What a surface does when the operator patches a physical input onto a channel that already
has one. The DOOR is strict either way — a channel sources at most one physical input
(2026-08-07-one-summing-bus.md §3c) — so this never decides what the desk ACCEPTS, only
whether the surface asks first.
warn names the input already patched and stops, leaving the unpatch to the operator.
unpatch re-patches in one move (a one-element write, which the door takes). warn is the
default because a patch is an operator decision and a show is a bad place to discover that a
click silently moved one.
It is session state rather than window state so every surface agrees: a phone at the stage
and the FOH screen behaving differently on the same gesture is the divergence this console
treats as a P0.
What a surface does when the operator patches a physical input onto a channel that already has one. The DOOR is strict either way — a channel sources at most one physical input (
2026-08-07-one-summing-bus.md§3c) — so this never decides what the desk ACCEPTS, only whether the surface asks first.warnnames the input already patched and stops, leaving the unpatch to the operator.unpatchre-patches in one move (a one-element write, which the door takes).warnis the default because a patch is an operator decision and a show is a bad place to discover that a click silently moved one.It is session state rather than window state so every surface agrees: a phone at the stage and the FOH screen behaving differently on the same gesture is the divergence this console treats as a P0.