fix: strip emoji between bot mention and command text

strip_mention_separator now skips all non-ASCII-alphanumeric chars
(emoji, colons, spaces) and returns a slice starting at the first
command character. Fixes mention pills with emoji display names
(e.g. "timmy ⚡️ status") not matching bot commands.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/src/chat/util.rs

@@ -72,16 +72,19 @@ pub fn strip_bot_mention<'a>(message: &'a str, bot_name: &str, bot_user_id: &str
     trimmed
 }
 
-/// Strip an optional Element tab-completion separator (`:` or `,`) and
-/// surrounding whitespace from the start of text that follows a bot mention.
+/// Strip decoration between a bot mention and the command text.
 ///
-/// Element's tab-completion inserts `DisplayName: ` (colon + space) after the
-/// name.  Without this strip the leading `:` would be treated as part of the
-/// command name and no command would match.
+/// After the bot name/ID is stripped, what remains may include whitespace,
+/// emoji from display names (e.g. `Timmy ⚡️`), and Element tab-completion
+/// separators (`:` or `,`).  This function skips all of that and returns a
+/// slice starting at the first ASCII alphanumeric character (the command).
 fn strip_mention_separator(rest: &str) -> &str {
-    let rest = rest.trim_start();
-    let rest = rest.strip_prefix([',', ':']).unwrap_or(rest);
-    rest.trim_start()
+    let byte_skip = rest
+        .char_indices()
+        .find(|(_, c)| c.is_ascii_alphanumeric())
+        .map(|(i, _)| i)
+        .unwrap_or(rest.len());
+    &rest[byte_skip..]
 }
 
 /// Returns `true` when `text` ends while inside an open fenced code block.
@@ -381,6 +384,15 @@ mod tests {
         assert_eq!(rest, "help");
     }
 
+    #[test]
+    fn strip_mention_short_name_emoji_suffix_in_body() {
+        // bot_name is "Timmy" (no emoji) but Element mention pill puts
+        // "Timmy ⚡️ status" in the body — the emoji is part of the display
+        // name as set on the Matrix server, not in bot.toml.
+        let rest = strip_bot_mention("Timmy ⚡️ status", "Timmy", "@timmy:homeserver.local");
+        assert_eq!(rest, "status");
+    }
+
     // -- drain_complete_paragraphs ------------------------------------------
 
     #[test]