Add ruff rules for TYPE_CHECKING (TCH) (#3999)

src/backend/base/langflow/api/utils.py

@@ -6,18 +6,18 @@ from typing import TYPE_CHECKING, Any
 from fastapi import HTTPException
 from loguru import logger
 from sqlalchemy import delete
-from sqlmodel import Session
 
 from langflow.graph.graph.base import Graph
-from langflow.services.chat.service import ChatService
 from langflow.services.database.models.flow import Flow
 from langflow.services.database.models.transactions.model import TransactionTable
 from langflow.services.database.models.vertex_builds.model import VertexBuildTable
-from langflow.services.store.schema import StoreComponentCreate
 from langflow.services.store.utils import get_lf_version_from_pypi
 
 if TYPE_CHECKING:
-    from langflow.services.database.models.flow.model import Flow
+    from sqlmodel import Session
+
+    from langflow.services.chat.service import ChatService
+    from langflow.services.store.schema import StoreComponentCreate
 
 
 API_WORDS = ["api", "key", "token"]

src/backend/base/langflow/base/agents/agent.py

@@ -1,9 +1,8 @@
 from abc import abstractmethod
-from typing import cast
+from typing import TYPE_CHECKING, cast
 
 from langchain.agents import AgentExecutor, BaseMultiActionAgent, BaseSingleActionAgent
 from langchain.agents.agent import RunnableAgent
-from langchain_core.messages import BaseMessage
 from langchain_core.runnables import Runnable
 
 from langflow.base.agents.callback import AgentAsyncHandler
@@ -17,6 +16,9 @@ from langflow.schema.message import Message
 from langflow.template import Output
 from langflow.utils.constants import MESSAGE_SENDER_AI
 
+if TYPE_CHECKING:
+    from langchain_core.messages import BaseMessage
+
 
 class LCAgentComponent(Component):
     trace_type = "agent"

src/backend/base/langflow/base/tools/component_tool.py

@@ -1,10 +1,8 @@
 from __future__ import annotations
 
 import re
-from collections.abc import Callable
 from typing import TYPE_CHECKING
 
-from langchain_core.tools import BaseTool
 from langchain_core.tools.structured import StructuredTool
 from loguru import logger
 
@@ -12,6 +10,10 @@ from langflow.base.tools.constants import TOOL_OUTPUT_NAME
 from langflow.io.schema import create_input_schema
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+
+    from langchain_core.tools import BaseTool
+
     from langflow.custom.custom_component.component import Component
     from langflow.inputs.inputs import InputTypes
     from langflow.io import Output

src/backend/base/langflow/base/tools/flow_tool.py

@@ -1,18 +1,21 @@
 from __future__ import annotations
 
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
-from langchain_core.runnables import RunnableConfig
 from langchain_core.tools import BaseTool, ToolException
 from loguru import logger
-from pydantic.v1 import BaseModel
 
 from langflow.base.flow_processing.utils import build_data_from_result_data, format_flow_output_data
-from langflow.graph.graph.base import Graph
-from langflow.graph.vertex.base import Vertex
 from langflow.helpers.flow import build_schema_from_inputs, get_arg_names, get_flow_inputs, run_flow
 from langflow.utils.async_helpers import run_until_complete
 
+if TYPE_CHECKING:
+    from langchain_core.runnables import RunnableConfig
+    from pydantic.v1 import BaseModel
+
+    from langflow.graph.graph.base import Graph
+    from langflow.graph.vertex.base import Vertex
+
 
 class FlowTool(BaseTool):
     name: str

src/backend/base/langflow/base/vectorstores/model.py

@@ -1,8 +1,7 @@
 from abc import abstractmethod
 from functools import wraps
-from typing import cast
+from typing import TYPE_CHECKING, cast
 
-from langchain_core.documents import Document
 from loguru import logger
 
 from langflow.custom import Component
@@ -11,6 +10,9 @@ from langflow.helpers.data import docs_to_data
 from langflow.io import Output
 from langflow.schema import Data
 
+if TYPE_CHECKING:
+    from langchain_core.documents import Document
+
 
 def check_cached_vector_store(f):
     """

src/backend/base/langflow/components/chains/SQLGenerator.py

@@ -1,12 +1,16 @@
+from typing import TYPE_CHECKING
+
 from langchain.chains import create_sql_query_chain
 from langchain_core.prompts import PromptTemplate
-from langchain_core.runnables import Runnable
 
 from langflow.base.chains.model import LCChainComponent
 from langflow.field_typing import Message
 from langflow.inputs import HandleInput, IntInput, MultilineInput
 from langflow.template import Output
 
