forge_notify: diff mentions against raw excerpt to avoid heading-mention duplication

hive-ag3nt/src/forge_notify.rs

@@ -508,21 +508,23 @@ async fn format_comment_notification(
     let author = if actor_login.is_empty() { "?" } else { actor_login };
     let NotifMeta { title, notif_type, num, repo, meta_suffix, .. } = meta;
 
-    // Escape ATX headings in the user-authored body so the embedded
-    // text doesn't blow into top-level h1/h2 in the wrapper message
-    // when the dashboard renders it (closes #455). Done once here
-    // because both code paths fall through the same truncate+embed
-    // pattern.
-    let escaped = escape_md_headings(body_text);
-    let body_for_embed = truncate(&escaped, BODY_TRUNCATE);
+    // Truncate the raw body first so the mention-overflow diff compares
+    // like-for-like (escape_md_headings rewrites `# foo` to `\# foo`, so
+    // doing it before the diff would re-surface heading-prefixed mention
+    // lines as fake overflow). Escape happens after for display only.
+    let raw_excerpt = truncate(body_text, BODY_TRUNCATE);
     // Surface @mentions that fell outside the truncation window so an
     // addressed agent never silently misses a tag on a long comment
     // (closes #539). Skipped when the embed wasn't actually truncated.
     let truncated_mentions = if body_text.len() > BODY_TRUNCATE {
-        render_truncated_mentions(&extract_truncated_mention_lines(body_text, &body_for_embed))
+        render_truncated_mentions(&extract_truncated_mention_lines(body_text, &raw_excerpt))
     } else {
         String::new()
     };
+    // Escape ATX headings in the user-authored body so the embedded
+    // text doesn't blow into top-level h1/h2 in the wrapper message
+    // when the dashboard renders it (closes #455).
+    let body_for_embed = escape_md_headings(&raw_excerpt);
     if let Some(review_label) = review_state {
         // Review submission on a PR.
         let kind = format!("PR {review_label}{num}{repo}");
@@ -610,10 +612,14 @@ fn format_state_change_notification(
         .map(str::trim)
         .filter(|s| !s.is_empty())
         .map(|raw| {
-            let escaped = escape_md_headings(raw);
-            let excerpt = truncate(&escaped, BODY_TRUNCATE);
-            let truncated = extract_truncated_mention_lines(raw, &excerpt);
+            // Truncate raw first so mention diff sees the same heading
+            // markers as full_body (see comment in
+            // format_comment_notification). Escape happens after for
+            // display only.
+            let raw_excerpt = truncate(raw, BODY_TRUNCATE);
+            let truncated = extract_truncated_mention_lines(raw, &raw_excerpt);
             let mentions = render_truncated_mentions(&truncated);
+            let excerpt = escape_md_headings(&raw_excerpt);
             format!("\n\n{excerpt}{mentions}")
         })
         .unwrap_or_default();
@@ -917,6 +923,21 @@ mod tests {
         assert_eq!(lines, vec!["@argus reviewer"]);
     }
 
+    #[test]
+    fn extract_truncated_does_not_resurface_heading_mention_inside_window() {
+        // Regression for argus's nit on PR #544: the diff used to
+        // compare full_body against the *escaped* excerpt. Lines like
+        // `# @argus check this` survived as-is in the body but became
+        // `\# @argus check this` in the excerpt, so the `contains`
+        // check failed and the mention was re-surfaced as if it had
+        // fallen outside the window. Pass the unescaped excerpt and
+        // the duplicate disappears.
+        let full = "# @argus check this\nmore body\n";
+        let raw_excerpt = full; // fits entirely
+        let lines = extract_truncated_mention_lines(full, raw_excerpt);
+        assert!(lines.is_empty(), "heading+mention inside window must not be re-surfaced, got {lines:?}");
+    }
+
     #[test]
     fn render_truncated_mentions_empty_is_empty_string() {
         // Zero overhead on the healthy short-body path: caller