dath

Color & Visual Comfort for VS Code

Your editor, tuned to your eyes.

Irish: dath — colour

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What is Dath?

Dath is a visual comfort layer that sits on top of any VS Code theme you already use. It does not replace your theme — it corrects it.

For developers with colour vision deficiency (CVD), the problem isn't that themes are badly designed — it's that they're designed for trichromat vision. Red strings and green comments look identical to a deuteranope. Dath shifts those specific colour ranges to safe alternatives while preserving the character of your theme.

For everyone else, Dath addresses the broader comfort problems that themes don't solve: harsh white backgrounds, snow blindness, visual noise, and the friction of font and spacing settings buried in JSON.

Everything is non-destructive. Dath writes only to VS Code's workbench.colorCustomizations override layer — never your theme files. Disable it and your editor is exactly as it was.

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Features

CVD Colour Correction

Applies LMS daltonization (Brettel, Viénot & Mollon, 1997) to your active theme's colours. Reads the theme JSON directly from disk and corrects both workbench UI tokens and TextMate syntax token colours.

Mode	Cone affected	Most common in
Deuteranopia	M (green)	~6% of males
Protanopia	L (red)	~2% of males
Tritanopia	S (blue)	~0.01% of population
Achromatopsia	All cones	Rod monochromacy — luminance only

A severity slider (0.1–1.0) lets you dial in the correction strength — 1.0 for complete CVD, lower for partial deficiency.

Simulate mode — instead of correcting, show what your current theme looks like to someone with the selected CVD type. Useful for theme authors and for demonstrating CVD to colleagues.

Custom palette slots (Custom 1, 2, 3) let you define your own per-role colour overrides directly in the panel using colour pickers.

Contrast Comfort

Mode	Effect
Soften	Lifts pure whites toward a warm off-white — reduces snow blindness
Warm	Warms the background tone
Cool	Cools the background tone
Dim	Reduces overall brightness

A temperature bias slider lets you add a persistent warm or cool hue tint on top of all other corrections.

Rainbow Brackets

CVD-safe bracket palettes derived from the Wong (2011) colour palette — distinguishable under all CVD types. The palette updates automatically to match your active CVD mode.

Shape hints add a subtle underline to matching bracket pairs so they are identifiable without relying on colour alone.

Rainbow indent guides colour VS Code's indent guide lines to match the bracket palette, giving an additional spatial cue for nested code structure.

Font & Spacing

Override editor typography without editing settings.json manually:

• Font family — quick picks for OpenDyslexic, Atkinson Hyperlegible, and Lexie Readable, or type any font installed on your system
• Font size — px override (0 = VS Code default)
• Line height — override for improved readability (suggested 1.4–1.8)
• Letter spacing — px override

Profiles

Named configurations that switch in one click. Save, rename, delete, export, and import profiles from the panel or command palette. Three built-in starters are included on first install:

Profile	Description
Deuteranopia	Full deuteranopia correction, softened backgrounds, CVD-safe brackets
Protanopia	Full protanopia correction, CVD-safe brackets
Dyslexia Comfort	Softened contrast, Atkinson Hyperlegible font, increased line height

Auto dark/light switching — set dath.darkModeProfile and dath.lightModeProfile to automatically apply the right profile when VS Code (or the OS) switches between dark and light mode.

Visual Panel

Click the status bar item to open the Dath panel — a live interactive control surface. Changes apply immediately as you adjust sliders or click mode buttons.

