Add PerfKit integration contract tests

[dangayle]

What this PR does

PerfKit.tsx had zero tests, so if someone accidentally changed a label, broke the load order, or stopped pinging PerfKit on navigation, nothing would catch it — it would just silently ship broken.

This PR adds a safety net. Three small things:

1. Writes the rules down as tests. A new PerfKit.test.tsx checks the adapter still does exactly what it should — loads the right script URL, sets the right data-* labels, waits until the script is loaded before wiring anything up, and calls PerfKit on the five view events. If anyone breaks the contract later, the test fails.
2. Names the PerfKit URL (PERF_KIT_URL) so the test can point at it, and so changing that URL becomes a deliberate, reviewed edit instead of a quiet one.
3. Tidies one line — groups the data-* labels into a single object so the test can read them. No behavior change.

That's the whole PR. No new features, nothing users see, no version bump. It's purely a guard so Hydrogen can't accidentally break its own PerfKit wiring.

What the tests lock down

PerfKit.test.tsx (PerfKit is mocked at the network level — the real script is never downloaded):

• Requests the pinned PerfKit SPA script URL.
• Passes the required data-* labels exactly: data-application=hydrogen, data-spa-mode=true, parsed data-shop-id, data-storefront-id (from hydrogenSubchannelId), data-monorail-region=global, data-resource-timing-sampling-rate=100.
• Parses the shop id out of the shop GID.
• Registers Internal_Shopify_Perf_Kit.
• Does not wire anything while the script is still loading, and not on error — only after it's done.
• Wires all five view subscriptions (page_viewed, product_viewed, collection_viewed, search_viewed, cart_viewed).
• Calls ready() exactly once, after wiring.
• Doesn't wire twice across a loading → done transition (the re-render guard).
• page_viewed → window.PerfKit.navigate(); product/collection/search/cart → setPageType(...).
• Doesn't throw if window.PerfKit isn't there yet (script-load race).

About versions

The PerfKit script URL is pinned in PERF_KIT_URL and asserted exactly in the test:
https://cdn.shopify.com/shopifycloud/perf-kit/shopify-perf-kit-spa.min.js

Heads-up for reviewers: this URL is not stable across Hydrogen versions (older builds used a versioned URL like shopify-perf-kit-1.0.1.min.js; the current build uses the unversioned -spa bundle), and window.PerfKit exposes no runtime version. This PR just pins the current -spa build. Giving PerfKit an explicit version/capability signal is a separate, cross-team follow-up.

Scope / impact

• Non-user-facing. PERF_KIT_URL is module-local — nothing new is exported from the package entrypoint. No runtime behavior change. No semver bump (empty changeset).
• Touches 3 files: PerfKit.tsx, PerfKit.test.tsx (new), and an empty changeset.

Checks run

• pnpm --dir packages/hydrogen typecheck ✅
• pnpm --dir packages/hydrogen test ✅ — 58 files, 548 tests
• pnpm --dir packages/hydrogen exec vitest run src/analytics-manager/PerfKit.test.tsx ✅ — 16 tests
• eslint + prettier on changed files ✅

Follow-ups (separate, not in this PR)

• Skeleton e2e coverage proving the default Hydrogen app emits the contract end to end.
• An explicit PerfKit version/capability signal so version checks can be deterministic.

Requested by Dan Gayle dan.gayle@shopify.com

[shopify]

Oxygen deployed a preview of your add-analytics-perfkit-diagnostics branch. Details:

Storefront	Status	Preview link	Deployment details	Last update (UTC)
Skeleton (skeleton.hydrogen.shop)	✅ Successful (Logs)	Preview deployment	Inspect deployment	June 2, 2026 1:21 AM

Learn more about Hydrogen's GitHub integration.

[andguy95]

This change set can be removed as there is not package bumps!

[andguy95]

Remove change set