Custom adapters

Use @verific/i18n when your locale library can perform an exact key-and-locale lookup but has no first-party adapter. The shared catalogue module supplies key generation, key-first fallback and missing-message diagnostics; your driver keeps locale negotiation and formatting in the locale library.

Install and connect a driver

pnpm add @verific/core @verific/i18n vue zod

import { createVerific } from '@verific/core'
import { createCatalogueMessages } from '@verific/i18n'
import { createApp, ref } from 'vue'
import App from './App.vue'

const locale = ref('en')
const catalogues: Readonly<Record<string, Readonly<Record<string, string>>>> = {
  en: { 'errors.invalidEmail': 'Enter a valid email address' },
  es: { 'errors.invalidEmail': 'Introduce una dirección de correo válida' },
} as const

const messages = createCatalogueMessages({
  locales: () => [locale.value, 'en'],
  lookup(key, selectedLocale) {
    const message = catalogues[selectedLocale]?.[key]
    if (message === undefined)
      return { resolved: false }

    return {
      resolved: true,
      message,
    }
  },
}, {
  fallbackPrefix: 'errors',
})

createApp(App)
  .use(createVerific({ messages }))
  .mount('#app')

lookup() must atomically decide exact existence and return the selected translation. Do not let it silently change locale: createCatalogueMessages() owns the shared key-first order.

Use the shared options

const messages = createCatalogueMessages(driver, {
  fallbackPrefix: 'errors',
  missing: 'throw',
  key({ identifier, defaultKeys }) {
    return [`validation.${identifier}`, ...defaultKeys]
  },
})

• fallbackPrefix adds the shared {prefix}.{identifier} candidate.
• missing accepts 'silent', 'warn', 'throw' or a diagnostic callback.
• key replaces the candidate list. Include defaultKeys to retain the normal field-specific and shared candidates.

A custom key function is also the place to escape dotted field names or handle symbol path segments. Duplicate keys and locales are removed while preserving their first occurrence.

Render errors normally

The adapter is configured once; forms only select their prefix and render the destructured controller members:

const { errorsFor, hasError, validate, validateFor } = useValidation(schema, form, {
  messagePrefix: 'forms.signup',
})

Read a Vue ref or computed locale inside locales() to update displayed errors without schema revalidation. For SSR, construct the driver and its mutable locale state within the request or application boundary.

If a library cannot provide exact lookup, use a core MessageResolver directly and return undefined on a miss. See Message resolution for that lower-level contract.