+if TYPE_CHECKING:
+    from langchain_core.runnables import Runnable
+
 
 class SQLGeneratorComponent(LCChainComponent):
     display_name = "Natural Language to SQL"

src/backend/base/langflow/components/deactivated/SubFlow.py

@@ -1,17 +1,19 @@
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from loguru import logger
 
 from langflow.base.flow_processing.utils import build_data_from_result_data
 from langflow.custom import CustomComponent
 from langflow.graph.graph.base import Graph
-from langflow.graph.schema import RunOutputs
 from langflow.graph.vertex.base import Vertex
 from langflow.helpers.flow import get_flow_inputs
 from langflow.schema import Data
 from langflow.schema.dotdict import dotdict
 from langflow.template.field.base import Input
 
+if TYPE_CHECKING:
+    from langflow.graph.schema import RunOutputs
+
 
 class SubFlowComponent(CustomComponent):
     display_name = "Sub Flow"

src/backend/base/langflow/components/embeddings/TextEmbedder.py

@@ -1,8 +1,12 @@
+from typing import TYPE_CHECKING
+
 from langflow.custom import Component
-from langflow.field_typing import Embeddings
 from langflow.io import HandleInput, MessageInput, Output
 from langflow.schema import Data
-from langflow.schema.message import Message
+
+if TYPE_CHECKING:
+    from langflow.field_typing import Embeddings
+    from langflow.schema.message import Message
 
 
 class TextEmbedderComponent(Component):

src/backend/base/langflow/components/prototypes/RunFlow.py

@@ -1,11 +1,13 @@
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from langflow.base.flow_processing.utils import build_data_from_run_outputs
 from langflow.custom import Component
-from langflow.graph.schema import RunOutputs
 from langflow.io import DropdownInput, MessageTextInput, NestedDictInput, Output
 from langflow.schema import Data, dotdict
 
+if TYPE_CHECKING:
+    from langflow.graph.schema import RunOutputs
+
 
 class RunFlowComponent(Component):
     display_name = "Run Flow"

src/backend/base/langflow/components/vectorstores/Chroma.py

@@ -1,8 +1,7 @@
 from copy import deepcopy
-from typing import TYPE_CHECKING
 
 from chromadb.config import Settings
-from langchain_chroma.vectorstores import Chroma
+from langchain_chroma import Chroma
 from loguru import logger
 
 from langflow.base.vectorstores.model import LCVectorStoreComponent, check_cached_vector_store
@@ -10,9 +9,6 @@ from langflow.base.vectorstores.utils import chroma_collection_to_data
 from langflow.io import BoolInput, DataInput, DropdownInput, HandleInput, IntInput, MultilineInput, StrInput
 from langflow.schema import Data
 
-if TYPE_CHECKING:
-    from langchain_chroma import Chroma
-
 
 class ChromaVectorStoreComponent(LCVectorStoreComponent):
     """

src/backend/base/langflow/components/vectorstores/OpenSearch.py

@@ -1,6 +1,6 @@
 import json
 import traceback
-from typing import TYPE_CHECKING, Any
+from typing import Any
 
 from langchain_community.vectorstores import OpenSearchVectorSearch
 from loguru import logger
@@ -19,9 +19,6 @@ from langflow.io import (
 )
 from langflow.schema import Data
 
-if TYPE_CHECKING:
-    from langchain_community.vectorstores import OpenSearchVectorSearch
-
 
 class OpenSearchVectorStoreComponent(LCVectorStoreComponent):
     """

src/backend/base/langflow/custom/custom_component/component.py

@@ -2,11 +2,9 @@ from __future__ import annotations
 
 import ast
 import inspect
-from collections.abc import Callable
 from copy import deepcopy
 from textwrap import dedent
 from typing import TYPE_CHECKING, Any, ClassVar, get_type_hints
-from uuid import UUID
 
 import nanoid  # type: ignore
 import yaml
@@ -14,13 +12,11 @@ from pydantic import BaseModel
 
