diff --git a/packages/tui/src/utils.ts b/packages/tui/src/utils.ts
index dace78c1..3c4f80bf 100644
--- a/packages/tui/src/utils.ts
+++ b/packages/tui/src/utils.ts
@@ -5,7 +5,8 @@ import stringWidth from "string-width";
  */
 export function visibleWidth(str: string): number {
 	if (!str) return 0;
-	const normalized = str.replace(/\t/g, "   ");
+	// Replace tabs and strip Unicode format characters (Cf) that crash string-width
+	const normalized = str.replace(/\t/g, "   ").replace(/\p{Cf}/gu, "");
 	return stringWidth(normalized);
 }