diff --git a/packages/cli/src/ui/components/shared/SlicingMaxSizedBox.tsx b/packages/cli/src/ui/components/shared/SlicingMaxSizedBox.tsx
index b756c40ee2..f8f851aed3 100644
--- a/packages/cli/src/ui/components/shared/SlicingMaxSizedBox.tsx
+++ b/packages/cli/src/ui/components/shared/SlicingMaxSizedBox.tsx
@@ -46,7 +46,7 @@ export function SlicingMaxSizedBox<T>({
           text = '...' + text.slice(-MAXIMUM_RESULT_DISPLAY_CHARACTERS);
         }
       }
-      if (maxLines) {
+      if (maxLines !== undefined) {
         const hasTrailingNewline = text.endsWith('\n');
         const contentText = hasTrailingNewline ? text.slice(0, -1) : text;
         const lines = contentText.split('\n');
@@ -71,7 +71,7 @@ export function SlicingMaxSizedBox<T>({
       };
     }
 
-    if (Array.isArray(data) && !isAlternateBuffer && maxLines) {
+    if (Array.isArray(data) && !isAlternateBuffer && maxLines !== undefined) {
       if (data.length > maxLines) {
         // We will have a label from MaxSizedBox. Reserve space for it.
         const targetLines = Math.max(1, maxLines - 1);
diff --git a/packages/cli/src/ui/utils/toolLayoutUtils.test.ts b/packages/cli/src/ui/utils/toolLayoutUtils.test.ts
index e93b5e56d0..35f5fb28e6 100644
--- a/packages/cli/src/ui/utils/toolLayoutUtils.test.ts
+++ b/packages/cli/src/ui/utils/toolLayoutUtils.test.ts
@@ -18,184 +18,191 @@ import {
 
 describe('toolLayoutUtils', () => {
   describe('calculateToolContentMaxLines', () => {
-    it('returns undefined if availableTerminalHeight is undefined', () => {
-      const result = calculateToolContentMaxLines({
-        availableTerminalHeight: undefined,
-        isAlternateBuffer: false,
-      });
-      expect(result).toBeUndefined();
-    });
+    interface CalculateToolContentMaxLinesTestCase {
+      desc: string;
+      options: Parameters<typeof calculateToolContentMaxLines>[0];
+      expected: number | undefined;
+    }
 
-    it('returns maxLinesLimit if maxLinesLimit applies but availableTerminalHeight is undefined', () => {
-      const result = calculateToolContentMaxLines({
-        availableTerminalHeight: undefined,
-        isAlternateBuffer: false,
-        maxLinesLimit: 10,
-      });
-      expect(result).toBe(10);
-    });
+    const testCases: CalculateToolContentMaxLinesTestCase[] = [
+      {
+        desc: 'returns undefined if availableTerminalHeight is undefined',
+        options: {
+          availableTerminalHeight: undefined,
+          isAlternateBuffer: false,
+        },
+        expected: undefined,
+      },
+      {
+        desc: 'returns maxLinesLimit if maxLinesLimit applies but availableTerminalHeight is undefined',
+        options: {
+          availableTerminalHeight: undefined,
+          isAlternateBuffer: false,
+          maxLinesLimit: 10,
+        },
+        expected: 10,
+      },
+      {
+        desc: 'returns available space directly in constrained terminal (Standard mode)',
+        options: {
+          availableTerminalHeight: 2,
+          isAlternateBuffer: false,
+        },
+        expected: 0,
+      },
+      {
+        desc: 'returns available space directly in constrained terminal (ASB mode)',
+        options: {
+          availableTerminalHeight: 4,
+          isAlternateBuffer: true,
+        },
+        expected: 2,
+      },
+      {
+        desc: 'returns remaining space if sufficient space exists (Standard mode)',
+        options: {
+          availableTerminalHeight: 20,
+          isAlternateBuffer: false,
+        },
+        expected: 18,
+      },
+      {
+        desc: 'returns remaining space if sufficient space exists (ASB mode)',
+        options: {
+          availableTerminalHeight: 20,
+          isAlternateBuffer: true,
+        },
+        expected: 18,
+      },
+    ];
 