 from langflow.base.tools.constants import TOOL_OUTPUT_NAME
 from langflow.custom.tree_visitor import RequiredInputsVisitor
-from langflow.events.event_manager import EventManager
-from langflow.field_typing import Tool
+from langflow.field_typing import Tool  # noqa: TCH001 Needed by add_toolkit_output
 from langflow.graph.state.model import create_state_model
 from langflow.helpers.custom import format_type
 from langflow.schema.artifact import get_artifact_type, post_process_raw
 from langflow.schema.data import Data
-from langflow.schema.log import LoggableType
 from langflow.schema.message import Message
 from langflow.services.settings.feature_flags import FEATURE_FLAGS
 from langflow.services.tracing.schema import Log
@@ -32,9 +28,14 @@ from langflow.utils.util import find_closest_match
 from .custom_component import CustomComponent
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+    from uuid import UUID
+
+    from langflow.events.event_manager import EventManager
     from langflow.graph.edge.schema import EdgeData
     from langflow.graph.vertex.base import Vertex
     from langflow.inputs.inputs import InputTypes
+    from langflow.schema.log import LoggableType
 
 
 _ComponentToolkit = None

src/backend/base/langflow/custom/custom_component/custom_component.py

@@ -12,11 +12,8 @@ from pydantic import BaseModel
 from langflow.custom.custom_component.base_component import BaseComponent
 from langflow.helpers.flow import list_flows, load_flow, run_flow
 from langflow.schema import Data
-from langflow.schema.dotdict import dotdict
-from langflow.schema.schema import OutputValue
 from langflow.services.deps import get_storage_service, get_variable_service, session_scope
 from langflow.services.storage.service import StorageService
-from langflow.services.tracing.schema import Log
 from langflow.template.utils import update_frontend_node_with_template_values
 from langflow.type_extraction.type_extraction import post_process_type
 from langflow.utils import validate
@@ -26,7 +23,10 @@ if TYPE_CHECKING:
 
     from langflow.graph.graph.base import Graph
     from langflow.graph.vertex.base import Vertex
+    from langflow.schema.dotdict import dotdict
+    from langflow.schema.schema import OutputValue
     from langflow.services.storage.service import StorageService
+    from langflow.services.tracing.schema import Log
     from langflow.services.tracing.service import TracingService
 
 

src/backend/base/langflow/graph/graph/base.py

@@ -15,10 +15,8 @@ from typing import TYPE_CHECKING, Any, cast
 import nest_asyncio
 from loguru import logger
 
-from langflow.events.event_manager import EventManager
 from langflow.exceptions.component import ComponentBuildException
 from langflow.graph.edge.base import CycleEdge, Edge
-from langflow.graph.edge.schema import EdgeData
 from langflow.graph.graph.constants import Finish, lazy_load_vertex_dict
 from langflow.graph.graph.runnable_vertices_manager import RunnableVerticesManager
 from langflow.graph.graph.schema import GraphData, GraphDump, StartConfigDict, VertexBuildResult
@@ -38,17 +36,19 @@ from langflow.graph.vertex.base import Vertex, VertexStates
 from langflow.graph.vertex.schema import NodeData, NodeTypeEnum
 from langflow.graph.vertex.types import ComponentVertex, InterfaceVertex, StateVertex
 from langflow.logging.logger import LogConfig, configure
-from langflow.schema import Data
 from langflow.schema.schema import INPUT_FIELD_NAME, InputType
 from langflow.services.cache.utils import CacheMiss
-from langflow.services.chat.schema import GetCache, SetCache
 from langflow.services.deps import get_chat_service, get_tracing_service
 from langflow.utils.async_helpers import run_until_complete
 
 if TYPE_CHECKING:
     from langflow.api.v1.schemas import InputValueRequest
     from langflow.custom.custom_component.component import Component
+    from langflow.events.event_manager import EventManager
+    from langflow.graph.edge.schema import EdgeData
     from langflow.graph.schema import ResultData
+    from langflow.schema import Data
+    from langflow.services.chat.schema import GetCache, SetCache
     from langflow.services.tracing.service import TracingService
 
 

src/backend/base/langflow/graph/graph/schema.py

@@ -6,11 +6,11 @@ from typing_extensions import NotRequired, TypedDict
 
 from langflow.graph.edge.schema import EdgeData
 from langflow.graph.vertex.schema import NodeData
-from langflow.schema.log import LoggableType
 
 if TYPE_CHECKING:
     from langflow.graph.schema import ResultData
     from langflow.graph.vertex.base import Vertex
+    from langflow.schema.log import LoggableType
 
 
 class ViewPort(TypedDict):

src/backend/base/langflow/graph/graph/state_manager.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-from collections.abc import Callable
 from typing import TYPE_CHECKING
 
 from loguru import logger
@@ -8,6 +7,8 @@ from loguru import logger
 from langflow.services.deps import get_settings_service, get_state_service
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+
     from langflow.services.state.service import StateService
 
