diff --git a/packages/cli/src/ui/components/Header.test.tsx b/packages/cli/src/ui/components/Header.test.tsx
index f3f10382e2..8b4aa6b674 100644
--- a/packages/cli/src/ui/components/Header.test.tsx
+++ b/packages/cli/src/ui/components/Header.test.tsx
@@ -5,50 +5,117 @@
  */
 
 import { render } from '../../test-utils/render.js';
-import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { describe, it, expect, vi, beforeEach, type Mock } from 'vitest';
 import { Header } from './Header.js';
 import * as useTerminalSize from '../hooks/useTerminalSize.js';
 import { longAsciiLogo } from './AsciiArt.js';
+import * as semanticColors from '../semantic-colors.js';
+import { Text } from 'ink';
+import type React from 'react';
 
 vi.mock('../hooks/useTerminalSize.js');
+vi.mock('ink-gradient', () => {
+  const MockGradient = ({ children }: { children: React.ReactNode }) => (
+    <>{children}</>
+  );
+  return {
+    default: vi.fn(MockGradient),
+  };
+});
+vi.mock('../semantic-colors.js');
+vi.mock('ink', async () => {
+  const originalInk = await vi.importActual<typeof import('ink')>('ink');
+  return {
+    ...originalInk,
+    Text: vi.fn(originalInk.Text),
+  };
+});
 
 describe('<Header />', () => {
-  beforeEach(() => {});
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
 
   it('renders the long logo on a wide terminal', () => {
     vi.spyOn(useTerminalSize, 'useTerminalSize').mockReturnValue({
       columns: 120,
       rows: 20,
     });
-    const { lastFrame, unmount } = render(
-      <Header version="1.0.0" nightly={false} />,
+    render(<Header version="1.0.0" nightly={false} />);
+    expect(Text).toHaveBeenCalledWith(
+      expect.objectContaining({
+        children: longAsciiLogo,
+      }),
+      undefined,
     );
-    expect(lastFrame()).toContain(longAsciiLogo);
-    unmount();
   });
 
   it('renders custom ASCII art when provided', () => {
     const customArt = 'CUSTOM ART';
-    const { lastFrame, unmount } = render(
+    render(
       <Header version="1.0.0" nightly={false} customAsciiArt={customArt} />,
     );
-    expect(lastFrame()).toContain(customArt);
-    unmount();
+    expect(Text).toHaveBeenCalledWith(
+      expect.objectContaining({
+        children: customArt,
+      }),
+      undefined,
+    );
   });
 
   it('displays the version number when nightly is true', () => {
-    const { lastFrame, unmount } = render(
-      <Header version="1.0.0" nightly={true} />,
-    );
-    expect(lastFrame()).toContain('v1.0.0');
-    unmount();
+    render(<Header version="1.0.0" nightly={true} />);
+    const textCalls = (Text as Mock).mock.calls;
+    expect(textCalls[1][0].children.join('')).toBe('v1.0.0');
   });
 
   it('does not display the version number when nightly is false', () => {
-    const { lastFrame, unmount } = render(
-      <Header version="1.0.0" nightly={false} />,
+    render(<Header version="1.0.0" nightly={false} />);
+    expect(Text).not.toHaveBeenCalledWith(
+      expect.objectContaining({
+        children: 'v1.0.0',
+      }),
+      undefined,
+    );
+  });
+
+  it('renders with no gradient when theme.ui.gradient is undefined', async () => {
+    vi.spyOn(semanticColors, 'theme', 'get').mockReturnValue({
+      ui: { gradient: undefined },
+    } as typeof semanticColors.theme);
+    const Gradient = await import('ink-gradient');
+    render(<Header version="1.0.0" nightly={false} />);
+    expect(Gradient.default).not.toHaveBeenCalled();
+    const textCalls = (Text as Mock).mock.calls;
+    expect(textCalls[0][0]).not.toHaveProperty('color');
+  });
+
+  it('renders with a single color when theme.ui.gradient has one color', async () => {
+    const singleColor = '#FF0000';
+    vi.spyOn(semanticColors, 'theme', 'get').mockReturnValue({
+      ui: { gradient: [singleColor] },
+    } as typeof semanticColors.theme);
+    const Gradient = await import('ink-gradient');
+    render(<Header version="1.0.0" nightly={false} />);
+    expect(Gradient.default).not.toHaveBeenCalled();
+    const textCalls = (Text as Mock).mock.calls;
+    console.log(JSON.stringify(textCalls, null, 2));
+    expect(textCalls.length).toBe(1);
+    expect(textCalls[0][0]).toHaveProperty('color', singleColor);
+  });
+
+  it('renders with a gradient when theme.ui.gradient has two or more colors', async () => {
+    const gradientColors = ['#FF0000', '#00FF00'];
+    vi.spyOn(semanticColors, 'theme', 'get').mockReturnValue({
+      ui: { gradient: gradientColors },
+    } as typeof semanticColors.theme);
+    const Gradient = await import('ink-gradient');
+    render(<Header version="1.0.0" nightly={false} />);
+    expect(Gradient.default).toHaveBeenCalledWith(
+      expect.objectContaining({
+        colors: gradientColors,
+      }),
+      undefined,
     );
-    expect(lastFrame()).not.toContain('v1.0.0');
-    unmount();
   });
 });
diff --git a/packages/cli/src/ui/components/Header.tsx b/packages/cli/src/ui/components/Header.tsx
index 694752312f..51e9cd8c71 100644
--- a/packages/cli/src/ui/components/Header.tsx
+++ b/packages/cli/src/ui/components/Header.tsx
@@ -18,6 +18,26 @@ interface HeaderProps {
   nightly: boolean;
 }
 
+const ThemedGradient: React.FC<{ children: React.ReactNode }> = ({
+  children,
+}) => {
+  const gradient = theme.ui.gradient;
+
+  if (gradient && gradient.length >= 2) {
+    return (
+      <Gradient colors={gradient}>
+        <Text>{children}</Text>
+      </Gradient>
+    );
+  }
+
+  if (gradient && gradient.length === 1) {
+    return <Text color={gradient[0]}>{children}</Text>;
+  }
+
+  return <Text>{children}</Text>;
+};
+
 export const Header: React.FC<HeaderProps> = ({
   customAsciiArt,
   version,
@@ -47,22 +67,10 @@ export const Header: React.FC<HeaderProps> = ({
       flexShrink={0}
       flexDirection="column"
     >
-      {theme.ui.gradient ? (
-        <Gradient colors={theme.ui.gradient}>
-          <Text>{displayTitle}</Text>
-        </Gradient>
-      ) : (
-        <Text>{displayTitle}</Text>
-      )}
+      <ThemedGradient>{displayTitle}</ThemedGradient>
       {nightly && (
         <Box width="100%" flexDirection="row" justifyContent="flex-end">
-          {theme.ui.gradient ? (
-            <Gradient colors={theme.ui.gradient}>
-              <Text>v{version}</Text>
-            </Gradient>
-          ) : (
-            <Text>v{version}</Text>
-          )}
+          <ThemedGradient>v{version}</ThemedGradient>
         </Box>
       )}
     </Box>