chore(langchain): cleanup ruff config

libs/langchain_v1/langchain/agents/factory.py

@@ -20,9 +20,9 @@
 from langgraph.constants import END, START
 from langgraph.graph.state import StateGraph
 from langgraph.prebuilt.tool_node import ToolCallWithContext, ToolNode
-from langgraph.runtime import Runtime  # noqa: TC002
+from langgraph.runtime import Runtime
 from langgraph.types import Command, Send
-from langgraph.typing import ContextT  # noqa: TC002
+from langgraph.typing import ContextT
 from typing_extensions import NotRequired, Required, TypedDict
 
 from langchain.agents.middleware.types import (
@@ -541,7 +541,7 @@ async def call_inner(req: ToolCallRequest) -> ToolMessage | Command:
     return result
 
 
-def create_agent(  # noqa: PLR0915
+def create_agent(
     model: str | BaseChatModel,
     tools: Sequence[BaseTool | Callable | dict[str, Any]] | None = None,
     *,
@@ -786,9 +786,9 @@ def check_weather(location: str) -> str:
         default_tools = list(built_in_tools)
 
     # validate middleware
-    assert len({m.name for m in middleware}) == len(middleware), (  # noqa: S101
-        "Please remove duplicate middleware instances."
-    )
+    if len({m.name for m in middleware}) != len(middleware):
+        msg = "Please remove duplicate middleware instances."
+        raise AssertionError(msg)
     middleware_w_before_agent = [
         m
         for m in middleware
@@ -881,12 +881,12 @@ def _handle_model_output(
                 )
                 try:
                     structured_response = provider_strategy_binding.parse(output)
-                except Exception as exc:  # noqa: BLE001
+                except Exception as exc:
                     schema_name = getattr(
                         effective_response_format.schema_spec.schema, "__name__", "response_format"
                     )
                     validation_error = StructuredOutputValidationError(schema_name, exc, output)
-                    raise validation_error
+                    raise validation_error from exc
                 else:
                     return {"messages": [output], "structured_response": structured_response}
             return {"messages": [output]}
@@ -947,13 +947,13 @@ def _handle_model_output(
                         ],
                         "structured_response": structured_response,
                     }
-                except Exception as exc:  # noqa: BLE001
+                except Exception as exc:
                     exception = StructuredOutputValidationError(tool_call["name"], exc, output)
                     should_retry, error_message = _handle_structured_output_error(
                         exception, effective_response_format
                     )
                     if not should_retry:
-                        raise exception
+                        raise exception from exc
 
                     return {
                         "messages": [

libs/langchain_v1/langchain/agents/middleware/_redaction.py

@@ -179,19 +179,22 @@ def detect_url(content: str) -> list[PIIMatch]:
 }
 """Registry of built-in detectors keyed by type name."""
 
+_CARD_NUMBER_MIN_DIGITS = 13
+_CARD_NUMBER_MAX_DIGITS = 19
+
 
 def _passes_luhn(card_number: str) -> bool:
     """Validate credit card number using the Luhn checksum."""
     digits = [int(d) for d in card_number if d.isdigit()]
-    if not 13 <= len(digits) <= 19:
+    if not _CARD_NUMBER_MIN_DIGITS <= len(digits) <= _CARD_NUMBER_MAX_DIGITS:
         return False
 
     checksum = 0
     for index, digit in enumerate(reversed(digits)):
         value = digit
         if index % 2 == 1:
             value *= 2
-            if value > 9:
+            if value > 9:  # noqa: PLR2004
                 value -= 9
         checksum += value
     return checksum % 10 == 0
@@ -205,18 +208,22 @@ def _apply_redact_strategy(content: str, matches: list[PIIMatch]) -> str:
     return result
 
