perf(session): limit sessions before counting messages (#11521)

crates/goose-cli/src/commands/session.rs

@@ -155,6 +155,18 @@ fn session_activity_at(session: &Session) -> chrono::DateTime<chrono::Utc> {
     session.last_message_at.unwrap_or(session.updated_at)
 }
 
+fn session_list_limit_if_safe_to_push_down(
+    ascending: bool,
+    working_dir: Option<&Path>,
+    limit: Option<usize>,
+) -> Option<usize> {
+    if !ascending && working_dir.is_none() {
+        limit
+    } else {
+        None
+    }
+}
+
 pub async fn handle_session_list(
     format: String,
     ascending: bool,
@@ -162,7 +174,13 @@ pub async fn handle_session_list(
     limit: Option<usize>,
 ) -> Result<()> {
     let session_manager = SessionManager::instance();
-    let mut sessions = session_manager.list_sessions().await?;
+    let mut sessions = if let Some(limit) =
+        session_list_limit_if_safe_to_push_down(ascending, working_dir.as_deref(), limit)
+    {
+        session_manager.list_sessions_with_limit(limit).await?
+    } else {
+        session_manager.list_sessions().await?
+    };
 
     if let Some(ref pat) = working_dir {
         let pat_lower = pat.to_string_lossy().to_lowercase();
@@ -223,6 +241,31 @@ pub async fn handle_session_list(
     Ok(())
 }
 
+#[cfg(test)]
+mod session_list_tests {
+    use super::*;
+
+    #[test]
+    fn pushes_down_only_safe_session_list_limits() {
+        assert_eq!(
+            session_list_limit_if_safe_to_push_down(false, None, Some(50)),
+            Some(50)
+        );
+        assert_eq!(
+            session_list_limit_if_safe_to_push_down(true, None, Some(50)),
+            None
+        );
+        assert_eq!(
+            session_list_limit_if_safe_to_push_down(false, Some(Path::new("/tmp")), Some(50)),
+            None
+        );
+        assert_eq!(
+            session_list_limit_if_safe_to_push_down(false, None, None),
+            None
+        );
+    }
+}
+
 pub async fn handle_session_export(
     session_id: String,
     output_path: Option<PathBuf>,