-    it('returns available space directly in constrained terminal (Standard mode)', () => {
-      const availableTerminalHeight = 2; // Very small
-      const result = calculateToolContentMaxLines({
-        availableTerminalHeight,
-        isAlternateBuffer: false,
-      });
-
-      // Math.max(0, 2 - 2) = 0
-      expect(result).toBe(0);
-    });
-
-    it('returns available space directly in constrained terminal (ASB mode)', () => {
-      const availableTerminalHeight = 4; // Very small
-      const result = calculateToolContentMaxLines({
-        availableTerminalHeight,
-        isAlternateBuffer: true,
-      });
-
-      // Math.max(0, 4 - 2) = 2
-      expect(result).toBe(2);
-    });
-
-    it('returns remaining space if sufficient space exists (Standard mode)', () => {
-      const availableTerminalHeight = 20;
-      const result = calculateToolContentMaxLines({
-        availableTerminalHeight,
-        isAlternateBuffer: false,
-      });
-
-      // Math.max(0, 20 - 2) = 18
-      expect(result).toBe(18);
-    });
-
-    it('returns remaining space if sufficient space exists (ASB mode)', () => {
-      const availableTerminalHeight = 20;
-      const result = calculateToolContentMaxLines({
-        availableTerminalHeight,
-        isAlternateBuffer: true,
-      });
-
-      // Math.max(0, 20 - 2) = 18
-      expect(result).toBe(18);
+    it.each(testCases)('$desc', ({ options, expected }) => {
+      const result = calculateToolContentMaxLines(options);
+      expect(result).toBe(expected);
     });
   });
 
   describe('calculateShellMaxLines', () => {
-    it('returns undefined when not constrained and is expandable', () => {
-      const result = calculateShellMaxLines({
-        status: CoreToolCallStatus.Executing,
-        isAlternateBuffer: false,
-        isThisShellFocused: false,
-        availableTerminalHeight: 20,
-        constrainHeight: false,
-        isExpandable: true,
-      });
-      expect(result).toBeUndefined();
-    });
+    interface CalculateShellMaxLinesTestCase {
+      desc: string;
+      options: Parameters<typeof calculateShellMaxLines>[0];
+      expected: number | undefined;
+    }
 
-    it('returns ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD for ASB mode when availableTerminalHeight is undefined', () => {
-      const result = calculateShellMaxLines({
-        status: CoreToolCallStatus.Executing,
-        isAlternateBuffer: true,
-        isThisShellFocused: false,
-        availableTerminalHeight: undefined,
-        constrainHeight: true,
-        isExpandable: false,
-      });
-      expect(result).toBe(ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD);
-    });
+    const testCases: CalculateShellMaxLinesTestCase[] = [
+      {
+        desc: 'returns undefined when not constrained and is expandable',
+        options: {
+          status: CoreToolCallStatus.Executing,
+          isAlternateBuffer: false,
+          isThisShellFocused: false,
+          availableTerminalHeight: 20,
+          constrainHeight: false,
+          isExpandable: true,
+        },
+        expected: undefined,
+      },
+      {
+        desc: 'returns ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD for ASB mode when availableTerminalHeight is undefined',
+        options: {
+          status: CoreToolCallStatus.Executing,
+          isAlternateBuffer: true,
+          isThisShellFocused: false,
+          availableTerminalHeight: undefined,
+          constrainHeight: true,
+          isExpandable: false,
+        },
+        expected: ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD,
+      },
+      {
+        desc: 'returns undefined for Standard mode when availableTerminalHeight is undefined',
+        options: {
+          status: CoreToolCallStatus.Executing,
+          isAlternateBuffer: false,
+          isThisShellFocused: false,
+          availableTerminalHeight: undefined,
+          constrainHeight: true,
+          isExpandable: false,
+        },
+        expected: undefined,
+      },
+      {
+        desc: 'handles small availableTerminalHeight gracefully without overflow in Standard mode',
+        options: {
+          status: CoreToolCallStatus.Executing,
+          isAlternateBuffer: false,
+          isThisShellFocused: false,
+          availableTerminalHeight: 2,
+          constrainHeight: true,
+          isExpandable: false,
+        },
+        expected: 0,
+      },
+      {
+        desc: 'handles small availableTerminalHeight gracefully without overflow in ASB mode',
+        options: {
+          status: CoreToolCallStatus.Executing,
+          isAlternateBuffer: true,
+          isThisShellFocused: false,
+          availableTerminalHeight: 6,
+          constrainHeight: true,
+          isExpandable: false,
+        },
+        expected: 4,
+      },
+      {
+        desc: 'handles negative availableTerminalHeight gracefully',
+        options: {
+          status: CoreToolCallStatus.Executing,
+          isAlternateBuffer: false,
+          isThisShellFocused: false,
+          availableTerminalHeight: -5,
+          constrainHeight: true,
+          isExpandable: false,
+        },
+        expected: 0,
+      },
+      {
+        desc: 'returns maxLinesBasedOnHeight for focused ASB shells',
+        options: {
+          status: CoreToolCallStatus.Executing,
+          isAlternateBuffer: true,
+          isThisShellFocused: true,
+          availableTerminalHeight: 30,
+          constrainHeight: false,
+          isExpandable: false,
+        },
+        expected: 28,
+      },
+      {
+        desc: 'falls back to COMPLETED_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD for completed shells if space allows',
+        options: {
+          status: CoreToolCallStatus.Success,
+          isAlternateBuffer: false,
+          isThisShellFocused: false,
+          availableTerminalHeight: 100,
+          constrainHeight: true,
+          isExpandable: false,
+        },
+        expected: COMPLETED_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD,
+      },
+      {
+        desc: 'falls back to ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD for executing shells if space allows',
+        options: {
+          status: CoreToolCallStatus.Executing,
+          isAlternateBuffer: false,
+          isThisShellFocused: false,
+          availableTerminalHeight: 100,
+          constrainHeight: true,
+          isExpandable: false,
+        },
+        expected: ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD,
+      },
+    ];
 
