Auto-reset incidents diff marker if ahead of log

handlers/system.py

@@ -420,11 +420,22 @@ async def incidents_diff(msg: Message):
         except Exception:
             last_dt = None
     rows = read_raw(cfg, hours=hours, limit=5000, include_old=True)
-    fresh: list[tuple[datetime, str]] = []
-    for dt, line in rows:
-        if last_dt and dt <= last_dt:
-            continue
-        fresh.append((dt, line))
+
+    def collect(from_dt):
+        fresh: list[tuple[datetime, str]] = []
+        for dt, line in rows:
+            if from_dt and dt <= from_dt:
+                continue
+            fresh.append((dt, line))
+        return fresh
+
+    fresh = collect(last_dt)
+    # auto-reset if marker is ahead of all rows
+    if not fresh and last_dt and rows and last_dt >= rows[-1][0]:
+        last_dt = None
+        runtime_state.set_state("incidents_diff_last_ts", None)
+        fresh = collect(None)
+
     if not fresh:
         note = f"since {last_dt.astimezone().strftime('%Y-%m-%d %H:%M')}" if last_dt else "for the period"
         await msg.answer(f"📣 No new incidents {note} (window {hours}h)", reply_markup=system_logs_audit_kb)