storkit: merge 391_bug_strip_prefix_ci_panics_on_multi_byte_utf_8_characters

server/src/chat/transport/matrix/commands/mod.rs

@@ -228,10 +228,8 @@ fn strip_bot_mention<'a>(message: &'a str, bot_name: &str, bot_user_id: &str) ->
 /// Case-insensitive prefix strip that also requires the match to end at a
 /// word boundary (whitespace, punctuation, or end-of-string).
 fn strip_prefix_ci<'a>(text: &'a str, prefix: &str) -> Option<&'a str> {
-    if text.len() < prefix.len() {
-        return None;
-    }
-    if !text[..prefix.len()].eq_ignore_ascii_case(prefix) {
+    let candidate = text.get(..prefix.len())?;
+    if !candidate.eq_ignore_ascii_case(prefix) {
         return None;
     }
     let rest = &text[prefix.len()..];
@@ -451,6 +449,22 @@ pub(crate) mod tests {
         assert_eq!(strip_prefix_ci("hello", "hello"), Some(""));
     }
 
+    #[test]
+    fn strip_prefix_ci_multibyte_no_panic_smart_quote() {
+        // "abcde\u{2019}xyz" — U+2019 is 3 bytes starting at byte 5.
+        // A prefix of length 6 (e.g. "abcdef") lands inside the 3-byte char.
+        // Previously this caused: "byte index 6 is not a char boundary".
+        let text = "abcde\u{2019}xyz";
+        assert_eq!(strip_prefix_ci(text, "abcdef"), None);
+    }
+
+    #[test]
+    fn strip_prefix_ci_multibyte_no_panic_emoji() {
+        // U+1F600 is 4 bytes starting at byte 3. Prefix length 4 lands inside it.
+        let text = "abc\u{1F600}def";
+        assert_eq!(strip_prefix_ci(text, "abcd"), None);
+    }
+
     // -- commands registry --------------------------------------------------
 
     #[test]