Make incidents diff resilient and send sample if empty

handlers/system.py

@@ -397,6 +397,7 @@ async def incidents_summary(msg: Message):
 async def incidents_diff(msg: Message):
     if not is_admin_msg(msg):
         return
+    try:
         parts = msg.text.split()
         hours = 24
         reset = False
@@ -410,8 +411,12 @@ async def incidents_diff(msg: Message):
                     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)
+            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):
@@ -436,30 +441,47 @@ async def incidents_diff(msg: Message):
             runtime_state.set_state("incidents_diff_last_ts", None)
             fresh = collect(None)
 
+        def fmt_lines(items: list[tuple[datetime, str]], limit_chars: int = 3500) -> str:
+            buf = []
+            total_len = 0
+            for dt, line in items:
+                entry = f"{dt.astimezone().strftime('%m-%d %H:%M')}  {line}"
+                if total_len + len(entry) + 1 > limit_chars:
+                    break
+                buf.append(entry)
+                total_len += len(entry) + 1
+            return "\n".join(buf)
+
         if not fresh:
             note = f"since {last_dt.astimezone().strftime('%Y-%m-%d %H:%M')}" if last_dt else "for the period"
             if rows:
-            sample = rows[-50:]
-            body = "\n".join(f"{dt.astimezone().strftime('%m-%d %H:%M')}  {line}" for dt, line in sample)
+                sample = rows[-50:][::-1]  # newest first
+                body = fmt_lines(sample)
                 await msg.answer(
                     f"📣 No new incidents {note} (window {hours}h).\nRecent sample:\n```\n{body}\n```",
                     reply_markup=system_logs_audit_kb,
                     parse_mode="Markdown",
                 )
             else:
-            await msg.answer(f"📣 No new incidents {note} (window {hours}h)", reply_markup=system_logs_audit_kb)
+                await msg.answer(
+                    f"📣 No new incidents {note} (window {hours}h)",
+                    reply_markup=system_logs_audit_kb,
+                )
             return
-    fresh.sort(key=lambda x: x[0])
-    body = "\n".join(f"{dt.astimezone().strftime('%m-%d %H:%M')}  {line}" for dt, line in fresh[-200:])
+
+        fresh.sort(key=lambda x: x[0], reverse=True)
+        body = fmt_lines(fresh)
         await msg.answer(
             f"📣 New incidents (since last mark, window {hours}h): {len(fresh)}\n```\n{body}\n```",
             reply_markup=system_logs_audit_kb,
             parse_mode="Markdown",
         )
         try:
-        runtime_state.set_state("incidents_diff_last_ts", fresh[-1][0].isoformat())
+            runtime_state.set_state("incidents_diff_last_ts", fresh[0][0].isoformat())
         except Exception:
             pass
+    except Exception as e:
+        await msg.answer(f"⚠️ Diff error: {type(e).__name__}: {e}", reply_markup=system_logs_audit_kb)
 
 
 @dp.message(F.text.startswith("/alerts_heatmap"))