Install

langium-ai-tools is a library which helps to guide the development of AI applications that leverage Langium DSLs. It contributes functionality to perform evaluation, analysis, and program splitting.

Ideally, you should already have a Langium language project in mind that you'd want to add this to. If you don't, you can always set up a fresh one using Langium's installation guide.

Looking for a command to run?

That's the lai CLI, published as langium-ai. It's responsible for driving the automated configuration and setup of both tools and evaluations, and it leverages this package to do so. lai init also offers to install this library into your project for you.

Install

Installation is straightforward from npm:

npm i --save langium-ai-tools

Or with your package manager of choice:

# pnpm
pnpm add langium-ai-tools

# yarn
yarn add langium-ai-tools

Requirements

• Node.js >= 22.0.0
• langium >= 4.0.0 (peer dep)
• ESM-only (see below for details)

Langium is a peer dependency so we can re-use your language's services. Versions vary, but the surface API is quite consistent. We mark it as a peer so we can run against your version of Langium, rather than pulling in an additional (and potentially breaking) version.

Version alignment with Langium

The current langium-ai-tools line is 5.x, and it accepts any Langium 4.x via the peer range above. On the older langium-ai-tools versions (4.x and lower), we tracked Langium majors more literally. So generally we would recommend being on the 5.x line at the minimum.

Langium 3.x and earlier are not explicitly supported.

ESM only

This package doesn't provide a CommonJS entry, so require('langium-ai-tools') won't resolve. Your consuming code has to be ESM (or reach it through a dynamic import()).

This matters most for eval files. lai evaluate loads .eval.ts files that import your language services, so your language project should be ESM-importable.

Entrypoints

Everything is re-exported from the root barrel file, but the subpath exports are what the docs are written against. They keep imports narrow and make it obvious which capability a file depends on.

Import specifier	Covers	Page
langium-ai-tools	Root barrel that re-exports all of the below, plus the generated message types	—
langium-ai-tools/splitter	splitByNode, splitByNodeToAst, ProgramMapper	Splitter
langium-ai-tools/evaluator	Evaluator, LangiumEvaluator, EvalMatrix, Runner, EvalCase, mergeEvaluators, loadFromYaml, and averaging logic	Evaluator
langium-ai-tools/evals	describe, evaluation, evaluation.each, lifecycle hooks, EvalContext, runEvalFile	Evals
langium-ai-tools/analyzer	LangiumDocumentAnalyzer, AnalysisMode	Analyzer

Bundled dependencies

Three runtime dependencies come along with the install as well:

• yaml: for parsing evaluation cases from YAML (loadFromYaml).
• @protobuf-ts/runtime: the generated message types used by the analyzer's statistics.
• tsx: the loader the eval runner registers to import() .eval.ts files directly.

Next steps

• Overview: outlines what each capability is for.
• Evals: the API you'll import first if you're writing .eval.ts files.
• Quickstart: the guided path via the lai CLI.