themes: lift muddy accent colors to a 3:1 legibility floor

styles/gitbash/profile.ps1

@@ -13,7 +13,7 @@ $Host.UI.RawUI.WindowTitle = 'GITBASH // MINGW64'
 function global:prompt {
     $Esc     = [char]27
     $Green   = "$Esc[38;2;0;128;0m"
-    $Yellow  = "$Esc[38;2;166;160;0m"
+    $Yellow  = "$Esc[38;2;155;150;29m"
     $Cyan    = "$Esc[38;2;0;119;119m"
     $Magenta = "$Esc[38;2;187;0;187m"
     $Gray    = "$Esc[38;2;56;56;56m"

styles/gitbash/scheme.json

@@ -7,15 +7,15 @@
     "black": "#000000",
     "red": "#a31515",
     "green": "#008000",
-    "yellow": "#a6a000",
+    "yellow": "#9b961d",
     "blue": "#0000bb",
     "purple": "#bb00bb",
     "cyan": "#007777",
     "white": "#bbbbbb",
     "brightBlack": "#555555",
     "brightRed": "#cd3131",
     "brightGreen": "#11a52b",
-    "brightYellow": "#c4a500",
+    "brightYellow": "#ad9000",
     "brightBlue": "#005ec1",
     "brightPurple": "#bc05bc",
     "brightCyan": "#00a3a3",

styles/golden-forest/scheme.json

@@ -8,7 +8,7 @@
     "red": "#a85a2a",
     "green": "#7a8f3e",
     "yellow": "#d4a017",
-    "blue": "#4d5d3a",
+    "blue": "#566743",
     "purple": "#8b6f3a",
     "cyan": "#a9b87c",
     "white": "#e8d68a",

styles/neon-rain/scheme.json

@@ -9,7 +9,7 @@
     "green": "#5ee090",
     "yellow": "#ffd848",
     "blue": "#5a90d0",
-    "purple": "#5a4870",
+    "purple": "#6c6279",
     "cyan": "#88c0e0",
     "white": "#e8e8e0",
     "brightBlack": "#2a3548",

styles/rain/profile.ps1

@@ -53,7 +53,7 @@ if (Get-Module -ListAvailable PSReadLine) {
         Keyword   = '#9CA0CC'
         Member    = '#C8C5DC'
         Default   = '#C8C5DC'
-        Error     = '#A85850'
+        Error     = '#A26D66'
         Selection = "$Esc[48;2;60;64;96m"
     }
     try {

styles/rain/scheme.json

@@ -5,7 +5,7 @@
     "cursorColor": "#9ca0cc",
     "selectionBackground": "#3c4060",
     "black": "#0f1220",
-    "red": "#a85850",
+    "red": "#a26d66",
     "green": "#5c8e5c",
     "yellow": "#a89860",
     "blue": "#7a8ac8",

styles/snowday/profile.ps1

@@ -24,7 +24,7 @@ if (Get-Module -ListAvailable PSReadLine) {
         Operator  = '#E8D4B8'
         Variable  = '#88A8B8'
         Type      = '#A08098'
-        Keyword   = '#3A6890'
+        Keyword   = '#44739B'
         Member    = '#E8D4B8'
         Default   = '#E8D4B8'
         Error     = '#C46850'

styles/snowday/scheme.json

@@ -8,7 +8,7 @@
     "red": "#c46850",
     "green": "#7a9078",
     "yellow": "#d8b878",
-    "blue": "#3a6890",
+    "blue": "#44739b",
     "purple": "#a08098",
     "cyan": "#88a8b8",
     "white": "#e8d4b8",

styles/umbrella/scheme.json

@@ -9,7 +9,7 @@
     "green": "#6e8e6e",
     "yellow": "#c9a66b",
     "blue": "#7b6e5a",
-    "purple": "#8b3030",
+    "purple": "#815350",
     "cyan": "#a89878",
     "white": "#e8dcc8",
     "brightBlack": "#4a423a",

tests/Scheme-Contrast.Tests.ps1

@@ -0,0 +1,58 @@
+# Legibility guard: every chromatic ANSI color in a bundled scheme.json must
+# stay readable against that scheme's own background. Colored text below ~3:1
+# reads as muddy syntax highlighting in the prompt. WCAG 1.4.11 puts the floor
+# for non-body / accent color at 3:1, which is the right bar for terminal token
+# colors (they are short identifiers, not paragraphs).
+#
+# Scope note: black / white (and their bright variants) are deliberately NOT
+# checked -- they are the achromatic ends that blend into the background by
+# design (e.g. gitbash is a light theme where white text is never used).
+#
+# Documented exceptions live in $allow below.
+# Run: Invoke-Pester -Path tests
+#Requires -Modules @{ ModuleName = 'Pester'; ModuleVersion = '5.0.0' }
+
+Describe 'Bundled scheme color contrast' {
+    BeforeDiscovery {
+        $repoRoot  = Split-Path $PSScriptRoot -Parent
+        $chromatic = 'red','green','yellow','blue','purple','cyan',
+                     'brightRed','brightGreen','brightYellow','brightBlue','brightPurple','brightCyan'
+
+        # (theme/key) pairs intentionally allowed below the 3:1 floor.
+        #   umbrella/red -- the theme's signature "blood red" (#b41e1e), used for
+        #   the banner, prompt scaffolding and cursor. It sits at 2.99:1, within
+        #   rounding of the floor; lifting it would shift the whole theme's
+        #   identity for an imperceptible contrast gain.
+        $allow = @{ 'umbrella/red' = $true }
+
+        $cases = foreach ($dir in Get-ChildItem -LiteralPath (Join-Path $repoRoot 'styles') -Directory) {
+            $schemePath = Join-Path $dir.FullName 'scheme.json'
+            if (-not (Test-Path -LiteralPath $schemePath)) { continue }
+            $scheme = Get-Content -LiteralPath $schemePath -Raw | ConvertFrom-Json
+            foreach ($key in $chromatic) {
+                if (-not $scheme.$key) { continue }
+                if ($allow.ContainsKey("$($dir.Name)/$key")) { continue }
+                @{ Theme = $dir.Name; Key = $key; Color = [string]$scheme.$key; Background = [string]$scheme.background }
+            }
+        }
+    }
+
+    It '<Theme>/<Key> (<Color>) is >=3:1 against <Background>' -ForEach $cases {
+        function Get-RelativeLuminance([string]$hex) {
+            $h = $hex.TrimStart('#')
+            $chan = 0, 2, 4 | ForEach-Object {
+                $v = [Convert]::ToInt32($h.Substring($_, 2), 16) / 255
+                if ($v -le 0.03928) { $v / 12.92 } else { [math]::Pow(($v + 0.055) / 1.055, 2.4) }
+            }
+            0.2126 * $chan[0] + 0.7152 * $chan[1] + 0.0722 * $chan[2]
+        }
+
+        $lColor = Get-RelativeLuminance $Color
+        $lBg    = Get-RelativeLuminance $Background
+        $hi     = [math]::Max($lColor, $lBg)
+        $lo     = [math]::Min($lColor, $lBg)
+        $ratio  = ($hi + 0.05) / ($lo + 0.05)
+
+        $ratio | Should -BeGreaterThan 3.0 -Because "$Theme/$Key ($Color) must stay readable on $Background"
+    }
+}