From 2504cb6a1bbc463f62fd30817f004ba629359968 Mon Sep 17 00:00:00 2001
From: Charles Packer <packercharles@gmail.com>
Date: Thu, 17 Apr 2025 17:50:49 -0700
Subject: [PATCH] fix: add a check to prevent agents from writing the line
 number warning into memory (#1770)

---
 letta/constants.py                    |  5 +++++
 letta/functions/function_sets/base.py | 13 +++++++++++++
 letta/schemas/agent.py                |  4 ++--
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/letta/constants.py b/letta/constants.py
index 0c903e0a..57e85b1f 100644
--- a/letta/constants.py
+++ b/letta/constants.py
@@ -103,6 +103,11 @@ ERROR_MESSAGE_PREFIX = "Error"
 
 NON_USER_MSG_PREFIX = "[This is an automated system message hidden from the user] "
 
+CORE_MEMORY_LINE_NUMBER_WARNING = (
+    "# NOTE: Line numbers shown below are to help during editing. Do NOT include line number prefixes in your memory edit tool calls."
+)
+
+
 # Constants to do with summarization / conversation length window
 # The max amount of tokens supported by the underlying model (eg 8k for gpt-4 and Mistral 7B)
 LLM_MAX_TOKENS = {
diff --git a/letta/functions/function_sets/base.py b/letta/functions/function_sets/base.py
index 0705a388..654675c9 100644
--- a/letta/functions/function_sets/base.py
+++ b/letta/functions/function_sets/base.py
@@ -1,6 +1,7 @@
 from typing import Optional
 
 from letta.agent import Agent
+from letta.constants import CORE_MEMORY_LINE_NUMBER_WARNING
 
 
 def send_message(self: "Agent", message: str) -> Optional[str]:
@@ -219,6 +220,10 @@ def memory_replace(agent_state: "AgentState", label: str, old_str: str, new_str:
         raise ValueError(
             "old_str contains a line number prefix, which is not allowed. Do not include line numbers when calling memory tools (line numbers are for display purposes only)."
         )
+    if CORE_MEMORY_LINE_NUMBER_WARNING in old_str:
+        raise ValueError(
+            "old_str contains a line number warning, which is not allowed. Do not include line number information when calling memory tools (line numbers are for display purposes only)."
+        )
     if bool(re.search(r"\nLine \d+: ", new_str)):
         raise ValueError(
             "new_str contains a line number prefix, which is not allowed. Do not include line numbers when calling memory tools (line numbers are for display purposes only)."
@@ -282,6 +287,10 @@ def memory_insert(agent_state: "AgentState", label: str, new_str: str, insert_li
         raise ValueError(
             "new_str contains a line number prefix, which is not allowed. Do not include line numbers when calling memory tools (line numbers are for display purposes only)."
         )
+    if CORE_MEMORY_LINE_NUMBER_WARNING in new_str:
+        raise ValueError(
+            "new_str contains a line number warning, which is not allowed. Do not include line number information when calling memory tools (line numbers are for display purposes only)."
+        )
 
     current_value = str(agent_state.memory.get_block(label).value).expandtabs()
     new_str = str(new_str).expandtabs()
@@ -340,6 +349,10 @@ def memory_rethink(agent_state: "AgentState", label: str, new_memory: str) -> No
         raise ValueError(
             "new_memory contains a line number prefix, which is not allowed. Do not include line numbers when calling memory tools (line numbers are for display purposes only)."
         )
+    if CORE_MEMORY_LINE_NUMBER_WARNING in new_memory:
+        raise ValueError(
+            "new_memory contains a line number warning, which is not allowed. Do not include line number information when calling memory tools (line numbers are for display purposes only)."
+        )
 
     if agent_state.memory.get_block(label) is None:
         agent_state.memory.create_block(label=label, value=new_memory)
diff --git a/letta/schemas/agent.py b/letta/schemas/agent.py
index e5380406..6d30afcd 100644
--- a/letta/schemas/agent.py
+++ b/letta/schemas/agent.py
@@ -3,7 +3,7 @@ from typing import Dict, List, Optional
 
 from pydantic import BaseModel, Field, field_validator
 
-from letta.constants import DEFAULT_EMBEDDING_CHUNK_SIZE
+from letta.constants import CORE_MEMORY_LINE_NUMBER_WARNING, DEFAULT_EMBEDDING_CHUNK_SIZE
 from letta.helpers import ToolRulesSolver
 from letta.schemas.block import CreateBlock
 from letta.schemas.embedding_config import EmbeddingConfig
@@ -284,7 +284,7 @@ def get_prompt_template_for_agent_type(agent_type: Optional[AgentType] = None):
         return (
             "{% for block in blocks %}"
             '<{{ block.label }} characters="{{ block.value|length }}/{{ block.limit }}">\n'
-            "# NOTE: Line numbers shown below are to help during editing. Do NOT include line number prefixes in your memory edit tool calls."
+            f"{CORE_MEMORY_LINE_NUMBER_WARNING}"
             "{% for line in block.value.split('\\n') %}"
             "Line {{ loop.index }}: {{ line }}\n"
             "{% endfor %}"