diff --git a/libs/checkpoint-postgres/langgraph/checkpoint/postgres/__init__.py b/libs/checkpoint-postgres/langgraph/checkpoint/postgres/__init__.py
index 54844c824..bf349856e 100644
--- a/libs/checkpoint-postgres/langgraph/checkpoint/postgres/__init__.py
+++ b/libs/checkpoint-postgres/langgraph/checkpoint/postgres/__init__.py
@@ -8,6 +8,7 @@ from typing import Any
 
 from langchain_core.runnables import RunnableConfig
 from langgraph.checkpoint.base import (
+    DELTA_SENTINEL,
     WRITES_IDX_MAP,
     ChannelVersions,
     Checkpoint,
@@ -448,7 +449,15 @@ class PostgresSaver(BasePostgresSaver):
         """
         thread_id = config["configurable"]["thread_id"]
         checkpoint_ns = config["configurable"].get("checkpoint_ns", "")
-        checkpoint_id = config["configurable"]["checkpoint_id"]
+        checkpoint_id = get_checkpoint_id(config)
+        if checkpoint_id is None:
+            # Caller didn't specify a target — resolve to the latest
+            # checkpoint on the thread. `get_tuple` without `checkpoint_id`
+            # returns the newest; its config carries the resolved id.
+            target = self.get_tuple(config)
+            if target is None:
+                return _ChannelWritesHistory(seed=DELTA_SENTINEL, writes=[])
+            checkpoint_id = target.config["configurable"]["checkpoint_id"]
         with self._cursor() as cur:
             cur.execute(SELECT_DELTA_PARENTS_SQL, (channel, thread_id, checkpoint_ns))
             parents_rows = cur.fetchall()
diff --git a/libs/checkpoint-postgres/langgraph/checkpoint/postgres/aio.py b/libs/checkpoint-postgres/langgraph/checkpoint/postgres/aio.py
index dc5a655e1..d76c10bf5 100644
--- a/libs/checkpoint-postgres/langgraph/checkpoint/postgres/aio.py
+++ b/libs/checkpoint-postgres/langgraph/checkpoint/postgres/aio.py
@@ -8,6 +8,7 @@ from typing import Any
 
 from langchain_core.runnables import RunnableConfig
 from langgraph.checkpoint.base import (
+    DELTA_SENTINEL,
     WRITES_IDX_MAP,
     ChannelVersions,
     Checkpoint,
@@ -409,7 +410,12 @@ class AsyncPostgresSaver(BasePostgresSaver):
         """
         thread_id = config["configurable"]["thread_id"]
         checkpoint_ns = config["configurable"].get("checkpoint_ns", "")
-        checkpoint_id = config["configurable"]["checkpoint_id"]
+        checkpoint_id = get_checkpoint_id(config)
+        if checkpoint_id is None:
+            target = await self.aget_tuple(config)
+            if target is None:
+                return _ChannelWritesHistory(seed=DELTA_SENTINEL, writes=[])
+            checkpoint_id = target.config["configurable"]["checkpoint_id"]
         async with self._cursor() as cur:
             await cur.execute(
                 SELECT_DELTA_PARENTS_SQL, (channel, thread_id, checkpoint_ns)
diff --git a/libs/checkpoint-postgres/tests/test_async.py b/libs/checkpoint-postgres/tests/test_async.py
index 9dc5c78cd..e342548a7 100644
--- a/libs/checkpoint-postgres/tests/test_async.py
+++ b/libs/checkpoint-postgres/tests/test_async.py
@@ -361,9 +361,9 @@ async def test_get_checkpoint_no_channel_values(
 
         load_checkpoint_tuple = saver._load_checkpoint_tuple
 
-        async def patched_load_checkpoint_tuple(value, cur):
+        async def patched_load_checkpoint_tuple(value):
             value["checkpoint"].pop("channel_values", None)
-            return await load_checkpoint_tuple(value, cur)
+            return await load_checkpoint_tuple(value)
 
         monkeypatch.setattr(
             saver, "_load_checkpoint_tuple", patched_load_checkpoint_tuple
diff --git a/libs/checkpoint-postgres/tests/test_sync.py b/libs/checkpoint-postgres/tests/test_sync.py
index cc78c615e..63b93715f 100644
--- a/libs/checkpoint-postgres/tests/test_sync.py
+++ b/libs/checkpoint-postgres/tests/test_sync.py
@@ -348,9 +348,9 @@ def test_get_checkpoint_no_channel_values(
 
         load_checkpoint_tuple = saver._load_checkpoint_tuple
 
-        def patched_load_checkpoint_tuple(value, cur):
+        def patched_load_checkpoint_tuple(value):
             value["checkpoint"].pop("channel_values", None)
-            return load_checkpoint_tuple(value, cur)
+            return load_checkpoint_tuple(value)
 
         monkeypatch.setattr(
             saver, "_load_checkpoint_tuple", patched_load_checkpoint_tuple