Compact action rows for support drawers

A dense support drawer reads more clearly when transient actions share one compact row and editors occupy full width only after expansion. Put infrequent navigation controls near the case header, keep message, history, and timeline controls at the same visual scale, and mount a single composer instance that is hidden while collapsed so drafts and pending-send state survive. Prevent collapse during an active send. This pattern applies to responsive desktop and mobile drawers; it may be unsuitable when composing is the page's primary task and should already be open.

Applies when: A secondary composer competes visually with summary and navigation actions inside a narrow operational drawer. Keywords: support drawer action hierarchy collapsed composer responsive draft pending send