Lint

libs/langgraph/langgraph/channels/any_value.py

@@ -1,4 +1,4 @@
-from typing import Any, Generic, Optional, Sequence, Type
+from typing import Any, Generic, Sequence, Type
 
 from typing_extensions import Self
 
@@ -30,7 +30,7 @@ class AnyValue(Generic[Value], BaseChannel[Value, Value, Value]):
         """The type of the update received by the channel."""
         return self.typ
 
-    def from_checkpoint(self, checkpoint: Optional[Value]) -> Self:
+    def from_checkpoint(self, checkpoint: Value) -> Self:
         empty = self.__class__(self.typ)
         empty.key = self.key
         if checkpoint is not MISSING:

libs/langgraph/langgraph/channels/base.py

@@ -1,5 +1,5 @@
 from abc import ABC, abstractmethod
-from typing import Any, Generic, Optional, Sequence, TypeVar
+from typing import Any, Generic, Sequence, TypeVar
 
 from typing_extensions import Self
 
@@ -29,14 +29,14 @@ class BaseChannel(Generic[Value, Update, C], ABC):
 
     # serialize/deserialize methods
 
-    def checkpoint(self) -> Optional[C]:
+    def checkpoint(self) -> C:
         """Return a serializable representation of the channel's current state.
         Raises EmptyChannelError if the channel is empty (never updated yet),
         or doesn't support checkpoints."""
         return self.get()
 
     @abstractmethod
-    def from_checkpoint(self, checkpoint: Optional[C]) -> Self:
+    def from_checkpoint(self, checkpoint: C) -> Self:
         """Return a new identical channel, optionally initialized from a checkpoint.
         If the checkpoint contains complex data structures, they should be copied."""
 

libs/langgraph/langgraph/channels/binop.py

@@ -1,11 +1,5 @@
 import collections.abc
-from typing import (
-    Callable,
-    Generic,
-    Optional,
-    Sequence,
-    Type,
-)
+from typing import Callable, Generic, Sequence, Type
 
 from typing_extensions import NotRequired, Required, Self
 
@@ -72,7 +66,7 @@ class BinaryOperatorAggregate(Generic[Value], BaseChannel[Value, Value, Value]):
         """The type of the update received by the channel."""
         return self.typ
 
-    def from_checkpoint(self, checkpoint: Optional[Value]) -> Self:
+    def from_checkpoint(self, checkpoint: Value) -> Self:
         empty = self.__class__(self.typ, self.operator)
         empty.key = self.key
         if checkpoint is not MISSING:

libs/langgraph/langgraph/channels/dynamic_barrier_value.py

@@ -50,8 +50,7 @@ class DynamicBarrierValue(
         return (self.names, self.seen)
 
     def from_checkpoint(
-        self,
-        checkpoint: Optional[tuple[Optional[set[Value]], set[Value]]],
+        self, checkpoint: tuple[Optional[set[Value]], set[Value]]
     ) -> Self:
         empty = self.__class__(self.typ)
         empty.key = self.key

libs/langgraph/langgraph/channels/ephemeral_value.py

@@ -1,4 +1,4 @@
-from typing import Any, Generic, Optional, Sequence, Type
+from typing import Any, Generic, Sequence, Type
 
 from typing_extensions import Self
 
@@ -30,7 +30,7 @@ class EphemeralValue(Generic[Value], BaseChannel[Value, Value, Value]):
         """The type of the update received by the channel."""
         return self.typ
 
-    def from_checkpoint(self, checkpoint: Optional[Value]) -> Self:
+    def from_checkpoint(self, checkpoint: Value) -> Self:
         empty = self.__class__(self.typ, self.guard)
         empty.key = self.key
         if checkpoint is not MISSING:

libs/langgraph/langgraph/channels/last_value.py

@@ -1,4 +1,4 @@
-from typing import Any, Generic, Optional, Sequence, Type
+from typing import Any, Generic, Sequence, Type
 
 from typing_extensions import Self
 
@@ -34,7 +34,7 @@ class LastValue(Generic[Value], BaseChannel[Value, Value, Value]):
         """The type of the update received by the channel."""
         return self.typ
 
