Hey everyone, wanted to share a project I’ve been working on using Claude Code in my terminal. I built Fine Print Guard (Chrome Web Store link), which is a Manifest V3 extension that instantly grades Privacy Policies and ToS agreements (A through F) while automatically handling cookie popups so you don’t have to deal with dark patterns. How I used Claude Code during the build: Using Claude Code directly in the CLI for an extension saved me a ton of headache, especially dealing with MV3 restrictions. A few specific parts where it helped: Service worker messaging: MV3 doesn’t allow persistent background pages anymore. Getting non-persistent event handlers working smoothly between content scripts, the popup UI, and chrome.storage.session was tricky, so I had Claude Code structure the async messaging pipeline. Shadow DOM & DOM parsing: Cookie banners are frustrating to target because so many live inside shadow roots or get dynamically injected. Claude helped generate mutation observers and dynamic selectors that actually catch these elements across different sites. ToS Chunking Logic: Privacy policies can be ridiculously long. I used Claude Code to write a local text-chunking parser to extract high-risk clauses (like data sharing or forced arbitration) before sending them off to be evaluated. Takeaways & things I learned: Give it Chrome API context: If you’re building extensions with Claude Code, pass explicit Chrome API signatures (chrome.runtime, chrome.declarativeNetRequest, etc.) in your prompts. Otherwise, it will occasionally default to old Manifest V2 methods that are deprecated. Handle MV3 port disconnects early: MV3 background channels like to drop silently. Having Claude write automated reconnect logic saved me a massive amount of debugging time. Claude worked on the first time when publishing. Keep parsing on-device: Doing the initial DOM and text parsing directly in the content script keeps things fast and respects user privacy. That I need to optimize my usage because claude runs through tokens so quickly Give it a shot on the Chrome Web Store if you’re interested. Would love to hear any feedback on the tool or answer any questions about using Claude Code for extension builds! Willing to give advice on how to optimize usage and anything else. submitted by /u/Late-Entertainer-732
Originally posted by u/Late-Entertainer-732 on r/ClaudeCode