fix(langgraph): stop at an interrupt_before breakpoint when a drain is requested before it

At a step boundary, tick() checked for a drain before the interrupt_before
breakpoints. A drain requested in the step before a breakpoint stopped the
run with GraphDrained, and the resume after it (invoke(None, config)) marks
the next step's breakpoints as passed, so the breakpoint never fired. The
drain check now runs after the breakpoint check, so the run stops at the
breakpoint as it would have without the drain. Subgraph breakpoints share
the fix, since subgraphs share the run's control.

libs/checkpoint-conformance/langgraph/checkpoint/conformance/spec/test_delta_channel_history.py

@@ -267,6 +267,61 @@ async def test_history_seed_ancestor_own_writes_are_replayed(
     )
 
 
+# Every uuid4 `build_delta_chain` tags its own writes with sorts between these
+# two, so task_id order is fixed and always disagrees with task_path order.
+TASK_ID_SORTS_FIRST = "00000000-0000-0000-0000-000000000000"
+TASK_ID_SORTS_LAST = "ffffffff-ffff-ffff-ffff-ffffffffffff"
+
+
+async def test_history_orders_parallel_writes_by_task_path(
+    saver: BaseCheckpointSaver,
+) -> None:
+    """Writes from parallel tasks replay in task_path order, not task_id order."""
+    configs = await build_delta_chain(
+        saver,
+        thread_id=str(uuid4()),
+        channel="ch",
+        snapshots_at_steps=[0],
+        total_steps=3,
+    )
+    step_1, head = configs[1], configs[2]
+    await saver.aput_writes(
+        step_1, [("ch", "second")], TASK_ID_SORTS_FIRST, "~pull, 02"
+    )
+    await saver.aput_writes(step_1, [("ch", "first")], TASK_ID_SORTS_LAST, "~pull, 01")
+
+    result = await saver.aget_delta_channel_history(config=head, channels=["ch"])
+    values = [w[2] for w in result["ch"]["writes"]]
+    assert values == [1, "first", "second"], (
+        f"Expected task_path order [1, 'first', 'second'], got {values}. "
+        "Ordering by (task_id, idx) alone yields [1, 'second', 'first']."
+    )
+
+
+async def test_history_orders_pathless_writes_first(
+    saver: BaseCheckpointSaver,
+) -> None:
+    """Writes stored without a task_path (graph input) replay before task writes."""
+    configs = await build_delta_chain(
+        saver,
+        thread_id=str(uuid4()),
+        channel="ch",
+        snapshots_at_steps=[0],
+        total_steps=3,
+    )
+    step_1, head = configs[1], configs[2]
+    await saver.aput_writes(
+        step_1, [("ch", "from_node")], TASK_ID_SORTS_FIRST, "~pull, a"
+    )
+    await saver.aput_writes(step_1, [("ch", "from_input")], TASK_ID_SORTS_LAST)
+
+    result = await saver.aget_delta_channel_history(config=head, channels=["ch"])
+    values = [w[2] for w in result["ch"]["writes"]]
+    assert values == [1, "from_input", "from_node"], (
+        f"Expected pathless writes first, got {values}"
+    )
+
+
 ALL_DELTA_CHANNEL_HISTORY_TESTS = [
     test_history_returns_writes_oldest_first,
     test_history_seed_is_nearest_snapshot,
@@ -276,6 +331,8 @@ ALL_DELTA_CHANNEL_HISTORY_TESTS = [
     test_history_walk_to_root_no_seed,
     test_history_migration_plain_value_as_seed,
     test_history_seed_ancestor_own_writes_are_replayed,
+    test_history_orders_parallel_writes_by_task_path,
+    test_history_orders_pathless_writes_first,
 ]
 
 

libs/checkpoint-conformance/langgraph/checkpoint/conformance/spec/test_get_tuple.py

@@ -176,6 +176,35 @@ async def test_get_tuple_pending_writes(saver: BaseCheckpointSaver) -> None:
     )
 
 
+async def test_get_tuple_pending_writes_in_writes_sort_key_order(
+    saver: BaseCheckpointSaver,
+) -> None:
+    """pending_writes come back in writes_sort_key order, not put or task_id order."""
+    config = generate_config(str(uuid4()))
+    stored = await saver.aput(config, generate_checkpoint(), generate_metadata(), {})
+    await saver.aput_writes(
+        stored, [("ch", "b")], "00000000-0000-0000-0000-000000000000", "~pull, 02"
+    )
+    await saver.aput_writes(
+        stored,
+        [("ch", "a1"), ("ch", "a2")],
+        "ffffffff-ffff-ffff-ffff-ffffffffffff",
+        "~pull, 01",
+    )
+    await saver.aput_writes(
+        stored, [("ch", "input")], "88888888-8888-8888-8888-888888888888"
+    )
+
+    tup = await saver.aget_tuple(stored)
+    assert tup is not None
+    values = [w[2] for w in tup.pending_writes or []]
+    assert values == ["input", "a1", "a2", "b"], (
+        f"Expected writes_sort_key order ['input', 'a1', 'a2', 'b'], got {values}. "
+        "Put order gives ['b', 'a1', 'a2', 'input'], task_id order gives "
+        "['b', 'input', 'a1', 'a2']."
+    )
+
+
 async def test_get_tuple_respects_namespace(saver: BaseCheckpointSaver) -> None:
     """checkpoint_ns filtering."""
     tid = str(uuid4())
@@ -223,6 +252,7 @@ ALL_GET_TUPLE_TESTS = [
     test_get_tuple_metadata,
     test_get_tuple_parent_config,
     test_get_tuple_pending_writes,
+    test_get_tuple_pending_writes_in_writes_sort_key_order,
     test_get_tuple_respects_namespace,
     test_get_tuple_nonexistent_checkpoint_id,
 ]

libs/checkpoint-conformance/tests/test_validate_memory.py

@@ -14,8 +14,8 @@ async def memory_checkpointer():
 
 
 @pytest.mark.asyncio
-async def test_validate_memory_base():
-    """InMemorySaver passes all base capability tests."""
+async def test_validate_memory():
+    """InMemorySaver passes the tests of every capability it implements."""
     report = await validate(memory_checkpointer)
     report.print_report()
-    assert report.passed_all_base(), f"Base tests failed: {report.to_dict()}"
+    assert report.passed_all(), f"Capability tests failed: {report.to_dict()}"

libs/checkpoint-conformance/uv.lock

@@ -279,7 +279,7 @@ wheels = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "4.2.0"
+version = "4.3.0"
 source = { editable = "../checkpoint" }
 dependencies = [
     { name = "langchain-core" },

libs/checkpoint-postgres/langgraph/checkpoint/postgres/__init__.py

@@ -451,7 +451,8 @@ class PostgresSaver(BasePostgresSaver):
         * Stage 1 (paged): dynamic SELECT over `checkpoints` with three
           columns per channel: its version, an `EXISTS` probe for a stored
           blob at that version, and its inline value. Pages newest-first by
-          `checkpoint_id` with a cursor; page size is `_DELTA_PAGE_SIZE`.
+          `checkpoint_id`, starting at the target; page size is
+          `_DELTA_PAGE_SIZE`.
           Stops paging when every channel has found its seed or a page comes
           back short.
 
