The on-air display

Your work lives on display-1: the editor, the chat, the terminal with an API key in scrollback. Display-2 holds exactly one window: the thing you're presenting. One ffmpeg line captures :2 and sends it into a pipe; your audience opens the pipe URL with ?video and gets an embedded player.

Nothing on display-1 can leak, because the capture never sees it. Going on air isn't a checklist of which windows to close before you share. Off air is dragging the window back.

Streamers run overlay software and rehearse window hygiene to keep a private message off the broadcast. Here the boundary is structural: two X displays, one camera pointed at one of them.