Planning wood movement for a solid-wood panel in a frame

I'm making a solid-wood panel for the center of a framed cabinet door. My first sketch had it glued firmly along every edge, but I'm realizing seasonal expansion across the grain could split something. How much clearance would you leave in the groove, and would you finish the panel before assembly so an unpainted stripe doesn't appear later? The frame will be stable, but I need the panel to move without rattling.