Desktop alerts when suspicious unicode characters found in Recipe (#4080)

crates/goose/src/utils.rs

@@ -1,17 +1,23 @@
 use tokio_util::sync::CancellationToken;
 use unicode_normalization::UnicodeNormalization;
 
+/// Check if a character is in the Unicode Tags Block range (U+E0000-U+E007F)
+/// These characters are invisible and can be used for steganographic attacks
+fn is_in_unicode_tag_range(c: char) -> bool {
+    matches!(c, '\u{E0000}'..='\u{E007F}')
+}
+
+pub fn contains_unicode_tags(text: &str) -> bool {
+    text.chars().any(is_in_unicode_tag_range)
+}
+
 /// Sanitize Unicode Tags Block characters from text
-/// Used to prevent Unicode-based prompt injection attacks
-///
-/// This function removes invisible Unicode Tags Block characters (U+E0000-U+E007F)
-/// that can be used for steganographic attacks while preserving legitimate Unicode.
 pub fn sanitize_unicode_tags(text: &str) -> String {
     let normalized: String = text.nfc().collect();
 
     normalized
         .chars()
-        .filter(|&c| !matches!(c, '\u{E0000}'..='\u{E007F}'))
+        .filter(|&c| !is_in_unicode_tag_range(c))
         .collect()
 }
 
@@ -45,6 +51,17 @@ pub fn is_token_cancelled(cancellation_token: &Option<CancellationToken>) -> boo
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_contains_unicode_tags() {
+        // Test detection of Unicode Tags Block characters
+        assert!(contains_unicode_tags("Hello\u{E0041}world"));
+        assert!(contains_unicode_tags("\u{E0000}"));
+        assert!(contains_unicode_tags("\u{E007F}"));
+        assert!(!contains_unicode_tags("Hello world"));
+        assert!(!contains_unicode_tags("Hello 世界 🌍"));
+        assert!(!contains_unicode_tags(""));
+    }
+
     #[test]
     fn test_sanitize_unicode_tags() {
         // Test that Unicode Tags Block characters are removed