Make Channel.from_checkpoint a regular function

- context manager no longer needed since Context became a managed value

libs/langgraph/langgraph/channels/any_value.py

@@ -1,7 +1,5 @@
-from contextlib import contextmanager
-from typing import Generator, Generic, Optional, Sequence, Type
+from typing import Generic, Optional, Sequence, Type
 
-from langchain_core.runnables import RunnableConfig
 from typing_extensions import Self
 
 from langgraph.channels.base import BaseChannel, Value
@@ -28,20 +26,12 @@ def UpdateType(self) -> Type[Value]:
         """The type of the update received by the channel."""
         return self.typ
 
-    @contextmanager
-    def from_checkpoint(
-        self, checkpoint: Optional[Value], config: RunnableConfig
-    ) -> Generator[Self, None, None]:
+    def from_checkpoint(self, checkpoint: Optional[Value]) -> Self:
         empty = self.__class__(self.typ)
+        empty.key = self.key
         if checkpoint is not None:
             empty.value = checkpoint
-        try:
-            yield empty
-        finally:
-            try:
-                del empty.value
-            except AttributeError:
-                pass
+        return empty
 
     def update(self, values: Sequence[Value]) -> bool:
         if len(values) == 0:

libs/langgraph/langgraph/channels/base.py

@@ -1,16 +1,6 @@
 from abc import ABC, abstractmethod
-from contextlib import asynccontextmanager, contextmanager
-from typing import (
-    Any,
-    AsyncIterator,
-    Generic,
-    Iterator,
-    Optional,
-    Sequence,
-    TypeVar,
-)
-
-from langchain_core.runnables import RunnableConfig
+from typing import Any, Generic, Optional, Sequence, TypeVar
+
 from typing_extensions import Self
 
 from langgraph.errors import EmptyChannelError, InvalidUpdateError
@@ -41,38 +31,10 @@ def checkpoint(self) -> Optional[C]:
         or doesn't support checkpoints."""
         return self.get()
 
-    @contextmanager
     @abstractmethod
-    def from_checkpoint(
-        self, checkpoint: Optional[C], config: RunnableConfig
-    ) -> Iterator[Self]:
-        """Return a new identical channel, optionally initialized from a checkpoint.
-        If the checkpoint contains complex data structures, they should be copied."""
-
-    @contextmanager
-    def from_checkpoint_named(
-        self, checkpoint: Optional[C], config: RunnableConfig
-    ) -> Iterator[Self]:
-        with self.from_checkpoint(checkpoint, config) as value:
-            value.key = self.key
-            yield value
-
-    @asynccontextmanager
-    async def afrom_checkpoint(
-        self, checkpoint: Optional[C], config: RunnableConfig
-    ) -> AsyncIterator[Self]:
+    def from_checkpoint(self, checkpoint: Optional[C]) -> Self:
         """Return a new identical channel, optionally initialized from a checkpoint.
         If the checkpoint contains complex data structures, they should be copied."""
-        with self.from_checkpoint(checkpoint, config) as value:
-            yield value
-
-    @asynccontextmanager
-    async def afrom_checkpoint_named(
-        self, checkpoint: Optional[C], config: RunnableConfig
-    ) -> AsyncIterator[Self]:
-        async with self.afrom_checkpoint(checkpoint, config) as value:
-            value.key = self.key
-            yield value
 
     # state methods
 

libs/langgraph/langgraph/channels/binop.py

@@ -1,15 +1,12 @@
 import collections.abc
-from contextlib import contextmanager
 from typing import (
     Callable,
-    Generator,
     Generic,
     Optional,
     Sequence,
     Type,
 )
 
-from langchain_core.runnables import RunnableConfig
 from typing_extensions import NotRequired, Required, Self
 
 from langgraph.channels.base import BaseChannel, Value
@@ -73,20 +70,12 @@ def UpdateType(self) -> Type[Value]:
         """The type of the update received by the channel."""
         return self.typ
 