@@ -468,7 +469,7 @@ class PostgresSaver(BasePostgresSaver):
         thread_id = config["configurable"]["thread_id"]
         checkpoint_ns = config["configurable"].get("checkpoint_ns", "")
         checkpoint_id = get_checkpoint_id(config)
-        if checkpoint_id is None:
+        if not checkpoint_id:
             target = self.get_tuple(config)
             if target is None:
                 return {ch: {"writes": []} for ch in channels}
@@ -476,7 +477,7 @@ class PostgresSaver(BasePostgresSaver):
 
         # Stage 1: paged K-JSONB-lookup scan, walking the parent chain in
         # Python after each page. Stops as soon as every channel has its seed.
-        stage1_sql = _build_delta_stage1_sql(channels, paged=True)
+        stage1_sql = _build_delta_stage1_sql(channels, paged=True, include_cursor=True)
         parent_of: dict[str, str | None] = {}
         ver_by_i_by_cid: list[dict[str, str | None]] = [{} for _ in channels]
         hb_by_i_by_cid: list[dict[str, bool]] = [{} for _ in channels]
@@ -486,7 +487,7 @@ class PostgresSaver(BasePostgresSaver):
         seed_inline_by_ch: dict[str, Any] = {}
         walk_cursor_by_ch: dict[str, str | None] = {}
         seeded: set[str] = set()
-        cursor: str | None = None
+        cursor: str | None = checkpoint_id
 
         with self._cursor() as cur:
             while True:
@@ -495,7 +496,7 @@ class PostgresSaver(BasePostgresSaver):
                     # ver_i, blob channel, blob version, inline_i
                     stage1_params.extend([ch, ch, ch, ch])
                 stage1_params.extend(
-                    [thread_id, checkpoint_ns, cursor, cursor, _DELTA_PAGE_SIZE]
+                    [thread_id, checkpoint_ns, cursor, _DELTA_PAGE_SIZE]
                 )
                 cur.execute(stage1_sql, stage1_params)
                 page = cur.fetchall()
@@ -527,6 +528,7 @@ class PostgresSaver(BasePostgresSaver):
                 if len(seeded) == len(channels) or len(page) < _DELTA_PAGE_SIZE:
                     break
                 cursor = oldest
+                stage1_sql = _build_delta_stage1_sql(channels, paged=True)
 
         # Stage 2: per-channel UNION ALL — one writes branch per channel
         # with non-empty chain, plus one blob branch per seeded channel.

libs/checkpoint-postgres/langgraph/checkpoint/postgres/aio.py

@@ -417,13 +417,13 @@ class AsyncPostgresSaver(BasePostgresSaver):
         thread_id = config["configurable"]["thread_id"]
         checkpoint_ns = config["configurable"].get("checkpoint_ns", "")
         checkpoint_id = get_checkpoint_id(config)
-        if checkpoint_id is None:
+        if not checkpoint_id:
             target = await self.aget_tuple(config)
             if target is None:
                 return {ch: {"writes": []} for ch in channels}
             checkpoint_id = target.config["configurable"]["checkpoint_id"]
 
-        stage1_sql = _build_delta_stage1_sql(channels, paged=True)
+        stage1_sql = _build_delta_stage1_sql(channels, paged=True, include_cursor=True)
         parent_of: dict[str, str | None] = {}
         ver_by_i_by_cid: list[dict[str, str | None]] = [{} for _ in channels]
         hb_by_i_by_cid: list[dict[str, bool]] = [{} for _ in channels]
@@ -433,7 +433,7 @@ class AsyncPostgresSaver(BasePostgresSaver):
         seed_inline_by_ch: dict[str, Any] = {}
         walk_cursor_by_ch: dict[str, str | None] = {}
         seeded: set[str] = set()
-        cursor: str | None = None
+        cursor: str | None = checkpoint_id
 
         async with self._cursor() as cur:
             while True:
@@ -442,7 +442,7 @@ class AsyncPostgresSaver(BasePostgresSaver):
                     # ver_i, blob channel, blob version, inline_i
                     stage1_params.extend([ch, ch, ch, ch])
                 stage1_params.extend(
-                    [thread_id, checkpoint_ns, cursor, cursor, _DELTA_PAGE_SIZE]
+                    [thread_id, checkpoint_ns, cursor, _DELTA_PAGE_SIZE]
                 )
                 await cur.execute(stage1_sql, stage1_params)
                 page = await cur.fetchall()
@@ -472,6 +472,7 @@ class AsyncPostgresSaver(BasePostgresSaver):
                 if len(seeded) == len(channels) or len(page) < _DELTA_PAGE_SIZE:
                     break
                 cursor = oldest
+                stage1_sql = _build_delta_stage1_sql(channels, paged=True)
 
         channels_with_chain = [ch for ch in channels if chain_by_ch[ch]]
         channels_with_seed = [ch for ch in channels if seed_ver_by_ch[ch] is not None]
@@ -687,5 +688,23 @@ class AsyncPostgresSaver(BasePostgresSaver):
             self.adelete_thread(thread_id), self.loop
         ).result()
 
+    def get_delta_channel_history(
+        self, *, config: RunnableConfig, channels: Sequence[str]
+    ) -> Mapping[str, DeltaChannelHistory]:
+        """Sync bridge to `aget_delta_channel_history`, guarded like `get_tuple`."""
+        try:
+            if asyncio.get_running_loop() is self.loop:
+                raise asyncio.InvalidStateError(
+                    "Synchronous calls to AsyncPostgresSaver are only allowed from a "
+                    "different thread. From the main thread, use the async interface. "
+                    "For example, use `await checkpointer.aget_delta_channel_history(...)`."
+                )
+        except RuntimeError:
+            pass
+        return asyncio.run_coroutine_threadsafe(
+            self.aget_delta_channel_history(config=config, channels=channels),
+            self.loop,
+        ).result()
+
 
 __all__ = ["AsyncPostgresSaver", "AsyncShallowPostgresSaver", "Conn"]

libs/checkpoint-postgres/langgraph/checkpoint/postgres/base.py

@@ -14,6 +14,7 @@ from langgraph.checkpoint.base import (
     DeltaChannelHistory,
     PendingWrite,
     get_checkpoint_id,
+    writes_sort_key,
 )
 from langgraph.checkpoint.serde.types import TASKS
 from psycopg.types.json import Jsonb
@@ -109,7 +110,7 @@ select
     ) as channel_values,
     (
         select
-        array_agg(array[cw.task_id::text::bytea, cw.channel::bytea, cw.type::bytea, cw.blob] order by cw.task_id, cw.idx)
+        array_agg(array[cw.task_id::text::bytea, cw.channel::bytea, cw.type::bytea, cw.blob, convert_to(cw.task_path, 'UTF8'), cw.idx::text::bytea])
         from checkpoint_writes cw
         where cw.thread_id = checkpoints.thread_id
             and cw.checkpoint_ns = checkpoints.checkpoint_ns
@@ -168,6 +169,7 @@ class _DeltaStage2Row(TypedDict, total=False):
     type: str | None
     blob: bytes | None
     task_id: str | None  # "w" rows only
+    task_path: str | None  # "w" rows only
     idx: int | None  # "w" rows only
     version: str | None  # "b" rows only
 
@@ -176,10 +178,13 @@ class _DeltaStage2Row(TypedDict, total=False):
 # `_build_delta_stage2_sql` document their shapes.
 
 
-def _build_delta_stage1_sql(channels: Sequence[str], *, paged: bool) -> str:
+def _build_delta_stage1_sql(
+    channels: Sequence[str], *, paged: bool, include_cursor: bool = False
+) -> str:
     """Build stage 1 SQL with K parallel version lookups + seed probes.
 
