From d20f9b80183419ed24190a7e66fe1ff1c6e57d4b Mon Sep 17 00:00:00 2001
From: Dave <futurechimp@users.noreply.github.com>
Date: Wed, 25 Feb 2026 17:00:29 +0000
Subject: [PATCH] Fixed up @ mentions on the bot

---
 server/src/matrix/bot.rs | 173 ++++++++++++++++++++++-----------------
 1 file changed, 100 insertions(+), 73 deletions(-)

diff --git a/server/src/matrix/bot.rs b/server/src/matrix/bot.rs
index d292537..1dba292 100644
--- a/server/src/matrix/bot.rs
+++ b/server/src/matrix/bot.rs
@@ -1,6 +1,5 @@
 use crate::llm::providers::claude_code::{ClaudeCodeProvider, ClaudeCodeResult};
 use crate::slog;
-use pulldown_cmark::{Options, Parser, html};
 use matrix_sdk::{
     Client,
     config::SyncSettings,
@@ -9,17 +8,18 @@ use matrix_sdk::{
     ruma::{
         OwnedEventId, OwnedRoomId, OwnedUserId,
         events::room::message::{
-            MessageType, OriginalSyncRoomMessageEvent, Relation,
-            RoomMessageEventContent, RoomMessageEventContentWithoutRelation,
+            MessageType, OriginalSyncRoomMessageEvent, Relation, RoomMessageEventContent,
+            RoomMessageEventContentWithoutRelation,
         },
     },
 };
+use pulldown_cmark::{Options, Parser, html};
 use std::collections::{HashMap, HashSet};
 use std::path::PathBuf;
 use std::sync::Arc;
 use std::sync::atomic::{AtomicBool, Ordering};
-use tokio::sync::watch;
 use tokio::sync::Mutex as TokioMutex;
+use tokio::sync::watch;
 
 use super::config::BotConfig;
 
@@ -112,10 +112,7 @@ pub async fn run_bot(config: BotConfig, project_root: PathBuf) -> Result<(), Str
         );
     }
 
-    slog!(
-        "[matrix-bot] Allowed users: {:?}",
-        config.allowed_users
-    );
+    slog!("[matrix-bot] Allowed users: {:?}", config.allowed_users);
 
     // Parse and join all configured rooms.
     let mut target_room_ids: Vec<OwnedRoomId> = Vec::new();
@@ -181,30 +178,46 @@ pub async fn run_bot(config: BotConfig, project_root: PathBuf) -> Result<(), Str
 // Address-filtering helpers
 // ---------------------------------------------------------------------------
 
-/// Returns `true` if `body` contains a mention of the bot.
+/// Returns `true` if the message mentions the bot.
 ///
-/// Two forms are recognised:
-/// - The bot's full Matrix user ID (e.g. `@timmy:homeserver.local`)
-/// - The bot's local part prefixed with `@` (e.g. `@timmy`)
+/// Checks both the plain-text `body` and an optional `formatted_body` (HTML).
+/// Recognised forms:
+/// - The bot's full Matrix user ID (e.g. `@timmy:homeserver.local`) in either body
+/// - The localpart with `@` prefix (e.g. `@timmy`) with word-boundary check
+/// - A `matrix.to` link containing the user ID (in `formatted_body`)
 ///
-/// A short mention (`@timmy`) is only counted when it is not immediately
-/// followed by an alphanumeric character, hyphen, or underscore — this avoids
-/// false-positives where a longer username (e.g. `@timmybot`) shares the same
-/// prefix.
-pub fn mentions_bot(body: &str, bot_user_id: &OwnedUserId) -> bool {
+/// Short mentions are only counted when not immediately followed by an
+/// alphanumeric character, hyphen, or underscore to avoid false positives.
+pub fn mentions_bot(body: &str, formatted_body: Option<&str>, bot_user_id: &OwnedUserId) -> bool {
     let full_id = bot_user_id.as_str();
+    let localpart = bot_user_id.localpart();
+
+    // Check formatted_body for a matrix.to link containing the bot's user ID.
+    if formatted_body.is_some_and(|html| html.contains(full_id)) {
+        return true;
+    }
+
+    // Check plain body for the full ID.
     if body.contains(full_id) {
         return true;
     }
 
-    let short = format!("@{}", bot_user_id.localpart());
+    // Check plain body for @localpart (e.g. "@timmy") with word boundaries.
+    if contains_word(body, &format!("@{localpart}")) {
+        return true;
+    }
+
+    false
+}
+
+/// Returns `true` if `haystack` contains `needle` at a word boundary.
+fn contains_word(haystack: &str, needle: &str) -> bool {
     let mut start = 0;
-    while let Some(rel) = body[start..].find(short.as_str()) {
+    while let Some(rel) = haystack[start..].find(needle) {
         let abs = start + rel;
-        let after = abs + short.len();
-        let next = body[after..].chars().next();
-        let is_word_end =
-            next.is_none_or(|c| !c.is_alphanumeric() && c != '-' && c != '_');
+        let after = abs + needle.len();
+        let next = haystack[after..].chars().next();
+        let is_word_end = next.is_none_or(|c| !c.is_alphanumeric() && c != '-' && c != '_');
         if is_word_end {
             return true;
         }
@@ -241,11 +254,7 @@ async fn is_reply_to_bot(
 
