fix(web): correct monitoring empty states and Space request headers

src/langbot/pkg/api/http/controller/groups/monitoring.py

@@ -24,12 +24,21 @@ def parse_iso_datetime(datetime_str: str | None) -> datetime.datetime | None:
     return dt
 
 
-def validate_monitoring_window(start_time: datetime.datetime | None, end_time: datetime.datetime | None) -> None:
+def validate_monitoring_window(
+    start_time: datetime.datetime | None,
+    end_time: datetime.datetime | None,
+    *,
+    allow_point_window: bool = False,
+) -> None:
     """Bound explicit dashboard windows to one year without silently truncating them."""
     if start_time is None:
         return
     end = end_time or datetime.datetime.now(datetime.timezone.utc).replace(tzinfo=None)
-    if start_time >= end or end - start_time > datetime.timedelta(days=365):
+    if (
+        start_time > end
+        or (start_time == end and not allow_point_window)
+        or end - start_time > datetime.timedelta(days=365)
+    ):
         quart.abort(400, description='Monitoring time range must be positive and no longer than 365 days')
 
 
@@ -580,7 +589,8 @@ class MonitoringRouterGroup(group.RouterGroup):
             """Get detailed analysis for a specific session"""
             start_time = parse_iso_datetime(quart.request.args.get('startTime'))
             end_time = parse_iso_datetime(quart.request.args.get('endTime'))
-            validate_monitoring_window(start_time, end_time)
+            # Message pages can contain one timestamp; tool-call bounds are inclusive.
+            validate_monitoring_window(start_time, end_time, allow_point_window=True)
             analysis = await self.ap.monitoring_service.get_session_analysis(
                 request_context,
                 session_id,