server/api/logout.post.ts

```typescript
import { eventHandler, deleteCookie } from 'h3'
import { sessionStore } from '../middleware/auth'

export default eventHandler((event) => {
  const sessionId = getCookie(event, 'session_id')
  
  if (sessionId) {
    sessionStore.delete(sessionId)
    deleteCookie(event, 'session_id', {
      path: '/',
      httpOnly: true
    })
  }
  
  return { success: true }
})

import { getCookie } from 'h3'
```