 

src/backend/base/langflow/graph/vertex/base.py

@@ -13,11 +13,9 @@ from typing import TYPE_CHECKING, Any
 import pandas as pd
 from loguru import logger
 
-from langflow.events.event_manager import EventManager
 from langflow.exceptions.component import ComponentBuildException
 from langflow.graph.schema import INPUT_COMPONENTS, OUTPUT_COMPONENTS, InterfaceComponentTypes, ResultData
 from langflow.graph.utils import UnbuiltObject, UnbuiltResult, log_transaction
-from langflow.graph.vertex.schema import NodeData
 from langflow.interface import initialize
 from langflow.interface.listing import lazy_load_dict
 from langflow.schema.artifact import ArtifactType
@@ -25,15 +23,17 @@ from langflow.schema.data import Data
 from langflow.schema.message import Message
 from langflow.schema.schema import INPUT_FIELD_NAME, OutputValue, build_output_logs
 from langflow.services.deps import get_storage_service
-from langflow.services.tracing.schema import Log
 from langflow.utils.constants import DIRECT_TYPES
 from langflow.utils.schemas import ChatOutputResponse
 from langflow.utils.util import sync_to_async, unescape_string
 
 if TYPE_CHECKING:
     from langflow.custom import Component
+    from langflow.events.event_manager import EventManager
     from langflow.graph.edge.base import CycleEdge, Edge
     from langflow.graph.graph.base import Graph
+    from langflow.graph.vertex.schema import NodeData
+    from langflow.services.tracing.schema import Log
 
 
 class VertexStates(str, Enum):

src/backend/base/langflow/graph/vertex/types.py

@@ -14,8 +14,6 @@ from langflow.graph.schema import CHAT_COMPONENTS, RECORDS_COMPONENTS, Interface
 from langflow.graph.utils import UnbuiltObject, log_transaction, log_vertex_build, rewrite_file_path, serialize_field
 from langflow.graph.vertex.base import Vertex
 from langflow.graph.vertex.exceptions import NoComponentInstance
-from langflow.graph.vertex.schema import NodeData
-from langflow.inputs.inputs import InputTypes
 from langflow.schema import Data
 from langflow.schema.artifact import ArtifactType
 from langflow.schema.message import Message
@@ -26,6 +24,8 @@ from langflow.utils.util import unescape_string
 
 if TYPE_CHECKING:
     from langflow.graph.edge.base import CycleEdge
+    from langflow.graph.vertex.schema import NodeData
+    from langflow.inputs.inputs import InputTypes
 
 
 class CustomComponentVertex(Vertex):

src/backend/base/langflow/helpers/flow.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-from collections.abc import Awaitable, Callable
 from typing import TYPE_CHECKING, Any, cast
 from uuid import UUID
 
@@ -8,16 +7,18 @@ from fastapi import HTTPException
 from pydantic.v1 import BaseModel, Field, create_model
 from sqlmodel import select
 
-from langflow.graph.schema import RunOutputs
-from langflow.schema import Data
 from langflow.schema.schema import INPUT_FIELD_NAME
 from langflow.services.database.models.flow import Flow
 from langflow.services.database.models.flow.model import FlowRead
 from langflow.services.deps import get_settings_service, session_scope
 
 if TYPE_CHECKING:
+    from collections.abc import Awaitable, Callable
+
     from langflow.graph.graph.base import Graph
+    from langflow.graph.schema import RunOutputs
     from langflow.graph.vertex.base import Vertex
+    from langflow.schema import Data
 
 INPUT_TYPE_MAP = {
     "ChatInput": {"type_hint": "Optional[str]", "default": '""'},

src/backend/base/langflow/interface/initialize/loading.py

@@ -10,13 +10,13 @@ from loguru import logger
 from pydantic import PydanticDeprecatedSince20
 
 from langflow.custom.eval import eval_custom_component_code
-from langflow.events.event_manager import EventManager
 from langflow.schema import Data
 from langflow.schema.artifact import get_artifact_type, post_process_raw
 from langflow.services.deps import get_tracing_service
 
 if TYPE_CHECKING:
     from langflow.custom import Component, CustomComponent
+    from langflow.events.event_manager import EventManager
     from langflow.graph.vertex.base import Vertex
 