-    For channels=["messages", "files"] (with `paged=True`) the result is::
+    For channels=["messages", "files"] (with `paged=True, include_cursor=True`)
+    the result is::
 
         SELECT checkpoint_id, parent_checkpoint_id,
                checkpoint -> 'channel_versions' ->> %s AS ver_0,
@@ -195,7 +200,7 @@ def _build_delta_stage1_sql(channels: Sequence[str], *, paged: bool) -> str:
                checkpoint -> 'channel_values' -> %s AS inline_1
         FROM checkpoints
         WHERE thread_id = %s AND checkpoint_ns = %s
-          AND (%s::text IS NULL OR checkpoint_id < %s)
+          AND checkpoint_id <= %s
         ORDER BY checkpoint_id DESC
         LIMIT %s
 
@@ -236,9 +241,16 @@ def _build_delta_stage1_sql(channels: Sequence[str], *, paged: bool) -> str:
     and uses safe identifiers).
 
     Caller must extend params with `[ch_0 x4, ch_1 x4, ..., thread_id, ns,
-    cursor, cursor, page_size]` when `paged=True` — four per channel: the
-    version lookup, the blob's channel, the version the blob must match, and the
-    inline lookup.
+    cursor, page_size]` when `paged=True` — four per channel: the version
+    lookup, the blob's channel, the version the blob must match, and the inline
+    lookup.
+
+    Pages run newest-first from the target down. The first page passes the
+    target as the cursor with `include_cursor=True`, so it opens with the
+    target's own row, whose parent starts the walk; each later page continues
+    below the oldest row read. A checkpoint's ancestors have smaller ids (uuid6
+    is time-ordered, which `get_tuple` also relies on to find the latest
+    checkpoint), so no row newer than the target is part of its chain.
 
     When `paged=False`, the WHERE has no cursor predicate and there's no
     LIMIT/ORDER BY — kept as a non-public helper for tests/diagnostics.
@@ -262,7 +274,7 @@ def _build_delta_stage1_sql(channels: Sequence[str], *, paged: bool) -> str:
     )
     if paged:
         sql += (
-            " AND (%s::text IS NULL OR checkpoint_id < %s)"
+            f" AND checkpoint_id {'<=' if include_cursor else '<'} %s"
             " ORDER BY checkpoint_id DESC LIMIT %s"
         )
     return sql
@@ -297,7 +309,7 @@ def _build_delta_stage2_sql(
         branches.append(
             "SELECT 'w'::text AS _kind, "
             "checkpoint_id, channel, "
-            "type, blob, task_id, idx, NULL::text AS version "
+            "type, blob, task_id, task_path, idx, NULL::text AS version "
             "FROM checkpoint_writes "
             "WHERE thread_id = %s AND checkpoint_ns = %s AND channel = %s "
             "AND checkpoint_id = ANY(%s)"
@@ -305,7 +317,8 @@ def _build_delta_stage2_sql(
     for _ in channels_with_seed:
         branches.append(
             "SELECT 'b'::text AS _kind, NULL::text AS checkpoint_id, channel, "
-            "type, blob, NULL::text AS task_id, NULL::int AS idx, version "
+            "type, blob, NULL::text AS task_id, NULL::text AS task_path, "
+            "NULL::int AS idx, version "
             "FROM checkpoint_blobs "
             "WHERE thread_id = %s AND checkpoint_ns = %s AND channel = %s "
             "AND version = %s"
@@ -410,8 +423,8 @@ class BasePostgresSaver(BaseCheckpointSaver[str]):
               materialized at this point),
           (c) the next ancestor cid isn't in `parent_of` yet (waiting for
               a later page; the cursor stays put), or
-          (d) the target's own row isn't in `parent_of` yet (the walk has
-              not started; no cursor is set, so a later page retries).
+          (d) the target's own row isn't in `parent_of` (the target doesn't
+              exist, so the walk never starts).
 
         Mutates `chain_by_ch`, `seed_ver_by_ch`, `seed_inline_by_ch`,
         `walk_cursor_by_ch`, and `seeded` in place.
@@ -419,8 +432,9 @@ class BasePostgresSaver(BaseCheckpointSaver[str]):
         for i, ch in enumerate(channels):
             if ch in seeded:
                 continue
-            # Pages start at the thread head, so the target may not have
-            # loaded yet; a `None` cursor would read as "target is a root".
+            # The first page opens with the target's row, so it's missing only
+            # when the target doesn't exist; a `None` cursor would read as
+            # "target is a root".
             if ch not in walk_cursor_by_ch:
                 if target_id not in parent_of:
                     continue
@@ -473,10 +487,11 @@ class BasePostgresSaver(BaseCheckpointSaver[str]):
         stored value, or when the seed blob is sentinel "empty" — in both cases
         the consumer treats absence as "start empty".
         """
-        # writes_by_ch_by_cid[channel][cid] = list of (type, blob, task_id, idx)
-        writes_by_ch_by_cid: dict[str, dict[str, list[tuple[str, bytes, str, int]]]] = {
-            ch: {} for ch in channels
-        }
+        # writes_by_ch_by_cid[channel][cid] = list of
+        # (type, blob, task_id, idx, task_path)
+        writes_by_ch_by_cid: dict[
+            str, dict[str, list[tuple[str, bytes, str, int, str]]]
+        ] = {ch: {} for ch in channels}
         # seed_blob_by_ver[(channel, version)] = (type, blob)
         seed_blob_by_ver: dict[tuple[str, str], tuple[str, bytes]] = {}
 
@@ -487,8 +502,14 @@ class BasePostgresSaver(BaseCheckpointSaver[str]):
                 cid = cast(str, r["checkpoint_id"])
                 writes_by_ch_by_cid.setdefault(ch, {}).setdefault(cid, []).append(
                     cast(
-                        "tuple[str, bytes, str, int]",
-                        (r["type"], r["blob"], r["task_id"], r["idx"]),
+                        "tuple[str, bytes, str, int, str]",
+                        (
+                            r["type"],
+                            r["blob"],
+                            r["task_id"],
+                            r["idx"],
+                            r["task_path"],
+                        ),
                     )
                 )
             else:  # kind == "b"
@@ -497,10 +518,10 @@ class BasePostgresSaver(BaseCheckpointSaver[str]):
                     "tuple[str, bytes]", (r["type"], r["blob"])
                 )
 
-        # Sort writes per (channel, cid) newest-first by (task_id, idx)
+        # Sort writes per (channel, cid) newest-first
         for cid_map in writes_by_ch_by_cid.values():
             for ws in cid_map.values():
-                ws.sort(key=lambda w: (w[2], w[3]), reverse=True)
+                ws.sort(key=lambda w: writes_sort_key(w[4], w[2], w[3]), reverse=True)
 
         result: dict[str, DeltaChannelHistory] = {}
         for ch in channels:
@@ -510,7 +531,9 @@ class BasePostgresSaver(BaseCheckpointSaver[str]):
             collected: list[PendingWrite] = []
             cid_writes = writes_by_ch_by_cid.get(ch, {})
             for cid in chain_cids:
-                for type_tag, write_blob, task_id, _idx in cid_writes.get(cid, []):
+                for type_tag, write_blob, task_id, _idx, _path in cid_writes.get(
+                    cid, []
+                ):
                     val = self.serde.loads_typed((type_tag, write_blob))
                     collected.append((task_id, ch, val))
             collected.reverse()
@@ -553,20 +576,15 @@ class BasePostgresSaver(BaseCheckpointSaver[str]):
         ]
 
     def _load_writes(
-        self, writes: list[tuple[bytes, bytes, bytes, bytes]]
+        self, writes: list[tuple[bytes, bytes, bytes, bytes, bytes, bytes]] | None
     ) -> list[tuple[str, str, Any]]:
-        return (
-            [
-                (
-                    tid.decode(),
-                    channel.decode(),
-                    self.serde.loads_typed((t.decode(), v)),
-                )
-                for tid, channel, t, v in writes
-            ]
-            if writes
-            else []
-        )
+        return [
+            (tid.decode(), channel.decode(), self.serde.loads_typed((t.decode(), v)))
+            for tid, channel, t, v, _, _ in sorted(
+                writes or [],
+                key=lambda w: writes_sort_key(w[4].decode(), w[0].decode(), int(w[5])),
+            )
+        ]
 
