A Flutter string renders without its placeholder

What you see

• •An error message, counter or title renders without the value it was supposed to include, in one locale.
• •`flutter gen-l10n` completes without complaint, because the key and its metadata are present.
• •The affected string is often a plural or an error path, which is exactly where nobody looks during review.

Why it happens

An .arb file pairs each message with a `@key` block that declares its placeholders. The generator wires those declarations into a typed method, but it does not verify that each translation actually uses them. A translation that drops `{error}` or `{count}` still compiles, still type-checks at the call site, and renders a sentence missing its subject.

Find every instance

Point the checker at the directory holding your .arb files:

npx @shipi18n/cli@latest check ./lib/l10n -s en --severity 'missing-key=off,untranslated=off,orphan-key=off'

The ARB grammar reads placeholders through the ICU parser, so arguments nested inside plural and select branches are counted, and `%{x}` sequences inside ARB text are not mistaken for placeholders.

✗ ko  coverage 100.0%  1 error(s), 0 warning(s)
    error  error  placeholder-missing — dropped {error}

How to fix it

1. 1Restore the placeholder in the translated message using the exact name from the `@key` metadata.
2. 2Check every plural branch, not just the one that was reported: `one` and `other` are separate strings and fail independently.
3. 3Run the check in CI ahead of `gen-l10n`, so a translation that drops a declared placeholder fails the pull request.

The rules that catch this