 

src/backend/base/langflow/interface/types.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import asyncio
 import json
 from typing import TYPE_CHECKING
 
@@ -9,6 +8,8 @@ from loguru import logger
 from langflow.custom.utils import abuild_custom_components, build_custom_components
 
 if TYPE_CHECKING:
+    import asyncio
+
     from langflow.services.cache.base import CacheService
     from langflow.services.settings.service import SettingsService
 

src/backend/base/langflow/processing/base.py

@@ -2,12 +2,12 @@ from __future__ import annotations
 
 from typing import TYPE_CHECKING
 
-from langchain_core.callbacks import BaseCallbackHandler
 from loguru import logger
 
 from langflow.services.deps import get_plugins_service
 
 if TYPE_CHECKING:
+    from langchain_core.callbacks import BaseCallbackHandler
     from langfuse.callback import CallbackHandler  # type: ignore
 
 

src/backend/base/langflow/processing/process.py

@@ -5,8 +5,6 @@ from typing import TYPE_CHECKING, Any, cast
 from loguru import logger
 from pydantic import BaseModel
 
-from langflow.graph.graph.base import Graph
-from langflow.graph.schema import RunOutputs
 from langflow.graph.vertex.base import Vertex
 from langflow.schema.graph import InputValue, Tweaks
 from langflow.schema.schema import INPUT_FIELD_NAME
@@ -14,6 +12,8 @@ from langflow.services.deps import get_settings_service
 
 if TYPE_CHECKING:
     from langflow.api.v1.schemas import InputValueRequest
+    from langflow.graph.graph.base import Graph
+    from langflow.graph.schema import RunOutputs
 
 
 class Result(BaseModel):

src/backend/base/langflow/schema/data.py

@@ -1,15 +1,17 @@
 import copy
 import json
-from typing import cast
+from typing import TYPE_CHECKING, cast
 
 from langchain_core.documents import Document
 from langchain_core.messages import AIMessage, BaseMessage, HumanMessage
-from langchain_core.prompt_values import ImagePromptValue
 from langchain_core.prompts.image import ImagePromptTemplate
 from pydantic import BaseModel, model_serializer, model_validator
 
 from langflow.utils.constants import MESSAGE_SENDER_AI, MESSAGE_SENDER_USER
 
+if TYPE_CHECKING:
+    from langchain_core.prompt_values import ImagePromptValue
+
 
 class Data(BaseModel):
     """

src/backend/base/langflow/schema/message.py

@@ -2,13 +2,12 @@ import asyncio
 import json
 from collections.abc import AsyncIterator, Iterator
 from datetime import datetime, timezone
-from typing import Annotated, Any
+from typing import TYPE_CHECKING, Annotated, Any
 from uuid import UUID
 
 from fastapi.encoders import jsonable_encoder
 from langchain_core.load import load
 from langchain_core.messages import AIMessage, BaseMessage, HumanMessage, SystemMessage
-from langchain_core.prompt_values import ImagePromptValue
 from langchain_core.prompts import BaseChatPromptTemplate, ChatPromptTemplate, PromptTemplate
 from langchain_core.prompts.image import ImagePromptTemplate
 from loguru import logger
@@ -24,6 +23,9 @@ from langflow.utils.constants import (
     MESSAGE_SENDER_USER,
 )
 
+if TYPE_CHECKING:
+    from langchain_core.prompt_values import ImagePromptValue
+
 
 def _timestamp_to_str(timestamp: datetime | str) -> str:
     if isinstance(timestamp, str):

src/backend/base/langflow/services/database/models/api_key/crud.py

@@ -1,13 +1,16 @@
 import datetime
 import secrets
 import threading
+from typing import TYPE_CHECKING
 from uuid import UUID
 
 from sqlmodel import Session, select
-from sqlmodel.sql.expression import SelectOfScalar
 
 from langflow.services.database.models.api_key import ApiKey, ApiKeyCreate, ApiKeyRead, UnmaskedApiKeyRead
 
