release(langgraph): 1.2.21 (#9683)

Bumps langgraph from 1.2.20 to 1.2.21.

Includes:

- Read a checkpoint namespace the graph doesn't declare, such as a
deepagents subagent's `tools:<task_id>`, with the parent graph instead
of raising `Subgraph tools not found`. The Python Agent Server no longer
returns 400 on `/history?checkpoint_ns=...` for these. Updates to such a
namespace still raise (#9614)
- Match whole namespace segments in `get_subgraphs` / `aget_subgraphs`.
With `namespace=` and `recurse=True` they now yield only the subgraph at
that namespace, and so does the Agent Server's `GET
/assistants/{id}/subgraphs/{namespace}?recurse=true` (#9615)
- Say each `interrupt()` call has its own id in the
`UnknownInterruptError` docstring (#9600)

libs/langgraph/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "langgraph"
-version = "1.2.20"
+version = "1.2.21"
 description = "Building stateful, multi-actor applications with LLMs"
 authors = []
 requires-python = ">=3.10"

libs/langgraph/uv.lock

@@ -1440,7 +1440,7 @@ wheels = [
 
 [[package]]
 name = "langgraph"
-version = "1.2.20"
+version = "1.2.21"
 source = { editable = "." }
 dependencies = [
     { name = "langchain-core" },

libs/prebuilt/uv.lock

@@ -381,7 +381,7 @@ wheels = [
 
 [[package]]
 name = "langgraph"
-version = "1.2.20"
+version = "1.2.21"
 source = { editable = "../langgraph" }
 dependencies = [
     { name = "langchain-core" },

libs/sdk-py/uv.lock

@@ -394,7 +394,7 @@ wheels = [
 
 [[package]]
 name = "langgraph"
-version = "1.2.20"
+version = "1.2.21"
 source = { editable = "../langgraph" }
 dependencies = [
     { name = "langchain-core" },