Kit: the plugin authoring toolkit

kubb/kit is what you import to author a plugin, a generator, a resolver, a parser, or a custom adapter or renderer. It groups definePlugin, defineGenerator, defineResolver, defineParser, createAdapter, createRenderer, the ast namespace and factory node builders you use to construct output, and the option and hook types that go with all of it. See Architecture for where kit sits in the pipeline, Plugins for what a plugin does once it is built, and AST for the tree kit's ast namespace wraps.

Why a separate surface from the engine

@kubb/core also runs the build engine: the plugin driver, the file manager, the CLI reporters. None of that is part of authoring a plugin. A plugin author calls definePlugin and returns an object. The engine discovers that object, walks the AST against it, and writes the result to disk. Mixing the two into one import would mean every plugin author pulls in driver internals they never call.

Kit keeps the two apart the same way kubb/ast and kubb/jsx separate the AST layer and the JSX renderer from the engine that drives them. You call kubb/kit to build things. The engine, reached through the kubb package and its CLI, runs them.

Why ast and factory live in kit, not kubb/ast

Node building is the most common thing a generator author does. Nearly every operation or schema handler ends with a call to ast.factory.createFile or one of its neighbors, so the node builders sit right next to definePlugin and defineGenerator instead of requiring a second import from kubb/ast.

kubb/ast still holds everything else: the guards, the macros, the schema and string helpers, the dialect, the printer, and the visitors. Import from there directly when you are working with the AST outside of a plugin, say a macro or a script that narrows a node on its own. Inside a plugin or generator, pull ast from kit instead, since you already import definePlugin or defineGenerator from the same place.

Reference

The full list of exports, definePlugin, defineGenerator, defineResolver, defineParser, createAdapter, createRenderer, createStorage, Diagnostics, memoryStorage, fsStorage, the ast and factory namespaces, and the kubb/kit/testing helpers, lives in the Kit API reference.

See also Plugins for the plugin lifecycle, AST for the tree kit's ast namespace wraps, and Creating your first plugin for a step-by-step build.