Fix up

libs/langgraph/langgraph/pregel/debug.py

@@ -32,6 +32,7 @@ from langgraph.constants import (
 from langgraph.pregel.io import read_channels
 from langgraph.pregel.utils import find_subgraph_pregel
 from langgraph.types import PregelExecutableTask, PregelTask, StateSnapshot
+from langgraph.utils.config import patch_checkpoint_map
 
 
 class TaskPayload(TypedDict):
@@ -177,8 +178,9 @@ def map_debug_checkpoint(
         "timestamp": checkpoint["ts"],
         "step": step,
         "payload": {
-            "config": config,
+            "config": patch_checkpoint_map(config, metadata),
             "parent_config": parent_config,
+            # "parent_config": patch_checkpoint_map(parent_config, metadata),
             "values": read_channels(channels, stream_channels),
             "metadata": metadata,
             "next": [t.name for t in tasks],

libs/langgraph/langgraph/pregel/loop.py

@@ -101,7 +101,7 @@ from langgraph.pregel.read import PregelNode
 from langgraph.pregel.utils import get_new_channel_versions
 from langgraph.store.base import BaseStore
 from langgraph.types import All, PregelExecutableTask, StreamMode
-from langgraph.utils.config import patch_checkpoint_map, patch_configurable
+from langgraph.utils.config import patch_configurable
 
 V = TypeVar("V")
 P = ParamSpec("P")
@@ -176,7 +176,6 @@ class PregelLoop:
     checkpoint_pending_writes: List[PendingWrite]
     checkpoint_previous_versions: dict[str, Union[str, float, int]]
     prev_checkpoint_config: Optional[RunnableConfig]
-    prev_checkpoint_metadata: Optional[CheckpointMetadata]
 
     step: int
     stop: int
@@ -363,16 +362,14 @@ class PregelLoop:
                 "debug",
                 map_debug_checkpoint,
                 self.step - 1,  # printing checkpoint for previous step
-                patch_checkpoint_map(self.checkpoint_config, self.checkpoint_metadata),
+                self.checkpoint_config,
                 self.channels,
                 self.stream_keys,
                 self.checkpoint_metadata,
                 self.checkpoint,
                 self.tasks.values(),
                 self.checkpoint_pending_writes,
-                patch_checkpoint_map(
-                    self.prev_checkpoint_config, self.prev_checkpoint_metadata
-                ),
+                self.prev_checkpoint_config,
                 self.output_keys,
             )
 
@@ -505,7 +502,7 @@ class PregelLoop:
             )
 
     def _put_checkpoint(self, metadata: CheckpointMetadata) -> None:
-        # assign step
+        # assign step and parents
         metadata["step"] = self.step
         metadata["parents"] = self.config[CONF].get(CONFIG_KEY_CHECKPOINT_MAP, {})
         # debug flag
@@ -521,7 +518,6 @@ class PregelLoop:
         self.checkpoint = create_checkpoint(self.checkpoint, self.channels, self.step)
         # bail if no checkpointer
         if self._checkpointer_put_after_previous is not None:
-            self.prev_checkpoint_metadata = self.checkpoint_metadata
             self.checkpoint_metadata = metadata
 
             self.prev_checkpoint_config = (

libs/langgraph/langgraph/utils/config.py

@@ -36,9 +36,11 @@ def patch_configurable(
 
 
 def patch_checkpoint_map(
-    config: RunnableConfig, metadata: Optional[CheckpointMetadata]
+    config: Optional[RunnableConfig], metadata: Optional[CheckpointMetadata]
 ) -> RunnableConfig:
-    if parents := (metadata.get("parents") if metadata else None):
+    if config is None:
+        return config
+    elif parents := (metadata.get("parents") if metadata else None):
         conf = config[CONF]
         return patch_configurable(
             config,

libs/langgraph/tests/test_pregel.py

@@ -11917,7 +11917,6 @@ def test_debug_nested_subgraphs():
         clean_config["thread_id"] = config["configurable"]["thread_id"]
         clean_config["checkpoint_id"] = config["configurable"]["checkpoint_id"]
         clean_config["checkpoint_ns"] = config["configurable"]["checkpoint_ns"]
-        clean_config["checkpoint_map"] = config["configurable"]["checkpoint_map"]
         if "checkpoint_map" in config["configurable"]:
             clean_config["checkpoint_map"] = config["configurable"]["checkpoint_map"]