Split the conflated overlay string into a structured flat-wash overlay and a structured scrim legibility facet, with a deprecation path for the raw-string passthrough.
1731c3d39527703be3c08d2c32519c0545a1da59d6overlay is constrained to none|dark|light (+ optional token reference / opacity).scrim facet provides legibility behind overlaid text via scrim-type (gradient default | frost), scrim-strength, scrim-blur, scrim-tone (dark|light, explicit), targeting the bg overlay or the media well (SPEC-087 routing).scrim-tone sets the overlaid content's foreground polarity (text/muted tokens), not just the wash — a dark scrim yields light text — so text colour follows the scrim, not the base surface.overlay passthrough is deprecated with a build warning for one minor then removed, gated on scrim shipping.overlay passthrough in engine.ts. Cover-mode scrim consumer is SPEC-089. SPEC-088 §3.
Completed: 2026-06-09
Branch: claude/spec-088-bg-gradients-scrim
overlay constrained to dark/light/token-reference (+ overlay-opacity); raw CSS still applies but warns (deprecated, gated on scrim shipping).scrim facet (universal): scrim (edge) + scrim-type (gradient|frost), scrim-strength, scrim-blur, scrim-tone. Engine emits the data-scrim-* contract + --scrim-* vars on a scrim element; bg.css renders the directional gradient / backdrop-blur frost. Scrim/overlay can stand alone (raise the layer with no image).scrim-tone flips the overlaid content's foreground via data-color-scheme on the host (dark scrim → light text), reusing the palette flip; an explicit tint scheme wins.bg.css in the used-CSS set (bg is now universal-attribute-driven).