Explain Code

Explain what code does, line by line, so you can understand and learn from it.

Instructions

When the user asks you to explain code:

Step 1: Identify the Code

If the user provides a file path, read that file. If they paste code directly, use that.

If no code is specified, ask:

"What code would you like me to explain? Please provide a file path or paste the code."

Step 2: Provide Overview

Start with a high-level summary:

• What is the purpose of this code?
• What problem does it solve?
• How does it fit into the larger application?

Step 3: Walk Through Line by Line

For each significant section, explain:

• What it does (literally)
• Why it's needed (purpose)
• How it works (mechanism)

Use this format:

Lines X-Y: [Brief description]
- This code [what it does]
- It's needed because [why]
- It works by [how]

Step 4: Highlight Key Concepts

Point out important patterns and concepts:

• Design patterns used
• Language features that might be unfamiliar
• Best practices demonstrated
• Potential gotchas or edge cases

Step 5: Summarize

End with:

• Key takeaways
• What the user should understand now
• Suggestions for further learning if applicable

Example Output

## Overview

This is a React custom hook that manages authentication state. It handles
login, logout, and automatic token refresh.

## Line-by-Line Explanation

### Lines 1-5: Imports
```typescript
import { useState, useEffect, useCallback } from 'react';
import { authApi } from '@/services/api';
import { User } from '@/types';

• Imports React hooks for state management and side effects
• Imports the auth API service for making authentication requests
• Imports the User type for type safety

Lines 7-15: Hook Definition and State

export function useAuth() {
  const [user, setUser] = useState<User | null>(null);
  const [loading, setLoading] = useState(true);

• Creates a custom hook that can be used in any component

• user

  state holds the current user (or null if logged out)

• loading

  state tracks whether we're still checking auth status
• Starting with

  loading: true

  prevents flash of unauthenticated content

Lines 17-30: Auto-refresh Effect

[... continue explanation ...]

Key Concepts

1. Custom Hooks: Reusable logic extracted from components
2. Optimistic Updates: UI updates before server confirms
3. Token Refresh: Automatic re-authentication before expiry

Takeaways

• This hook centralizes all auth logic in one place
• Components just need to call

  useAuth()

  to access auth state
• The refresh logic runs automatically in the background

## Tips for Users

Ask me to explain:
- "Explain this function" (paste code)
- "Explain src/hooks/useAuth.ts"
- "Explain lines 50-100 of api.ts"
- "What does this regex do?"
- "Why is this pattern used here?"

I'll adjust the depth based on what you ask. For simple code, I'll be brief. For complex code, I'll be thorough.