 /// Matrix event handler for room messages. Each invocation spawns an
 /// independent task so the sync loop is not blocked by LLM calls.
-async fn on_room_message(
-    ev: OriginalSyncRoomMessageEvent,
-    room: Room,
-    Ctx(ctx): Ctx<BotContext>,
-) {
+async fn on_room_message(ev: OriginalSyncRoomMessageEvent, room: Room, Ctx(ctx): Ctx<BotContext>) {
     let incoming_room_id = room.room_id().to_owned();
 
     slog!(
@@ -255,11 +264,7 @@ async fn on_room_message(
     );
 
     // Only handle messages from rooms we are configured to listen in.
-    if !ctx
-        .target_room_ids
-        .iter()
-        .any(|r| r == &incoming_room_id)
-    {
+    if !ctx.target_room_ids.iter().any(|r| r == &incoming_room_id) {
         slog!("[matrix-bot] Ignoring message from unconfigured room {incoming_room_id}");
         return;
     }
@@ -279,19 +284,15 @@ async fn on_room_message(
     }
 
     // Only handle plain text messages.
-    let body = match &ev.content.msgtype {
-        MessageType::Text(t) => t.body.clone(),
+    let (body, formatted_body) = match &ev.content.msgtype {
+        MessageType::Text(t) => (t.body.clone(), t.formatted.as_ref().map(|f| f.body.clone())),
         _ => return,
     };
 
     // Only respond when the bot is directly addressed (mentioned by name/ID)
     // or when the message is a reply to one of the bot's own messages.
-    if !mentions_bot(&body, &ctx.bot_user_id)
-        && !is_reply_to_bot(
-            ev.content.relates_to.as_ref(),
-            &ctx.bot_sent_event_ids,
-        )
-        .await
+    if !mentions_bot(&body, formatted_body.as_deref(), &ctx.bot_user_id)
+        && !is_reply_to_bot(ev.content.relates_to.as_ref(), &ctx.bot_sent_event_ids).await
     {
         slog!(
             "[matrix-bot] Ignoring unaddressed message from {}",
@@ -358,8 +359,7 @@ async fn handle_message(
     };
 
     // Build the prompt with conversation context.
-    let prompt_with_context =
-        build_context_prefix(&history_snapshot, &sender, &user_message);
+    let prompt_with_context = build_context_prefix(&history_snapshot, &sender, &user_message);
 
     let provider = ClaudeCodeProvider::new();
     let (cancel_tx, mut cancel_rx) = watch::channel(false);
@@ -566,44 +566,52 @@ mod tests {
     #[test]
     fn mentions_bot_by_full_id() {
         let uid = make_user_id("@timmy:homeserver.local");
-        assert!(mentions_bot("hello @timmy:homeserver.local can you help?", &uid));
+        assert!(mentions_bot(
+            "hello @timmy:homeserver.local can you help?",
+            None,
+            &uid
+        ));
     }
 
     #[test]
     fn mentions_bot_by_localpart_at_start() {
         let uid = make_user_id("@timmy:homeserver.local");
-        assert!(mentions_bot("@timmy please list open stories", &uid));
+        assert!(mentions_bot("@timmy please list open stories", None, &uid));
     }
 
     #[test]
     fn mentions_bot_by_localpart_mid_sentence() {
         let uid = make_user_id("@timmy:homeserver.local");
-        assert!(mentions_bot("hey @timmy what's the status?", &uid));
+        assert!(mentions_bot("hey @timmy what's the status?", None, &uid));
     }
 
     #[test]
     fn mentions_bot_not_mentioned() {
         let uid = make_user_id("@timmy:homeserver.local");
-        assert!(!mentions_bot("can someone help me with this PR?", &uid));
+        assert!(!mentions_bot(
+            "can someone help me with this PR?",
+            None,
+            &uid
+        ));
     }
 
     #[test]
     fn mentions_bot_no_false_positive_longer_username() {
         // "@timmybot" must NOT match "@timmy"
         let uid = make_user_id("@timmy:homeserver.local");
-        assert!(!mentions_bot("hey @timmybot can you help?", &uid));
+        assert!(!mentions_bot("hey @timmybot can you help?", None, &uid));
     }
 
     #[test]
     fn mentions_bot_at_end_of_string() {
         let uid = make_user_id("@timmy:homeserver.local");
-        assert!(mentions_bot("shoutout to @timmy", &uid));
+        assert!(mentions_bot("shoutout to @timmy", None, &uid));
     }
 
     #[test]
     fn mentions_bot_followed_by_comma() {
         let uid = make_user_id("@timmy:homeserver.local");
-        assert!(mentions_bot("@timmy, can you help?", &uid));
+        assert!(mentions_bot("@timmy, can you help?", None, &uid));
     }
 
