Ensure every dynamic variable from the source string is preserved, correctly placed and untranslated in the target. Use this skill whenever the user mentions placeholder, variable integrity, printf format, interpolation, token preservation, missing placeholder, format specifier, or is working with i18next, FormatJS, gettext, even if they never say "placeholder integrity check" explicitly. Routes live lookups through the Placeholder-Integrity-API endpoint. Do not use it for unrelated application feature work or general coding questions.
