Playwright can test Chrome extensions. So why does my AI agent still need my help?

What happens when you let an AI write a browser extension

I've been building Chrome extensions with AI coding agents — Claude Code, Cursor, whatever. Writing the code is the fast part. The problem is everything after.

"Build it, load it into the browser, open the popup, click the button, check the console."

That part? All me. Every time. The agent can write the code, but it can't see what the code looks like on screen. It can't click anything. It can't read the logs. So the human becomes the agent's eyes and hands.

At first I accepted this as the cost of doing business. Then I hit the UI-polishing phase and it turned into hell. Every "move that button 20px right" or "make the font 14px" meant: build → load → screenshot → paste it into chat → "how's this?" → agent edits code → build → load → screenshot. Forever.