fix(session): remove message time replay prefixes

nanobot/agent/loop.py

@@ -1183,7 +1183,6 @@ class AgentLoop:
         _hist_kwargs: dict[str, Any] = {
             "max_messages": self._max_messages,
             "max_tokens": self._replay_token_budget(),
-            "include_timestamps": True,
             "extend_to_user": is_subagent,
         }
         history = session.get_history(**_hist_kwargs)
@@ -1462,7 +1461,6 @@ class AgentLoop:
         _hist_kwargs: dict[str, Any] = {
             "max_messages": self._max_messages,
             "max_tokens": self._replay_token_budget(),
-            "include_timestamps": True,
             "extend_to_user": False,
         }
         ctx.history = ctx.session.get_history(**_hist_kwargs)

nanobot/agent/memory.py

@@ -712,17 +712,12 @@ class Consolidator:
     @staticmethod
     def _full_unconsolidated_history(
         session: Session,
-        *,
-        include_timestamps: bool = False,
     ) -> list[dict[str, Any]]:
         """Return the whole unconsolidated tail for consolidation decisions."""
         unconsolidated_count = len(session.messages) - session.last_consolidated
         if unconsolidated_count <= 0:
             return []
-        return session.get_history(
-            max_messages=unconsolidated_count,
-            include_timestamps=include_timestamps,
-        )
+        return session.get_history(max_messages=unconsolidated_count)
 
     @staticmethod
     def _replay_overflow_boundary(
@@ -797,7 +792,7 @@ class Consolidator:
         session: Session,
     ) -> tuple[int, str]:
         """Estimate prompt size from the full unconsolidated session tail."""
-        history = self._full_unconsolidated_history(session, include_timestamps=True)
+        history = self._full_unconsolidated_history(session)
         channel, chat_id = (session.key.split(":", 1) if ":" in session.key else (None, None))
         # Include archived summary in estimation so the budget accounts for it.
         meta = session.metadata.get("_last_summary")

nanobot/session/manager.py

@@ -118,25 +118,6 @@ class Session:
         ):
             self.last_consolidated = 0
 
-    @staticmethod
-    def _annotate_message_time(message: dict[str, Any], content: Any) -> Any:
-        """Expose persisted turn timestamps to the model for relative-date reasoning.
-
-        Annotating *every* assistant turn trains the model (via in-context
-        demonstrations) to start its own replies with the same
-        ``[Message Time: ...]`` prefix, which leaks metadata back to the user.
-        We therefore only annotate user turns. User-side stamps are enough to
-        pin adjacent assistant replies for relative-time reasoning, including
-        proactive messages the user replies to later.
-        """
-        timestamp = message.get("timestamp")
-        if not timestamp or not isinstance(content, str):
-            return content
-        role = message.get("role")
-        if role != "user":
-            return content
-        return f"[Message Time: {timestamp}]\n{content}"
-
     def add_message(self, role: str, content: str, **kwargs: Any) -> None:
         """Add a message to the session."""
         msg = {
@@ -153,7 +134,6 @@ class Session:
         max_messages: int = 120,
         *,
         max_tokens: int = 0,
-        include_timestamps: bool = False,
         extend_to_user: bool = False,
     ) -> list[dict[str, Any]]:
         """Return unconsolidated messages for LLM input.
@@ -243,8 +223,6 @@ class Session:
                 if mcp_lines:
                     breadcrumbs = "\n".join(mcp_lines)
                     content = f"{content}\n{breadcrumbs}" if content else breadcrumbs
-            if include_timestamps:
-                content = self._annotate_message_time(message, content)
             if role == "assistant" and isinstance(content, str) and not content.strip():
                 if not any(key in message for key in ("tool_calls", "reasoning_content", "thinking_blocks")):
                     continue

tests/agent/test_auto_compact.py

@@ -223,7 +223,7 @@ class TestAgentLoopTTLParam:
         kwargs = session.get_history.call_args.kwargs
         assert isinstance(kwargs.get("max_tokens"), int)
         assert kwargs["max_tokens"] > 0
-        assert kwargs["include_timestamps"] is True
+        assert set(kwargs) == {"max_messages", "max_tokens", "extend_to_user"}
 
