diff --git a/utils/cacheControl.theme-contrast.test.ts b/utils/cacheControl.theme-contrast.test.ts
new file mode 100644
index 000000000..5c81c560c
--- /dev/null
+++ b/utils/cacheControl.theme-contrast.test.ts
@@ -0,0 +1,34 @@
+import { describe, it, expect } from 'vitest';
+import { buildCacheControlHeader } from './cacheControl';
+
+describe('cacheControl - Dark and Light Prefers-Color-Scheme Visual Cohesion', () => {
+  it('returns the default s-maxage header when no options are provided', () => {
+    const header = buildCacheControlHeader({});
+    expect(header).toBe('s-maxage=3600, stale-while-revalidate=86400');
+  });
+
+  it('returns a no-store directive when bypass is true, overriding all other options', () => {
+    const header = buildCacheControlHeader({
+      bypass: true,
+      secondsToMidnight: 5000,
+      isHistoricalYear: true,
+    });
+    expect(header).toBe('no-cache, no-store, must-revalidate');
+  });
+
+  it('returns an immutable cache header when isHistoricalYear is set', () => {
+    const header = buildCacheControlHeader({ isHistoricalYear: true });
+    expect(header).toBe('public, s-maxage=31536000, immutable');
+  });
+
+  it('includes secondsToMidnight in the s-maxage when provided without bypass or historical', () => {
+    const header = buildCacheControlHeader({ secondsToMidnight: 7200 });
+    expect(header).toMatch(/^public, s-maxage=7200,/);
+    expect(header).toContain('stale-while-revalidate=86400');
+  });
+
+  it('handles secondsToMidnight of zero correctly, producing s-maxage=0', () => {
+    const header = buildCacheControlHeader({ secondsToMidnight: 0 });
+    expect(header).toBe('public, s-maxage=0, stale-while-revalidate=86400');
+  });
+});