diff --git a/nanobot/agent/loop.py b/nanobot/agent/loop.py
index e3a9d67..6fe37e9 100644
--- a/nanobot/agent/loop.py
+++ b/nanobot/agent/loop.py
@@ -444,18 +444,19 @@ class AgentLoop:
         from datetime import datetime
         for m in messages[skip:]:
             entry = {k: v for k, v in m.items() if k != "reasoning_content"}
-            if entry.get("role") == "tool" and isinstance(entry.get("content"), str):
-                content = entry["content"]
-                if len(content) > self._TOOL_RESULT_MAX_CHARS:
-                    entry["content"] = content[:self._TOOL_RESULT_MAX_CHARS] + "\n... (truncated)"
-            if entry.get("role") == "user" and isinstance(entry.get("content"), list):
-                entry["content"] = [
-                    {"type": "text", "text": "[image]"} if (
-                        c.get("type") == "image_url"
-                        and c.get("image_url", {}).get("url", "").startswith("data:image/")
-                    ) else c
-                    for c in entry["content"]
-                ]
+            role, content = entry.get("role"), entry.get("content")
+            if role == "tool" and isinstance(content, str) and len(content) > self._TOOL_RESULT_MAX_CHARS:
+                entry["content"] = content[:self._TOOL_RESULT_MAX_CHARS] + "\n... (truncated)"
+            elif role == "user":
+                if isinstance(content, str) and content.startswith(ContextBuilder._RUNTIME_CONTEXT_TAG):
+                    continue
+                if isinstance(content, list):
+                    entry["content"] = [
+                        {"type": "text", "text": "[image]"} if (
+                            c.get("type") == "image_url"
+                            and c.get("image_url", {}).get("url", "").startswith("data:image/")
+                        ) else c for c in content
+                    ]
             entry.setdefault("timestamp", datetime.now().isoformat())
             session.messages.append(entry)
         session.updated_at = datetime.now()