     def _dump_writes(
         self,

libs/checkpoint-postgres/langgraph/checkpoint/postgres/shallow.py

@@ -97,7 +97,7 @@ select
     ) as channel_values,
     (
         select
-        array_agg(array[cw.task_id::text::bytea, cw.channel::bytea, cw.type::bytea, cw.blob] order by cw.task_id, cw.idx)
+        array_agg(array[cw.task_id::text::bytea, cw.channel::bytea, cw.type::bytea, cw.blob, convert_to(cw.task_path, 'UTF8'), cw.idx::text::bytea])
         from checkpoint_writes cw
         where cw.thread_id = checkpoints.thread_id
             and cw.checkpoint_ns = checkpoints.checkpoint_ns

libs/checkpoint-postgres/langgraph/store/postgres/base.py

@@ -36,6 +36,7 @@ from langgraph.store.base import (
     ensure_embeddings,
     get_text_at_path,
     tokenize_path,
+    validate_op_namespace,
 )
 from psycopg import Capabilities, Connection, Cursor, Pipeline
 from psycopg.rows import DictRow, dict_row
@@ -1386,6 +1387,7 @@ def _group_ops(ops: Iterable[Op]) -> tuple[dict[type, list[tuple[int, Op]]], int
     grouped_ops: dict[type, list[tuple[int, Op]]] = defaultdict(list)
     tot = 0
     for idx, op in enumerate(ops):
+        validate_op_namespace(op)
         grouped_ops[type(op)].append((idx, op))
         tot += 1
     return grouped_ops, tot

libs/checkpoint-postgres/pyproject.toml

@@ -12,7 +12,7 @@ readme = "README.md"
 license = "MIT"
 license-files = ['LICENSE']
 dependencies = [
-  "langgraph-checkpoint>=4.1.0,<5.0.0",
+  "langgraph-checkpoint>=4.3.0,<5.0.0",
   "orjson>=3.11.5",
   "psycopg>=3.2.0",
   "psycopg-pool>=3.2.0",

libs/checkpoint-postgres/tests/test_async_store.py

@@ -13,8 +13,10 @@ import pytest
 from langchain_core.embeddings import Embeddings
 from langgraph.store.base import (
     GetOp,
+    InvalidNamespaceError,
     Item,
     ListNamespacesOp,
+    MatchCondition,
     PutOp,
     SearchOp,
 )
@@ -871,3 +873,65 @@ async def test_omit_expired_search_pagination(store: AsyncPostgresStore) -> None
     page2 = await store.asearch(ns, limit=2, offset=2)
     assert [i.key for i in page1] == ["a", "b"]
     assert [i.key for i in page2] == ["c"]
+
+
+@pytest.mark.parametrize("namespace", [("foo.bar",), ("foo", ""), ("foo", 1)])
+async def test_abatch_rejects_invalid_namespace_labels(
+    store: AsyncPostgresStore, namespace: tuple
+) -> None:
+    await store.aput(("foo", "bar"), "key", {"original": True})
+
+    for op in (
+        GetOp(namespace, "key"),
+        GetOp(namespace, "key", refresh_ttl=True),
+        PutOp(namespace, "key", {"changed": True}),
+        PutOp(namespace, "key", None),
+        SearchOp(namespace),
+        ListNamespacesOp((MatchCondition("prefix", namespace),)),
+        ListNamespacesOp((MatchCondition("suffix", namespace),)),
+    ):
+        with pytest.raises(InvalidNamespaceError):
+            await store.abatch([op])
+
+    item = await store.aget(("foo", "bar"), "key")
+    assert item is not None and item.value == {"original": True}
+
+
+async def test_invalid_namespace_only_fails_its_own_call(
+    store: AsyncPostgresStore,
+) -> None:
+    """Concurrent calls share one `abatch`, which fails every op if it raises.
+
+    Labels are checked before an op is queued, so one caller's bad label cannot
+    fail another caller's request.
+    """
+    await store.aput(("foo", "bar"), "key", {"original": True})
+
+    valid, invalid = await asyncio.gather(
+        store.aget(("foo", "bar"), "key"),
+        store.aget(("foo.bar",), "key"),
+        return_exceptions=True,
+    )
+
+    assert isinstance(valid, Item) and valid.value == {"original": True}
+    assert isinstance(invalid, InvalidNamespaceError)
+
+
+async def test_sync_methods_reject_invalid_namespace_labels(
+    store: AsyncPostgresStore,
+) -> None:
+    """The sync wrappers run off the event loop thread and must validate too."""
+    await store.aput(("foo", "bar"), "key", {"original": True})
+
+    for call in (
+        lambda: store.get(("foo.bar",), "key"),
+        lambda: store.search(("foo.bar",)),
+        lambda: store.delete(("foo.bar",), "key"),
+        lambda: store.list_namespaces(prefix=("foo.bar",)),
+        lambda: store.batch([GetOp(("foo.bar",), "key")]),
+    ):
+        with pytest.raises(InvalidNamespaceError):
+            await asyncio.to_thread(call)
+
+    item = await store.aget(("foo", "bar"), "key")
+    assert item is not None and item.value == {"original": True}

libs/checkpoint-postgres/tests/test_delta_pagination.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from collections.abc import Mapping, Sequence
 from typing import Any
 from uuid import uuid4
 
@@ -14,7 +15,7 @@ from langgraph.checkpoint.serde.types import _DeltaSnapshot
 
 from langgraph.checkpoint.postgres import PostgresSaver
 from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver
-from langgraph.checkpoint.postgres.base import _DELTA_PAGE_SIZE
+from langgraph.checkpoint.postgres.base import _DELTA_PAGE_SIZE, BasePostgresSaver
 from tests.conftest import DEFAULT_URI
 
 CHANNEL = "items"
@@ -23,8 +24,8 @@ SEED_STEP = 1
 SEED_VALUE = [10, 20]
 TARGET_STEP = 4
 
-# The real page size is the control; the rest leave the target off the first
-# page (three checkpoints are newer than it).
+# The real page size is the control; the rest split the walk from the target
+# to its seed across pages.
 PAGE_SIZES = [_DELTA_PAGE_SIZE, 3, 2, 1]
 
 
@@ -92,7 +93,7 @@ def _assert_history(entry: DeltaChannelHistory, page_size: int) -> None:
 
 
 @pytest.mark.parametrize("page_size", PAGE_SIZES)
-async def test_async_target_older_than_the_first_page(
+async def test_async_walk_continues_across_pages(
     page_size: int, monkeypatch: pytest.MonkeyPatch
 ) -> None:
     monkeypatch.setattr("langgraph.checkpoint.postgres.aio._DELTA_PAGE_SIZE", page_size)
@@ -106,7 +107,7 @@ async def test_async_target_older_than_the_first_page(
 
 
 @pytest.mark.parametrize("page_size", PAGE_SIZES)
-def test_sync_target_older_than_the_first_page(
+def test_sync_walk_continues_across_pages(
     page_size: int, monkeypatch: pytest.MonkeyPatch
 ) -> None:
     monkeypatch.setattr("langgraph.checkpoint.postgres._DELTA_PAGE_SIZE", page_size)
@@ -119,6 +120,84 @@ def test_sync_target_older_than_the_first_page(
         _assert_history(result[CHANNEL], page_size)
 