 
+_UNMASKED_CHAR_NUMBER = 4
+_IPV4_PARTS_NUMBER = 4
+
+
 def _apply_mask_strategy(content: str, matches: list[PIIMatch]) -> str:
     result = content
     for match in sorted(matches, key=lambda item: item["start"], reverse=True):
         value = match["value"]
         pii_type = match["type"]
         if pii_type == "email":
             parts = value.split("@")
-            if len(parts) == 2:
+            if len(parts) == 2:  # noqa: PLR2004
                 domain_parts = parts[1].split(".")
                 masked = (
                     f"{parts[0]}@****.{domain_parts[-1]}"
-                    if len(domain_parts) >= 2
+                    if len(domain_parts) > 1
                     else f"{parts[0]}@****"
                 )
             else:
@@ -225,12 +232,15 @@ def _apply_mask_strategy(content: str, matches: list[PIIMatch]) -> str:
             digits_only = "".join(c for c in value if c.isdigit())
             separator = "-" if "-" in value else " " if " " in value else ""
             if separator:
-                masked = f"****{separator}****{separator}****{separator}{digits_only[-4:]}"
+                masked = (
+                    f"****{separator}****{separator}****{separator}"
+                    f"{digits_only[-_UNMASKED_CHAR_NUMBER:]}"
+                )
             else:
-                masked = f"************{digits_only[-4:]}"
+                masked = f"************{digits_only[-_UNMASKED_CHAR_NUMBER:]}"
         elif pii_type == "ip":
             octets = value.split(".")
-            masked = f"*.*.*.{octets[-1]}" if len(octets) == 4 else "****"
+            masked = f"*.*.*.{octets[-1]}" if len(octets) == _IPV4_PARTS_NUMBER else "****"
         elif pii_type == "mac_address":
             separator = ":" if ":" in value else "-"
             masked = (
@@ -239,7 +249,11 @@ def _apply_mask_strategy(content: str, matches: list[PIIMatch]) -> str:
         elif pii_type == "url":
             masked = "[MASKED_URL]"
         else:
-            masked = f"****{value[-4:]}" if len(value) > 4 else "****"
+            masked = (
+                f"****{value[-_UNMASKED_CHAR_NUMBER:]}"
+                if len(value) > _UNMASKED_CHAR_NUMBER
+                else "****"
+            )
         result = result[: match["start"]] + masked + result[match["end"] :]
     return result
 

libs/langchain_v1/langchain/agents/middleware/context_editing.py

@@ -229,6 +229,7 @@ def wrap_model_call(
 
             def count_tokens(messages: Sequence[BaseMessage]) -> int:
                 return count_tokens_approximately(messages)
+
         else:
             system_msg = (
                 [SystemMessage(content=request.system_prompt)] if request.system_prompt else []
@@ -258,6 +259,7 @@ async def awrap_model_call(
 
             def count_tokens(messages: Sequence[BaseMessage]) -> int:
                 return count_tokens_approximately(messages)
+
         else:
             system_msg = (
                 [SystemMessage(content=request.system_prompt)] if request.system_prompt else []

libs/langchain_v1/langchain/agents/middleware/model_call_limit.py

@@ -6,7 +6,7 @@
 
 from langchain_core.messages import AIMessage
 from langgraph.channels.untracked_value import UntrackedValue
-from typing_extensions import NotRequired
+from typing_extensions import NotRequired, override
 
 from langchain.agents.middleware.types import (
     AgentMiddleware,
@@ -157,7 +157,8 @@ def __init__(
         self.exit_behavior = exit_behavior
 
     @hook_config(can_jump_to=["end"])
-    def before_model(self, state: ModelCallLimitState, runtime: Runtime) -> dict[str, Any] | None:  # noqa: ARG002
+    @override
+    def before_model(self, state: ModelCallLimitState, runtime: Runtime) -> dict[str, Any] | None:
         """Check model call limits before making a model call.
 
         Args:
@@ -222,7 +223,8 @@ async def abefore_model(
         """
         return self.before_model(state, runtime)
 
-    def after_model(self, state: ModelCallLimitState, runtime: Runtime) -> dict[str, Any] | None:  # noqa: ARG002
+    @override
+    def after_model(self, state: ModelCallLimitState, runtime: Runtime) -> dict[str, Any] | None:
         """Increment model call counts after a model call.
 