-    @contextmanager
-    def from_checkpoint(
-        self, checkpoint: Optional[Value], config: RunnableConfig
-    ) -> Generator[Self, None, None]:
+    def from_checkpoint(self, checkpoint: Optional[Value]) -> Self:
         empty = self.__class__(self.typ, self.operator)
+        empty.key = self.key
         if checkpoint is not None:
             empty.value = checkpoint
-        try:
-            yield empty
-        finally:
-            try:
-                del empty.value
-            except AttributeError:
-                pass
+        return empty
 
     def update(self, values: Sequence[Value]) -> bool:
         if not values:

libs/langgraph/langgraph/channels/dynamic_barrier_value.py

@@ -1,7 +1,5 @@
-from contextlib import contextmanager
-from typing import Generator, Generic, NamedTuple, Optional, Sequence, Type, Union
+from typing import Generic, NamedTuple, Optional, Sequence, Type, Union
 
-from langchain_core.runnables import RunnableConfig
 from typing_extensions import Self
 
 from langgraph.channels.base import BaseChannel, Value
@@ -48,22 +46,17 @@ def UpdateType(self) -> Type[Value]:
     def checkpoint(self) -> tuple[Optional[set[Value]], set[Value]]:
         return (self.names, self.seen)
 
-    @contextmanager
     def from_checkpoint(
         self,
         checkpoint: Optional[tuple[Optional[set[Value]], set[Value]]],
-        config: RunnableConfig,
-    ) -> Generator[Self, None, None]:
+    ) -> Self:
         empty = self.__class__(self.typ)
+        empty.key = self.key
         if checkpoint is not None:
             names, seen = checkpoint
-            empty.names = names.copy() if names is not None else None
-            empty.seen = seen.copy()
-
-        try:
-            yield empty
-        finally:
-            pass
+            empty.names = names if names is not None else None
+            empty.seen = seen
+        return empty
 
     def update(self, values: Sequence[Union[Value, WaitForNames]]) -> bool:
         if wait_for_names := [v for v in values if isinstance(v, WaitForNames)]:

libs/langgraph/langgraph/channels/ephemeral_value.py

@@ -1,7 +1,5 @@
-from contextlib import contextmanager
-from typing import Generator, Generic, Optional, Sequence, Type
+from typing import Generic, Optional, Sequence, Type
 
-from langchain_core.runnables import RunnableConfig
 from typing_extensions import Self
 
 from langgraph.channels.base import BaseChannel, Value
@@ -28,20 +26,12 @@ def UpdateType(self) -> Type[Value]:
         """The type of the update received by the channel."""
         return self.typ
 
-    @contextmanager
-    def from_checkpoint(
-        self, checkpoint: Optional[Value], config: RunnableConfig
-    ) -> Generator[Self, None, None]:
+    def from_checkpoint(self, checkpoint: Optional[Value]) -> Self:
         empty = self.__class__(self.typ, self.guard)
+        empty.key = self.key
         if checkpoint is not None:
             empty.value = checkpoint
-        try:
-            yield empty
-        finally:
-            try:
-                del empty.value
-            except AttributeError:
-                pass
+        return empty
 
     def update(self, values: Sequence[Value]) -> bool:
         if len(values) == 0:

libs/langgraph/langgraph/channels/last_value.py

@@ -1,7 +1,5 @@
-from contextlib import contextmanager
-from typing import Generator, Generic, Optional, Sequence, Type
+from typing import Generic, Optional, Sequence, Type
 
-from langchain_core.runnables import RunnableConfig
 from typing_extensions import Self
 
 from langgraph.channels.base import BaseChannel, Value
@@ -27,20 +25,12 @@ def UpdateType(self) -> Type[Value]:
         """The type of the update received by the channel."""
         return self.typ
 
-    @contextmanager
-    def from_checkpoint(
-        self, checkpoint: Optional[Value], config: RunnableConfig
-    ) -> Generator[Self, None, None]:
+    def from_checkpoint(self, checkpoint: Optional[Value]) -> Self:
         empty = self.__class__(self.typ)
+        empty.key = self.key
         if checkpoint is not None:
             empty.value = checkpoint
-        try:
-            yield empty
-        finally:
-            try:
-                del empty.value
-            except AttributeError:
-                pass
+        return empty
 
     def update(self, values: Sequence[Value]) -> bool:
         if len(values) == 0:

libs/langgraph/langgraph/channels/named_barrier_value.py

@@ -1,7 +1,5 @@
-from contextlib import contextmanager
-from typing import Generator, Generic, Optional, Sequence, Type
+from typing import Generic, Optional, Sequence, Type
 