• Per-section reset buttons restore individual sections to defaults
• Global reset restores all Dath settings at once
• Live colour correction preview shows before/after swatches for representative theme colours
• Bracket palette preview updates in real time
• Profile management — apply, save, rename, delete, export, and import profiles without leaving the panel
• Simulate toggle — preview what your theme looks like to a CVD user
• Status bar shows a warning indicator if the theme file could not be read

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How It Works

1. On activation, Dath reads your active theme's JSON file from disk (including JSONC comment stripping and include chain resolution)
2. It applies the LMS daltonization pipeline to workbench colour tokens, TextMate syntax scopes, and semantic token colours
3. Corrected values are written to workbench.colorCustomizations, editor.tokenColorCustomizations, and editor.semanticTokenColorCustomizations in your global settings
4. When you disable Dath or change settings, only Dath's entries are removed — your own customisations are preserved

Dath manages 185 workbench colour tokens spanning the editor, sidebar, tabs, terminal, diff view, and more. It also reads and corrects semanticTokenColors from the theme file, covering the semantic highlighting layer used by modern themes alongside TextMate scopes.

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Getting Started

1. Install from the VS Code Marketplace
2. The setup wizard runs automatically on first install — choose your CVD type, contrast preference, and bracket options
3. Click the $(eye) Dath item in the status bar to open the panel at any time
4. Or: Ctrl+Alt+D / Cmd+Alt+D — or Ctrl/Cmd+Shift+P → Dath: Open Panel

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Commands

Command	Description
Dath: Open Panel	Open the visual control panel
Dath: Toggle On/Off	Enable or disable all corrections
Dath: Switch Profile	Switch to a saved profile
Dath: Save Current Settings as Profile	Save current config as a named profile
Dath: Open Settings	Jump to Dath settings in the VS Code settings UI
Dath: Run Setup Wizard	Run the onboarding wizard again
Dath: Export Profiles to Clipboard	Copy all saved profiles as JSON
Dath: Import Profiles from Clipboard	Import profiles from clipboard JSON
Dath: Rename Profile	Rename a saved profile
Dath: Delete Profile	Delete a saved profile

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Settings

Setting	Default	Description
dath.enabled	true	Enable or disable all corrections
dath.cvdMode	none	CVD correction: none · deuteranopia · protanopia · tritanopia · achromatopsia · custom1 · custom2 · custom3
dath.cvdSeverity	1.0	Correction strength 0.1–1.0 (ignored for custom and achromatopsia modes)
dath.simulationMode	false	Show how the theme looks to a CVD user rather than correcting it
dath.contrastMode	none	Background adjustment: none · soften · warm · cool · dim
dath.contrastStrength	0.5	Contrast adjustment strength 0.1–1.0
dath.warmthBias	0	Hue tint: positive = warm, negative = cool, 0 = neutral
dath.rainbowBrackets	false	CVD-safe rainbow bracket colouring
dath.rainbowIndents	false	Colour indent guides to match the rainbow bracket palette
dath.bracketShapeHints	false	Underline hints on bracket pairs
dath.fontOverride	none	Any installed font name, or none for VS Code default
dath.fontSizeOverride	0	Font size in px (0 = VS Code default)
dath.lineHeightOverride	0	Line height override (0 = VS Code default)
dath.letterSpacingOverride	0	Letter spacing in px (0 = VS Code default)
dath.activeProfile	""	Active profile name — managed by Dath
dath.customPalettes	{}	Custom colour role mappings for Custom 1/2/3 modes
dath.darkModeProfile	""	Profile to auto-apply when VS Code switches to a dark theme
dath.lightModeProfile	""	Profile to auto-apply when VS Code switches to a light theme

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Architecture

extension.ts          ← entry point, commands, config listener, onboarding
├── cvd.ts            ← LMS daltonization engine (zero external dependencies)
├── themeReader.ts    ← locates and parses active theme JSON from disk
├── themeEngine.ts    ← read → correct → write pipeline (185 tokens)
├── panel.ts          ← interactive webview control surface
├── profiles.ts       ← named profile save/apply/delete
└── statusBar.ts      ← status bar item and toggle

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Development

npm install
npm run compile
# Press F5 in VS Code to launch an Extension Development Host

npm run watch    # incremental compilation
npm run lint     # ESLint
npm run package  # build .vsix for local install or publishing

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Licence

PolyForm Noncommercial 1.0.0 — free to use and modify for non-commercial purposes.