ui: fix Immediate ALERT_STARTUP_PENDING after going onroad (#35509)

fix timeout alerts could appear immediately after going onroad

selfdrive/ui/onroad/alert_renderer.py

@@ -72,13 +72,15 @@ class AlertRenderer(Widget):
     # Check if selfdriveState messages have stopped arriving
     if not sm.updated['selfdriveState']:
       recv_frame = sm.recv_frame['selfdriveState']
-      if (sm.frame - recv_frame) > 5 * DEFAULT_FPS:
-        # Check if waiting to start
-        if recv_frame < ui_state.started_frame:
+      time_since_onroad = (sm.frame - ui_state.started_frame) / DEFAULT_FPS
+
+      # 1. Never received selfdriveState since going onroad
+      waiting_for_startup = recv_frame < ui_state.started_frame
+      if waiting_for_startup and time_since_onroad > 5:
         return ALERT_STARTUP_PENDING
 
-        # Handle selfdrive timeout
-        if TICI:
+      # 2. Lost communication with selfdriveState after receiving it
+      if TICI and not waiting_for_startup:
         ss_missing = time.monotonic() - sm.recv_time['selfdriveState']
         if ss_missing > SELFDRIVE_STATE_TIMEOUT:
           if ss.enabled and (ss_missing - SELFDRIVE_STATE_TIMEOUT) < SELFDRIVE_UNRESPONSIVE_TIMEOUT: