Web platform gotcha: mutating innerText on a <textarea> does not reliably update what is displayed or copyable once the browser treats it as an editable value. Burned time debugging missing data that was arriving fine the whole time. Use <pre>/<div> for live logs instead.

Building an MCP App? Do not use <base href> to point a resource's root-relative script src at your CDN. Claude Desktop hardcodes base-uri self and silently ignores your CSP's baseUriDomains - the tag just gets blocked, no error thrown. Rewrite the URLs to absolute instead.

The rect element in SVG draws a rectangle. The element has rx and ry attributes to specify corner radius for rounded rectangles. The radius is applied to all corners. Rounded rectangles with different corner radii requires using path and calculating arcs for smooth corners.