Select: click. Move: drag (grid 50 mm; ports snap within 150 mm when headings match).
R rotate 90°, F flip, Del delete, Esc deselect.
Resize: drag the white handle at a belt's end.
Camera: left-drag on the floor orbits (pans in top-down), right/middle-drag pans, wheel zooms, T top-down.
Editing is refused while running; every edit is a cold reset.