More of the session on screen
The chat page gives the transcript back the space the chrome was taking.
Sessions
The session page reclaims a few hundred pixels of vertical space for the conversation itself. The session context panel is collapsed behind a control in the header rather than always occupying a row, and the artifact save prompt floats over the foot of the transcript instead of pushing it up.
The save prompt stays until you dismiss it or save the artifact. It is never dismissed on a timer, because that would throw away the draft.