Stop attaching timestamps to LLM messages (#209)

* Strip internal message metadata before LLM calls

Co-authored-by: OpenAI Codex <codex@openai.com>

* Simplify timestamp handling for provider messages

Co-authored-by: OpenAI Codex <codex@openai.com>

* Remove timestamp metadata regression test

Co-authored-by: OpenAI Codex <codex@openai.com>

---------

Co-authored-by: OpenAI Codex <codex@openai.com>

agent/context_manager/manager.py

@@ -257,8 +257,6 @@ class ContextManager:
         """Add a message to the history"""
         if token_count:
             self.running_context_usage = token_count
-        if not getattr(message, "timestamp", None):
-            message.timestamp = datetime.now().isoformat()
         self.items.append(message)
         if self.on_message_added:
             self.on_message_added(message)
@@ -331,7 +329,6 @@ class ContextManager:
                             content="Tool was not executed (interrupted or error).",
                             tool_call_id=tc.id,
                             name=tc.function.name,
-                            timestamp=datetime.now().isoformat(),
                         )
                     )
 
@@ -562,7 +559,6 @@ class ContextManager:
         summarized_message = Message(
             role="assistant",
             content=summary,
-            timestamp=datetime.now().isoformat(),
         )
 
         # Reconstruct: system + first user msg + summary + recent messages

tests/unit/test_dangling_tool_calls.py

@@ -67,15 +67,6 @@ def test_no_orphan_means_no_stub():
     assert tool_msgs[0].content == "ok"
 
 
-def test_add_message_records_message_timestamp():
-    cm = _make_cm()
-    msg = Message(role="user", content="hello")
-
-    cm.add_message(msg)
-
-    assert getattr(cm.items[-1], "timestamp", None)
-
-
 def test_multiple_dangling_tool_calls_in_one_assistant_message_are_all_patched():
     cm = _make_cm()
     cm.items.extend([