Colored dark themes put chips on a mid-tone user bubble where the shared
accents nearly vanish (Ember video, Grove terminal). Each chip now gets one
color per theme: the accent's OKLCH hue at the most chroma sRGB allows,
lightened or darkened only until it reads at 4.5:1 on the bubble, the reply
canvas and the composer. Surfaces with opposite-shade text, like Material
You's light bubble, get their own match.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>