D162 - No control without something behind it

Status: decided Date: 2026-09-26

A settings control exists only when something honours it. A pane for a subsystem with nothing behind it says what is missing; a control that cannot work yet is disabled with its reason on hover, never hidden and never inert.

Why: a dropdown over an unimplemented subsystem changes nothing, and nobody can tell whether the setting, the emulator or the title is at fault. A control that vanishes reads as a bug; a greyed one with a reason reads as a state.

Rejected:

• Controls built ahead of their subsystems: a lie with a widget.
• Hiding unavailable controls: users search for them and assume a defect.