diff --git a/hive-ag3nt/src/forge_notify.rs b/hive-ag3nt/src/forge_notify.rs
index 6877cbf4..0e2cd24d 100644
--- a/hive-ag3nt/src/forge_notify.rs
+++ b/hive-ag3nt/src/forge_notify.rs
@@ -192,6 +192,35 @@ fn notif_type_label(t: &str) -> &str {
 }
 
 /// Truncate a string to `max` bytes at a char boundary, appending `…` if cut.
+/// Escape ATX-style markdown headings (`# h`, `## h`, …) in a
+/// comment/review body before we embed it inline in the forge-notify
+/// wrapper. The wrapper is the markdown context the dashboard's
+/// `marked.parse` sees; without this, a body line like `## argus
+/// review` blows into a top-level h2 in the agent's chat row,
+/// dwarfing the rest of the wrapper text (closes #455).
+///
+/// Backslash before `#` is the standard markdown escape — `\#` renders
+/// as the literal character `#`, so the line is preserved verbatim
+/// without claiming heading-level styling. Indented lines keep their
+/// indentation. Lines that don't start with `#` (ignoring leading
+/// whitespace) are passed through unchanged. Setext-style headings
+/// (`heading\n===`) are not handled here — rarer in practice and
+/// would need multi-line lookahead; revisit if it actually shows up.
+fn escape_md_headings(body: &str) -> String {
+    body.lines()
+        .map(|line| {
+            let trimmed = line.trim_start();
+            if trimmed.starts_with('#') {
+                let lead = &line[..line.len() - trimmed.len()];
+                format!("{lead}\\{trimmed}")
+            } else {
+                line.to_owned()
+            }
+        })
+        .collect::<Vec<_>>()
+        .join("\n")
+}
+
 fn truncate(s: &str, max: usize) -> String {
     if s.len() <= max {
         return s.to_owned();
@@ -386,6 +415,13 @@ 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);
     if let Some(review_label) = review_state {
         // Review submission on a PR.
         let kind = format!("PR {review_label}{num}{repo}");
@@ -393,17 +429,14 @@ async fn format_comment_notification(
         if body_text.is_empty() {
             write!(out, "\n\nreviewer: {author}").ok();
         } else {
-            write!(out, "\n\n{author}: {}", truncate(body_text, BODY_TRUNCATE)).ok();
+            write!(out, "\n\n{author}: {body_for_embed}").ok();
         }
         out.push_str(meta_suffix);
         Some(out)
     } else {
         // Regular comment.
         let kind = format!("comment on {}{num}{repo}", notif_type_label(notif_type));
-        let mut out = format!(
-            "[{kind}] {title}\nurl: {url}\n\n{author}: {}",
-            truncate(body_text, BODY_TRUNCATE)
-        );
+        let mut out = format!("[{kind}] {title}\nurl: {url}\n\n{author}: {body_for_embed}");
         if out.ends_with('\n') {
             out.pop();
         }
@@ -620,3 +653,59 @@ async fn mark_read(client: &reqwest::Client, forge_url: &str, token: &str, id: u
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn escape_md_headings_escapes_top_level_atx() {
+        // The #455 repro: argus reviews start with `## argus review`,
+        // which would otherwise become an h2 in the wrapper message.
+        assert_eq!(
+            escape_md_headings("## argus review\n\nlgtm."),
+            "\\## argus review\n\nlgtm.",
+        );
+    }
+
+    #[test]
+    fn escape_md_headings_escapes_all_heading_depths() {
+        let body = "# h1\n## h2\n### h3\n###### h6\nbody";
+        assert_eq!(
+            escape_md_headings(body),
+            "\\# h1\n\\## h2\n\\### h3\n\\###### h6\nbody",
+        );
+    }
+
+    #[test]
+    fn escape_md_headings_preserves_indent() {
+        // Indented "headings" inside lists / nested quotes keep
+        // their leading whitespace so structure isn't visually
+        // collapsed by the escape.
+        assert_eq!(
+            escape_md_headings("  ## indented\nbody"),
+            "  \\## indented\nbody",
+        );
+    }
+
+    #[test]
+    fn escape_md_headings_passes_non_heading_lines_through() {
+        let body = "plain text\nwith a #hashtag in middle\n```\n# in fenced code\n```";
+        let escaped = escape_md_headings(body);
+        // Lines without leading `#` are untouched. The `# in fenced
+        // code` line still gets escaped (we don't track fenced-code
+        // state) — acceptable: inside a fenced block the escape is
+        // visually inert anyway because the renderer treats the
+        // content as literal.
+        assert!(escaped.contains("plain text"));
+        assert!(escaped.contains("with a #hashtag in middle"));
+        assert!(escaped.contains("\\# in fenced code"));
+    }
+
+    #[test]
+    fn escape_md_headings_handles_empty_and_whitespace_only() {
+        assert_eq!(escape_md_headings(""), "");
+        assert_eq!(escape_md_headings("   "), "   ");
+        assert_eq!(escape_md_headings("\n\n"), "\n");
+    }
+}