# AGENTS.md — typescript-config

Shared TypeScript base configs (`tsconfig.json` files) and Vitest base config, consumed by all packages.

## What it owns

- **`base.json`** — Base `tsconfig.json`: target ES2022, module ESM, `experimentalDecorators` + `emitDecoratorMetadata` for InversifyJS
- **`nextjs.json`** — Next.js app config: extends base, adds `jsx: "preserve"`, Next.js lib types
- **`react-library.json`** — React library config: extends base, adds `jsx: "react-jsx"`, DOM lib
- **`vitest.base.ts`** — Vitest base config: globals, isolate modules, common ignore patterns

## How packages consume them

Packages extend the appropriate base:

```json
// packages/blog/tsconfig.json
{
  "extends": "@repo/typescript-config/base.json",
  "compilerOptions": {
    "rootDir": ".",
    "outDir": "dist",
    "lib": ["ES2022"]
  },
  "include": ["src/**/*"]
}
```

Apps extend Next.js config:

```json
// apps/web-next/tsconfig.json
{
  "extends": "@repo/typescript-config/nextjs.json",
  "compilerOptions": {
    "rootDir": ".",
    "outDir": ".next"
  }
}
```

Vitest configs import the base:

```typescript
// packages/blog/vitest.config.ts
import { defineConfig } from "vitest/config";
import path from "path";
import { vitestBase } from "@repo/typescript-config";

export default defineConfig({
  ...vitestBase,
  test: {
    environment: "node",
  },
  resolve: {
    alias: {
      "@": path.resolve(__dirname, "./src"),
    },
  },
});
```

## Test conventions

- No unit tests (config validation via `pnpm typecheck` in other packages)
- Verify at CI: `pnpm typecheck` succeeds across all packages
- Type errors should propagate: `pnpm typecheck` fails on invalid source code

## Structure

```
base.json                    # ES2022, ESM, decorators
nextjs.json                  # Next.js-specific paths + lib
react-library.json           # React JSX + DOM
vitest.base.ts               # Vitest defaults (globals, isolate)
package.json                 # Exports above files
```