How the Birkly admin panel loads translations for core UI and plugins.

Two systems

System	Purpose
Admin UI i18n	Panel chrome, settings, plugin admin pages
Content multilang	Site visitor content (see Multilingual templating)

Admin language is chosen per user (user menu → language). It does not follow browser Accept-Language automatically.

Selectable admin UI languages

Curated picker list (birkly_admin_ui_selectable_language_codes()): en, de, fr, ja, es. Tier-1 quality bar matches de / fr / ja for es (core + Wave 1 plugins). Rebuild: ./scripts/p85-es-full-pass.sh from the CMS repo.

Core strings

• Canonical catalog: lang/en.json under the CMS root (admin.* keys).
• PHP: __('admin.save') with {{param}} interpolation.
• HTML templates: {translate 'admin.settings'}.
• PHP partials (not plugin HTML): <?= __('admin.save') ?> — use {translate} in plugin .html admin pages.
• JavaScript: Birkly.i18n.t('admin.save') (flat full-key dictionary injected in layout_head.php).

Admin language is stored on the user profile and applied on the next full page load after api/users.php set_language. There is no separate per-plugin language control.

Plugin strings

Plugins ship their own catalogs:

plugins/my-plugin/lang/en.json
plugins/my-plugin/lang/de.json

Declare in plugin.json:

"admin": {
  "i18n": { "path": "lang", "namespace": "plugins.my_plugin" }
}

Keys use namespace plugins.{plugin_id}.{key} (underscores in plugin id).

• HTML: {translate 'plugins.commerce.tab_orders'}
• JS: Birkly.i18n.t('plugins.commerce.tab_orders')
• Settings labels: "label": "@i18n:plugins.commerce.settings.default_currency.label"

Core merges active plugin catalogs when loading the admin language. Inactive plugins contribute nothing.

Tier-1 locales (P85)

French (fr) and Spanish (es) are tier-1 admin locales: full admin.* parity with lang/en.json, plus Wave 1 official plugins (User, Commerce, Automation, Events, Studio).

Spanish catalogs are rebuilt from English only (no machine translation, no French fallback). After adding or changing lang/en.json keys:

./scripts/p85-es-full-pass.sh
php scripts/i18n-audit.php --locale=es --strict
php scripts/i18n-audit-es-quality.php

i18n-audit-es-quality.php flags FR→ES heuristic leaks (same-as-fr.json, mixed EN/ES, French phrases). CI runs it warn-only for core and sibling plugin repos.

Do not use scripts/p85-es-fr-to-es.php (deprecated).

Tooling

php scripts/i18n-audit.php --locale=de --strict
php scripts/i18n-sync-locale.php de

• --strict: fail on missing keys vs en.json.
• --check-untranslated: also fail when locale values are identical to English.