-    it('returns undefined for Standard mode when availableTerminalHeight is undefined', () => {
-      const result = calculateShellMaxLines({
-        status: CoreToolCallStatus.Executing,
-        isAlternateBuffer: false,
-        isThisShellFocused: false,
-        availableTerminalHeight: undefined,
-        constrainHeight: true,
-        isExpandable: false,
-      });
-      expect(result).toBeUndefined();
-    });
-
-    it('handles small availableTerminalHeight gracefully without overflow in Standard mode', () => {
-      const result = calculateShellMaxLines({
-        status: CoreToolCallStatus.Executing,
-        isAlternateBuffer: false,
-        isThisShellFocused: false,
-        availableTerminalHeight: 2,
-        constrainHeight: true,
-        isExpandable: false,
-      });
-
-      // Math.max(0, 2 - 2) = 0
-      expect(result).toBe(0);
-    });
-
-    it('handles small availableTerminalHeight gracefully without overflow in ASB mode', () => {
-      const result = calculateShellMaxLines({
-        status: CoreToolCallStatus.Executing,
-        isAlternateBuffer: true,
-        isThisShellFocused: false,
-        availableTerminalHeight: 6,
-        constrainHeight: true,
-        isExpandable: false,
-      });
-
-      // Math.max(0, 6 - 2) = 4
-      expect(result).toBe(4);
-    });
-
-    it('handles negative availableTerminalHeight gracefully', () => {
-      const result = calculateShellMaxLines({
-        status: CoreToolCallStatus.Executing,
-        isAlternateBuffer: false,
-        isThisShellFocused: false,
-        availableTerminalHeight: -5,
-        constrainHeight: true,
-        isExpandable: false,
-      });
-
-      expect(result).toBe(0);
-    });
-
-    it('returns maxLinesBasedOnHeight for focused ASB shells', () => {
-      const result = calculateShellMaxLines({
-        status: CoreToolCallStatus.Executing,
-        isAlternateBuffer: true,
-        isThisShellFocused: true,
-        availableTerminalHeight: 30,
-        constrainHeight: false,
-        isExpandable: false,
-      });
-
-      // 30 - 2 = 28
-      expect(result).toBe(28);
-    });
-
-    it('falls back to COMPLETED_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD for completed shells if space allows', () => {
-      const result = calculateShellMaxLines({
-        status: CoreToolCallStatus.Success,
-        isAlternateBuffer: false,
-        isThisShellFocused: false,
-        availableTerminalHeight: 100,
-        constrainHeight: true,
-        isExpandable: false,
-      });
-
-      expect(result).toBe(COMPLETED_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD);
-    });
-
-    it('falls back to ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD for executing shells if space allows', () => {
-      const result = calculateShellMaxLines({
-        status: CoreToolCallStatus.Executing,
-        isAlternateBuffer: false,
-        isThisShellFocused: false,
-        availableTerminalHeight: 100,
-        constrainHeight: true,
-        isExpandable: false,
-      });
-
-      expect(result).toBe(ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD);
+    it.each(testCases)('$desc', ({ options, expected }) => {
+      const result = calculateShellMaxLines(options);
+      expect(result).toBe(expected);
     });
   });
 });