+if TYPE_CHECKING:
+    from sqlmodel.sql.expression import SelectOfScalar
+
 
 def get_api_keys(session: Session, user_id: UUID) -> list[ApiKeyRead]:
     query: SelectOfScalar = select(ApiKey).where(ApiKey.user_id == user_id)

src/backend/base/langflow/services/database/models/flow/model.py

@@ -14,13 +14,13 @@ from sqlalchemy import Text, UniqueConstraint
 from sqlmodel import JSON, Column, Field, Relationship, SQLModel
 
 from langflow.schema import Data
-from langflow.services.database.models.vertex_builds.model import VertexBuildTable
 
 if TYPE_CHECKING:
     from langflow.services.database.models import TransactionTable
     from langflow.services.database.models.folder import Folder
     from langflow.services.database.models.message import MessageTable
     from langflow.services.database.models.user import User
+    from langflow.services.database.models.vertex_builds.model import VertexBuildTable
 
 
 class FlowBase(SQLModel):

src/backend/base/langflow/services/database/models/folder/model.py

@@ -1,14 +1,11 @@
-from typing import TYPE_CHECKING, Optional
+from typing import Optional
 from uuid import UUID, uuid4
 
 from sqlalchemy import Text, UniqueConstraint
 from sqlmodel import Column, Field, Relationship, SQLModel
 
-from langflow.services.database.models.flow.model import FlowRead
-
-if TYPE_CHECKING:
-    from langflow.services.database.models.flow.model import Flow
-    from langflow.services.database.models.user.model import User
+from langflow.services.database.models.flow.model import Flow, FlowRead
+from langflow.services.database.models.user.model import User
 
 
 class FolderBase(SQLModel):
@@ -26,8 +23,8 @@ class Folder(FolderBase, table=True):  # type: ignore
     )
     children: list["Folder"] = Relationship(back_populates="parent")
     user_id: UUID | None = Field(default=None, foreign_key="user.id")
-    user: "User" = Relationship(back_populates="folders")
-    flows: list["Flow"] = Relationship(
+    user: User = Relationship(back_populates="folders")
+    flows: list[Flow] = Relationship(
         back_populates="folder", sa_relationship_kwargs={"cascade": "all, delete, delete-orphan"}
     )
 
@@ -47,7 +44,7 @@ class FolderRead(FolderBase):
 class FolderReadWithFlows(FolderBase):
     id: UUID
     parent_id: UUID | None = Field()
-    flows: list["FlowRead"] = Field(default=[])
+    flows: list[FlowRead] = Field(default=[])
 
 
 class FolderUpdate(SQLModel):

src/backend/base/langflow/services/database/models/folder/utils.py

@@ -1,4 +1,3 @@
-from typing import TYPE_CHECKING
 from uuid import UUID
 
 from sqlmodel import Session, and_, select, update
@@ -8,9 +7,6 @@ from langflow.services.database.models.flow.model import Flow
 from .constants import DEFAULT_FOLDER_DESCRIPTION, DEFAULT_FOLDER_NAME
 from .model import Folder
 
-if TYPE_CHECKING:
-    pass
-
 
 def create_default_folder_if_it_doesnt_exist(session: Session, user_id: UUID):
     folder = session.exec(select(Folder).where(Folder.user_id == user_id)).first()

src/backend/base/langflow/services/database/service.py

@@ -26,8 +26,6 @@ from langflow.services.deps import get_settings_service
 from langflow.services.utils import teardown_superuser
 
 if TYPE_CHECKING:
-    from sqlalchemy.engine import Engine
-
     from langflow.services.settings.service import SettingsService
 
 

src/backend/base/langflow/services/deps.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-from collections.abc import Generator
 from contextlib import contextmanager
 from typing import TYPE_CHECKING
 
@@ -9,6 +8,8 @@ from loguru import logger
 from langflow.services.schema import ServiceType
 
 if TYPE_CHECKING:
+    from collections.abc import Generator
+
     from sqlmodel import Session
 
     from langflow.services.cache.service import CacheService

src/backend/base/langflow/services/factory.py

@@ -77,7 +77,7 @@ def import_all_services_into_a_dict():
             for name, obj in inspect.getmembers(module, inspect.isclass):
                 if issubclass(obj, Service) and obj is not Service:
                     services[name] = obj
-                    break
+                    # break
         except Exception as exc:
             logger.exception(exc)
             msg = "Could not initialize services. Please check your settings."

src/backend/base/langflow/services/session/service.py

@@ -1,9 +1,12 @@
 from collections.abc import Coroutine
+from typing import TYPE_CHECKING
 
 from langflow.services.base import Service
-from langflow.services.cache.base import CacheService
 from langflow.services.session.utils import compute_dict_hash, session_id_generator
 
