From 0bd862b814ae6e89117422202e60fb429e511ca6 Mon Sep 17 00:00:00 2001
From: Christophe Bornet <cbornet@hotmail.com>
Date: Sat, 27 Dec 2025 08:36:47 +0100
Subject: [PATCH] style(langchain): add ruff rule RUF012 (#34497)

Co-authored-by: Mason Daugherty <mason@langchain.dev>
Co-authored-by: Mason Daugherty <github@mdrxy.com>
---
 libs/langchain_v1/langchain/agents/middleware/types.py        | 4 ++--
 libs/langchain_v1/pyproject.toml                              | 1 -
 .../tests/unit_tests/agents/middleware/core/test_tools.py     | 2 +-
 .../agents/middleware/implementations/test_summarization.py   | 2 +-
 .../agents/middleware/implementations/test_tool_emulator.py   | 4 ++--
 .../tests/unit_tests/agents/test_response_format.py           | 2 +-
 6 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/libs/langchain_v1/langchain/agents/middleware/types.py b/libs/langchain_v1/langchain/agents/middleware/types.py
index ae2565f0eaa..0a953ad2767 100644
--- a/libs/langchain_v1/langchain/agents/middleware/types.py
+++ b/libs/langchain_v1/langchain/agents/middleware/types.py
@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from collections.abc import Awaitable, Callable
+from collections.abc import Awaitable, Callable, Sequence
 from dataclasses import dataclass, field, replace
 from inspect import iscoroutinefunction
 from typing import (
@@ -338,7 +338,7 @@ class AgentMiddleware(Generic[StateT, ContextT]):
     state_schema: type[StateT] = cast("type[StateT]", AgentState)
     """The schema for state passed to the middleware nodes."""
 
-    tools: list[BaseTool]
+    tools: Sequence[BaseTool]
     """Additional tools registered by the middleware."""
 
     @property
diff --git a/libs/langchain_v1/pyproject.toml b/libs/langchain_v1/pyproject.toml
index afe23b2c464..b143e7762e7 100644
--- a/libs/langchain_v1/pyproject.toml
+++ b/libs/langchain_v1/pyproject.toml
@@ -112,7 +112,6 @@ ignore = [
     "FIX002",  # Line contains TODO
     "PERF203", # Rarely useful
     "PLR09",   # Too many something (arg, statements, etc)
-    "RUF012",  # Doesn't play well with Pydantic
     "TD002",   # Missing author in TODO
     "TD003",   # Missing issue link in TODO
 
diff --git a/libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_tools.py b/libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_tools.py
index 4a22a34ae18..12274cd3b63 100644
--- a/libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_tools.py
+++ b/libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_tools.py
@@ -293,7 +293,7 @@ def test_middleware_with_additional_tools() -> None:
         return "middleware"
 
     class ToolProvidingMiddleware(AgentMiddleware):
-        tools = [middleware_tool]
+        tools = (middleware_tool,)
 
     # Model calls the middleware-provided tool
     model = FakeToolCallingModel(
diff --git a/libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_summarization.py b/libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_summarization.py
index ce5ff5c1ee2..2507f6f3e5d 100644
--- a/libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_summarization.py
+++ b/libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_summarization.py
@@ -31,7 +31,7 @@ class ProfileChatModel(BaseChatModel):
     def _generate(self, messages, **kwargs):  # type: ignore[no-untyped-def]
         return ChatResult(generations=[ChatGeneration(message=AIMessage(content="Summary"))])
 
-    profile: ModelProfile | None = {"max_input_tokens": 1000}
+    profile: ModelProfile | None = ModelProfile(max_input_tokens=1000)
 
     @property
     def _llm_type(self) -> str:
diff --git a/libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_tool_emulator.py b/libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_tool_emulator.py
index 3b656ba61e7..e6bd57e6377 100644
--- a/libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_tool_emulator.py
+++ b/libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_tool_emulator.py
@@ -1,7 +1,7 @@
 """Unit tests for tool emulator middleware."""
 
 import typing
-from collections.abc import Callable
+from collections.abc import Callable, Sequence
 from itertools import cycle
 from typing import Any, Literal
 
@@ -86,7 +86,7 @@ class FakeModel(GenericFakeChatModel):
 class FakeEmulatorModel(BaseChatModel):
     """Fake model for emulating tool responses."""
 
-    responses: list[str] = ["Emulated response"]
+    responses: Sequence[str] = ("Emulated response",)
     response_index: int = 0
 
     def _generate(
diff --git a/libs/langchain_v1/tests/unit_tests/agents/test_response_format.py b/libs/langchain_v1/tests/unit_tests/agents/test_response_format.py
index e0bae8332d7..44573309069 100644
--- a/libs/langchain_v1/tests/unit_tests/agents/test_response_format.py
+++ b/libs/langchain_v1/tests/unit_tests/agents/test_response_format.py
@@ -776,7 +776,7 @@ class TestDynamicModelWithResponseFormat:
         # Custom model that we'll use to test whether the tool strategy is applied
         # correctly at runtime.
         class CustomModel(GenericFakeChatModel):
-            tool_bindings: list[Any] = []
+            tool_bindings: list[Any] = Field(default_factory=list)
 
             def bind_tools(
                 self,