-    def from_checkpoint(self, checkpoint: Optional[Value]) -> Self:
+    def from_checkpoint(self, checkpoint: Value) -> Self:
         empty = self.__class__(self.typ)
         empty.key = self.key
         if checkpoint is not MISSING:

libs/langgraph/langgraph/channels/named_barrier_value.py

@@ -1,4 +1,4 @@
-from typing import Generic, Optional, Sequence, Type
+from typing import Generic, Sequence, Type
 
 from typing_extensions import Self
 
@@ -36,7 +36,7 @@ class NamedBarrierValue(Generic[Value], BaseChannel[Value, Value, set[Value]]):
     def checkpoint(self) -> set[Value]:
         return self.seen
 
-    def from_checkpoint(self, checkpoint: Optional[set[Value]]) -> Self:
+    def from_checkpoint(self, checkpoint: set[Value]) -> Self:
         empty = self.__class__(self.typ, self.names)
         empty.key = self.key
         if checkpoint is not MISSING:

libs/langgraph/langgraph/channels/topic.py

@@ -1,4 +1,4 @@
-from typing import Any, Generic, Iterator, Optional, Sequence, Type, Union
+from typing import Any, Generic, Iterator, Sequence, Type, Union
 
 from typing_extensions import Self
 
@@ -17,9 +17,7 @@ def flatten(values: Sequence[Union[Value, list[Value]]]) -> Iterator[Value]:
 
 class Topic(
     Generic[Value],
-    BaseChannel[
-        Sequence[Value], Union[Value, list[Value]], tuple[set[Value], list[Value]]
-    ],
+    BaseChannel[Sequence[Value], Union[Value, list[Value]], list[Value]],
 ):
     """A configurable PubSub Topic.
 
@@ -50,14 +48,15 @@ class Topic(
         """The type of the update received by the channel."""
         return Union[self.typ, list[self.typ]]  # type: ignore[name-defined]
 
-    def checkpoint(self) -> tuple[set[Value], list[Value]]:
+    def checkpoint(self) -> list[Value]:
         return self.values
 
-    def from_checkpoint(self, checkpoint: Optional[list[Value]]) -> Self:
+    def from_checkpoint(self, checkpoint: list[Value]) -> Self:
         empty = self.__class__(self.typ, self.accumulate)
         empty.key = self.key
         if checkpoint is not MISSING:
             if isinstance(checkpoint, tuple):
+                # backwards compatibility
                 empty.values = checkpoint[1]
             else:
                 empty.values = checkpoint

libs/langgraph/langgraph/channels/untracked_value.py

@@ -1,4 +1,4 @@
-from typing import Generic, Optional, Sequence, Type
+from typing import Generic, Sequence, Type
 
 from typing_extensions import Self
 
@@ -33,7 +33,7 @@ class UntrackedValue(Generic[Value], BaseChannel[Value, Value, Value]):
     def checkpoint(self) -> Value:
         raise EmptyChannelError()
 
-    def from_checkpoint(self, checkpoint: Optional[Value]) -> Self:
+    def from_checkpoint(self, checkpoint: Value) -> Self:
         empty = self.__class__(self.typ, self.guard)
         empty.key = self.key
         return empty

libs/langgraph/langgraph/utils/future.py

@@ -164,7 +164,7 @@ def _ensure_future(
         elif EAGER_NOT_SUPPORTED or lazy:
             return loop.create_task(coro_or_future, name=name, context=context)
         else:
-            return asyncio.eager_task_factory(
+            return asyncio.eager_task_factory(  # type:ignore[attr-defined]
                 loop, coro_or_future, name=name, context=context
             )
     except RuntimeError: