Replaces the body-portal approach: render ChatBar as a sibling of the
contain:[layout paint] chat wrapper (inside the same runtime boundary) rather
than portaling the floating instance to <body>. The wrapper is a containing
block for — and clips — position:fixed descendants, which is what stranded the
popped-out composer off-screen. As a sibling it anchors to the outer relative
container: docked stays absolute (identical placement), floating resolves
against the viewport. Both states stay mounted, so dock<->float no longer
remounts the editor (the portal toggle did).
Brooklyn Nicholson
aff5ae692f