 
+def _record_rows_read(monkeypatch: pytest.MonkeyPatch) -> list[str]:
+    read: list[str] = []
+    ingest = BasePostgresSaver._ingest_stage1_page
+
+    def record(rows: Sequence[Mapping[str, Any]], *args: Any) -> str | None:
+        read.extend(row["checkpoint_id"] for row in rows)
+        return ingest(rows, *args)
+
+    monkeypatch.setattr(BasePostgresSaver, "_ingest_stage1_page", staticmethod(record))
+    return read
+
+
+def _ids_from_target_down(configs: list[dict]) -> list[str]:
+    return [c["configurable"]["checkpoint_id"] for c in configs[TARGET_STEP::-1]]
+
+
+async def test_async_walk_reads_nothing_newer_than_the_target(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    read = _record_rows_read(monkeypatch)
+    async with AsyncPostgresSaver.from_conn_string(DEFAULT_URI) as saver:
+        await saver.setup()
+        configs = await _abuild_chain(saver)
+        result = await saver.aget_delta_channel_history(
+            config=configs[TARGET_STEP], channels=[CHANNEL]
+        )
+    _assert_history(result[CHANNEL], _DELTA_PAGE_SIZE)
+    assert read == _ids_from_target_down(configs)
+
+
+def test_sync_walk_reads_nothing_newer_than_the_target(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    read = _record_rows_read(monkeypatch)
+    with PostgresSaver.from_conn_string(DEFAULT_URI) as saver:
+        saver.setup()
+        configs = _build_chain(saver)
+        result = saver.get_delta_channel_history(
+            config=configs[TARGET_STEP], channels=[CHANNEL]
+        )
+    _assert_history(result[CHANNEL], _DELTA_PAGE_SIZE)
+    assert read == _ids_from_target_down(configs)
+
+
+def _empty_checkpoint_id(config: dict) -> dict:
+    return {"configurable": {**config["configurable"], "checkpoint_id": ""}}
+
+
+async def test_async_empty_checkpoint_id_reads_from_the_latest_checkpoint() -> None:
+    async with AsyncPostgresSaver.from_conn_string(DEFAULT_URI) as saver:
+        await saver.setup()
+        configs = await _abuild_chain(saver)
+        latest = await saver.aget_delta_channel_history(
+            config=configs[-1], channels=[CHANNEL]
+        )
+
+        result = await saver.aget_delta_channel_history(
+            config=_empty_checkpoint_id(configs[-1]), channels=[CHANNEL]
+        )
+
+    assert latest[CHANNEL]["writes"]
+    assert result == latest
+
+
+def test_sync_empty_checkpoint_id_reads_from_the_latest_checkpoint() -> None:
+    with PostgresSaver.from_conn_string(DEFAULT_URI) as saver:
+        saver.setup()
+        configs = _build_chain(saver)
+        latest = saver.get_delta_channel_history(config=configs[-1], channels=[CHANNEL])
+
+        result = saver.get_delta_channel_history(
+            config=_empty_checkpoint_id(configs[-1]), channels=[CHANNEL]
+        )
+
+    assert latest[CHANNEL]["writes"]
+    assert result == latest
+
+
 async def test_root_target_has_no_history_and_still_terminates(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:

libs/checkpoint-postgres/tests/test_store.py

@@ -11,6 +11,7 @@ import pytest
 from langchain_core.embeddings import Embeddings
 from langgraph.store.base import (
     GetOp,
+    InvalidNamespaceError,
     Item,
     ListNamespacesOp,
     MatchCondition,
@@ -1164,3 +1165,51 @@ def test_namespace_labels_with_trailing_newline(store) -> None:
     assert set(store.list_namespaces(prefix=["users", "alice"], limit=100)) == {
         ("users", "alice"),
     }
+
+
+@pytest.mark.parametrize("namespace", [("foo.bar",), ("foo", ""), ("foo", 1)])
+@pytest.mark.parametrize(
+    "kind", ["get", "put", "delete", "search", "list_prefix", "list_suffix"]
+)
+def test_batch_rejects_invalid_namespace_labels(
+    store, namespace: tuple, kind: str
+) -> None:
+    """Ops passed straight to `batch` must not reach another namespace.
+
+    Namespaces are stored dot-joined, so `("foo.bar",)` flattens to the same
+    text as `("foo", "bar")`. `BaseStore` methods validate labels themselves,
+    but `batch` takes ops as given.
+    """
+    op = {
+        "get": GetOp(namespace, "key"),
+        "put": PutOp(namespace, "key", {"changed": True}),
+        "delete": PutOp(namespace, "key", None),
+        "search": SearchOp(namespace),
+        "list_prefix": ListNamespacesOp((MatchCondition("prefix", namespace),)),
+        "list_suffix": ListNamespacesOp((MatchCondition("suffix", namespace),)),
+    }[kind]
+    store.put(("foo", "bar"), "key", {"original": True})
+
+    with pytest.raises(InvalidNamespaceError):
+        store.batch([PutOp(("valid",), "key", {}), op])
+
+    item = store.get(("foo", "bar"), "key")
+    assert item is not None and item.value == {"original": True}
+    # The whole batch is rejected before any SQL runs.
+    assert store.get(("valid",), "key") is None
+
+
+def test_batch_allows_empty_search_prefix_and_listing_wildcards(
+    store,
+) -> None:
+    store.put(("foo", "bar"), "key", {"v": 1})
+
+    found, listed = store.batch(
+        [
+            SearchOp(()),
+            ListNamespacesOp((MatchCondition("prefix", ("foo", "*")),)),
+        ]
+    )
+
+    assert [item.namespace for item in found] == [("foo", "bar")]
+    assert listed == [("foo", "bar")]

libs/checkpoint-postgres/uv.lock

@@ -278,7 +278,7 @@ wheels = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "4.2.0"
+version = "4.3.0"
 source = { editable = "../checkpoint" }
 dependencies = [
     { name = "langchain-core" },

libs/checkpoint-sqlite/langgraph/checkpoint/sqlite/__init__.py

@@ -29,7 +29,11 @@ from langgraph.checkpoint.sqlite._delta import (
     build_delta_stage2_sql,
     step_walk_with_row,
 )
-from langgraph.checkpoint.sqlite.utils import search_where
+from langgraph.checkpoint.sqlite.utils import (
+    load_pending_writes,
+    pending_writes_sql,
+    search_where,
+)
 
 _AIO_ERROR_MSG = (
     "The SqliteSaver does not support async methods. "
@@ -81,6 +85,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
 
     conn: sqlite3.Connection
     is_setup: bool
+    _has_task_path: bool = True
 
     def __init__(
         self,
@@ -154,6 +159,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
                 checkpoint_ns TEXT NOT NULL DEFAULT '',
                 checkpoint_id TEXT NOT NULL,
                 task_id TEXT NOT NULL,
+                task_path TEXT NOT NULL DEFAULT '',
                 idx INTEGER NOT NULL,
                 channel TEXT NOT NULL,
                 type TEXT,
@@ -162,6 +168,19 @@ class SqliteSaver(BaseCheckpointSaver[str]):
             );
             """
         )
+        # sqlite has no ADD COLUMN IF NOT EXISTS; this migrates databases
+        # created before `task_path` existed and is a no-op on the rest.
+        try:
+            self.conn.execute(
+                "ALTER TABLE writes ADD COLUMN task_path TEXT NOT NULL DEFAULT ''"
+            )
+        except sqlite3.OperationalError as e:
+            # A read-only database from before the column can still be read;
+            # its rows would all read back as '' anyway.
+            if "readonly database" in str(e):
+                self._has_task_path = False
+            elif "duplicate column name" not in str(e):
+                raise
 
