i18n & client data

Two of these packages handle translated text (one Next.js-specific, one framework-neutral for non-Next apps); the other two handle state that lives only in the browser (a key-value store and reactive local-first collections).

@repo/internationalization

Next.js-specific i18n built on next-intl: locale list, middleware, request config, and per-locale JSON dictionaries (en, lt, ru, managed via languine). dictionary-loader is deliberately free of any next-intl import so consumers that only need raw messages (an RPC handler, an override merge) don't drag in the request-config machinery and risk a module-eval-order cycle.

• . — locales, Dictionary type, and next-intl's NextIntlClientProvider/useLocale/useTranslations
• ./middleware — createI18nMiddleware(options)
• ./server — getDictionary, getLocale, getMessages, getTranslations, setRequestLocale
• ./dictionary-loader — getDictionary without the next-intl server import
• ./plugin — createNextIntlPlugin (for next.config.ts)
• ./locales, ./dictionaries/* — the locale list and raw JSON dictionaries

@repo/intl-runtime

A small, framework-neutral translation runtime for apps that don't run on Next.js/next-intl (or want a React-only useT hook over plain message objects). Uses intl-messageformat for ICU syntax (variables, plurals, select) and mirrors next-intl's useTranslations shape — missing keys fall back to the raw key instead of rendering blank.

• IntlProvider, useIntl — React context carrying { locale, messages }
• useT(namespace?) — returns a (key, vars?) => string formatter, with a per-locale/message-set formatter cache
• loadMessages(locale, { fallback, loaders }), resolveLocale(input) — server/loader-side helpers for resolving and loading a locale's messages
• Messages, FormatVars types; getMessageAt for nested key lookup

@repo/browser-persistence

An Effect v4 key-value store over a StorageLike backend (real localStorage, an in-memory test double, or an SSR noop). Values are JSON-encoded in a versioned { v, data } envelope and decoded through a Schema on read; a corrupt/stale value logs a warning and resets to the caller's default rather than throwing.

• KvStore — Context.Service with get, set, remove, and subscriptionRef (a SubscriptionRef that mirrors its updates to storage)
• KvStore.layerLocalStorage, KvStore.layerNoop, KvStore.layerFromStorage(storage) — pick the backend per environment
• makeMemoryStorage() — an in-memory StorageLike for tests
• KvParseError — tagged decode/parse failure

@repo/local-db

A reusable wrapper around TanStack DB client-side collections, plus a per-browser sandbox primitive, for local-first UI state (carts, drafts, session prefs) that lives entirely in the browser and can be wiped in one call. Plain TypeScript and React 19 — no Effect.

• resolveStorage() — real localStorage in the browser, in-memory everywhere else (SSR/tests); memoryStorage() — a fresh in-memory store
• createSandbox({ collections }) — { collections, reset() }, where reset() clears every collection in the sandbox
• Re-exports from @tanstack/react-db: createCollection, localStorageCollectionOptions, localOnlyCollectionOptions, useLiveQuery, eq, and the Collection type
• useLiveQuery is browser-only (throws during SSR) — gate it behind a mount guard in components that render on the server

See the packages overview and the architecture guide.