diff --git a/nanobot/agent/memory.py b/nanobot/agent/memory.py
index 42b92825f..4d7fd8de7 100644
--- a/nanobot/agent/memory.py
+++ b/nanobot/agent/memory.py
@@ -713,11 +713,10 @@ class MemoryStore:
                 if tools_used
                 else ""
             )
-            timestamp = cast(str, message.get("timestamp", "?"))
-            role = cast(str, message["role"])
-            lines.append(
-                f"[{timestamp[:16]}] {role.upper()}{tools}: {content}"
-            )
+            raw_timestamp = message.get("timestamp")
+            timestamp = str(raw_timestamp) if raw_timestamp is not None else "?"
+            role = str(message.get("role") or "unknown")
+            lines.append(f"[{timestamp[:16]}] {role.upper()}{tools}: {content}")
         return "\n".join(lines)
 
     def raw_archive(
diff --git a/tests/agent/test_memory_store.py b/tests/agent/test_memory_store.py
index 052743156..502a126f1 100644
--- a/tests/agent/test_memory_store.py
+++ b/tests/agent/test_memory_store.py
@@ -579,3 +579,21 @@ def test_history_skips_non_dict_jsonl_lines(tmp_path: Path) -> None:
     }]
     next_cursor = memory.append_history("next", session_key="cli:t")
     assert next_cursor == 2
+
+def test_raw_archive_handles_none_timestamp_and_missing_role(tmp_path: Path) -> None:
+    """raw_archive and _format_messages must safely format messages with None timestamp or missing role.
+
+    Prevents TypeError on NoneType[:16] slicing and KeyError on missing 'role'
+    when raw-dumping unconsolidated history entries without timestamps or role fields.
+    """
+    memory = MemoryStore(tmp_path)
+    messages = [
+        {"content": "message with none timestamp", "timestamp": None, "role": "user"},
+        {"content": "message with int timestamp", "timestamp": 1720000000, "role": "assistant"},
+        {"content": "message with missing role", "timestamp": "2026-07-28T12:00:00"},
+    ]
+    memory.raw_archive(messages, session_key="cli:test")
+    raw_history = memory.history_file.read_text(encoding="utf-8")
+    assert "[?] USER: message with none timestamp" in raw_history
+    assert "[1720000000] ASSISTANT: message with int timestamp" in raw_history
+    assert "[2026-07-28T12:00] UNKNOWN: message with missing role" in raw_history