dank16: use the real primary_container and fix light-mode derivation

fixes #3405
fixes #3406
ref #3408
port 1.6

core/cmd/dms/commands_dank16.go

@@ -79,11 +79,11 @@ func runDank16(cmd *cobra.Command, args []string) {
 			primaryLight = primaryColor
 		}
 		variantOpts := dank16.VariantOptions{
-			PrimaryDark:  primaryDark,
-			PrimaryLight: primaryLight,
-			Background:   background,
-			UseDPS:       contrastAlgo == "dps",
-			IsLightMode:  isLight,
+			PrimaryDark:    primaryDark,
+			PrimaryLight:   primaryLight,
+			BackgroundDark: background,
+			UseDPS:         contrastAlgo == "dps",
+			IsLightMode:    isLight,
 		}
 		variantColors := dank16.GenerateVariantPalette(variantOpts)
 		fmt.Print(dank16.GenerateVariantJSON(variantColors))

core/internal/dank16/dank16.go

@@ -455,6 +455,7 @@ func EnsureContrastDPSBidirectional(hexColor, hexBg string, minLc float64, isLig
 type PaletteOptions struct {
 	IsLight    bool
 	Background string
+	Container  string
 	UseDPS     bool
 }
 
@@ -520,8 +521,18 @@ func DeriveContainer(primary string, isLight bool) string {
 	return RGBToHex(HSVToRGB(HSV{H: hsv.H, S: containerS, V: containerV}))
 }
 
+// DeriveContainer only approximates the Material tone pairing, so a caller that
+// has the real primary_container should pass it: color5 and color6 are the
+// primary/container pair and their contrast with each other is the invariant.
+func resolveContainer(primaryColor string, opts PaletteOptions) string {
+	if opts.Container != "" {
+		return opts.Container
+	}
+	return DeriveContainer(primaryColor, opts.IsLight)
+}
+
 func GeneratePalette(primaryColor string, opts PaletteOptions) Palette {
-	baseColor := DeriveContainer(primaryColor, opts.IsLight)
+	baseColor := resolveContainer(primaryColor, opts)
 
 	rgb := HexToRGB(baseColor)
 	hsv := RGBToHSV(rgb)
@@ -531,13 +542,20 @@ func GeneratePalette(primaryColor string, opts PaletteOptions) Palette {
 
 	var palette Palette
 
-	var normalTextTarget, secondaryTarget float64
-	if opts.UseDPS {
+	// Delta Phi Star is not symmetric across polarity: on a light background the
+	// same Lc buys far less real contrast, so the light targets are the numbers
+	// that land on the same measured WCAG ratios the dark ones already deliver.
+	var normalTextTarget, accentTarget float64
+	switch {
+	case opts.UseDPS && opts.IsLight:
+		normalTextTarget = 70.0
+		accentTarget = 58.0
+	case opts.UseDPS:
 		normalTextTarget = 40.0
-		secondaryTarget = 35.0
-	} else {
+		accentTarget = 24.5
+	default:
 		normalTextTarget = 4.5
-		secondaryTarget = 3.0
+		accentTarget = 2.1
 	}
 
 	var bgColor string
@@ -557,8 +575,6 @@ func GeneratePalette(primaryColor string, opts PaletteOptions) Palette {
 	greenH := blendHue(0.33, ph.H, 0.10)
 	yellowH := blendHue(0.14, ph.H, 0.04)
 
-	accentTarget := secondaryTarget * 0.7
-
 	if opts.IsLight {
 		redS := math.Min(baseSat*1.2, 1.0)
 		redV := baseVal * 0.95
@@ -570,15 +586,13 @@ func GeneratePalette(primaryColor string, opts PaletteOptions) Palette {
 
 		yellowS := math.Min(baseSat*1.5, 1.0)
 		yellowV := math.Min(baseVal*1.2, 1.0)
-		palette.Color3 = NewColorInfo(ensureContrastBidirectional(RGBToHex(HSVToRGB(HSV{H: yellowH, S: yellowS, V: yellowV})), bgColor, accentTarget, opts))
+		palette.Color3 = NewColorInfo(ensureContrastAuto(RGBToHex(HSVToRGB(HSV{H: yellowH, S: yellowS, V: yellowV})), bgColor, normalTextTarget, opts))
 
 		blueS := math.Min(ph.S*1.05, 1.0)
 		blueV := math.Min(ph.V*1.05, 1.0)
 		palette.Color4 = NewColorInfo(ensureContrastAuto(RGBToHex(HSVToRGB(HSV{H: ph.H, S: blueS, V: blueV})), bgColor, normalTextTarget, opts))
 
