From a434f3aa08a3cd384db74b788260dae7084edf01 Mon Sep 17 00:00:00 2001
From: ccurme <chester.curme@gmail.com>
Date: Thu, 5 Feb 2026 09:37:25 -0500
Subject: [PATCH] fix(langchain): bump min core version and improve approximate
 token counting (#35026)

---
 .../langchain/agents/middleware/summarization.py            | 6 ++++--
 libs/langchain_v1/pyproject.toml                            | 2 +-
 libs/langchain_v1/uv.lock                                   | 4 ++--
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/libs/langchain_v1/langchain/agents/middleware/summarization.py b/libs/langchain_v1/langchain/agents/middleware/summarization.py
index cd5a38b0b71..a59b23ffc03 100644
--- a/libs/langchain_v1/langchain/agents/middleware/summarization.py
+++ b/libs/langchain_v1/langchain/agents/middleware/summarization.py
@@ -144,8 +144,10 @@ def _get_approximate_token_counter(model: BaseChatModel) -> TokenCounter:
     if model._llm_type == "anthropic-chat":  # noqa: SLF001
         # 3.3 was estimated in an offline experiment, comparing with Claude's token-counting
         # API: https://platform.claude.com/docs/en/build-with-claude/token-counting
-        return partial(count_tokens_approximately, chars_per_token=3.3)
-    return count_tokens_approximately
+        return partial(
+            count_tokens_approximately, use_usage_metadata_scaling=True, chars_per_token=3.3
+        )
+    return partial(count_tokens_approximately, use_usage_metadata_scaling=True)
 
 
 class SummarizationMiddleware(AgentMiddleware[AgentState[ResponseT], ContextT, ResponseT]):
diff --git a/libs/langchain_v1/pyproject.toml b/libs/langchain_v1/pyproject.toml
index 6828a11d883..8b7bd1c9452 100644
--- a/libs/langchain_v1/pyproject.toml
+++ b/libs/langchain_v1/pyproject.toml
@@ -24,7 +24,7 @@ classifiers = [
 version = "1.2.9"
 requires-python = ">=3.10.0,<4.0.0"
 dependencies = [
-    "langchain-core>=1.2.8,<2.0.0",
+    "langchain-core>=1.2.9,<2.0.0",
     "langgraph>=1.0.7,<1.1.0",
     "pydantic>=2.7.4,<3.0.0",
 ]
diff --git a/libs/langchain_v1/uv.lock b/libs/langchain_v1/uv.lock
index 0b7efb148dc..fc92e0beab6 100644
--- a/libs/langchain_v1/uv.lock
+++ b/libs/langchain_v1/uv.lock
@@ -1,5 +1,5 @@
 version = 1
-revision = 3
+revision = 2
 requires-python = ">=3.10.0, <4.0.0"
 resolution-markers = [
     "python_full_version >= '3.14' and platform_python_implementation == 'PyPy'",
@@ -2125,7 +2125,7 @@ wheels = [
 
 [[package]]
 name = "langchain-core"
-version = "1.2.8"
+version = "1.2.9"
 source = { editable = "../core" }
 dependencies = [
     { name = "jsonpatch" },