+if TYPE_CHECKING:
+    from langflow.services.cache.base import CacheService
+
 
 class SessionService(Service):
     name = "session_service"

src/backend/base/langflow/services/task/backends/celery.py

@@ -1,11 +1,14 @@
 from collections.abc import Callable
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from celery.result import AsyncResult  # type: ignore
 
 from langflow.services.task.backends.base import TaskBackend
 from langflow.worker import celery_app
 
+if TYPE_CHECKING:
+    from celery import Task
+
 
 class CeleryBackend(TaskBackend):
     name = "celery"
@@ -15,7 +18,6 @@ class CeleryBackend(TaskBackend):
 
     def launch_task(self, task_func: Callable[..., Any], *args: Any, **kwargs: Any) -> tuple[str, AsyncResult]:
         # I need to type the delay method to make it easier
-        from celery import Task  # type: ignore
 
         if not hasattr(task_func, "delay"):
             msg = f"Task function {task_func} does not have a delay method"

src/backend/base/langflow/services/task/service.py

@@ -7,11 +7,11 @@ from loguru import logger
 
 from langflow.services.base import Service
 from langflow.services.task.backends.anyio import AnyIOBackend
-from langflow.services.task.backends.base import TaskBackend
 from langflow.services.task.utils import get_celery_worker_status
 
 if TYPE_CHECKING:
     from langflow.services.settings.service import SettingsService
+    from langflow.services.task.backends.base import TaskBackend
 
 
 def check_celery_availability():

src/backend/base/langflow/services/task/utils.py

@@ -1,7 +1,8 @@
-import contextlib
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
+    import contextlib
+
     with contextlib.suppress(ImportError):
         from celery import Celery  # type: ignore
 

src/backend/base/langflow/services/telemetry/service.py

@@ -9,7 +9,6 @@ from typing import TYPE_CHECKING
 
 import httpx
 from loguru import logger
-from pydantic import BaseModel
 
 from langflow.services.base import Service
 from langflow.services.telemetry.opentelemetry import OpenTelemetry
@@ -23,6 +22,8 @@ from langflow.services.telemetry.schema import (
 from langflow.utils.version import get_version_info
 
 if TYPE_CHECKING:
+    from pydantic import BaseModel
+
     from langflow.services.settings.service import SettingsService
 
 

src/backend/base/langflow/services/tracing/base.py

@@ -1,16 +1,16 @@
 from __future__ import annotations
 
 from abc import ABC, abstractmethod
-from collections.abc import Sequence
 from typing import TYPE_CHECKING, Any
-from uuid import UUID
-
-from langflow.services.tracing.schema import Log
 
 if TYPE_CHECKING:
+    from collections.abc import Sequence
+    from uuid import UUID
+
     from langchain.callbacks.base import BaseCallbackHandler
 
     from langflow.graph.vertex.base import Vertex
+    from langflow.services.tracing.schema import Log
 
 
 class BaseTracer(ABC):

src/backend/base/langflow/services/tracing/langfuse.py

@@ -1,21 +1,22 @@
 from __future__ import annotations
 
 import os
-from collections.abc import Sequence
 from datetime import datetime, timezone
 from typing import TYPE_CHECKING, Any
-from uuid import UUID
 
 from loguru import logger
 
 from langflow.services.tracing.base import BaseTracer
-from langflow.services.tracing.schema import Log
 
 if TYPE_CHECKING:
+    from collections.abc import Sequence
+    from uuid import UUID
+
     from langchain.callbacks.base import BaseCallbackHandler
     from langfuse.client import StatefulSpanClient
 
     from langflow.graph.vertex.base import Vertex
+    from langflow.services.tracing.schema import Log
 
 
 class LangFuseTracer(BaseTracer):

src/backend/base/langflow/services/tracing/langsmith.py

@@ -3,21 +3,22 @@ from __future__ import annotations
 import os
 import traceback
 import types
-from collections.abc import Sequence
 from datetime import datetime, timezone
 from typing import TYPE_CHECKING, Any
-from uuid import UUID
 
 from loguru import logger
 
 from langflow.schema.data import Data
 from langflow.services.tracing.base import BaseTracer
-from langflow.services.tracing.schema import Log
 
 if TYPE_CHECKING:
+    from collections.abc import Sequence
+    from uuid import UUID
+
     from langchain.callbacks.base import BaseCallbackHandler
 
     from langflow.graph.vertex.base import Vertex
+    from langflow.services.tracing.schema import Log
 
