The list of languages

interface DiffineLanguageOption {
  id: string;
  name: string;
}

const DIFFINE_LANGUAGES: readonly DiffineLanguageOption[];

Every language language accepts, plain first and then thirty-four highlight.js identifiers in alphabetical order. id is what language takes and name is what the bar writes beside the panes — English in every locale, because TypeScript is TypeScript in all of them. It is names and nothing else: the grammars sit behind an import() apiece, so a menu built from this list costs a list.

The editor's own menu is built from this list, and an application building a menu somewhere else should build it from the same one rather than from a copy that goes stale.

highlight.js and each grammar sit behind an import(). Nothing is fetched until a language other than plain is asked for, and what is fetched then is that one grammar. The first paint after it arrives is the document coloured; the one before it is the document.

class DiffineLanguageOption {
  final String id;
  final String name;
}

const List<DiffineLanguageOption> kDiffineLanguages;

DiffineHighlight? diffineHighlighterFor(String? language, List<String> before, List<String> after);

Every language language accepts, plain first and then thirty-four identifiers in alphabetical order — the same identifiers the React package takes, so a service that stores one alongside a document stores the same string for both. id is what language takes and name is what the bar writes beside the panes, in English in every locale.

The editor's own menu is built from this list, and an application building a menu somewhere else should build it from the same one rather than from a copy that goes stale.

The grammars are in the package rather than fetched, because an app bundle has no network to defer to. They are approximate for the same reason: a correct parser for thirty-four languages is not a thing to keep beside a diff viewer. diffineHighlighterFor is the one behind language, exposed for an application that wants to colour something else with the same rules.