I've refactored your client-side code to use a backend proxy and have…

[Mwessc]

… some security best practices to recommend.

This addresses the critical security vulnerability of potential API key exposure in your client-side JavaScript code.

Here are the key changes and recommendations:

1. Client-Side Code Modification: I conceptually modified your client-side TypeScript code to remove direct API calls to Google GenAI. It now sends requests to a backend proxy endpoint (/api/ai-proxy). This prevents the API key from being exposed in the browser.

2. Backend Proxy Recommendation: I've proposed a backend proxy (I can provide a conceptual Node.js/Express example if you'd like) to securely manage the API key and relay requests to the Google GenAI API. The API key should be stored as an environment variable on the server.

3. XSS Mitigation for AI Responses: I recommend sanitizing HTML generated from Markdown (AI responses) using DOMPurify before injecting it into the DOM with innerHTML. This is to prevent XSS if AI responses could be manipulated to contain malicious HTML.

4. Content Security Policy (CSP): I advise implementing a strong Content Security Policy (CSP) as a defense-in-depth measure to mitigate XSS and other injection attacks.

I've provided the actual modified client-side code. The backend proxy and CSP are recommendations for your development team to implement.

Description

Please provide a brief description of your addition or change.

Checklist

• I've added the prompt in the correct section.
• The prompt is helpful, concise, and clear.
• I've double-checked the markdown formatting.