From 2a0d9d05fb5f0d770639753d39217efc26c9ba56 Mon Sep 17 00:00:00 2001
From: Eugene Yurtsev <eyurtsev@gmail.com>
Date: Thu, 26 Sep 2024 13:02:30 -0400
Subject: [PATCH] docs: Fix trim_messages invocations in the memory migration
 guide (#26902)

Should only be start_on="human", not start_on=("human", "ai")
---
 .../conversation_buffer_window_memory.ipynb   | 63 +++++++++++--------
 1 file changed, 36 insertions(+), 27 deletions(-)

diff --git a/docs/docs/versions/migrating_memory/conversation_buffer_window_memory.ipynb b/docs/docs/versions/migrating_memory/conversation_buffer_window_memory.ipynb
index 0e84de6001a..f031e1dbb70 100644
--- a/docs/docs/versions/migrating_memory/conversation_buffer_window_memory.ipynb
+++ b/docs/docs/versions/migrating_memory/conversation_buffer_window_memory.ipynb
@@ -222,13 +222,15 @@
     "    token_counter=len,  # <-- len will simply count the number of messages rather than tokens\n",
     "    max_tokens=5,  # <-- allow up to 5 messages.\n",
     "    strategy=\"last\",\n",
-    "    # The start_on is specified\n",
-    "    # to make sure we do not generate a sequence where\n",
-    "    # a ToolMessage that contains the result of a tool invocation\n",
-    "    # appears before the AIMessage that requested a tool invocation\n",
-    "    # as this will cause some chat models to raise an error.\n",
-    "    start_on=(\"human\", \"ai\"),\n",
-    "    include_system=True,  # <-- Keep the system message\n",
+    "    # Most chat models expect that chat history starts with either:\n",
+    "    # (1) a HumanMessage or\n",
+    "    # (2) a SystemMessage followed by a HumanMessage\n",
+    "    # start_on=\"human\" makes sure we produce a valid chat history\n",
+    "    start_on=\"human\",\n",
+    "    # Usually, we want to keep the SystemMessage\n",
+    "    # if it's present in the original history.\n",
+    "    # The SystemMessage has special instructions for the model.\n",
+    "    include_system=True,\n",
     "    allow_partial=False,\n",
     ")\n",
     "\n",
@@ -280,13 +282,16 @@
     "    token_counter=ChatOpenAI(model=\"gpt-4o\"),\n",
     "    max_tokens=80,  # <-- token limit\n",
     "    # The start_on is specified\n",
-    "    # to make sure we do not generate a sequence where\n",
-    "    # a ToolMessage that contains the result of a tool invocation\n",
-    "    # appears before the AIMessage that requested a tool invocation\n",
-    "    # as this will cause some chat models to raise an error.\n",
-    "    start_on=(\"human\", \"ai\"),\n",
+    "    # Most chat models expect that chat history starts with either:\n",
+    "    # (1) a HumanMessage or\n",
+    "    # (2) a SystemMessage followed by a HumanMessage\n",
+    "    # start_on=\"human\" makes sure we produce a valid chat history\n",
+    "    start_on=\"human\",\n",
+    "    # Usually, we want to keep the SystemMessage\n",
+    "    # if it's present in the original history.\n",
+    "    # The SystemMessage has special instructions for the model.\n",
+    "    include_system=True,\n",
     "    strategy=\"last\",\n",
-    "    include_system=True,  # <-- Keep the system message\n",
     ")\n",
     "\n",
     "for msg in selected_messages:\n",
@@ -361,13 +366,15 @@
     "        token_counter=len,  # <-- len will simply count the number of messages rather than tokens\n",
     "        max_tokens=5,  # <-- allow up to 5 messages.\n",
     "        strategy=\"last\",\n",
-    "        # The start_on is specified\n",
-    "        # to make sure we do not generate a sequence where\n",
-    "        # a ToolMessage that contains the result of a tool invocation\n",
-    "        # appears before the AIMessage that requested a tool invocation\n",
-    "        # as this will cause some chat models to raise an error.\n",
-    "        start_on=(\"human\", \"ai\"),\n",
-    "        include_system=True,  # <-- Keep the system message\n",
+    "        # Most chat models expect that chat history starts with either:\n",
+    "        # (1) a HumanMessage or\n",
+    "        # (2) a SystemMessage followed by a HumanMessage\n",
+    "        # start_on=\"human\" makes sure we produce a valid chat history\n",
+    "        start_on=\"human\",\n",
+    "        # Usually, we want to keep the SystemMessage\n",
+    "        # if it's present in the original history.\n",
+    "        # The SystemMessage has special instructions for the model.\n",
+    "        include_system=True,\n",
     "        allow_partial=False,\n",
     "    )\n",
     "\n",
@@ -501,13 +508,15 @@
     "        token_counter=len,  # <-- len will simply count the number of messages rather than tokens\n",
     "        max_tokens=5,  # <-- allow up to 5 messages.\n",
     "        strategy=\"last\",\n",
-    "        # The start_on is specified\n",
-    "        # to make sure we do not generate a sequence where\n",
-    "        # a ToolMessage that contains the result of a tool invocation\n",
-    "        # appears before the AIMessage that requested a tool invocation\n",
-    "        # as this will cause some chat models to raise an error.\n",
-    "        start_on=(\"human\", \"ai\"),\n",
-    "        include_system=True,  # <-- Keep the system message\n",
+    "        # Most chat models expect that chat history starts with either:\n",
+    "        # (1) a HumanMessage or\n",
+    "        # (2) a SystemMessage followed by a HumanMessage\n",
+    "        # start_on=\"human\" makes sure we produce a valid chat history\n",
+    "        start_on=\"human\",\n",
+    "        # Usually, we want to keep the SystemMessage\n",
+    "        # if it's present in the original history.\n",
+    "        # The SystemMessage has special instructions for the model.\n",
+    "        include_system=True,\n",
     "        allow_partial=False,\n",
     "    )\n",
     "\n",