The shape of the room a surface is drawn in — the GEOMETRIC sibling of the density axis
(spec: an internal spec §2). Density says how much
room a control gets; the screen class says what shape the room is.
The derivation lives on the surface (web-ui/app/composables/useScreenClass.ts), which is
the only place that can measure a viewport; the vocabulary lives here because the surface's
own fit questions are stated against it. The two lists are pinned equal by a client test,
exactly as DENSITY_PREFERENCES is. (The per-class PANEL PLACEMENT pin that used to
cross the wire beside it is retired — 2026-08-04-processing-view-layout.md Amendment
2026-09-15d gave the trace one place; the break is in an internal spec.)
The shape of the room a surface is drawn in — the GEOMETRIC sibling of the density axis (spec:
an internal spec§2). Density says how much room a control gets; the screen class says what shape the room is.The derivation lives on the surface (
web-ui/app/composables/useScreenClass.ts), which is the only place that can measure a viewport; the vocabulary lives here because the surface's own fit questions are stated against it. The two lists are pinned equal by a client test, exactly as DENSITY_PREFERENCES is. (The per-class PANEL PLACEMENT pin that used to cross the wire beside it is retired —2026-08-04-processing-view-layout.mdAmendment 2026-09-15d gave the trace one place; the break is inan internal spec.)