diff --git a/handlers/system.py b/handlers/system.py
index 8dd6924..4c55162 100644
--- a/handlers/system.py
+++ b/handlers/system.py
@@ -399,11 +399,19 @@ async def incidents_diff(msg: Message):
         return
     parts = msg.text.split()
     hours = 24
+    reset = False
     if len(parts) >= 2:
-        try:
-            hours = max(1, int(parts[1]))
-        except ValueError:
-            hours = 24
+        if parts[1].lower() in {"reset", "clear"}:
+            reset = True
+        else:
+            try:
+                hours = max(1, int(parts[1]))
+            except ValueError:
+                hours = 24
+    if reset:
+        runtime_state.set_state("incidents_diff_last_ts", None)
+        await msg.answer("📣 Diff marker reset. Next run will show all within window.", reply_markup=system_logs_audit_kb)
+        return
     last_iso = runtime_state.get("incidents_diff_last_ts")
     last_dt = None
     if isinstance(last_iso, str):