diff --git a/scripts/check_light_theme_contrast.ts b/scripts/check_light_theme_contrast.ts
new file mode 100644
index 0000000000..a26a71530b
--- /dev/null
+++ b/scripts/check_light_theme_contrast.ts
@@ -0,0 +1,85 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import tinycolor from 'tinycolor2';
+import {
+  lightTheme,
+  darkTheme,
+  type ColorsTheme,
+} from '../packages/cli/src/ui/themes/theme.js';
+
+function hexToAnsi(fgHex: string, bgHex: string, text: string): string {
+  const fg = tinycolor(fgHex).toRgb();
+  const bg = tinycolor(bgHex).toRgb();
+  return `\x1b[38;2;${fg.r};${fg.g};${fg.b}m\x1b[48;2;${bg.r};${bg.g};${bg.b}m ${text} \x1b[0m`;
+}
+
+function checkTheme(theme: ColorsTheme, themeName: string) {
+  const background =
+    theme.Background || (theme.type === 'light' ? '#FAFAFA' : '#1E1E2E');
+  const defaultForeground =
+    theme.Foreground || (theme.type === 'light' ? '#000000' : '#CDD6F4');
+
+  console.log(`Checking contrast ratios for ${themeName} colors...\n`);
+  console.log(
+    `${'Name'.padEnd(20)} | ${'FG Hex'.padEnd(10)} | ${'Sample'.padEnd(
+      10,
+    )} | ${'Contrast'.padEnd(8)} | ${'Passes'}`,
+  );
+  console.log('-'.repeat(75));
+
+  const results = [];
+
+  for (const [name, color] of Object.entries(theme)) {
+    if (name === 'Background' || name === 'type' || name === 'GradientColors')
+      continue;
+
+    // Skip non-color strings (except Foreground which we handle with a default)
+    if (
+      name !== 'Foreground' &&
+      (typeof color !== 'string' || !color.startsWith('#'))
+    )
+      continue;
+
+    const isBgLike =
+      name.toLowerCase().includes('background') ||
+      name.toLowerCase().includes('diff');
+    const fg = isBgLike ? defaultForeground : color || defaultForeground;
+    const bg = isBgLike ? color || background : background;
+
+    const contrast = tinycolor.readability(bg, fg);
+    const passes = contrast >= 4.5;
+    const sample = hexToAnsi(fg, bg, 'TEXT');
+
+    console.log(
+      `${name.padEnd(20)} | ${fg.padEnd(10)} | ${sample}      | ${contrast
+        .toFixed(2)
+        .padEnd(8)} | ${passes ? '✅ PASS' : '❌ FAIL'}`,
+    );
+
+    results.push({ name, color, contrast, passes });
+  }
+
+  const failures = results.filter((r) => !r.passes);
+  if (failures.length > 0) {
+    console.log(`\nFailures detected in ${themeName}:`);
+    failures.forEach((f) => {
+      console.log(`- ${f.name} (${f.color}): ${f.contrast.toFixed(2)}`);
+    });
+    return false;
+  } else {
+    console.log(`\nAll ${themeName} colors pass the 4.5:1 contrast ratio!`);
+    return true;
+  }
+}
+
+const lightPass = checkTheme(lightTheme, 'lightTheme');
+console.log('\n' + '='.repeat(75) + '\n');
+const darkPass = checkTheme(darkTheme, 'darkTheme');
+
+if (!lightPass || !darkPass) {
+  process.exit(1);
+}