Explain Code

Provide a clear, thorough explanation of the specified code.

Input

The user will provide one of:

• A file path: /explain src/auth/jwt.ts

• A file path with line range: /explain src/auth/jwt.ts:45-80

• A function/class name: /explain parseToken

• Just /explain — explain the currently open or most recently discussed file

Explanation Structure

1. Overview (2-3 sentences)

What does this code do at a high level? What problem does it solve?

2. Key Components

Break down the major parts:

Function: functionName

Purpose: One sentence description

Parameters:

• param1 (type) — what it's for
• param2 (type) — what it's for

Returns: What and when

Side effects: Any mutations, API calls, state changes

3. Control Flow

Explain the execution path:

• First, it does X

• Then checks Y

• If Y is true, Z happens

• Otherwise, W happens

Use a simple flowchart for complex logic:

Input -> Validate -> Transform -> Output | Error -> Log -> Return null

4. Dependencies

What does this code depend on?

• External libraries

• Internal modules

• Environment variables

• Database/API connections

5. Gotchas & Edge Cases

Things that might surprise someone:

• Non-obvious behavior

• Edge cases handled (or not handled)

• Performance considerations

• Known limitations

6. Usage Example

Show how to use this code:

// Example usage const result = functionName(arg1, arg2);

Tone

• Assume the reader is a competent developer unfamiliar with this specific code

• Avoid jargon unless defining it

• Use "this code" not "the code" for clarity

• Be concise but complete