Skill: Translation and formatting

Read the bundled conventions before applying this skill.

Decisions that affect behavior

• Separate application language, source language, formatter locale, formatter timezone, and storage timezone. Changing one does not necessarily change the others. Preserve the project’s category names, message identifiers, extraction configuration, and translation-file layout.
• Yii::t() resolves a category’s message source then formats parameters. Keep ICU plural/select placeholders intact across languages; concatenated translated fragments do not reliably preserve grammar. Verify source-language and fallback behavior before adding duplicate message entries or forceTranslation.
• PHP, database, and Gettext message sources have different lookup/cache behavior. Keep the selected source and invalidation policy. The removed DbMessageSource::CACHE_KEY_PREFIX is not a public cache customization point.
• Inspect ext-intl availability when formatting or message behavior differs. Fallback implementations are not proof of identical ICU behavior. Dates must be interpreted in the input/default timezone before display conversion; localized strings should not silently replace canonical persisted values. Preserve an explicitly configured display timezone unless the requested policy changes. Formatter::defaultTimeZone defaults to UTC; an omitted setting alone does not explain differences between users. Verify input representation and effective overrides before proposing a different timezone.
• Formatter output is contextual. Raw/HTML formats may preserve markup while other formats encode it; choose the format required by the consuming view. Translation does not automatically make untrusted substitutions safe in every HTML/attribute/JavaScript context.
• Do not translate identifiers or rewrite every source string for a focused message change. Locale-prefixed URL behavior belongs to the installed routing extension and needs its separately resolved version.

Observable acceptance

Check the changed messages with representative parameters in the target language and relevant source/fallback language. For plural/select changes include the branches actually used. For time or number formatting verify known canonical values, configured locale/timezone, and any relevant boundary such as DST. State whether ext-intl or a fallback implementation was exercised. Confirm output remains safe in its actual rendering context.

Evidence routes

Read framework/i18n/{I18N,MessageSource,PhpMessageSource,DbMessageSource,Formatter,MessageFormatter}.php and matching files under framework/messages/. Tests: tests/framework/i18n/I18NTest.php, PhpMessageSourceTest.php, MessageFormatterTest.php, FallbackMessageFormatterTest.php, FormatterDateTest.php, and FormatterNumberTest.php in that directory. Guides: tutorial-i18n, output-formatting.

Install and activate this skill

Select yii2-i18n-formatting in the installation and client verification guide. Install the complete bundle, including referenced resources. The canonical SKILL.md is also available for direct reading.

Continue with the related framework guide.