Function draw_agent_identity_mark 

pub fn draw_agent_identity_mark(
    scene: &mut Scene,
    transform: Affine,
    rect: Rect,
    color: AlphaColor<Srgb>,
    theme: &Theme,
    style: AgentIdentityStyle,
)

Paint Tilo’s shared agent identity mark into rect.

color is the principal’s stable identity colour. Interior ink is chosen through the active theme rather than fixed black or white, preserving the same contrast behaviour as other themed controls. The geometry scales down to the 9px live-presence badge without relying on a font or a UTF symbol.