-		// Color5 matches primary_container exactly (light container in light mode)
-		container5 := DeriveContainer(primaryColor, true)
-		palette.Color5 = NewColorInfo(container5)
+		palette.Color5 = NewColorInfo(baseColor)
 
 		palette.Color6 = NewColorInfo(primaryColor)
 
@@ -604,8 +618,9 @@ func GeneratePalette(primaryColor string, opts PaletteOptions) Palette {
 		brightBlueV := math.Min(ph.V*1.15, 1.0)
 		palette.Color12 = NewColorInfo(ensureContrastBidirectional(RGBToHex(HSVToRGB(HSV{H: ph.H, S: brightBlueS, V: brightBlueV})), bgColor, accentTarget, opts))
 
-		lightContainer := DeriveContainer(primaryColor, true)
-		palette.Color13 = NewColorInfo(lightContainer)
+		color13S := ph.S * 0.7
+		color13V := math.Min(ph.V*1.3, 1.0)
+		palette.Color13 = NewColorInfo(ensureContrastBidirectional(RGBToHex(HSVToRGB(HSV{H: ph.H, S: color13S, V: color13V})), bgColor, accentTarget, opts))
 
 		brightCyanS := ph.S * 0.5
 		brightCyanV := math.Min(ph.V*1.3, 1.0)
@@ -632,9 +647,7 @@ func GeneratePalette(primaryColor string, opts PaletteOptions) Palette {
 		blueV := ph.V * 0.95
 		palette.Color4 = NewColorInfo(ensureContrastAuto(RGBToHex(HSVToRGB(HSV{H: ph.H, S: blueS, V: blueV})), bgColor, normalTextTarget, opts))
 
-		// Color5 matches primary_container exactly (dark container in dark mode)
-		darkContainer := DeriveContainer(primaryColor, false)
-		palette.Color5 = NewColorInfo(darkContainer)
+		palette.Color5 = NewColorInfo(baseColor)
 
 		palette.Color6 = NewColorInfo(primaryColor)
 
@@ -681,11 +694,14 @@ func GeneratePalette(primaryColor string, opts PaletteOptions) Palette {
 }
 
 type VariantOptions struct {
-	PrimaryDark  string
-	PrimaryLight string
-	Background   string
-	UseDPS       bool
-	IsLightMode  bool
+	PrimaryDark     string
+	PrimaryLight    string
+	BackgroundDark  string
+	BackgroundLight string
+	ContainerDark   string
+	ContainerLight  string
+	UseDPS          bool
+	IsLightMode     bool
 }
 
 func mergeColorInfo(dark, light ColorInfo, isLightMode bool) VariantColorInfo {
@@ -702,8 +718,8 @@ func mergeColorInfo(dark, light ColorInfo, isLightMode bool) VariantColorInfo {
 }
 
 func GenerateVariantPalette(opts VariantOptions) VariantPalette {
-	darkOpts := PaletteOptions{IsLight: false, Background: opts.Background, UseDPS: opts.UseDPS}
-	lightOpts := PaletteOptions{IsLight: true, Background: opts.Background, UseDPS: opts.UseDPS}
+	darkOpts := PaletteOptions{IsLight: false, Background: opts.BackgroundDark, Container: opts.ContainerDark, UseDPS: opts.UseDPS}
+	lightOpts := PaletteOptions{IsLight: true, Background: opts.BackgroundLight, Container: opts.ContainerLight, UseDPS: opts.UseDPS}
 
 	dark := GeneratePalette(opts.PrimaryDark, darkOpts)
 	light := GeneratePalette(opts.PrimaryLight, lightOpts)

