For full-page captures, I'm using Chrome's native DevTools screenshot API (the same one you get with Cmd+Shift+P → "Capture full size screenshot"). So the behavior for sticky headers, lazy-loaded content, and dynamic pages essentially matches what DevTools does—both the benefits and limitations.

Sticky headers: Captured in their fixed position throughout the scroll, as DevTools does.

Lazy-loaded content: Depends on how Chrome's capture handles it. Generally works well for standard lazy loading, but infinite scroll or heavily JS-dependent dynamic content can be hit-or-miss. That's a Chrome limitation rather than something I can work around in the extension.

Dynamic resizing: The viewport setting works well here since it's part of the DevTools protocol. Pages render at the specified dimensions during capture.

For visible area captures (not full-page), I have more control and it's straightforward—basically a direct screenshot of what's rendered in the viewport.

The main use case I'm targeting is for people creating documentation/manuals who want to annotate screenshots on the spot without switching to another tool.

The goal is to keep everything within the same workflow - capture, annotate, and save - all in the sidebar.

I'd love it if you could give it a try and let me know what you think!