# CI Environment Support

Automatically detect CI environments and toggle features based on local vs CI builds.

## Overview

tsdown uses the [`is-in-ci`](https://www.npmjs.com/package/is-in-ci) package to detect CI environments. This covers GitHub Actions, GitLab CI, Jenkins, CircleCI, Travis CI, and more.

## CI-Aware Values

Several options accept CI-aware string values:

| Value          | Behavior                             |
| -------------- | ------------------------------------ |
| `true`         | Always enabled                       |
| `false`        | Always disabled                      |
| `'ci-only'`    | Enabled only in CI, disabled locally |
| `'local-only'` | Enabled only locally, disabled in CI |

## Supported Options

These options accept CI-aware values:

- `dts` - TypeScript declaration file generation
- `publint` - Package lint validation
- `attw` - "Are the types wrong" validation
- `report` - Bundle size reporting
- `exports` - Auto-generate `package.json` exports
- `unused` - Unused dependency check
- `devtools` - DevTools integration
- `failOnWarn` - Fail on warnings (defaults to `'ci-only'`)

## Usage

### String Form

```ts
export default defineConfig({
  dts: 'local-only', // Skip DTS in CI for faster builds
  publint: 'ci-only', // Only run publint in CI
  failOnWarn: 'ci-only', // Fail on warnings in CI only (default)
});
```

### Object Form

When an option takes a configuration object, set `enabled` to a CI-aware value:

```ts
export default defineConfig({
  publint: {
    enabled: 'ci-only',
    level: 'error',
  },
  attw: {
    enabled: 'ci-only',
    profile: 'node16',
  },
});
```

### Config Function

The config function receives a `ci` boolean in its context:

```ts
export default defineConfig((_, { ci }) => ({
  minify: ci,
  sourcemap: !ci,
}));
```

## Typical CI Configuration

```ts
export default defineConfig({
  entry: 'src/index.ts',
  format: ['esm', 'cjs'],
  dts: true,
  failOnWarn: 'ci-only',
  publint: 'ci-only',
  attw: 'ci-only',
});
```

## Related Options

- [Package Validation](option-lint.md) - publint and attw configuration
- [Log Level](option-log-level.md) - `failOnWarn` option details
