[Hellraiser28]

What

Adds a German translation (messages/de.json) and lets Tagr choose the UI language from the browser's Accept-Language header instead of the hard-coded en.

How

• src/i18n/locale.ts (new) — the list of supported locales (en, de), the default (en) and negotiateLocale(), which walks the Accept-Language entries by quality value, matches regional tags to their base language (de-AT → de) and falls back to English for anything unsupported or malformed.
• src/i18n/request.ts — uses negotiateLocale((await headers()).get('accept-language')) instead of const locale = 'en'.
• src/app/layout.tsx — <html lang> now reflects the active locale (getLocale()), so the layout is async. No other change in that file.
• messages/de.json (new) — all 420 keys of en.json, same structure, same placeholders and plural branches, ICU syntax unchanged.
• src/i18n/locale.test.ts (new) — tests for the negotiation, plus a check that every non-English message file has exactly the keys and placeholders of en.json, so a future key added only to en.json shows up in CI.
• README.md — one bullet under Additional describing the language selection and how to add a language.

Browsers asking for any other language keep getting English, so nothing changes for existing users.

Testing

• vitest run: all test files pass, including the 6 new tests.
• eslint and prettier --check pass on the new and changed files. (src/app/layout.tsx was already not Prettier-formatted on main; I only changed the lines above and left the rest untouched to keep the diff small.)
• tsc --noEmit reports the same two errors in detail-panel-preview-card.tsx on main and on this branch — none are introduced here.
• Built the Docker image from this branch and ran it: with a German browser the login page, folder tree, song list and detail panel are German; with Accept-Language: en or fr everything stays English.

Not included

Dates in the song list are still formatted with a fixed 'en-US' in src/components/panels/main-content/utils.ts. That could follow the active locale too, but I kept this PR to the translation itself.

The translation was prepared with the help of an AI assistant (Claude) and reviewed by me as a native German speaker.

[suitux]

Thanks for the German translation 🙌

Right now the language comes only from the browser's Accept-Language, so users can't change it by hand. Could you add a language setting to the Settings dialog?

• Add a locale key to ConfigKey and a language section in SETTINGS_SECTIONS (minimumRole: 'listener'). It should be a Select with Automatic / English / Deutsch, built from locales, read with useConfig and saved with useUpdateConfig.
• In src/i18n/request.ts, use the user's saved locale when it's set, otherwise fall back to negotiateLocale.
• Call router.refresh() after saving, and add the new strings to en.json / de.json.

Thanks!

[Hellraiser28]

Done, thanks for the detailed pointers!

• Setting: a locale config key and a Language section in SETTINGS_SECTIONS (minimumRole: 'listener') with a Select for Automatic / English / Deutsch.
  • The options are built from locales, with the display names in a new localeNames map next to them.
  • The choice is read with useConfig, saved with useUpdateConfig and followed by router.refresh().
  • "Automatic" is stored as auto.
• src/i18n/request.ts: uses the saved locale when it names a supported one, otherwise negotiateLocale as before.
  • The rule lives in resolveLocale() in locale.ts and has its own tests.
  • Pages without a session, like the login page, still follow the browser.
• New strings: I merged current main into the branch (no conflicts) and added German for the 34 strings that came in since: Insights, the song panel fields and the hidden custom tags hint. The new setting's strings are in en.json / de.json as well.

Checked:

• vitest run: 296 tests pass.
• eslint and prettier --check: clean on the new and changed files.
  • The two tsc errors in detail-panel-preview-card.tsx are the same on main.
  • So are the prettier warnings on layout.tsx, domain.ts and settings-modal.tsx.
• In a Docker build:
  • Switching to Deutsch with an English browser changes the UI right away and survives a reload.
  • Back on Automatic it follows the browser again.
  • A saved English wins over a German browser.

[suitux]

There you go

https://github.com/suitux/Tagr/releases/tag/v1.14.0

😄