         Args:

libs/langchain_v1/langchain/agents/middleware/model_fallback.py

@@ -87,14 +87,14 @@ def wrap_model_call(
         last_exception: Exception
         try:
             return handler(request)
-        except Exception as e:  # noqa: BLE001
+        except Exception as e:
             last_exception = e
 
         # Try fallback models
         for fallback_model in self.models:
             try:
                 return handler(request.override(model=fallback_model))
-            except Exception as e:  # noqa: BLE001
+            except Exception as e:
                 last_exception = e
                 continue
 
@@ -121,14 +121,14 @@ async def awrap_model_call(
         last_exception: Exception
         try:
             return await handler(request)
-        except Exception as e:  # noqa: BLE001
+        except Exception as e:
             last_exception = e
 
         # Try fallback models
         for fallback_model in self.models:
             try:
                 return await handler(request.override(model=fallback_model))
-            except Exception as e:  # noqa: BLE001
+            except Exception as e:
                 last_exception = e
                 continue
 

libs/langchain_v1/langchain/agents/middleware/model_retry.py

@@ -223,7 +223,7 @@ def wrap_model_call(
         for attempt in range(self.max_retries + 1):
             try:
                 return handler(request)
-            except Exception as exc:  # noqa: BLE001
+            except Exception as exc:
                 attempts_made = attempt + 1  # attempt is 0-indexed
 
                 # Check if we should retry this exception
@@ -270,7 +270,7 @@ async def awrap_model_call(
         for attempt in range(self.max_retries + 1):
             try:
                 return await handler(request)
-            except Exception as exc:  # noqa: BLE001
+            except Exception as exc:
                 attempts_made = attempt + 1  # attempt is 0-indexed
 
                 # Check if we should retry this exception

libs/langchain_v1/langchain/agents/middleware/pii.py

@@ -5,6 +5,7 @@
 from typing import TYPE_CHECKING, Any, Literal
 
 from langchain_core.messages import AIMessage, AnyMessage, HumanMessage, ToolMessage
+from typing_extensions import override
 
 from langchain.agents.middleware._redaction import (
     PIIDetectionError,
@@ -92,6 +93,8 @@ class PIIMiddleware(AgentMiddleware):
 
     def __init__(
         self,
+        # From a typing point of view, the literals are covered by 'str'.
+        # Nonetheless, we escape PYI051 to keep hints and autocompletion for the caller.
         pii_type: Literal["email", "credit_card", "ip", "mac_address", "url"] | str,  # noqa: PYI051
         *,
         strategy: Literal["block", "redact", "mask", "hash"] = "redact",
@@ -158,10 +161,11 @@ def _process_content(self, content: str) -> tuple[str, list[PIIMatch]]:
         return sanitized, matches
 
     @hook_config(can_jump_to=["end"])
+    @override
     def before_model(
         self,
         state: AgentState,
-        runtime: Runtime,  # noqa: ARG002
+        runtime: Runtime,
     ) -> dict[str, Any] | None:
         """Check user messages and tool results for PII before model invocation.
 
@@ -273,10 +277,11 @@ async def abefore_model(
         """
         return self.before_model(state, runtime)
 
+    @override
     def after_model(
         self,
         state: AgentState,
-        runtime: Runtime,  # noqa: ARG002
+        runtime: Runtime,
     ) -> dict[str, Any] | None:
         """Check AI messages for PII after model invocation.
 

libs/langchain_v1/langchain/agents/middleware/shell_tool.py

@@ -22,7 +22,7 @@
 from langgraph.channels.untracked_value import UntrackedValue
 from pydantic import BaseModel, model_validator
 from pydantic.json_schema import SkipJsonSchema
-from typing_extensions import NotRequired
+from typing_extensions import NotRequired, override
 
 from langchain.agents.middleware._execution import (
     SHELL_TEMP_PREFIX,
@@ -78,10 +78,10 @@ class _SessionResources:
     session: ShellSession
     tempdir: tempfile.TemporaryDirectory[str] | None
     policy: BaseExecutionPolicy
-    _finalizer: weakref.finalize = field(init=False, repr=False)
+    finalizer: weakref.finalize = field(init=False, repr=False)
 
     def __post_init__(self) -> None:
-        self._finalizer = weakref.finalize(
+        self.finalizer = weakref.finalize(
             self,
             _cleanup_resources,
             self.session,
@@ -489,7 +489,8 @@ def _normalize_env(env: Mapping[str, Any] | None) -> dict[str, str] | None:
             normalized[key] = str(value)
         return normalized
 