 
 class LangSmithTracer(BaseTracer):

src/backend/base/langflow/services/tracing/langwatch.py

@@ -1,21 +1,22 @@
 from __future__ import annotations
 
-from collections.abc import Sequence
 from typing import TYPE_CHECKING, Any, cast
-from uuid import UUID
 
 import nanoid  # type: ignore
 from loguru import logger
 
 from langflow.schema.data import Data
 from langflow.services.tracing.base import BaseTracer
-from langflow.services.tracing.schema import Log
 
 if TYPE_CHECKING:
+    from collections.abc import Sequence
+    from uuid import UUID
+
     from langchain.callbacks.base import BaseCallbackHandler
     from langwatch.tracer import ContextSpan
 
     from langflow.graph.vertex.base import Vertex
+    from langflow.services.tracing.schema import Log
 
 
 class LangWatchTracer(BaseTracer):

src/backend/base/langflow/services/tracing/service.py

@@ -5,20 +5,21 @@ import os
 from collections import defaultdict
 from contextlib import asynccontextmanager
 from typing import TYPE_CHECKING, Any
-from uuid import UUID
 
 from loguru import logger
 
 from langflow.services.base import Service
-from langflow.services.tracing.base import BaseTracer
-from langflow.services.tracing.schema import Log
 
 if TYPE_CHECKING:
+    from uuid import UUID
+
     from langchain.callbacks.base import BaseCallbackHandler
 
     from langflow.custom.custom_component.component import Component
     from langflow.graph.vertex.base import Vertex
     from langflow.services.settings.service import SettingsService
+    from langflow.services.tracing.base import BaseTracer
+    from langflow.services.tracing.schema import Log
 
 
 def _get_langsmith_tracer():

src/backend/base/langflow/services/variable/kubernetes.py

@@ -1,19 +1,24 @@
 from __future__ import annotations
 
 import os
-from uuid import UUID
+from typing import TYPE_CHECKING
 
 from loguru import logger
-from sqlmodel import Session
 
 from langflow.services.auth import utils as auth_utils
 from langflow.services.base import Service
 from langflow.services.database.models.variable.model import Variable, VariableCreate
-from langflow.services.settings.service import SettingsService
 from langflow.services.variable.base import VariableService
 from langflow.services.variable.constants import CREDENTIAL_TYPE, GENERIC_TYPE
 from langflow.services.variable.kubernetes_secrets import KubernetesSecretManager, encode_user_id
 
+if TYPE_CHECKING:
+    from uuid import UUID
+
+    from sqlmodel import Session
+
+    from langflow.services.settings.service import SettingsService
+
 
 class KubernetesSecretService(VariableService, Service):
     def __init__(self, settings_service: SettingsService):

src/backend/base/langflow/services/variable/service.py

@@ -1,10 +1,8 @@
 from __future__ import annotations
 
 import os
-from collections.abc import Sequence
 from datetime import datetime, timezone
 from typing import TYPE_CHECKING
-from uuid import UUID
 
 from fastapi import Depends
 from loguru import logger
@@ -18,6 +16,9 @@ from langflow.services.variable.base import VariableService
 from langflow.services.variable.constants import CREDENTIAL_TYPE, GENERIC_TYPE
 
 if TYPE_CHECKING:
+    from collections.abc import Sequence
+    from uuid import UUID
+
     from langflow.services.settings.service import SettingsService
 
 

src/backend/base/pyproject.toml

@@ -156,6 +156,11 @@ flake8-bugbear.extend-immutable-calls = [
     "fastapi.Query",
     "typer.Option",
 ]
+flake8-type-checking.runtime-evaluated-base-classes = [
+    "pydantic.BaseModel",
+    "typing.TypedDict", # Needed by fastapi
+    "typing_extensions.TypedDict", # Needed by fastapi
+]
 select = [
     "A",
     "ASYNC",
@@ -188,6 +193,7 @@ select = [
     "SIM",
     "SLOT",
     "T10",
+    "TCH",
     "TID",
     "UP",
     "W",
@@ -198,6 +204,11 @@ ignore = [
     "ISC001", # Messes with the formatter
 ]
 
+[tool.ruff.lint.per-file-ignores]
+"langflow/api/v1/*" = [
+    "TCH", # FastAPI needs to evaluate types at runtime
+]
+
 [tool.uv]
 dev-dependencies = [
     "asgi-lifespan>=2.1.0",