         self.is_setup = True
 
@@ -260,7 +279,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
                     }
                 # find any pending writes
                 cur.execute(
-                    "SELECT task_id, channel, type, value FROM writes WHERE thread_id = ? AND checkpoint_ns = ? AND checkpoint_id = ? ORDER BY task_id, idx",
+                    pending_writes_sql(self._has_task_path),
                     (
                         str(config["configurable"]["thread_id"]),
                         checkpoint_ns,
@@ -286,10 +305,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
                         if parent_checkpoint_id
                         else None
                     ),
-                    [
-                        (task_id, channel, self.serde.loads_typed((type, value)))
-                        for task_id, channel, type, value in cur
-                    ],
+                    load_pending_writes(cur, self.serde),
                 )
 
     def list(
@@ -351,7 +367,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
                 metadata,
             ) in cur:
                 wcur.execute(
-                    "SELECT task_id, channel, type, value FROM writes WHERE thread_id = ? AND checkpoint_ns = ? AND checkpoint_id = ? ORDER BY task_id, idx",
+                    pending_writes_sql(self._has_task_path),
                     (thread_id, checkpoint_ns, checkpoint_id),
                 )
                 yield CheckpointTuple(
@@ -378,10 +394,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
                         if parent_checkpoint_id
                         else None
                     ),
-                    [
-                        (task_id, channel, self.serde.loads_typed((type, value)))
-                        for task_id, channel, type, value in wcur
-                    ],
+                    load_pending_writes(wcur, self.serde),
                 )
 
     def put(
@@ -460,9 +473,9 @@ class SqliteSaver(BaseCheckpointSaver[str]):
             task_path: Path of the task creating the writes.
         """
         query = (
-            "INSERT OR REPLACE INTO writes (thread_id, checkpoint_ns, checkpoint_id, task_id, idx, channel, type, value) VALUES (?, ?, ?, ?, ?, ?, ?, ?)"
+            "INSERT OR REPLACE INTO writes (thread_id, checkpoint_ns, checkpoint_id, task_id, task_path, idx, channel, type, value) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)"
             if all(w[0] in WRITES_IDX_MAP for w in writes)
-            else "INSERT OR IGNORE INTO writes (thread_id, checkpoint_ns, checkpoint_id, task_id, idx, channel, type, value) VALUES (?, ?, ?, ?, ?, ?, ?, ?)"
+            else "INSERT OR IGNORE INTO writes (thread_id, checkpoint_ns, checkpoint_id, task_id, task_path, idx, channel, type, value) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)"
         )
         with self.cursor() as cur:
             cur.executemany(
@@ -473,6 +486,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
                         str(config["configurable"]["checkpoint_ns"]),
                         str(config["configurable"]["checkpoint_id"]),
                         task_id,
+                        task_path,
                         WRITES_IDX_MAP.get(channel, idx),
                         channel,
                         *self.serde.dumps_typed(value),
@@ -525,7 +539,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
         thread_id = str(config["configurable"]["thread_id"])
         checkpoint_ns = config["configurable"].get("checkpoint_ns", "")
         checkpoint_id = get_checkpoint_id(config)
-        if checkpoint_id is None:
+        if not checkpoint_id:
             target = self.get_tuple(config)
             if target is None:
                 return {ch: {"writes": []} for ch in channels}
@@ -559,6 +573,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
 
             channels_with_chain = [ch for ch in channels if chain_by_ch[ch]]
             stage2_sql = build_delta_stage2_sql(
+                has_task_path=self._has_task_path,
                 chain_lens=[len(chain_by_ch[ch]) for ch in channels_with_chain],
             )
             if stage2_sql:
@@ -569,7 +584,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
                     )
                 cur.execute(stage2_sql, stage2_params)
                 stage2_rows = cast(
-                    "list[tuple[str, str, str, int, str, bytes]]", cur.fetchall()
+                    "list[tuple[str, str, str, int, str, bytes, str]]", cur.fetchall()
                 )
             else:
                 stage2_rows = []

libs/checkpoint-sqlite/langgraph/checkpoint/sqlite/_delta.py

@@ -24,7 +24,11 @@ from __future__ import annotations
 from collections.abc import Mapping, Sequence
 from typing import Any
 
-from langgraph.checkpoint.base import DeltaChannelHistory, PendingWrite
+from langgraph.checkpoint.base import (
+    DeltaChannelHistory,
+    PendingWrite,
+    writes_sort_key,
+)
 
 # Stage 1 streams target, then its ancestors nearest-first, by following
 # `parent_checkpoint_id` rather than id order: ids are only monotonic within
@@ -56,7 +60,9 @@ DELTA_STAGE1_SQL = (
 )
 
 
-def build_delta_stage2_sql(*, chain_lens: Sequence[int]) -> str:
+def build_delta_stage2_sql(
+    *, chain_lens: Sequence[int], has_task_path: bool = True
+) -> str:
     """Stage-2 per-channel UNION ALL fetching writes from `writes`.
 
     One branch per channel with a non-empty chain. Each branch inlines its
@@ -70,11 +76,12 @@ def build_delta_stage2_sql(*, chain_lens: Sequence[int]) -> str:
     of a single `channel = ANY(channels)` filter when channels have
     different chain depths — same rationale as postgres.
     """
+    task_path = "task_path" if has_task_path else "''"
     branches: list[str] = []
     for n in chain_lens:
         cid_placeholders = ",".join("?" * n)
         branches.append(
-            "SELECT checkpoint_id, channel, task_id, idx, type, value "
+            f"SELECT checkpoint_id, channel, task_id, idx, type, value, {task_path} "
             "FROM writes "
             "WHERE thread_id = ? AND checkpoint_ns = ? AND channel = ? "
             f"AND checkpoint_id IN ({cid_placeholders})"
@@ -141,29 +148,31 @@ def build_delta_channels_writes_history(
     chain_by_ch: Mapping[str, list[str]],
     seed_val_by_ch: Mapping[str, Any],
     seeded: set[str],
-    stage2_rows: Sequence[tuple[str, str, str, int, str, bytes]],
+    stage2_rows: Sequence[tuple[str, str, str, int, str, bytes, str]],
     serde: Any,
 ) -> dict[str, DeltaChannelHistory]:
     """Demux stage-2 rows per channel; produce per-channel histories.
 
-    Stage-2 rows are `(checkpoint_id, channel, task_id, idx, type, value)`.
-    Final write order is oldest→newest globally and `(task_id, idx)` within
-    a checkpoint, matching the contract on `DeltaChannelHistory.writes`.
+    Stage-2 rows are
+    `(checkpoint_id, channel, task_id, idx, type, value, task_path)`.
+    Final write order is oldest→newest globally and `writes_sort_key`
+    within a checkpoint, matching the contract on
+    `DeltaChannelHistory.writes`.
 