core/internal/dank16/dank16_test.go

@@ -701,7 +701,8 @@ func TestGeneratePaletteWithDPS(t *testing.T) {
 
 			bgColor := result.Color0.Hex
 			for i := 1; i < 8; i++ {
-				// Skip Color5 (container) and Color6 (exact primary) - intentionally not contrast-adjusted
+				// Color5 is the container and Color6 the exact primary: they pair
+				// with each other, not with the background
 				if i == 5 || i == 6 {
 					continue
 				}
@@ -862,3 +863,112 @@ func TestGeneratePaletteLightColor8StaysLight(t *testing.T) {
 			palette.Color8.Hex, palette.Color0.Hex, bgRatio)
 	}
 }
+
+func TestGeneratePaletteLightYellowMeetsNormalTextContrast(t *testing.T) {
+	primaries := []string{"#63568f", "#7d5800", "#116d2b", "#1c5070", "#8b3f68"}
+
+	for _, primary := range primaries {
+		t.Run(primary, func(t *testing.T) {
+			palette := GeneratePalette(primary, PaletteOptions{IsLight: true, Background: "#f5fafc", UseDPS: true})
+
+			ratio := ContrastRatio(palette.Color3.Hex, palette.Color0.Hex)
+			if ratio < 4.5 {
+				t.Errorf("light Color3 %s vs bg %s ratio %.2f, expected >= 4.5 (yellow must clear the normal-text target)",
+					palette.Color3.Hex, palette.Color0.Hex, ratio)
+			}
+		})
+	}
+}
+
+func TestGenerateVariantPaletteUsesPerVariantBackground(t *testing.T) {
+	const darkBg = "#0f1417"
+	const lightBg = "#f5fafc"
+
+	variants := GenerateVariantPalette(VariantOptions{
+		PrimaryDark:     "#8ecff2",
+		PrimaryLight:    "#1c5070",
+		BackgroundDark:  darkBg,
+		BackgroundLight: lightBg,
+		UseDPS:          true,
+	})
+
+	if variants.Color0.Dark.Hex != darkBg {
+		t.Errorf("dark Color0 = %s, expected the dark background %s", variants.Color0.Dark.Hex, darkBg)
+	}
+	if variants.Color0.Light.Hex != lightBg {
+		t.Errorf("light Color0 = %s, expected the light background %s", variants.Color0.Light.Hex, lightBg)
+	}
+
+	lightDim := variants.Color8.Light.Hex
+	if lstar := getLstar(lightDim); lstar < 60.0 {
+		t.Errorf("light Color8 %s has L* %.2f, expected >= 60 (derived from the dark surface it collapses to near-black)",
+			lightDim, lstar)
+	}
+	if ratio := ContrastRatio(lightDim, lightBg); ratio > 3.0 {
+		t.Errorf("light Color8 %s vs bg %s ratio %.2f, expected <= 3.0 (bright black stays dim)", lightDim, lightBg, ratio)
+	}
+
+	darkDim := variants.Color8.Dark.Hex
+	if ratio := ContrastRatio(darkDim, darkBg); ratio > 3.0 {
+		t.Errorf("dark Color8 %s vs bg %s ratio %.2f, expected <= 3.0", darkDim, darkBg, ratio)
+	}
+}
+
+func TestGeneratePaletteColor5PairsWithColor6(t *testing.T) {
+	tests := []struct {
+		name      string
+		primary   string
+		container string
+		bg        string
+		isLight   bool
+	}{
+		{"violet dark", "#cdbdff", "#4b3e76", "#141318", false},
+		{"violet light", "#63568f", "#e8deff", "#fdf7ff", true},
+		{"green dark", "#9ed49d", "#1f5027", "#101510", false},
+		{"green light", "#38693c", "#b9f0b8", "#f7fbf2", true},
+		{"amber light", "#805610", "#ffddb3", "#fff8f4", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			palette := GeneratePalette(tt.primary, PaletteOptions{
+				IsLight:    tt.isLight,
+				Background: tt.bg,
+				Container:  tt.container,
+				UseDPS:     true,
+			})
+
+			if palette.Color5.Hex != tt.container {
+				t.Errorf("Color5 = %s, expected the supplied container %s", palette.Color5.Hex, tt.container)
+			}
+			if palette.Color6.Hex != tt.primary {
+				t.Errorf("Color6 = %s, expected the primary %s", palette.Color6.Hex, tt.primary)
+			}
+
+			pair := ContrastRatio(palette.Color5.Hex, palette.Color6.Hex)
+			if pair < 4.5 {
+				t.Errorf("Color5 %s vs Color6 %s ratio %.2f, expected >= 4.5 (the container/primary pair carries the prompt themes that use ANSI 5 on 6)",
+					palette.Color5.Hex, palette.Color6.Hex, pair)
+			}
+
+			if palette.Color5.Hex == palette.Color13.Hex {
+				t.Errorf("Color5 and Color13 are both %s, expected a distinct bright variant", palette.Color5.Hex)
+			}
+			if sep := ContrastRatio(palette.Color5.Hex, palette.Color13.Hex); sep < 2.0 {
+				t.Errorf("Color5 %s vs Color13 %s ratio %.2f, expected >= 2.0 (normal and bright must be tellable apart)",
+					palette.Color5.Hex, palette.Color13.Hex, sep)
+			}
+		})
+	}
+}
+
+func TestGeneratePaletteFallsBackToDerivedContainer(t *testing.T) {
+	const primary = "#cdbdff"
+
+	palette := GeneratePalette(primary, PaletteOptions{Background: "#141318", UseDPS: true})
+
+	want := DeriveContainer(primary, false)
+	if palette.Color5.Hex != want {
+		t.Errorf("Color5 = %s with no container supplied, expected the derived %s", palette.Color5.Hex, want)
+	}
+}

core/internal/matugen/matugen.go

@@ -343,7 +343,7 @@ func buildOnce(opts *Options) (bool, error) {
 
 	oldColors, _ := os.ReadFile(opts.ColorsOutput())
 
