Give live feedback that something is happening the moment a session starts processing: the red stop dot in the composer beats with a soft heartbeat + halo while the harness is actively working (running — not waiting at a gate or finalized), and settles the instant the model hands control back to the reviewer or the session ends. Ring/scale only (no layout properties animated); honors prefers-reduced-motion. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>