-hydrogen test src/commands/hydrogen/project-json.test.ts src/lib/onboarding/local.test.ts

Build and typecheck were checked at each layer. The full stack passed 498 tests (6 skipped), lint, and schema discovery for all 22 finite commands. Command-line smoke checks covered a successful unlink result, fatal project errors, watch-mode rejection and schema environment flags. Live authenticated Shopify operations have not been exercised.

Stack

Draft 7 of 9. Previous: #4100. Next: #4102. One changeset is included in #4103.

1. Prepare Hydrogen commands for typed JSON output
2. Add typed JSON output to Hydrogen build tooling
3. Add typed JSON output to hydrogen customer-account-push
4. Add typed JSON output to hydrogen deploy
5. Add typed JSON output to Hydrogen environment commands
6. Add typed JSON output to Hydrogen route generation
7. Add typed JSON output to Hydrogen project and account commands
8. Add typed JSON output to Hydrogen setup commands
9. Add typed JSON output to Hydrogen maintenance commands

[shopify]

Oxygen deployed a preview of your gonzalo/hydrogen-json-project branch. Details:

Storefront	Status	Preview link	Deployment details	Last update (UTC)
Skeleton (skeleton.hydrogen.shop)	✅ Successful (Logs)	Preview deployment	Inspect deployment	September 29, 2026 2:56 PM

Learn more about Hydrogen's GitHub integration.

[fredericoo]

Went through this one. It's a clean follow-on from the rest of the stack: same jsonOutputSchema / writeJsonResult / descriptionForHelp pattern as the env and route PRs, results carry no tokens (login just picks shop/shopName/email), and the human-readable output looks unchanged for all six commands. Moving renderProjectReady and the remote-template info into presentTemplateResult is a nice split.

Prompts in --json mode look fine too. When stdout is piped, cli-kit's throwInNonTTY rejects them, so login/link/init fail fast with a JSON error instead of hanging.

Two small comments, neither blocking. Overall LGTM

[fredericoo]

non-blocking: list takes shop from session.storeFqdn, but this takes it from config.shop!. Let's use the session here as well. It's the same authenticated shop, the two commands then read it from the same place, and we get rid of the !:

Suggested change

	const result = {shop: config.shop!, storefront: linkedStore ?? null};
	const result = {shop: session.storeFqdn, storefront: linkedStore ?? null};

[fredericoo]

non-blocking: the AbortError is built twice now, once for this JSON branch and once for renderFatalError below, and the two copies could drift. Let's build it once above the if and pass it to both.

Also, this JSON fatal path isn't tested. project-json.test.ts covers presentTemplateResult, but nothing checks that an init failure in --json mode emits the error event and exits 1. One test with process.exit spied would cover it. Note that this branch also skips the SHOPIFY_UNIT_TEST guard below, so a test that hits it without spying on process.exit would kill the runner.