-	var primaryDark, primaryLight, surface string
+	var primaryDark, primaryLight, surfaceDark, surfaceLight, containerDark, containerLight string
 	var dank16JSON string
 	var importArgs []string
 	var sourceImage string
@@ -373,7 +373,10 @@ func buildOnce(opts *Options) (bool, error) {
 		log.Info("Using stock/custom theme colors with matugen base")
 		primaryDark = extractNestedColor(opts.StockColors, "primary", "dark")
 		primaryLight = extractNestedColor(opts.StockColors, "primary", "light")
-		surface = extractNestedColor(opts.StockColors, "surface", "dark")
+		surfaceDark = extractNestedColor(opts.StockColors, "surface", "dark")
+		surfaceLight = extractNestedColor(opts.StockColors, "surface", "light")
+		containerDark = extractNestedColor(opts.StockColors, "primary_container", "dark")
+		containerLight = extractNestedColor(opts.StockColors, "primary_container", "light")
 
 		if primaryDark == "" {
 			return false, fmt.Errorf("failed to extract primary dark from stock colors")
@@ -382,7 +385,7 @@ func buildOnce(opts *Options) (bool, error) {
 			primaryLight = primaryDark
 		}
 
-		dank16JSON = generateDank16Variants(primaryDark, primaryLight, surface, opts.Mode)
+		dank16JSON = generateDank16Variants(primaryDark, primaryLight, surfaceDark, surfaceLight, containerDark, containerLight, opts.Mode)
 		importData := fmt.Sprintf(`{"colors": %s, "dank16": %s}`, opts.StockColors, dank16JSON)
 		importArgs = []string{"--import-json-string", importData}
 
@@ -403,7 +406,10 @@ func buildOnce(opts *Options) (bool, error) {
 
 		primaryDark = extractMatugenColor(matJSON, "primary", "dark")
 		primaryLight = extractMatugenColor(matJSON, "primary", "light")
-		surface = extractMatugenColor(matJSON, "surface", "dark")
+		surfaceDark = extractMatugenColor(matJSON, "surface", "dark")
+		surfaceLight = extractMatugenColor(matJSON, "surface", "light")
+		containerDark = extractMatugenColor(matJSON, "primary_container", "dark")
+		containerLight = extractMatugenColor(matJSON, "primary_container", "light")
 
 		if primaryDark == "" {
 			return false, fmt.Errorf("failed to extract primary color")
@@ -412,7 +418,7 @@ func buildOnce(opts *Options) (bool, error) {
 			primaryLight = primaryDark
 		}
 
-		dank16JSON = generateDank16Variants(primaryDark, primaryLight, surface, opts.Mode)
+		dank16JSON = generateDank16Variants(primaryDark, primaryLight, surfaceDark, surfaceLight, containerDark, containerLight, opts.Mode)
 		importArgs = []string{"--import-json-string", buildImportData(dank16JSON, sourceImage)}
 
 		log.Infof("Running matugen %s with dank16 injection", opts.Kind)
@@ -1125,13 +1131,16 @@ func extractNestedColor(jsonStr, colorName, variant string) string {
 	return color
 }
 
-func generateDank16Variants(primaryDark, primaryLight, surface string, mode ColorMode) string {
+func generateDank16Variants(primaryDark, primaryLight, surfaceDark, surfaceLight, containerDark, containerLight string, mode ColorMode) string {
 	variantOpts := dank16.VariantOptions{
-		PrimaryDark:  primaryDark,
-		PrimaryLight: primaryLight,
-		Background:   surface,
-		UseDPS:       true,
-		IsLightMode:  mode == ColorModeLight,
+		PrimaryDark:     primaryDark,
+		PrimaryLight:    primaryLight,
+		BackgroundDark:  surfaceDark,
+		BackgroundLight: surfaceLight,
+		ContainerDark:   containerDark,
+		ContainerLight:  containerLight,
+		UseDPS:          true,
+		IsLightMode:     mode == ColorModeLight,
 	}
 	variantColors := dank16.GenerateVariantPalette(variantOpts)
 	return dank16.GenerateVariantJSON(variantColors)