A single-color gradient effect for segments too narrow for a real
two-stop gradient to render as anything but a solid color:
dark-gradient(#color) runs from that exact color to a darker
shade, light-gradient(#color) to a lighter one.
The shade drops (or raises) HCL lightness only, by a fraction of
the base color's own headroom toward the target end, keeping hue
exact and walking chroma down only as far as the sRGB gamut
forces - blending toward black/white directly pulls chroma down
with it, reading as the color going muddy rather than
deepening/brightening. The reference delta is tuned so a 3-cell
segment - the common case this exists for - lands its shade close
to a just-noticeable-difference rather than a hard color swap; a
width multiplier grows that delta for wider segments as a
saturating curve (not linear growth with a hard clamp - that hit
its clamp by ~15-20 cells and crushed every wider segment to the
exact same near-white/near-black color, which is what "the
gradient stops working on a larger segment" turned out to be),
so a very wide segment still shades further than a moderately
wide one while topping out at a moderate, recognizably-still-the-
same-hue color instead of washing out to white or black.
GradientLastForCells mirrors the same shading (for a given cell
count) on the raw stop text, so powerline separators, diamond
caps, and inline color-override edges (via a new
gradientRenderCells package var in the terminal writer) line up
with the color the body actually ends on for that segment's own
width. GradientLast (no cell count - used by parentBackground/
parentForeground crossing into another segment, and wherever
width isn't known) falls back to the narrowest, gentlest shade.
WithGradientStops rebuilds a gradient string keeping its own
prefix (linear-gradient, dark-gradient, or light-gradient), so
resolving a palette-referenced stop (dark-gradient(p:teal)) keeps
its darken semantics instead of silently becoming a plain
linear-gradient - whole-string palette resolution only ever
expanded a bare "p:name" that itself resolved to a gradient,
never a "p:name" used as one stop inside a gradient literal, so a
palette-referenced stop reached GradientLast unresolved and fell
back to the raw, unshaded base color.
linear-gradient itself goes back to requiring two or more stops;
the single-stop overload it briefly had is now dark-gradient's job.
Entire-Checkpoint: 85522027570b
Jan De DobbeleerandJan De Dobbeleer
5f2e723a6d