feat: strip IRC formatting codes from messages sent to Owncast

Add irc_format module that removes mIRC control codes (bold, color,
italic, underline, reverse, strikethrough, monospace, reset) before
forwarding to Owncast. Color codes with fg/bg digit params are
consumed correctly. Multi-byte UTF-8 (emoji, accented chars, CJK)
is preserved.

Made-with: Cursor

chat-summaries/2026-03-12_strip-irc-formatting-summary.md

@@ -0,0 +1,17 @@
+# Strip IRC Formatting Codes from Owncast-bound Messages
+
+**Date:** 2026-03-12
+
+## Task
+
+IRC messages forwarded to Owncast contained mIRC formatting control codes (`\x02`, `\x03`, `\x0F`, etc.) that rendered as garbage glyphs since Owncast doesn't support any message styling.
+
+## Changes
+
+- **New file: `src/irc_format.rs`** — `strip_formatting()` function that removes all IRC formatting control codes: bold, color (with fg/bg digit parameters), reset, monospace, reverse, italic, strikethrough, and underline. Includes 18 unit tests.
+- **`src/irc_task.rs`** — Call `strip_formatting()` on the message body before constructing the `BridgeEvent`, so all downstream consumers see clean text.
+- **`src/main.rs`** — Registered the new `irc_format` module.
+
+## Follow-up
+
+- None identified. No new dependencies added.

src/irc_format.rs

@@ -0,0 +1,159 @@
+/// 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).
+pub fn strip_formatting(input: &str) -> String {
+    let bytes = input.as_bytes();
+    let len = bytes.len();
+    let mut out: Vec<u8> = Vec::with_capacity(len);
+    let mut i = 0;
+
+    while i < len {
+        match bytes[i] {
+            b'\x02' | b'\x0F' | b'\x11' | b'\x16' | b'\x1D' | b'\x1E' | b'\x1F' => {
+                i += 1;
+            }
+            b'\x03' => {
+                i += 1;
+                let mut digits = 0;
+                while i < len && digits < 2 && bytes[i].is_ascii_digit() {
+                    i += 1;
+                    digits += 1;
+                }
+                if i < len && bytes[i] == b',' && i + 1 < len && bytes[i + 1].is_ascii_digit() {
+                    i += 1;
+                    digits = 0;
+                    while i < len && digits < 2 && bytes[i].is_ascii_digit() {
+                        i += 1;
+                        digits += 1;
+                    }
+                }
+            }
+            b => {
+                out.push(b);
+                i += 1;
+            }
+        }
+    }
+
+    // IRC control codes are single-byte ASCII (< 0x80) so removing them from
+    // valid UTF-8 always yields valid UTF-8.
+    String::from_utf8(out).expect("stripping ASCII control codes preserves UTF-8")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn clean_text_unchanged() {
+        assert_eq!(strip_formatting("hello world"), "hello world");
+    }
+
+    #[test]
+    fn strips_bold() {
+        assert_eq!(strip_formatting("\x02bold\x02"), "bold");
+    }
+
+    #[test]
+    fn strips_italic() {
+        assert_eq!(strip_formatting("\x1Ditalic\x1D"), "italic");
+    }
+
+    #[test]
+    fn strips_underline() {
+        assert_eq!(strip_formatting("\x1Funderline\x1F"), "underline");
+    }
+
+    #[test]
+    fn strips_reset() {
+        assert_eq!(strip_formatting("styled\x0F plain"), "styled plain");
+    }
+
+    #[test]
+    fn strips_color_no_params() {
+        assert_eq!(strip_formatting("\x03hello"), "hello");
+    }
+
+    #[test]
+    fn strips_color_fg_only() {
+        assert_eq!(strip_formatting("\x034red text"), "red text");
+    }
+
+    #[test]
+    fn strips_color_two_digit_fg() {
+        assert_eq!(strip_formatting("\x0312blue text"), "blue text");
+    }
+
+    #[test]
+    fn strips_color_fg_and_bg() {
+        assert_eq!(strip_formatting("\x034,2red on blue"), "red on blue");
+    }
+
+    #[test]
+    fn strips_color_two_digit_fg_and_bg() {
+        assert_eq!(strip_formatting("\x0304,12colored"), "colored");
+    }
+
+    #[test]
+    fn color_comma_without_bg_digit_preserves_comma() {
+        // \x03 followed by digit then comma but no bg digit — comma is kept
+        assert_eq!(strip_formatting("\x034,text"), ",text");
+    }
+
+    #[test]
+    fn mixed_codes() {
+        assert_eq!(
+            strip_formatting("\x02\x034,5bold color\x0F normal"),
+            "bold color normal"
+        );
+    }
+
+    #[test]
+    fn color_at_end_of_string() {
+        assert_eq!(strip_formatting("text\x03"), "text");
+        assert_eq!(strip_formatting("text\x034"), "text");
+        assert_eq!(strip_formatting("text\x0304,"), "text,");
+        assert_eq!(strip_formatting("text\x0304,1"), "text");
+    }
+
+    #[test]
+    fn strips_monospace() {
+        assert_eq!(strip_formatting("\x11code\x11"), "code");
+    }
+
+    #[test]
+    fn strips_reverse() {
+        assert_eq!(strip_formatting("\x16reversed\x16"), "reversed");
+    }
+
+    #[test]
+    fn strips_strikethrough() {
+        assert_eq!(strip_formatting("\x1Estruck\x1E"), "struck");
+    }
+
+    #[test]
+    fn empty_input() {
+        assert_eq!(strip_formatting(""), "");
+    }
+
+    #[test]
+    fn preserves_multibyte_utf8() {
+        assert_eq!(strip_formatting("✨ hello ⚡"), "✨ hello ⚡");
+    }
+
+    #[test]
+    fn strips_codes_around_emoji() {
+        // \x034 = color fg 4; \x0333 = color fg 33, leaving trailing "3"
+        assert_eq!(
+            strip_formatting("\x02✨\x02 boosted \x034⚡\x03333 sats"),
+            "✨ boosted ⚡3 sats"
+        );
+    }
+
+    #[test]
+    fn preserves_cjk_and_accented_chars() {
+        assert_eq!(strip_formatting("\x02café\x02 日本語"), "café 日本語");
+    }
+}

src/irc_task.rs

@@ -74,7 +74,7 @@ async fn connect_and_run(
                                 let event = BridgeEvent::ChatMessage {
                                     source: Source::Irc,
                                     username: nick,
-                                    body: text.clone(),
+                                    body: crate::irc_format::strip_formatting(text),
                                     id: None,
                                 };
                                 if event_tx.send(event).await.is_err() {

src/main.rs

@@ -3,6 +3,7 @@ mod control;
 mod events;
 mod health;
 mod html;
+mod irc_format;
 mod irc_task;
 mod owncast_api;
 mod router;
@@ -69,11 +70,15 @@ async fn main() -> anyhow::Result<()> {
     });
 
     let _ws_handle = if config.owncast.websocket_enabled {
-        let ws_url = config.owncast.url.clone();
+        let ws_api = owncast_api::OwncastApiClient::new(
+            config.owncast.url.clone(),
+            String::new(),
+        );
+        let ws_display_name = config.owncast.ws_display_name.clone();
         let ws_event_tx = event_tx.clone();
         let ws_shutdown = shutdown_rx.clone();
         Some(tokio::spawn(async move {
-            websocket::run_websocket_task(ws_url, ws_event_tx, ws_shutdown).await;
+            websocket::run_websocket_task(ws_api, ws_display_name, ws_event_tx, ws_shutdown).await;
         }))
     } else {
         None