Restore original test_truncate_description test

- Restore ASCII text test cases that were accidentally removed
- Keep both original and new CJK-specific tests for comprehensive coverage
- Ensures backward compatibility verification

Author: mzkmnk

crates/chat-cli/src/cli/chat/cli/prompts.rs

@@ -2522,12 +2522,35 @@ mod tests {
     }
 
     #[test]
-    fn test_truncate_description_ascii() {
-        // Test with ASCII text
-        assert_eq!(truncate_description("Hello World", 20), "Hello World");
-        assert_eq!(truncate_description("Hello World", 11), "Hello World");
-        assert_eq!(truncate_description("Hello World", 8), "Hello...");
-        assert_eq!(truncate_description("Hello World", 5), "He...");
+    fn test_truncate_description() {
+        // Test normal length
+        let short = "Short description";
+        assert_eq!(truncate_description(short, 40), "Short description");
+
+        // Test truncation
+        let long =
+            "This is a very long description that should be truncated because it exceeds the maximum length limit";
+        let result = truncate_description(long, 40);
+        assert!(result.len() <= 40);
+        assert!(result.ends_with("..."));
+        // Length may be less than 40 due to trim_end() removing trailing spaces
+        assert!(result.len() >= 37); // At least max_length - 3 chars
+
+        // Test exact length
+        let exact = "A".repeat(40);
+        assert_eq!(truncate_description(&exact, 40), exact);
+
+        // Test very short max length
+        let result = truncate_description("Hello world", 5);
+        assert_eq!(result, "He...");
+        assert_eq!(result.len(), 5);
+
+        // Test space trimming before ellipsis
+        let with_space = "Prompt to explain available tools and how";
+        let result = truncate_description(with_space, 40);
+        assert!(!result.contains(" ..."));
+        assert!(result.ends_with("..."));
+        assert_eq!(result, "Prompt to explain available tools and...");
     }
 
     #[test]