-from langchain_core.runnables import RunnableConfig
 from typing_extensions import Self
 
 from langgraph.channels.base import BaseChannel, Value
@@ -32,18 +30,12 @@ def UpdateType(self) -> Type[Value]:
     def checkpoint(self) -> set[Value]:
         return self.seen
 
-    @contextmanager
-    def from_checkpoint(
-        self, checkpoint: Optional[set[Value]], config: RunnableConfig
-    ) -> Generator[Self, None, None]:
+    def from_checkpoint(self, checkpoint: Optional[set[Value]]) -> Self:
         empty = self.__class__(self.typ, self.names)
+        empty.key = self.key
         if checkpoint is not None:
-            empty.seen = checkpoint.copy()
-
-        try:
-            yield empty
-        finally:
-            pass
+            empty.seen = checkpoint
+        return empty
 
     def update(self, values: Sequence[Value]) -> bool:
         updated = False

libs/langgraph/langgraph/channels/topic.py

@@ -1,7 +1,5 @@
-from contextlib import contextmanager
-from typing import Any, Generator, Generic, Iterator, Optional, Sequence, Type, Union
+from typing import Any, Generic, Iterator, Optional, Sequence, Type, Union
 
-from langchain_core.runnables import RunnableConfig
 from typing_extensions import Self
 
 from langgraph.channels.base import BaseChannel, Value
@@ -53,22 +51,15 @@ def UpdateType(self) -> Any:
     def checkpoint(self) -> tuple[set[Value], list[Value]]:
         return self.values
 
-    @contextmanager
-    def from_checkpoint(
-        self,
-        checkpoint: Optional[list[Value]],
-        config: RunnableConfig,
-    ) -> Generator[Self, None, None]:
+    def from_checkpoint(self, checkpoint: Optional[list[Value]]) -> Self:
         empty = self.__class__(self.typ, self.accumulate)
+        empty.key = self.key
         if checkpoint is not None:
             if isinstance(checkpoint, tuple):
-                empty.values = checkpoint[1].copy()
+                empty.values = checkpoint[1]
             else:
-                empty.values = checkpoint.copy()
-        try:
-            yield empty
-        finally:
-            pass
+                empty.values = checkpoint
+        return empty
 
     def update(self, values: Sequence[Union[Value, list[Value]]]) -> None:
         current = list(self.values)

libs/langgraph/langgraph/channels/untracked_value.py

@@ -1,7 +1,5 @@
-from contextlib import contextmanager
-from typing import Generator, Generic, Optional, Sequence, Type
+from typing import Generic, Optional, Sequence, Type
 
-from langchain_core.runnables import RunnableConfig
 from typing_extensions import Self
 
 from langgraph.channels.base import BaseChannel, Value
@@ -31,18 +29,10 @@ def UpdateType(self) -> Type[Value]:
     def checkpoint(self) -> Value:
         raise EmptyChannelError()
 
-    @contextmanager
-    def from_checkpoint(
-        self, checkpoint: Optional[Value], config: RunnableConfig
-    ) -> Generator[Self, None, None]:
+    def from_checkpoint(self, checkpoint: Optional[Value]) -> Self:
         empty = self.__class__(self.typ, self.guard)
-        try:
-            yield empty
-        finally:
-            try:
-                del empty.value
-            except AttributeError:
-                pass
+        empty.key = self.key
+        return empty
 
     def update(self, values: Sequence[Value]) -> bool:
         if len(values) == 0:

libs/langgraph/langgraph/pregel/manager.py

@@ -42,9 +42,7 @@ def ChannelsManager(
     with ExitStack() as stack:
         yield (
             {
-                k: stack.enter_context(
-                    v.from_checkpoint_named(checkpoint["channel_values"].get(k), config)
-                )
+                k: v.from_checkpoint(checkpoint["channel_values"].get(k))
                 for k, v in channel_specs.items()
             },
             ManagedValueMapping(
@@ -100,11 +98,7 @@ async def AsyncChannelsManager(
         yield (
             # channels: enter each channel with checkpoint
             {
-                k: await stack.enter_async_context(
-                    v.afrom_checkpoint_named(
-                        checkpoint["channel_values"].get(k), config
-                    )
-                )
+                k: v.from_checkpoint(checkpoint["channel_values"].get(k))
                 for k, v in channel_specs.items()
             },
             # managed: build mapping from spec to result