[velis74]

formatParams(t, format) returns a translation function that passes each placeholder value through format before t substitutes it. vue-i18n's t substitutes a value as String(value), so numbers miss the locale's digits and separators and dates print as Date.prototype.toString. With formatParams(t, v => typeof v === 'number' ? n(v) : v instanceof Date ? d(v) : v) the application formats values once, for every library, and the package still does not depend on vue-i18n.

• Values are read and formatted on every call: getters return their current value, and reactive state format reads (vue-i18n's locale through n/d) is tracked by the computed or render that reads the string.
• named is not mutated; the result of t is returned unchanged, so a returned key still means no translation.
• The English-default fallback in translate is unchanged and interpolates unformatted values.

Tests (real vue-i18n): Persian digits with n in fa, a date with d, an unchanged value, no mutation, a getter read per call, a locale switch fa → en inside a computed, reactivity of state read only by format (over a non-reactive t), the unformatted English fallback, and formatParams over an interpolate-based t with Intl.

readme: formatParams in the intro, the values named holds, new section Formatting values in the application part, two vue-i18n notes. changelog and version 0.3.0.

[github-actions]

✅ Incremental coverage — 100%

████████████████████ 5 / 5 changed lines covered · threshold 70% · main → format-params

	File	Coverage	Covered	Uncovered lines
✅	src/translatable.ts	100%	5 / 5	—
	Total	100%	5 / 5

6 files not graded (2 ignored by pattern, 4 not source files)

File	Reason
changelog.md	not a source file
package-lock.json	not a source file
package.json	not a source file
readme.md	not a source file
src/index.ts	ignored by **/index.ts
src/translatable.spec.ts	ignored by *.spec.*

_{Coverage reports: coverage/coverage-final.json (istanbul, 1 file) — incremental-coverage-check v3.0.0}