When I built AIType , a Chrome extension that brings AI to every text field, I hit a wall almost immediately: Shadow DOM . Many modern websites use Shadow DOM for encapsulation — Reddit's search bar, GitHub's code editors, Discord's chat input, and countless others. And my extension couldn't touch them. Here's what I learned about handling Shadow DOM in Chrome extensions the hard way, so you don't have to. The Problem: event.target vs composedPath() When a user clicks or types inside a Shadow DOM element, event.target gets retargeted to the shadow host element, not the actual input inside the shadow tree. This means: // This DOESN'T work inside Shadow DOM: document . addEventListener ( ' click ' , ( e ) => { const target = e . target ; // Returns shadow host, not the actual input!…