fix: confirm OLED alert count updates

app/runtime.py

@@ -167,10 +167,11 @@ class Controller:
             self.stop_event.wait(1)
 
     def oled_loop(self):
-        last=None;last_time=0
+        last=None;last_time=0;last_alert_ids=None
         while not self.stop_event.is_set():
             try:
                 v=self.view();page=v['page'];system=v['system'];network=v['network'];home=False
+                alert_ids=tuple(a['id'] for a in v['alerts'])
                 if page=='NORMAL_HOME':
                     home=True
                     ip=network.get('ip','NO IP');label=network.get('ip_label','IP4')
@@ -189,7 +190,18 @@ class Controller:
                     lines=[(a['title'],f"{index}/{len(v['alerts'])}"),(a['l2'],''),(a['l3'],''),(a['l4'],'')]
                 state=(lines,home)
                 if state!=last or self.clock()-last_time>=v['config']['oled']['refresh_seconds']:
-                    self.driver.oled(lines,home);last=state;last_time=self.clock()
+                    self.driver.oled(lines,home)
+                    # Alert recovery changes only a few header pixels (for
+                    # example 1/2 -> 1/1). Confirm that rare topology change
+                    # with a second complete frame: during undervoltage an
+                    # OLED transfer can be only partly applied without an
+                    # I2C exception being reported by the controller.
+                    if last_alert_ids is not None and alert_ids!=last_alert_ids:
+                        self.stop_event.wait(.05)
+                        if not self.stop_event.is_set():self.driver.oled(lines,home)
+                    last=state
+                    last_time=self.clock()
+                    last_alert_ids=alert_ids
                 self.recovered('oled')
             except Exception as exc:self.error('oled',exc)
             self.stop_event.wait(.1)