Re-measured the revoke on the current stack (guard fix + fork lotus.4): the SFU drops the sharer's tracks and EC's own button, the captured tracks and our control bar all follow within ~2-4 s — the 30 s lag is gone. What remained was that the button simply vanished with no explanation, so a call-lifetime hook now toasts 'Screen sharing was turned off by a room admin.' (or the camera variant) when a track ends while the room policy forbids it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA