The screen at the front of a room is the one screen in a building that regularly stops a meeting.
Presentation in meeting rooms generally depends on a physical connection: a cable, an adapter that fits the laptop in the room, or guest network access arranged in advance. Each is a failure point at the start of a meeting, and the room screen is where meetings most often stall.
The room screen shows a code, as digits and as a QR. A guest scans it and asks for the screen, the host accepts, and the guest presents from their seat. No cable, no HDMI, no adapter that fits one laptop, no client software and no guest network arranged in advance. The host sets the validity window and the target, which may be a single screen or every screen in the room.
Joins are restricted to networks the organization has declared, enforced at the door rather than assumed: a device on any other network is refused. Each join is recorded against the device that took the screen, so room usage is attributable.
Digits and QR rendered on the screen. The guest scans and presents from their seat.
Scanning asks for the screen. Nothing appears until the host accepts, and the host can end it.
The code lasts the window the host sets. Ending the session voids it.
Target selected at issue: one screen or every screen in the room.
Restricted to declared networks. No declared network, no joins.
Every join attributable to the joining device.
The target is selected when the code is issued. In a room with multiple screens, one code places the presenter on all of them.
None of the above is a playlist somebody maintains. Each screen is a surface for Ava, which holds one understanding of the place and knows which room it is in, so what belongs there at that hour is composed rather than authored. A room list and a meeting time are enough for her to keep the sign outside a door and the screen inside it saying the same thing.