Quartz

Quartz answers an agent's TypeScript questions with the compiler's own answers.

npm install -g @skastr0/quartz

The pain

Your agent is changing TypeScript whose types it can't see.

• It guesses types from text. It greps for a declaration and rebuilds the type in its head, through generics and inference it can't see.
• It finds out from tsc. Write, run tsc, read the error, try again. Many turns go to flailing on type errors.
• It rewrites what already exists. Nothing tells it there's already a User → UserDTO function two files over.

What Quartz does

Quartz keeps the TypeScript 7 native compiler open on your project and answers questions as JSON. Your agent checks a type, a snippet, or whether a converter already exists before it writes code, not after tsc fails.

your agent wants to know	command	it gets back
what a type contains	info, expand	resolved members and signatures
whether code compiles	check-snippet	compiler errors with line and column; nothing is written to disk
whether a converter already exists	transform-search	matching functions, each checked by a test compile
whether a planned conversion is safe	verify-contract	each check, passed or failed, and one overall answer

Quartz is	Quartz is not
a JSON CLI and OpenCode plugin that agents call mid-task	a language server or editor extension
answers from the TypeScript compiler	a guess from text search
evidence that a type or change checks out	proof that the code is correct at runtime

Version 0.2.3, on npm for macOS and Linux (arm64, x64). There is no Windows build. Quartz needs a tsconfig.json in the project.

Quick start

Run these from any folder that has a tsconfig.json. The output below comes from a small project with User and UserDTO types.

# 1. Install
npm install -g @skastr0/quartz

# 2. See which TypeScript projects quartz finds
quartz packages

# 3. Ask what a type contains
quartz info '{"symbol":"User"}'

# 4. Check code before writing it
quartz check-snippet '{"code":"const u: User = { id: \"1\", name: \"Ada\" };"}'

Step 3 returns the resolved members:

{"ok":true,"command":"info","data":{"name":"User","kind":"interface","location":{"file":"types/basic.ts","line":8},
 "properties":[{"name":"id","type":"string"},{"name":"name","type":"string"},{"name":"email","type":"string"}]}}

Step 4 catches the missing field without touching a file:

{"ok":true,"command":"check-snippet","data":{"valid":false,"errors":[
 {"message":"Property 'email' is missing in type '{ id: string; name: string; }' but required in type 'User'.","line":1,"column":7}]}}

Project types are in scope in a snippet without an import. A snippet can import packages by name; tsconfig path aliases (paths) don't resolve there.

Or run it without installing: npx -y @skastr0/quartz@latest packages, or bunx @skastr0/quartz packages.

Use

Is there already a function that turns a User into a UserDTO?

$ quartz transform-search '{"from":"User","to":"UserDTO","verifiedOnly":true,"limit":2}'
toDTO(from: User): UserDTO        types/transforms.ts:30   verified
transform(input: User): UserDTO   types/transforms.ts:211  verified

Can toDTO convert a User here? Four checks, one answer.

$ quartz verify-contract '{"from":"User","to":"UserDTO","symbol":"toDTO"}'
ok: true
compatibility  failed   User is not directly assignable to UserDTO; verified transform evidence can still satisfy a conversion contract.
snippet        skipped  Skipped because no snippet was provided.
diagnostics    passed   Package diagnostics are clean.
transform      passed   A compiler-verified transform satisfies the requested contract.

The direct assignment fails, but a verified converter exists, so the answer is yes.

Both outputs are trimmed from the JSON envelope. Every command takes a JSON payload inline, from a file (@payload.json), or from stdin (-). Agents can discover every command and payload with quartz capabilities and quartz schema show <command>.

Each one-shot command starts a fresh compiler (0.7 to 2.8 s on Quartz's own repo). For repeated calls, send a batch payload (a JSON array) or use the OpenCode plugin; both keep one compiler warm.

All commands:

area	commands
look up	packages, symbols, info, expand, search, file, at-position
evaluate	eval, explain, compatible, check-snippet
errors	diagnostics, why-error
relationships	related, graph, refactor-preview
evidence	transform-search, verify-contract
discovery	capabilities, schema, examples, doctor

Payload fields, batch calls, artifacts, and error envelopes are in docs/reference.md.

How it works

@skastr0/quartz-engine opens one TypeScript 7 native compiler per project through its async API. Snippets and transform checks compile as temporary virtual files, so your files are never changed. The CLI reuses one compiler across a batch of payloads. The OpenCode plugin keeps it warm for the whole session and refreshes it when files change.

OpenCode plugin

Load @skastr0/quartz-opencode-plugin/server in OpenCode. It exposes the same analysis as 19 type_* tools rooted at your workspace, with one compiler kept warm across calls. Tool list: docs/reference.md#opencode-plugin.

Where it fits

Quartz gives every agent in a TypeScript repo the same compiler facts. Pulsar builds its TypeScript scoring on @skastr0/quartz-engine. More at castro.engineer/projects/quartz.

Development

bun install
bun run verify

Architecture checks: docs/architecture-fitness.md. Performance: docs/performance.md. Release process: docs/publishing.md.

Contributing, security, license

Issues are the way in; see CONTRIBUTING.md. Report vulnerabilities privately; see SECURITY.md. MIT; see LICENSE.