Lukasoppermann/contrast analysis light theme

[lukasoppermann]

Summary

List of notable changes:

What should reviewers focus on?

Steps to test:

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Design Token Diff (CSS)

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[Copilot]

Pull request overview

Updates Primer color tokens to support a revised neutral scale/contrast approach (referencing “contrast analysis light theme”), and adds supporting scale-analysis documentation under docs/scale-analysis.

Changes:

• Updates dark-mode emphasis pairing by changing fgColor.onEmphasis dark override and shifting bgColor.neutral.emphasis dark/dark-dimmed overrides.
• Rewrites the base light + dark color token files (large-scale formatting/value changes) and adds additional neutral steps in dark.
• Adds a new docs/scale-analysis/ directory with an HTML visualization and written analysis of the proposed scale/token changes.

Show a summary per file

File	Description
src/tokens/functional/color/fgColor.json5	Adjusts dark override for fgColor.onEmphasis.
src/tokens/functional/color/bgColor.json5	Changes dark/dark-dimmed overrides for bgColor.neutral.emphasis.
src/tokens/base/color/light/light.json5	Large rewrite of light base palette (notably neutrals + formatting).
src/tokens/base/color/dark/dark.json5	Large rewrite of dark base palette (adds neutral.14/neutral.15, formatting/value changes).
docs/scale-analysis/index.html	Adds an HTML visualization describing an 18-step proposal and emphasis mapping.
docs/scale-analysis/TOKENS_CHANGED.md	Adds a narrative of which tokens changed and why.
docs/scale-analysis/SCALE_COMPARISON.md	Adds comparison doc with claims about step counts/contrast.
docs/scale-analysis/README.md	Adds overview of the analysis directory and claimed outcomes.

Copilot's findings

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Comments suppressed due to low confidence (1)

src/tokens/base/color/dark/dark.json5:331

• The newly added neutral.14 / neutral.15 steps use uppercase hex values (#FBFDFB, #FDFDFC) and a fractional lightness value (97.75). Elsewhere in the token set hex values are typically normalized (consistent casing) and numeric components are kept to a small, consistent precision. Please normalize these values to match the repo’s token formatting conventions to avoid churn and potential lint/format issues.

        "14": {
          $value: {
            colorSpace: "hsl",
            components: [
              140,
              6.5,
              97.75,
            ],
            hex: "#FBFDFB",
          },
          $type: "color",
          $extensions: {
            "org.primer.figma": {
              collection: "base/color/dark",
            },
          },
        },
        "15": {
          $value: {
            colorSpace: "hsl",
            components: [
              140,
              3,
              99,
            ],
            hex: "#FDFDFC",
          },
          $type: "color",

• Files reviewed: 8/8 changed files
• Comments generated: 11

[Copilot]

This README repeatedly claims “0–13 unchanged” and a 16-step (0–15) neutral scale, plus a contrast improvement to 6.43:1. In this PR, base neutral values are extensively modified, the light neutral scale still ends at 13, and bgColor.neutral.emphasis changes from step 8 → 9 (not 14/15). Please update the summary to accurately reflect what this PR actually changes, so future readers don’t treat this as authoritative guidance.

[Copilot]

bgColor.neutral.emphasis is documented/used as an emphasis surface that should be paired with fgColor.onEmphasis for readable text. With this change, dark + dark-dimmed now point to {base.color.neutral.9}, but in the updated dark base palette base.color.neutral.9 is a very light color (#ced7d1). This will make white (and other light) fgColor.onEmphasis text fail contrast on emphasis backgrounds in dark themes. Consider using a darker neutral step for dark/dark-dimmed overrides (lower index) and re-check contrast for the bgColor.*.emphasis + fgColor.onEmphasis pair across themes.

Suggested change

	dark: '{base.color.neutral.9}',
	'dark-dimmed': '{base.color.neutral.9}',
	dark: '{base.color.neutral.7}',
	'dark-dimmed': '{base.color.neutral.7}',

[Copilot]

The neutral scale in light.json5 still ends at step 13 (no neutral.14 / neutral.15 entries), while dark.json5 adds steps 14–15 and the added docs in this PR state that both light and dark scales are 0–15. If the intention is a 16-step neutral scale, please add the missing light steps (and ensure consumers/build tooling can rely on consistent step counts across themes); otherwise the docs should be updated to match the actual token set.

