Removing the inline chat pills leaves a one-line message 24px tall, but its visible debug button is 28px tall. Reserve 28px of message height when a diagnostics control exists so the button remains inside its message.

This follows the combined behavior of #243 and #245. The image shows the actual rendered Chat component; outlines mark measured message and button bounds.

Validation: the unchanged native containment test reproduced the 4px overflow before this patch and passes afterward at both narrow and desktop widths. All 26 affected native tests pass in the combined candidate. Independent source review approved the four-line CSS change; formatting and repository CI pass on this branch.