Overlay

The one mount above z-float: modal (460/640px) or bare. Focus trap, Esc, scroll lock, stage shadow, scale-in. Overlays never stack two deep.

Posture

Modal — focus trap, Esc, never stacked two deep

npx candlelight-ds add overlay

Use when: The user must address something before continuing on this surface — a blocking decision.
Don't use when: Editing an object adjacent to a list (Sheet) or a whole workflow (a route). Modal is the last resort, not the first thought.
States: closedopen sm (460px)open lg (640px)barelocked (typed-confirm)
Keyboard: Esccloses (unless locked)
Tabcycles inside the trap
Acceptance: Overlays never stack two deep — a modal needing a picker uses an inline combobox.
Scrim is stage/80 with 2px blur; the panel wears shadow-stage.