diff --git a/nanobot/agent/loop.py b/nanobot/agent/loop.py
index 6cf65bb..ed92421 100644
--- a/nanobot/agent/loop.py
+++ b/nanobot/agent/loop.py
@@ -3,6 +3,7 @@
 import asyncio
 import json
 import time
+from datetime import datetime
 from pathlib import Path
 from typing import Any
 
@@ -290,10 +291,33 @@ class AgentLoop:
         if isinstance(cron_tool, CronTool):
             cron_tool.set_context(msg.channel, msg.chat_id)
         
+        # Prepend time-gap notice if >5 minutes since last user message
+        current_message = msg.content
+        last_user_ts = None
+        for m in reversed(session.messages):
+            if m.get("role") == "user":
+                last_user_ts = m.get("timestamp")
+                break
+        if last_user_ts:
+            try:
+                last_dt = datetime.fromisoformat(last_user_ts)
+                now_dt = datetime.now()
+                elapsed_seconds = (now_dt - last_dt).total_seconds()
+                if elapsed_seconds > 300:  # 5 minutes
+                    if elapsed_seconds < 3600:
+                        gap_str = f"{int(elapsed_seconds // 60)} minutes"
+                    elif elapsed_seconds < 86400:
+                        gap_str = f"{int(elapsed_seconds // 3600)} hours"
+                    else:
+                        gap_str = f"{int(elapsed_seconds // 86400)} days"
+                    current_message = f"[SYSTEM ANNOUNCEMENT: {gap_str} have elapsed since last user message; take this into account when replying to user]\n\n{msg.content}"
+            except (ValueError, TypeError):
+                pass  # Malformed timestamp — skip silently
+
         # Build initial messages (use get_history for LLM-formatted messages)
         messages = self.context.build_messages(
             history=session.get_history(),
-            current_message=msg.content,
+            current_message=current_message,
             media=msg.media if msg.media else None,
             channel=msg.channel,
             chat_id=msg.chat_id,