chore: Flip default in BaseCache

libs/checkpoint-postgres/uv.lock

@@ -259,7 +259,7 @@ wheels = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "3.0.1"
+version = "4.0.0"
 source = { editable = "../checkpoint" }
 dependencies = [
     { name = "langchain-core" },

libs/checkpoint-sqlite/uv.lock

@@ -246,7 +246,7 @@ wheels = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "3.0.1"
+version = "4.0.0"
 source = { editable = "../checkpoint" }
 dependencies = [
     { name = "langchain-core" },

libs/checkpoint/langgraph/cache/base/__init__.py

@@ -15,7 +15,7 @@ FullKey = tuple[Namespace, str]
 class BaseCache(ABC, Generic[ValueT]):
     """Base class for a cache."""
 
-    serde: SerializerProtocol = JsonPlusSerializer(pickle_fallback=True)
+    serde: SerializerProtocol = JsonPlusSerializer(pickle_fallback=False)
 
     def __init__(self, *, serde: SerializerProtocol | None = None) -> None:
         """Initialize the cache with a serializer."""

libs/checkpoint/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "langgraph-checkpoint"
-version = "3.0.1"
+version = "4.0.0"
 description = "Library with base interfaces for LangGraph checkpoint savers."
 authors = []
 requires-python = ">=3.10"

libs/prebuilt/uv.lock

@@ -355,7 +355,7 @@ test = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "3.0.1"
+version = "4.0.0"
 source = { editable = "../checkpoint" }
 dependencies = [
     { name = "langchain-core" },