diff --git a/packages/cli/src/ui/utils/textUtils.test.ts b/packages/cli/src/ui/utils/textUtils.test.ts
index eaf501a1fb..f9a90c63b4 100644
--- a/packages/cli/src/ui/utils/textUtils.test.ts
+++ b/packages/cli/src/ui/utils/textUtils.test.ts
@@ -9,9 +9,26 @@ import type {
   ToolCallConfirmationDetails,
   ToolEditConfirmationDetails,
 } from '@google/gemini-cli-core';
-import { escapeAnsiCtrlCodes, stripUnsafeCharacters } from './textUtils.js';
+import {
+  escapeAnsiCtrlCodes,
+  stripUnsafeCharacters,
+  getCachedStringWidth,
+} from './textUtils.js';
 
 describe('textUtils', () => {
+  describe('getCachedStringWidth', () => {
+    it('should handle unicode characters that crash string-width', () => {
+      // U+0602 caused string-width to crash (see #16418)
+      const char = '؂';
+      expect(getCachedStringWidth(char)).toBe(1);
+    });
+
+    it('should handle unicode characters that crash string-width with ANSI codes', () => {
+      const charWithAnsi = '\u001b[31m' + '؂' + '\u001b[0m';
+      expect(getCachedStringWidth(charWithAnsi)).toBe(1);
+    });
+  });
+
   describe('stripUnsafeCharacters', () => {
     it('should not strip tab characters', () => {
       const input = 'hello	world';
diff --git a/packages/cli/src/ui/utils/textUtils.ts b/packages/cli/src/ui/utils/textUtils.ts
index 5da186c423..13c009a136 100644
--- a/packages/cli/src/ui/utils/textUtils.ts
+++ b/packages/cli/src/ui/utils/textUtils.ts
@@ -136,7 +136,15 @@ export const getCachedStringWidth = (str: string): number => {
     return stringWidthCache.get(str)!;
   }
 
-  const width = stringWidth(str);
+  let width: number;
+  try {
+    width = stringWidth(str);
+  } catch {
+    // Fallback for characters that cause string-width to crash (e.g. U+0602)
+    // See: https://github.com/google-gemini/gemini-cli/issues/16418
+    width = toCodePoints(stripAnsi(str)).length;
+  }
+
   stringWidthCache.set(str, width);
 
   return width;