     `seed` is omitted when the walk reached a true root with no snapshot
     found (channel never entered `seeded`); consumers treat absence as
     "start empty".
     """
-    writes_by_ch_by_cid: dict[str, dict[str, list[tuple[str, bytes, str, int]]]] = {
-        ch: {} for ch in channels
-    }
-    for cid, ch, task_id, idx, type_tag, value_blob in stage2_rows:
+    writes_by_ch_by_cid: dict[
+        str, dict[str, list[tuple[str, bytes, str, int, str]]]
+    ] = {ch: {} for ch in channels}
+    for cid, ch, task_id, idx, type_tag, value_blob, task_path in stage2_rows:
         writes_by_ch_by_cid.setdefault(ch, {}).setdefault(cid, []).append(
-            (type_tag, value_blob, task_id, idx)
+            (type_tag, value_blob, task_id, idx, task_path)
         )
     for cid_map in writes_by_ch_by_cid.values():
         for ws in cid_map.values():
-            ws.sort(key=lambda w: (w[2], w[3]))
+            ws.sort(key=lambda w: writes_sort_key(w[4], w[2], w[3]))
 
     result: dict[str, DeltaChannelHistory] = {}
     for ch in channels:
@@ -172,7 +181,7 @@ def build_delta_channels_writes_history(
         collected: list[PendingWrite] = []
         # Chain is newest-first; iterate oldest-first for the public order.
         for cid in reversed(chain_cids):
-            for type_tag, value_blob, task_id, _idx in cid_writes.get(cid, []):
+            for type_tag, value_blob, task_id, _idx, _path in cid_writes.get(cid, []):
                 collected.append(
                     (task_id, ch, serde.loads_typed((type_tag, value_blob)))
                 )

libs/checkpoint-sqlite/langgraph/checkpoint/sqlite/aio.py

@@ -30,7 +30,11 @@ from langgraph.checkpoint.sqlite._delta import (
     build_delta_stage2_sql,
     step_walk_with_row,
 )
-from langgraph.checkpoint.sqlite.utils import search_where
+from langgraph.checkpoint.sqlite.utils import (
+    load_pending_writes,
+    pending_writes_sql,
+    search_where,
+)
 
 T = TypeVar("T", bound=Callable)
 
@@ -114,6 +118,7 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
 
     lock: asyncio.Lock
     is_setup: bool
+    _has_task_path: bool = True
 
     def __init__(
         self,
@@ -331,6 +336,7 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
                     checkpoint_ns TEXT NOT NULL DEFAULT '',
                     checkpoint_id TEXT NOT NULL,
                     task_id TEXT NOT NULL,
+                    task_path TEXT NOT NULL DEFAULT '',
                     idx INTEGER NOT NULL,
                     channel TEXT NOT NULL,
                     type TEXT,
@@ -341,6 +347,21 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
             ):
                 await self.conn.commit()
 
+            # sqlite has no ADD COLUMN IF NOT EXISTS; this migrates databases
+            # created before `task_path` existed and is a no-op on the rest.
+            try:
+                await self.conn.execute(
+                    "ALTER TABLE writes ADD COLUMN task_path TEXT NOT NULL DEFAULT ''"
+                )
+                await self.conn.commit()
+            except aiosqlite.OperationalError as e:
+                # A read-only database from before the column can still be read;
+                # its rows would all read back as '' anyway.
+                if "readonly database" in str(e):
+                    self._has_task_path = False
+                elif "duplicate column name" not in str(e):
+                    raise
+
             self.is_setup = True
 
     async def aget_tuple(self, config: RunnableConfig) -> CheckpointTuple | None:
@@ -395,7 +416,7 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
                     }
                 # find any pending writes
                 await cur.execute(
-                    "SELECT task_id, channel, type, value FROM writes WHERE thread_id = ? AND checkpoint_ns = ? AND checkpoint_id = ? ORDER BY task_id, idx",
+                    pending_writes_sql(self._has_task_path),
                     (
                         str(config["configurable"]["thread_id"]),
                         checkpoint_ns,
@@ -421,10 +442,7 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
                         if parent_checkpoint_id
                         else None
                     ),
-                    [
-                        (task_id, channel, self.serde.loads_typed((type, value)))
-                        async for task_id, channel, type, value in cur
-                    ],
+                    load_pending_writes(await cur.fetchall(), self.serde),
                 )
 
     async def alist(
@@ -473,7 +491,7 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
                 metadata,
             ) in cur:
                 await wcur.execute(
-                    "SELECT task_id, channel, type, value FROM writes WHERE thread_id = ? AND checkpoint_ns = ? AND checkpoint_id = ? ORDER BY task_id, idx",
+                    pending_writes_sql(self._has_task_path),
                     (thread_id, checkpoint_ns, checkpoint_id),
                 )
                 yield CheckpointTuple(
@@ -500,10 +518,7 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
                         if parent_checkpoint_id
                         else None
                     ),
-                    [
-                        (task_id, channel, self.serde.loads_typed((type, value)))
-                        async for task_id, channel, type, value in wcur
-                    ],
+                    load_pending_writes(await wcur.fetchall(), self.serde),
                 )
 
     async def aput(
@@ -576,9 +591,9 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
             task_path: Path of the task creating the writes.
         """
         query = (
-            "INSERT OR REPLACE INTO writes (thread_id, checkpoint_ns, checkpoint_id, task_id, idx, channel, type, value) VALUES (?, ?, ?, ?, ?, ?, ?, ?)"
+            "INSERT OR REPLACE INTO writes (thread_id, checkpoint_ns, checkpoint_id, task_id, task_path, idx, channel, type, value) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)"
             if all(w[0] in WRITES_IDX_MAP for w in writes)
-            else "INSERT OR IGNORE INTO writes (thread_id, checkpoint_ns, checkpoint_id, task_id, idx, channel, type, value) VALUES (?, ?, ?, ?, ?, ?, ?, ?)"
+            else "INSERT OR IGNORE INTO writes (thread_id, checkpoint_ns, checkpoint_id, task_id, task_path, idx, channel, type, value) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)"
         )
         await self.setup()
         async with self.lock, self.conn.cursor() as cur:
@@ -590,6 +605,7 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
                         str(config["configurable"]["checkpoint_ns"]),
                         str(config["configurable"]["checkpoint_id"]),
                         task_id,
+                        task_path,
                         WRITES_IDX_MAP.get(channel, idx),
                         channel,
                         *self.serde.dumps_typed(value),
@@ -637,7 +653,7 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
         thread_id = str(config["configurable"]["thread_id"])
         checkpoint_ns = config["configurable"].get("checkpoint_ns", "")
         checkpoint_id = get_checkpoint_id(config)
-        if checkpoint_id is None:
+        if not checkpoint_id:
             target = await self.aget_tuple(config)
             if target is None:
                 return {ch: {"writes": []} for ch in channels}
@@ -671,6 +687,7 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
 
             channels_with_chain = [ch for ch in channels if chain_by_ch[ch]]
             stage2_sql = build_delta_stage2_sql(
+                has_task_path=self._has_task_path,
                 chain_lens=[len(chain_by_ch[ch]) for ch in channels_with_chain],
             )
             if stage2_sql:
@@ -681,7 +698,7 @@ class AsyncSqliteSaver(BaseCheckpointSaver[str]):
                     )
                 await cur.execute(stage2_sql, stage2_params)
                 stage2_rows = cast(
-                    "list[tuple[str, str, str, int, str, bytes]]",
+                    "list[tuple[str, str, str, int, str, bytes, str]]",
                     await cur.fetchall(),
                 )
             else:

libs/checkpoint-sqlite/langgraph/checkpoint/sqlite/utils.py

@@ -2,11 +2,12 @@ from __future__ import annotations
 
 import json
 import re
-from collections.abc import Sequence
+from collections.abc import Iterable, Sequence
 from typing import Any
 
 from langchain_core.runnables import RunnableConfig
-from langgraph.checkpoint.base import get_checkpoint_id
+from langgraph.checkpoint.base import PendingWrite, get_checkpoint_id, writes_sort_key
+from langgraph.checkpoint.serde.base import SerializerProtocol
 
 _FILTER_PATTERN = re.compile(r"^[a-zA-Z0-9_.-]+$")
 
