test(functional): assert the de l10n bundle is delivered

[vbudhram]

Because

• FXA-14361 served English to every locale and nothing failed. Every response was a 200, and the only symptom was untranslated copy.
• packages/functional-tests has no l10n coverage, so neither PR CI nor the stage and production smoke runs would have caught it.

This pull request

• Adds l10nBundleDelivery.spec.ts under tests/misc/. It forces de with Playwright's locale context option, waits for the main.ftl response, then asserts a 200 and a body that parses as FTL.
• Matches the plain path and the hashed manifest path, for example locales/de/main.ebcab539.ftl.
• Tags the block severity-1. That is what the stage and production Playwright runs grep for.

Issue that this pull request solves

Closes: https://mozilla-hub.atlassian.net/browse/FXA-14366

Checklist

Put an x in the boxes that apply

• My commit is GPG signed.
• If applicable, I have modified or added tests which pass locally.
• I have added necessary documentation (if appropriate).
• I have verified that my changes render correctly in RTL (if appropriate).
• I have manually reviewed all AI generated code.

How to review (Optional)

• Key files/areas to focus on: packages/functional-tests/tests/misc/l10nBundleDelivery.spec.ts
• Suggested review order: one file.
• Risky or complex parts: the response wait. It is registered before page.goto, so a request that never happens keeps it pending and the test fails on timeout.

Screenshots (Optional)

No user interface change.

Other information (Optional)

How the locale reaches the fetch: public/lang-fix.js sets document.documentElement.lang from navigator.languages, getCurrentLocale() reads that value, and AppLocalizationProvider then fetches main.ftl for it.

The test asserts nothing about the static asset manifest, so #21060 needs no rework here. It asserts no translated string and no FTL message id. The body check matches any message line, which rules out an error page served with a 200.

Read this before you approve: I did not run the spec, and I did not exercise the negative case against a running stack. To confirm it, remove the de main.ftl entry from the manifest and check that the test fails.

Verification done here: npx tsc -p packages/functional-tests/tsconfig.json --noEmit reports only the three errors that already exist on main, in lib/sub-helpers.ts and lib/testAccountTracker.ts. npx nx lint functional-tests passes with no finding on the new file.

[Copilot]

Pull request overview

Adds functional coverage ensuring the German Fluent bundle is requested and valid in local, stage, and production environments.

Changes:

• Forces the browser locale to German.
• Supports plain and hashed bundle paths.
• Verifies a successful response containing FTL messages.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.