dsh-color

Color toolbox for DeepSeek Harness (dsh): parse and convert any CSS color, evaluate WCAG contrast, look up CSS color names, generate harmonious palettes, adjust and blend colors, and repair contrast.

Pure local math — zero runtime dependencies, no network, no side effects.

Tools

Tool	Description
convert_color	Parse any CSS color (hex #rgb/#rgba/#rrggbb/#rrggbbaa, rgb()/rgba(), hsl()/hsla(), hwb(), CSS color names) and convert it to hex / rgb / hsl / hwb — or all formats at once
contrast_ratio	WCAG 2.x contrast ratio between two colors with AA/AAA verdicts for normal or large text (WCAG 1.4.3 thresholds)
color_info	CSS named-color lookup: search by name substring ("blue" → blue, blueviolet, lightblue, …) or by exact value (aqua ≡ cyan), with hex/rgb/hsl/luminance per match
color_scheme	Harmonious palettes from a base color: complementary, analogous (3/5), triadic, split-complementary, tetradic, square, monochromatic (2–9 shades) — every color as hex + rgb + hsl
adjust_color	lighten / darken / saturate / desaturate (percentage points) or hue-rotate (degrees) a color — result as hex + rgb + hsl
blend_colors	Blend two colors: over (alpha compositing — what a translucent overlay actually shows) or mix (premultiplied sRGB interpolation, the math behind CSS color-mix(in srgb, …)) with a weight
ensure_contrast	The nearest color to a foreground that reaches a WCAG target on a given background: hue and saturation kept, lightness moved toward black or white, ratio before/after and the lightness shift reported; says so — with the best achievable ratio — when the target is impossible

Install

dsh plugin --profile web add github:TYEclipse/dsh-color

Replace web with your profile name (dsh plugin has no default profile).

Usage examples

convert_color("rebeccapurple")
  → hex #663399, rgb(102, 51, 153), hsl(270, 50%, 40%), hwb(270 20% 40%)

convert_color("#ff000080", format: "hex")
  → #ff000080 (alpha preserved)

contrast_ratio("#777777", "#ffffff")
  → ratio 4.48 — fail for normal text, AA for large text

contrast_ratio("white", "hsl(0, 100%, 50%)")
  → ratio 4.0 — AA for large text only

color_info(query: "blue", limit: 5)
  → blue #0000ff, blueviolet #8a2be2, cadetblue #5f9ea0, …

color_info(query: "#00ffff", by: "value")
  → aqua, cyan (both map to #00ffff)

color_scheme("#336699", type: "triadic")
  → #336699, #993366, #669933

color_scheme("#ff0000", type: "analogous", count: 5)
  → #ff00ff, #ff0080, #ff0000, #ff8000, #ffff00

color_scheme("#336699", type: "monochromatic", count: 4)
  → #030508, #24476b, #4f8ac4, #b3cce6

adjust_color("#336699", op: "lighten", amount: 25)
  → #79a6d2

adjust_color("#ff0000", op: "hue", amount: 120)
  → #00ff00

blend_colors("rgba(255, 0, 0, 0.5)", "#ffffff")
  → #ff8080 — half-transparent red on white

blend_colors("#ff0000", "#0000ff", mode: "mix", weight: 0.5)
  → #800080 — purple, the color-mix() midpoint

ensure_contrast("#777777", "#ffffff")
  → #767676 at 4.54:1 — darkens just enough to pass AA

ensure_contrast("#555555", "#000000", level: "AAA")
  → #959595 at 7.01:1 — lighten, +24.9 lightness points

ensure_contrast("#8080ff", "#808080", level: "AAA")
  → target unreachable; best #000000 at 5.32:1

Feature notes

• Input formats: hex shorthand/full (3/4/6/8 digits), legacy comma syntax (rgb(255, 0, 0)) and modern space syntax (rgb(255 0 0 / 50%)), percentages (rgb(100% 0% 0%)), angle units for hue (deg/rad/grad/turn), all 148 CSS Color Module Level 4 named colors, and transparent.
• Alpha is preserved through every conversion; hex output switches to 8-digit form only when alpha < 1.
• WCAG math: relative luminance per WCAG 2.x (sRGB linearization), ratio (L1+0.05)/(L2+0.05), thresholds AA 4.5 / AAA 7 for normal text and AA 3 / AAA 4.5 for large text (≥18pt or ≥14pt bold).
• Palette math: rotation harmonies keep the base saturation/lightness and rotate the hue by the canonical offsets (complementary +180°, triadic +120°/+240°, split-complementary +150°/+210°, tetradic +60°/+180°/+240°, square +90°/+180°/+270°); analogous is centered on the base (−30°/0/+30°, or −60°/−30°/0/+30°/+60° for 5 colors); monochromatic keeps hue/saturation and steps lightness evenly across [l−0.4, l+0.4] (clamped to [0.02, 0.98]).
• Adjustment math: lighten/darken/saturate/desaturate shift the channel by N percentage points (clamped 0–100); hue rotates by N degrees (any sign, normalized). Saturating a gray is a no-op, matching CSS filter semantics.
• Blend math: over is Porter-Duff source-over with non-premultiplied channels (CSS Compositing and Blending §9.1) — the color a browser paints for a translucent overlay; mix interpolates premultiplied sRGB channels and divides the alpha back out, which is exactly color-mix(in srgb, …). Weights outside 0–1 are clamped instead of extrapolated.
• Contrast repair: ensure_contrast keeps hue and saturation and moves lightness toward black or white — auto picks whichever extreme scores higher against the background. It scans 1000 lightness steps and tests the 8-bit rounded color at each step (what passes is what a renderer will show), then bisects 20 times so the shift stays minimal (e.g. #777777 → #767676, not #757575). Unreachable targets report the best achievable ratio rather than a color that silently misses.
• Input channel scales (fixed in v0.3.0): a bare number in rgb() is on the 0–255 scale (rgb(51, 102, 153) = #336699) while a percentage is a share of 255; in hsl()/hwb() a bare number means the same as a percentage (hsl(210 100 50) = hsl(210, 100%, 50%)).
• Channel serialization rounds half up with a floating-point dust guard, matching CSS serialization (e.g. hsl(210, 100%, 50%) → rgb(0, 128, 255)).
• Out-of-range channels are clamped (modern CSS behavior).

Development

pnpm install     # CI=true if pnpm asks about build scripts
pnpm build       # tsc → dist/
pnpm test        # vitest
pnpm lint        # oxlint src test

License

MIT