Chart Color System

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io.github.socraticstatic/chart-color-systemv0.1.2

Solve, audit and simulate colorblind-safe chart palettes. WCAG contrast, OKLab ΔE. Read-only.

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audit_palette Read-only

Audit existing chart colors for accessibility: pairwise OKLab separation under normal vision, deuteranopia, protanopia, tritanopia and achromatopsia, plus WCAG 2.2 non-text contrast (3:1) of every color against the chart background. Returns a pass / warn / fail verdict with the numbers behind it. Set ramp=true for sequential or diverging scales, whose steps are meant to be close.

colorsarray, required

Palette colors in slot order (CSS syntax)

rampboolean

true for a sequential or diverging scale (skips pairwise separation)

backgroundstring

Chart background color

Tools (4)

audit_palette

read-only

Argument	Type	Description
ramp	boolean	true for a sequential or diverging scale (skips pairwise separation)
colors*	array	Palette colors in slot order (CSS syntax)
background	string	Chart background color

Input schema (JSON)

{
  "type": "object",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "required": [
    "colors"
  ],
  "properties": {
    "ramp": {
      "type": "boolean",
      "default": false,
      "description": "true for a sequential or diverging scale (skips pairwise separation)"
    },
    "colors": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "maxItems": 24,
      "minItems": 1,
      "description": "Palette colors in slot order (CSS syntax)"
    },
    "background": {
      "type": "string",
      "default": "#ffffff",
      "description": "Chart background color"
    }
  },
  "additionalProperties": false
}

build_ramp

Build an evenly spaced perceptual (OKLab) color scale: sequential from start to end, or diverging from start through mid to end. Returns the steps and a background-contrast audit (pairwise separation is not judged for ramps).

read-only

Argument	Type	Description
end*	string	Last color (or the positive end)
mid	string	Middle color for a diverging scale; default a neutral near the background
kind*	string
start*	string	First color (or the negative end of a diverging scale)
steps	integer
background	string

Input schema (JSON)

{
  "type": "object",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "required": [
    "kind",
    "start",
    "end"
  ],
  "properties": {
    "end": {
      "type": "string",
      "description": "Last color (or the positive end)"
    },
    "mid": {
      "type": "string",
      "description": "Middle color for a diverging scale; default a neutral near the background"
    },
    "kind": {
      "enum": [
        "sequential",
        "diverging"
      ],
      "type": "string"
    },
    "start": {
      "type": "string",
      "description": "First color (or the negative end of a diverging scale)"
    },
    "steps": {
      "type": "integer",
      "default": 7,
      "maximum": 24,
      "minimum": 3
    },
    "background": {
      "type": "string",
      "default": "#ffffff"
    }
  },
  "additionalProperties": false
}

simulate_palette

Show what each color looks like to readers with deuteranopia, protanopia, tritanopia or achromatopsia (published Machado 2009 matrices), so an assistant can describe or render the palette as a colorblind reader sees it.

read-only

Argument	Type	Description
modes	array	Vision modes to simulate; default all
colors*	array	Colors in slot order (CSS syntax)

Input schema (JSON)

{
  "type": "object",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "required": [
    "colors"
  ],
  "properties": {
    "modes": {
      "type": "array",
      "items": {
        "enum": [
          "normal",
          "deutan",
          "protan",
          "tritan",
          "achromatopsia"
        ],
        "type": "string"
      },
      "description": "Vision modes to simulate; default all"
    },
    "colors": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "maxItems": 24,
      "minItems": 1,
      "description": "Colors in slot order (CSS syntax)"
    }
  },
  "additionalProperties": false
}

solve_palette

Generate a categorical chart palette of n colors (1-12) that maximizes perceptual separation under normal vision and colorblindness, with the given brand colors locked as anchors in slot order. Returns the palette, the worst pair distances, the engine's relaxation notes, a full accessibility audit against the background, and a link to open it in the app. Honest cap is 6 slots; above that the result says so.

read-only

Argument	Type	Description
n	integer	Number of categorical slots
grid	string	Gridline color; defaults to a light or dark gray to match the background
anchors	array	Brand or required colors, kept exactly, in slot order (CSS syntax)
posture	string	kpi: few strong colors; comparative: balanced; exploratory: many muted
background	string	Chart background color

Input schema (JSON)

{
  "type": "object",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "properties": {
    "n": {
      "type": "integer",
      "default": 6,
      "maximum": 12,
      "minimum": 1,
      "description": "Number of categorical slots"
    },
    "grid": {
      "type": "string",
      "description": "Gridline color; defaults to a light or dark gray to match the background"
    },
    "anchors": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "default": [],
      "maxItems": 12,
      "description": "Brand or required colors, kept exactly, in slot order (CSS syntax)"
    },
    "posture": {
      "enum": [
        "kpi",
        "comparative",
        "exploratory"
      ],
      "type": "string",
      "default": "comparative",
      "description": "kpi: few strong colors; comparative: balanced; exploratory: many muted"
    },
    "background": {
      "type": "string",
      "default": "#ffffff",
      "description": "Chart background color"
    }
  },
  "additionalProperties": false
}