     @pytest.mark.asyncio
     async def test_session_file_cap_archives_and_trims_old_messages(self, tmp_path):

tests/agent/test_loop_save_turn.py

@@ -1222,11 +1222,9 @@ async def test_system_subagent_followup_is_persisted_before_prompt_assembly(tmp_
     non_system = [m for m in seen["initial_messages"] if m.get("role") != "system"]
     assert "question" in non_system[0]["content"]
     assert "working" in non_system[1]["content"]
-    # User turns carry the timestamp prefix so the model can reason about
-    # relative time. Assistant turns do NOT, otherwise the model treats those
-    # past replies as in-context examples and starts its own outputs with
-    # ``[Message Time: ...]`` (which then leaks back to the user).
-    assert "[Message Time:" in non_system[0]["content"]
+    # Persisted timestamps stay in session records, but replay content is not
+    # rewritten with volatile ``[Message Time: ...]`` prefixes.
+    assert "[Message Time:" not in non_system[0]["content"]
     assert "[Message Time:" not in non_system[1]["content"]
     assert non_system[2]["content"].count("subagent result") == 1
     assert "Current Time:" in non_system[2]["content"]

tests/agent/test_session_manager_history.py

@@ -266,13 +266,8 @@ def test_get_history_preserves_reasoning_content():
     ]
 
 
-def test_get_history_annotates_user_turns_but_not_assistant_turns():
-    """Only user turns carry the timestamp prefix.
-
-    Annotating assistant turns trains the model (via in-context examples) to
-    start its own replies with ``[Message Time: ...]``. User-side stamps are
-    enough to pin adjacent assistant replies for relative-time reasoning.
-    """
+def test_get_history_does_not_inject_persisted_timestamps_into_replay_content():
+    """Persisted timestamps are session metadata, not prompt content."""
     session = Session(key="test:timestamps")
     session.messages.append({
         "role": "user",
@@ -285,12 +280,14 @@ def test_get_history_annotates_user_turns_but_not_assistant_turns():
         "timestamp": "2026-04-26T22:00:05",
     })
 
-    history = session.get_history(max_messages=500, include_timestamps=True)
+    history = session.get_history(max_messages=500)
 
+    assert session.messages[0]["timestamp"] == "2026-04-26T22:00:00"
+    assert session.messages[1]["timestamp"] == "2026-04-26T22:00:05"
     assert history == [
         {
             "role": "user",
-            "content": "[Message Time: 2026-04-26T22:00:00]\n10 点提醒是昨天发生的",
+            "content": "10 点提醒是昨天发生的",
         },
         {
             "role": "assistant",
@@ -299,8 +296,8 @@ def test_get_history_annotates_user_turns_but_not_assistant_turns():
     ]
 
 
-def test_get_history_does_not_annotate_proactive_assistant_deliveries_with_timestamps():
-    """Assistant-side timestamp examples can leak back into future replies."""
+def test_get_history_keeps_proactive_delivery_timestamps_out_of_replay_content():
+    """Timestamp metadata remains persisted without becoming prompt text."""
     session = Session(key="test:proactive-timestamps")
     session.messages.append({
         "role": "assistant",
@@ -314,8 +311,10 @@ def test_get_history_does_not_annotate_proactive_assistant_deliveries_with_times
         "timestamp": "2026-04-26T18:00:00",
     })
 
-    history = session.get_history(max_messages=500, include_timestamps=True)
+    history = session.get_history(max_messages=500)
 
+    assert session.messages[0]["timestamp"] == "2026-04-26T15:00:00"
+    assert session.messages[1]["timestamp"] == "2026-04-26T18:00:00"
     assert history == [
         {
             "role": "assistant",
@@ -323,18 +322,18 @@ def test_get_history_does_not_annotate_proactive_assistant_deliveries_with_times
         },
         {
             "role": "user",
-            "content": "[Message Time: 2026-04-26T18:00:00]\n好",
+            "content": "好",
         },
     ]
 
 
-def test_get_history_does_not_annotate_tool_results_with_timestamps():
+def test_get_history_does_not_inject_tool_result_timestamps():
     session = Session(key="test:tool-timestamps")
     session.messages.append({"role": "user", "content": "run tool"})
     session.messages.extend(_tool_turn("ts", 0))
     session.messages[-1]["timestamp"] = "2026-04-26T22:00:10"
 
-    history = session.get_history(max_messages=500, include_timestamps=True)
+    history = session.get_history(max_messages=500)
 
     tool_result = history[-1]
     assert tool_result["role"] == "tool"
@@ -555,7 +554,7 @@ def test_get_history_sanitizes_existing_assistant_replay_artifacts():
         }
     )
 
-    history = session.get_history(max_messages=500, include_timestamps=True)
+    history = session.get_history(max_messages=500)
 
     assert history == [{"role": "assistant", "content": "来了 🎨"}]