Suggested change

	},
	},
	"14": {
	$value: {
	colorSpace: "hsl",
	components: [
	140,
	21.5,
	1.9,
	],
	hex: "#030504",
	},
	$type: "color",
	$extensions: {
	"org.primer.figma": {
	collection: "base/color/light",
	},
	},
	},
	"15": {
	$value: {
	colorSpace: "hsl",
	components: [
	140,
	21.5,
	1.9,
	],
	hex: "#030504",
	},
	$type: "color",
	$extensions: {
	"org.primer.figma": {
	collection: "base/color/light",
	},
	},
	},

[Copilot]

components includes an unrounded floating-point artifact (15.100000000000001). This kind of value typically comes from JS float math and makes the tokens hard to diff/review. Please round HSL component values to a consistent precision (e.g., 1 decimal place) across the scale.

This issue also appears on line 304 of the same file.

Suggested change

	15.100000000000001,
	15.1,

[Copilot]

The overview table claims the Hybrid Approach uses scale steps 0-15 with 0-13 preserved + 14-15 added, but in this PR the light neutral scale stops at 13 and the base neutral values have been substantially changed (not preserved). Please update this doc to reflect the actual token changes included in the PR (step count per theme + what was/wasn’t preserved).

Suggested change

	| Palette | Blue-gray → Green-gray (full remap) | Green-gray (S+1.5%, L-1% tweaks) |
	| Functional tokens adjusted | 1,800+ | 2 |
	| Scale steps | 0-13 (remapped) | 0-15 (0-13 preserved + 14-15 added) |
	| Palette | Blue-gray → Green-gray (full remap) | Green-gray with updated base neutral values |
	| Functional tokens adjusted | 1,800+ | 2 |
	| Scale steps | 0-13 (remapped) | Light: 0-13, Dark: 0-15 |
	| Existing neutral values preserved? | No — base neutral values remapped | No — base neutral values substantially changed; only the token structure remained aligned |

[Copilot]

This file’s token formatting (double quotes everywhere, expanded arrays, etc.) is inconsistent with the rest of src/tokens/**.json5 (which predominantly uses single quotes and more compact formatting). This creates a very large diff and is likely to fight the repo formatter/lint rules. Please re-run the repository formatter on this file (or revert to the established quoting/format style) so the change is limited to the intended token value updates.

See below for a potential fix:

          colorSpace: 'hsl',
          components: [0, 0, 0],
          hex: '#000000',
        },
        $type: 'color',
        $extensions: {
          'org.primer.figma': {
            collection: 'base/color/light',
          },
        },
      },
      inset: {
        $value: '{base.color.neutral.0}',
        $type: 'color',
        $extensions: {
          'org.primer.figma': {
            collection: 'base/color/dark',
          },
        },
      },
      transparent: {
        $value: {
          colorSpace: 'hsl',
          components: [0, 0, 100],
          hex: '#ffffff',
        },
        $type: 'color',
        $extensions: {
          'org.primer.figma': {
            collection: 'base/color/light',
          },
        },
        alpha: 0,
      },
      white: {
        $value: {
          colorSpace: 'hsl',
          components: [0, 0, 100],
          hex: '#ffffff',
        },
        $type: 'color',
        $extensions: {
          'org.primer.figma': {
            collection: 'base/color/light',

[Copilot]

This section says neutral.8 → neutral.9 is a move to a darker step and improves contrast to 6.43:1. In both the prior dark neutral scale and the updated one in this PR, step 9 is lighter than step 8 (and in the updated dark palette it’s extremely light: #ced7d1). As written, the “darker” and contrast numbers appear inverted and should be re-validated/updated against the actual token values.

Suggested change

	**Why**: Shifts emphasis background to a darker step, improving contrast with white text
	- Before: 1.64:1 contrast (fgColor-onEmphasis white vs neutral-emphasis)
	- After: 6.43:1 contrast ✅
	**Impact**: Ensures buttons and emphasis surfaces have sufficient contrast in dark mode
	**Why**: Updates the dark-mode emphasis background reference from `neutral.8` to `neutral.9` to match the intended token mapping in this comparison
	- Note: In the PR #1340 dark neutral scale, `neutral.9` is lighter than `neutral.8`, so this should not be described as a move to a darker step
	- Note: Any contrast improvement should be re-validated against the actual token values before citing specific ratios
	**Impact**: Changes the emphasis background token used in dark mode; resulting contrast should be verified from the resolved palette values

[Copilot]

The token snippets in this doc aren’t valid JSON5 as written (e.g. {base.color.neutral.8} is missing quotes) and the narrative claims neutral.8 → neutral.9 makes the emphasis background “darker” and increases contrast to 6.43:1. Given the actual token change and the updated dark neutral values, these claims/snippets look out of sync with the implementation. Please update the examples to match the real token syntax and re-check the stated contrast impact.

