folderColorTint

folderColorTint(value, theme, alpha = 0.15) returns the Proton-style tint of a stored FOLDER_COLORS key: the resolved theme hex as an rgba() string at low alpha, for the circle behind a colored vault glyph (and CnIconColorPicker's preview).

<span :style="{ backgroundColor: folderColorTint(folder.customColor, currentTheme()) }">
  <component
    :is="resolveFolderIcon(folder.customIcon) ?? Safe"
    :fill-color="resolveFolderColor(folder.customColor, currentTheme())" />
</span>

The tint is derived from the same hex the glyph uses — never a second palette — so glyph and circle can never disagree, in either theme. That is the approach the original folder-customization work (53a36006) took with hexToRgba(hex, 0.12).

Returns null for an unset or unknown key, so the caller keeps its neutral chrome. Pass a custom alpha for stronger emphasis (the reference used 0.28 for an active row).