Glossary of i18n Terms
This glossary defines standard internationalization (i18n) and React Router concepts used throughout the lingui-rr documentation.
BCP-47
A standardized format for language tags (e.g., en, en-US, ar-EG). lingui-rr supports BCP-47 language tags and automatically handles regional fallback: if a user requests en-US but your app only configures en, it automatically resolves to en.
Default Locale
The primary language the application renders if no language preference is detected or if a URL-Prefix app receives an unprefixed root path.
Detector
A pluggable utility that attempts to read the user's preferred language. Common detection targets include HTTP headers (Accept-Language), cookies, browser-level configuration (navigator.languages), or storage keys.
Framework Mode
The unified full-stack architecture introduced in React Router v8 (previously Remix). It manages server/client routing, data loading (loaders), actions (actions), and request lifecycle filters (middleware) inside a single compile target.
Isomorphic Cookies
Cookies that are accessible in both browser and server runtime environments. In lingui-rr, client cookie detectors and persistence adapters are isomorphic: they read/write document.cookie when executing in the browser, but will read the request headers and output Set-Cookie if executed server-side (like during SSR actions).
Persistence
The mechanism by which a user's language selection is saved for future visits. Common persistence drivers write to cookies, session stores, or localStorage.
Revalidation
React Router's process of re-executing active loaders (including the root layout loader) to refresh page state after navigations or action submissions. In React Router v8, call sites can opt out with defaultShouldRevalidate={false}; lingui-rr's createLinguiShouldRevalidate is only an optional guardrail for locale-switch submissions.
Serialization
The process of translating JavaScript runtime data structures into a string format (JSON) suitable for network transit. React Router requires loader data to be JSON-serializable. Because compiled Lingui catalogs contain runtime structures, lingui-rr provides safe loader wrappers that serialize cleanly without needing unsafe code-casting assertions.