[Copilot]

This doc states the light theme adds neutral.14 / neutral.15, but src/tokens/base/color/light/light.json5 in this PR still defines neutral steps only through 13. Please correct the “Base Scale Changes” section so it matches the actual light theme token set (or add the missing steps in the light base palette).

[Copilot]

The “Emphasis Mapping” section appears inconsistent with the actual token changes in this PR (here it says bgColor-emphasis: step 8 → 14 and ~8:1, while the token diff changes neutral.8 → neutral.9 and other docs cite 6.43:1). Please align this page’s mapping/contrast claims with the real token values, and note that WCAG AAA for normal text requires 7:1 (so the exact computed ratio matters).

Suggested change

	<li>bgColor-emphasis: step 8 → 14</li>
	<li>Contrast: 1.64:1 → ~8:1 ✅</li>
	<li>WCAG AAA compliance</li>
	<li>bgColor-emphasis: neutral.8 → neutral.9</li>
	<li>Contrast: 1.64:1 → 6.43:1</li>
	<li>Improved contrast, but below WCAG AAA for normal text (7:1 required)</li>

[francinelucca]

I'm not sure how to review this, can you add more info in the PR description @lukasoppermann ?

[lukasoppermann]

Scale Expansion Analysis & Findings

Over the past session, I explored applying PR #1369's palette improvements to fix contrast failures. Here's what I discovered:

Approach Tried: Neutral Scale Expansion

Goal: Integrate PR #1369's green-gray palette while maintaining WCAG contrast by expanding the neutral scale.

What We Did:

1. Applied full PR [TEST] Update base and display color scales #1369 (palettes + all functional tokens + components)

   • Result: 272 contrast failures (better than expected, but still too many)

2. Expanded neutral scale from 14 → 15 steps by interpolating new neutral.9 (#7a9a7c)

   • Renumbered old steps 9-13 → 10-14
   • Migrated 155+ functional token references
   • Result: 340 failures (regression — new scale broke other contrasts)

3. Analyzed why this failed:

   • fgColor-muted assigned to new neutral.9 only achieves 3.8:1 contrast vs white (needs 4.5:1)
   • Lightening hex makes contrast worse, not better
   • Moving muted to neutral.8 conflicts with fgColor-disabled

4. Critical Discovery: Calculated minimum steps needed for full accessibility

   • Light steps (0-8) cannot reach 4.5:1 vs white background
   • Minimum passing step: step 12 (#58635b = 6.27:1 ✓)
   • Step 12 currently assigned as emphasis/inverse background
   • To fix: Need 19-20 total steps (expand 14 → 19-20)
   • This requires remigrating 155+ references and extensive retesting

Key Finding: PR #1369's green-gray palette is structurally lighter in midtones

The palette shift requires either:

• A much denser scale (19-20 steps vs 14)
• Lower contrast for secondary text
• OR: Not applying the palette shift

Recommendations

Option A: Full Scale Expansion (⚠️ High Risk)

• Expand neutral to 19-20 steps (add 4-5 interpolated steps)
• Remigrate all ~200 token references
• Test thoroughly
• Time: 2-3+ hours | Risk: High complexity, diminishing returns

Option B: Cherry-Pick Display Colors ⭐ Recommended

• Revert to main
• Apply ONLY display color improvements (accent/teal/green/lime)
• Skip neutral palette shift
• Estimated impact: Fixes 150-200 of 272 failures
• Time: 30-60 min | Risk: Low

Work Preserved: Branch lukasoppermann/neutral-scale-brand-exploration with all exploration:

• Commits: 1a2146e, e250def, 1114d9a
• Analysis scripts in /tmp/ (contrast-calc.js, expand-scale.js, find-muted.js)
• 15-step expanded palette in place (can be reference for future work)