     // -- is_reply_to_bot ----------------------------------------------------
@@ -668,20 +676,29 @@ mod tests {
     #[test]
     fn markdown_to_html_bold() {
         let html = markdown_to_html("**bold**");
-        assert!(html.contains("<strong>bold</strong>"), "expected <strong>: {html}");
+        assert!(
+            html.contains("<strong>bold</strong>"),
+            "expected <strong>: {html}"
+        );
     }
 
     #[test]
     fn markdown_to_html_unordered_list() {
         let html = markdown_to_html("- item one\n- item two");
         assert!(html.contains("<ul>"), "expected <ul>: {html}");
-        assert!(html.contains("<li>item one</li>"), "expected list item: {html}");
+        assert!(
+            html.contains("<li>item one</li>"),
+            "expected list item: {html}"
+        );
     }
 
     #[test]
     fn markdown_to_html_inline_code() {
         let html = markdown_to_html("`inline_code()`");
-        assert!(html.contains("<code>inline_code()</code>"), "expected <code>: {html}");
+        assert!(
+            html.contains("<code>inline_code()</code>"),
+            "expected <code>: {html}"
+        );
     }
 
     #[test]
@@ -689,13 +706,19 @@ mod tests {
         let html = markdown_to_html("```rust\nfn main() {}\n```");
         assert!(html.contains("<pre>"), "expected <pre>: {html}");
         assert!(html.contains("<code"), "expected <code> inside pre: {html}");
-        assert!(html.contains("fn main() {}"), "expected code content: {html}");
+        assert!(
+            html.contains("fn main() {}"),
+            "expected code content: {html}"
+        );
     }
 
     #[test]
     fn markdown_to_html_plain_text_passthrough() {
         let html = markdown_to_html("Hello, world!");
-        assert!(html.contains("Hello, world!"), "expected plain text passthrough: {html}");
+        assert!(
+            html.contains("Hello, world!"),
+            "expected plain text passthrough: {html}"
+        );
     }
 
     // -- bot_context_is_clone -----------------------------------------------
@@ -773,8 +796,9 @@ mod tests {
         // A blank line inside a fenced code block must NOT trigger a split.
         // Before the fix the function would split at the blank line and the
         // second half would be sent without the opening fence, breaking rendering.
-        let mut buf = "```rust\nfn foo() {\n    let x = 1;\n\n    let y = 2;\n}\n```\n\nNext paragraph."
-            .to_string();
+        let mut buf =
+            "```rust\nfn foo() {\n    let x = 1;\n\n    let y = 2;\n}\n```\n\nNext paragraph."
+                .to_string();
         let paras = drain_complete_paragraphs(&mut buf);
         assert_eq!(
             paras.len(),
@@ -797,8 +821,7 @@ mod tests {
     #[test]
     fn drain_complete_paragraphs_text_before_and_after_fenced_block() {
         // Text paragraph, then a code block with an internal blank line, then more text.
-        let mut buf =
-            "Before\n\n```\ncode\n\nmore code\n```\n\nAfter".to_string();
+        let mut buf = "Before\n\n```\ncode\n\nmore code\n```\n\nAfter".to_string();
         let paras = drain_complete_paragraphs(&mut buf);
         assert_eq!(paras.len(), 2, "expected two paragraphs: {paras:?}");
         assert_eq!(paras[0], "Before");
@@ -892,8 +915,7 @@ mod tests {
 
     #[tokio::test]
     async fn history_trims_to_configured_size() {
-        let history: ConversationHistory =
-            Arc::new(TokioMutex::new(HashMap::new()));
+        let history: ConversationHistory = Arc::new(TokioMutex::new(HashMap::new()));
         let room_id: OwnedRoomId = "!test:example.com".parse().unwrap();
         let history_size = 4usize; // keep at most 4 entries
 
@@ -935,23 +957,28 @@ mod tests {
 
     #[tokio::test]
     async fn each_room_has_independent_history() {
-        let history: ConversationHistory =
-            Arc::new(TokioMutex::new(HashMap::new()));
+        let history: ConversationHistory = Arc::new(TokioMutex::new(HashMap::new()));
         let room_a: OwnedRoomId = "!room_a:example.com".parse().unwrap();
         let room_b: OwnedRoomId = "!room_b:example.com".parse().unwrap();
 
         {
             let mut guard = history.lock().await;
-            guard.entry(room_a.clone()).or_default().push(ConversationEntry {
-                role: ConversationRole::User,
-                sender: "@alice:example.com".to_string(),
-                content: "Room A message".to_string(),
-            });
-            guard.entry(room_b.clone()).or_default().push(ConversationEntry {
-                role: ConversationRole::User,
-                sender: "@bob:example.com".to_string(),
-                content: "Room B message".to_string(),
-            });
+            guard
+                .entry(room_a.clone())
+                .or_default()
+                .push(ConversationEntry {
+                    role: ConversationRole::User,
+                    sender: "@alice:example.com".to_string(),
+                    content: "Room A message".to_string(),
+                });
+            guard
+                .entry(room_b.clone())
+                .or_default()
+                .push(ConversationEntry {
+                    role: ConversationRole::User,
+                    sender: "@bob:example.com".to_string(),
+                    content: "Room B message".to_string(),
+                });
         }
 
         let guard = history.lock().await;