# Kavach — Logger (@kavach/logger)

> Structured audit logging with pluggable transport adapters. Used by kavach
> to emit auth events (sign-in, sign-out, access denied) to your chosen backend.

## Install

```bash
npm install @kavach/logger
```

## Usage

The logger is configured automatically when using the full kavach package via
`kavach.config.js`. For standalone usage:

```js
import { createLogger } from '@kavach/logger'

const logger = createLogger({
  level: 'info', // 'debug' | 'info' | 'warn' | 'error'
  adapter: 'console' // transport adapter
})
```

## API

### createLogger(options)

```ts
createLogger({
  level?: 'debug' | 'info' | 'warn' | 'error'
  adapter?: string | LogAdapter
})
```

### logger.info(event, data?)

```ts
logger.info('auth.signIn', { userId, email })
logger.info('auth.signOut', { userId })
logger.warn('auth.accessDenied', { path, role })
logger.error('auth.error', { message, stack })
```

### logger.debug / logger.warn / logger.error

Same signature as `logger.info`.

## Auth Events

Kavach emits these events automatically:

| Event                 | When                            |
| --------------------- | ------------------------------- |
| `auth.signIn`         | Successful sign-in              |
| `auth.signOut`        | Sign-out                        |
| `auth.accessDenied`   | Route protection blocked access |
| `auth.sessionRefresh` | Session token refreshed         |
| `auth.error`          | Auth error occurred             |

## Transports

Built-in adapters:

- `'console'` — logs to stdout (default in development)
- Custom adapter: implement `{ log(level, event, data): void }`

## Integration with Supabase

The Supabase adapter supports writing audit logs directly to a Supabase table.
See [Supabase adapter](./adapter-supabase.txt) for configuration.