feat: drill-down filters on overview and outdated agent version highlight

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/host_health.py

@@ -62,3 +62,39 @@ def count_stale_hosts(db: Session, stale_minutes: int) -> int:
         for host_id in host_ids
         if agent_status(hb_map.get(host_id), stale_minutes=stale_minutes) == "stale"
     )
+
+
+def apply_agent_status_host_filter(
+    stmt,
+    count_stmt,
+    agent_status_filter: str,
+    *,
+    stale_minutes: int,
+):
+    """Ограничить выборку Host по online / stale / unknown (как в agent_status)."""
+    from datetime import timedelta
+
+    hb_subq = (
+        select(Event.host_id, func.max(Event.received_at).label("last_hb"))
+        .where(Event.type == HEARTBEAT_TYPE)
+        .group_by(Event.host_id)
+        .subquery()
+    )
+    cutoff = datetime.now(timezone.utc) - timedelta(minutes=stale_minutes)
+
+    if agent_status_filter == "online":
+        join = stmt.join(hb_subq, Host.id == hb_subq.c.host_id)
+        count_join = count_stmt.join(hb_subq, Host.id == hb_subq.c.host_id)
+        cond = hb_subq.c.last_hb >= cutoff
+        return join.where(cond), count_join.where(cond)
+    if agent_status_filter == "stale":
+        join = stmt.join(hb_subq, Host.id == hb_subq.c.host_id)
+        count_join = count_stmt.join(hb_subq, Host.id == hb_subq.c.host_id)
+        cond = hb_subq.c.last_hb < cutoff
+        return join.where(cond), count_join.where(cond)
+    if agent_status_filter == "unknown":
+        join = stmt.outerjoin(hb_subq, Host.id == hb_subq.c.host_id)
+        count_join = count_stmt.outerjoin(hb_subq, Host.id == hb_subq.c.host_id)
+        cond = hb_subq.c.last_hb.is_(None)
+        return join.where(cond), count_join.where(cond)
+    return stmt, count_stmt