-    def before_agent(self, state: ShellToolState, runtime: Runtime) -> dict[str, Any] | None:  # noqa: ARG002
+    @override
+    def before_agent(self, state: ShellToolState, runtime: Runtime) -> dict[str, Any] | None:
         """Start the shell session and run startup commands."""
         resources = self._get_or_create_resources(state)
         return {"shell_session_resources": resources}
@@ -498,7 +499,8 @@ async def abefore_agent(self, state: ShellToolState, runtime: Runtime) -> dict[s
         """Async start the shell session and run startup commands."""
         return self.before_agent(state, runtime)
 
-    def after_agent(self, state: ShellToolState, runtime: Runtime) -> None:  # noqa: ARG002
+    @override
+    def after_agent(self, state: ShellToolState, runtime: Runtime) -> None:
         """Run shutdown commands and release resources when an agent completes."""
         resources = state.get("shell_session_resources")
         if not isinstance(resources, _SessionResources):
@@ -507,7 +509,7 @@ def after_agent(self, state: ShellToolState, runtime: Runtime) -> None:  # noqa:
         try:
             self._run_shutdown_commands(resources.session)
         finally:
-            resources._finalizer()
+            resources.finalizer()
 
     async def aafter_agent(self, state: ShellToolState, runtime: Runtime) -> None:
         """Async run shutdown commands and release resources when an agent completes."""

libs/langchain_v1/langchain/agents/middleware/summarization.py

@@ -18,6 +18,7 @@
     REMOVE_ALL_MESSAGES,
 )
 from langgraph.runtime import Runtime
+from typing_extensions import override
 
 from langchain.agents.middleware.types import AgentMiddleware, AgentState
 from langchain.chat_models import BaseChatModel, init_chat_model
@@ -165,7 +166,8 @@ def __init__(
             )
             raise ValueError(msg)
 
-    def before_model(self, state: AgentState, runtime: Runtime) -> dict[str, Any] | None:  # noqa: ARG002
+    @override
+    def before_model(self, state: AgentState, runtime: Runtime) -> dict[str, Any] | None:
         """Process messages before model invocation, potentially triggering summarization."""
         messages = state["messages"]
         self._ensure_message_ids(messages)
@@ -192,7 +194,8 @@ def before_model(self, state: AgentState, runtime: Runtime) -> dict[str, Any] |
             ]
         }
 
-    async def abefore_model(self, state: AgentState, runtime: Runtime) -> dict[str, Any] | None:  # noqa: ARG002
+    @override
+    async def abefore_model(self, state: AgentState, runtime: Runtime) -> dict[str, Any] | None:
         """Process messages before model invocation, potentially triggering summarization."""
         messages = state["messages"]
         self._ensure_message_ids(messages)
@@ -438,7 +441,7 @@ def _create_summary(self, messages_to_summarize: list[AnyMessage]) -> str:
         try:
             response = self.model.invoke(self.summary_prompt.format(messages=trimmed_messages))
             return response.text.strip()
-        except Exception as e:  # noqa: BLE001
+        except Exception as e:
             return f"Error generating summary: {e!s}"
 
     async def _acreate_summary(self, messages_to_summarize: list[AnyMessage]) -> str:
@@ -455,7 +458,7 @@ async def _acreate_summary(self, messages_to_summarize: list[AnyMessage]) -> str
                 self.summary_prompt.format(messages=trimmed_messages)
             )
             return response.text.strip()
-        except Exception as e:  # noqa: BLE001
+        except Exception as e:
             return f"Error generating summary: {e!s}"
 
     def _trim_messages_for_summary(self, messages: list[AnyMessage]) -> list[AnyMessage]:
@@ -472,5 +475,5 @@ def _trim_messages_for_summary(self, messages: list[AnyMessage]) -> list[AnyMess
                 allow_partial=True,
                 include_system=True,
             )
-        except Exception:  # noqa: BLE001
+        except Exception:
             return messages[-_DEFAULT_FALLBACK_MESSAGE_COUNT:]