fix: format IRC ACTION messages as * nick action * and strip CTCP delimiters

CTCP ACTION messages (/me) were relayed with raw \x01 bytes, rendering
as boxed-X characters in OwnCast. Detect the ACTION pattern, extract the
body, and format it like traditional IRC clients. Also strip \x01 in
irc_format as a safety net for other CTCP leakage.

Made-with: Cursor

src/irc_format.rs

@@ -1,8 +1,8 @@
 /// Strip mIRC-style formatting control codes from a string.
 ///
-/// Removes bold (\x02), color (\x03 + optional fg[,bg] digits), reset (\x0F),
-/// monospace (\x11), reverse (\x16), italic (\x1D), strikethrough (\x1E),
-/// and underline (\x1F).
+/// Removes CTCP delimiter (\x01), bold (\x02), color (\x03 + optional fg[,bg]
+/// digits), reset (\x0F), monospace (\x11), reverse (\x16), italic (\x1D),
+/// strikethrough (\x1E), and underline (\x1F).
 pub fn strip_formatting(input: &str) -> String {
     let bytes = input.as_bytes();
     let len = bytes.len();
@@ -11,7 +11,7 @@ pub fn strip_formatting(input: &str) -> String {
 
     while i < len {
         match bytes[i] {
-            b'\x02' | b'\x0F' | b'\x11' | b'\x16' | b'\x1D' | b'\x1E' | b'\x1F' => {
+            b'\x01' | b'\x02' | b'\x0F' | b'\x11' | b'\x16' | b'\x1D' | b'\x1E' | b'\x1F' => {
                 i += 1;
             }
             b'\x03' => {
@@ -156,4 +156,17 @@ mod tests {
     fn preserves_cjk_and_accented_chars() {
         assert_eq!(strip_formatting("\x02café\x02 日本語"), "café 日本語");
     }
+
+    #[test]
+    fn strips_ctcp_delimiter() {
+        assert_eq!(strip_formatting("\x01ACTION sniffs\x01"), "ACTION sniffs");
+    }
+
+    #[test]
+    fn strips_ctcp_delimiter_mixed_with_formatting() {
+        assert_eq!(
+            strip_formatting("\x01\x02ACTION bold\x02\x01"),
+            "ACTION bold"
+        );
+    }
 }