Setup And Tooling

Use this file when bootstrapping an Effect repo, auditing project setup, or deciding which packages and compiler settings belong in the project.

Source Notes

• effect-solutions is the opinionated setup guide and recommends the language service, strict TypeScript defaults, and a local Effect source checkout.
• effect.website is the canonical reference for runtime, config, and package APIs.
• The Effect monorepo confirms current package names such as effect, @effect/platform, @effect/cli, @effect/vitest, and @effect/platform-node

Package Selection

• Install effect in every Effect project.
• Add @effect/platform for HTTP clients, filesystem, platform services, and general app integration.
• Add exactly one platform runtime package for the host:
  • @effect/platform-node
  • @effect/platform-bun
  • @effect/platform-browser
• Add @effect/cli for CLIs.
• Add vitest and @effect/vitest for tests.
• Do not install @effect/schema for new work — Schema lives in effect

Language Service

effect-solutions recommends installing @effect/language-service and wiring it into tsconfig.json

{
  "compilerOptions": {
    "plugins": [
      {
        "name": "@effect/language-service"
      }
    ]
  }
}

For VS Code or Cursor, prefer workspace TypeScript:

{
  "typescript.tsdk": "./node_modules/typescript/lib",
  "typescript.enablePromptUseWorkspaceTsdk": true
}

If the project wants build-time diagnostics, run effect-language-service patch and persist it via a prepare script.

TypeScript Defaults

From effect-solutions, these are the main defaults worth checking before code changes:

• strict: true
• exactOptionalPropertyTypes: true
• noUnusedLocals: true
• noImplicitOverride: true
• verbatimModuleSyntax: true
• incremental: true and composite: true when the repo benefits from project references

Module settings depend on the project shape:

• Bundled apps: use "module": "preserve" with "moduleResolution": "bundler"
• Node apps and libraries: use "module": "NodeNext"

Local Reference Checkout

effect-solutions recommends cloning the Effect repo locally so agents can grep real implementations when docs are not enough. If the repo already has a local reference path in AGENTS.md or CLAUDE.md, use that before browsing the web.

Setup Audit Checklist

1. Inspect package.json, lockfiles, and tsconfig*
2. Check whether the repo already uses Effect and which runtime package it uses.
3. Check whether @effect/language-service is present and configured.
4. Confirm test tooling and scripts.
5. Confirm the platform package matches the host runtime.
6. Check for stale or deprecated packages before adding anything new.

Validation

• Run the repo's existing install, typecheck, lint, and test commands.
• If you changed compiler settings, run a real tsc-backed check, not only the editor.
• If you changed runtime packages, run one representative entrypoint after install.