@@ -114,3 +115,23 @@ def search_where(
         param_values.append(get_checkpoint_id(before))
 
     return ("WHERE " + " AND ".join(wheres) if wheres else "", param_values)
+
+
+def pending_writes_sql(has_task_path: bool) -> str:
+    task_path = "task_path" if has_task_path else "''"
+    return (
+        f"SELECT task_id, channel, type, value, {task_path}, idx FROM writes "
+        "WHERE thread_id = ? AND checkpoint_ns = ? AND checkpoint_id = ?"
+    )
+
+
+def load_pending_writes(
+    rows: Iterable[Any], serde: SerializerProtocol
+) -> list[PendingWrite]:
+    """Deserialize `pending_writes_sql` rows in `writes_sort_key` order."""
+    return [
+        (task_id, channel, serde.loads_typed((type_, value)))
+        for task_id, channel, type_, value, _, _ in sorted(
+            rows, key=lambda r: writes_sort_key(r[4], r[0], r[5])
+        )
+    ]

libs/checkpoint-sqlite/langgraph/store/sqlite/base.py

@@ -28,6 +28,7 @@ from langgraph.store.base import (
     ensure_embeddings,
     get_text_at_path,
     tokenize_path,
+    validate_op_namespace,
 )
 
 _AIO_ERROR_MSG = (
@@ -257,6 +258,7 @@ def _group_ops(ops: Iterable[Op]) -> tuple[dict[type, list[tuple[int, Op]]], int
     grouped_ops: dict[type, list[tuple[int, Op]]] = defaultdict(list)
     tot = 0
     for idx, op in enumerate(ops):
+        validate_op_namespace(op)
         grouped_ops[type(op)].append((idx, op))
         tot += 1
     return grouped_ops, tot

libs/checkpoint-sqlite/pyproject.toml

@@ -12,7 +12,7 @@ readme = "README.md"
 license = "MIT"
 license-files = ['LICENSE']
 dependencies = [
-    "langgraph-checkpoint>=4.1.0,<5.0.0",
+    "langgraph-checkpoint>=4.3.0,<5.0.0",
     "aiosqlite>=0.20",
     "sqlite-vec>=0.1.6",
 ]

libs/checkpoint-sqlite/tests/test_async_store.py

@@ -9,8 +9,10 @@ from typing import cast
 import pytest
 from langgraph.store.base import (
     GetOp,
+    InvalidNamespaceError,
     Item,
     ListNamespacesOp,
+    MatchCondition,
     PutOp,
     SearchOp,
 )
@@ -745,3 +747,65 @@ async def test_async_namespace_segment_boundary(store: AsyncSqliteStore) -> None
     assert set(await store.alist_namespaces(suffix=["alice"], limit=100)) == {
         ("uid", "users", "alice"),
     }
+
+
+@pytest.mark.parametrize("namespace", [("foo.bar",), ("foo", ""), ("foo", 1)])
+async def test_abatch_rejects_invalid_namespace_labels(
+    store: AsyncSqliteStore, namespace: tuple
+) -> None:
+    await store.aput(("foo", "bar"), "key", {"original": True})
+
+    for op in (
+        GetOp(namespace, "key"),
+        GetOp(namespace, "key", refresh_ttl=True),
+        PutOp(namespace, "key", {"changed": True}),
+        PutOp(namespace, "key", None),
+        SearchOp(namespace),
+        ListNamespacesOp((MatchCondition("prefix", namespace),)),
+        ListNamespacesOp((MatchCondition("suffix", namespace),)),
+    ):
+        with pytest.raises(InvalidNamespaceError):
+            await store.abatch([op])
+
+    item = await store.aget(("foo", "bar"), "key")
+    assert item is not None and item.value == {"original": True}
+
+
+async def test_invalid_namespace_only_fails_its_own_call(
+    store: AsyncSqliteStore,
+) -> None:
+    """Concurrent calls share one `abatch`, which fails every op if it raises.
+
+    Labels are checked before an op is queued, so one caller's bad label cannot
+    fail another caller's request.
+    """
+    await store.aput(("foo", "bar"), "key", {"original": True})
+
+    valid, invalid = await asyncio.gather(
+        store.aget(("foo", "bar"), "key"),
+        store.aget(("foo.bar",), "key"),
+        return_exceptions=True,
+    )
+
+    assert isinstance(valid, Item) and valid.value == {"original": True}
+    assert isinstance(invalid, InvalidNamespaceError)
+
+
+async def test_sync_methods_reject_invalid_namespace_labels(
+    store: AsyncSqliteStore,
+) -> None:
+    """The sync wrappers run off the event loop thread and must validate too."""
+    await store.aput(("foo", "bar"), "key", {"original": True})
+
+    for call in (
+        lambda: store.get(("foo.bar",), "key"),
+        lambda: store.search(("foo.bar",)),
+        lambda: store.delete(("foo.bar",), "key"),
+        lambda: store.list_namespaces(prefix=("foo.bar",)),
+        lambda: store.batch([GetOp(("foo.bar",), "key")]),
+    ):
+        with pytest.raises(InvalidNamespaceError):
+            await asyncio.to_thread(call)
+
+    item = await store.aget(("foo", "bar"), "key")
+    assert item is not None and item.value == {"original": True}

libs/checkpoint-sqlite/tests/test_delta_parent_walk.py

@@ -65,6 +65,39 @@ async def test_async_walk_reaches_parent_whatever_the_id_order(
         assert got[CHANNEL] == EXPECTED
 
 
+EMPTY_CHECKPOINT_ID: dict[str, Any] = {
+    "configurable": {**CONFIG["configurable"], "checkpoint_id": ""}
+}
+
+
+def test_sync_empty_checkpoint_id_reads_from_the_latest_checkpoint() -> None:
+    with SqliteSaver.from_conn_string(":memory:") as saver:
+        root = saver.put(CONFIG, _checkpoint("a-older", {CHANNEL: "seed"}), {}, {})
+        saver.put_writes(root, [(CHANNEL, "write-root")], "task")
+        saver.put(root, _checkpoint("z-newer", {}), {}, {})
+
+        got = saver.get_delta_channel_history(
+            config=EMPTY_CHECKPOINT_ID, channels=[CHANNEL]
+        )
+
+        assert got[CHANNEL] == EXPECTED
+
+
+async def test_async_empty_checkpoint_id_reads_from_the_latest_checkpoint() -> None:
+    async with AsyncSqliteSaver.from_conn_string(":memory:") as saver:
+        root = await saver.aput(
+            CONFIG, _checkpoint("a-older", {CHANNEL: "seed"}), {}, {}
+        )
+        await saver.aput_writes(root, [(CHANNEL, "write-root")], "task")
+        await saver.aput(root, _checkpoint("z-newer", {}), {}, {})
+
+        got = await saver.aget_delta_channel_history(
+            config=EMPTY_CHECKPOINT_ID, channels=[CHANNEL]
+        )
+
+        assert got[CHANNEL] == EXPECTED
+
+
 def test_walk_reaches_root_of_long_chain_with_descending_ids() -> None:
     steps = 40
     with SqliteSaver.from_conn_string(":memory:") as saver:

libs/checkpoint-sqlite/tests/test_store.py

@@ -14,6 +14,7 @@ import pytest
 from langchain_core.embeddings import Embeddings
 from langgraph.store.base import (
     GetOp,
+    InvalidNamespaceError,
     Item,
     ListNamespacesOp,
     MatchCondition,
@@ -1435,3 +1436,51 @@ def test_list_namespaces_metacharacter_labels(store: SqliteStore) -> None:
         assert set(store.list_namespaces(prefix=[label, "child"], limit=100)) == {
             (label, "child"),
         }
+
+
+@pytest.mark.parametrize("namespace", [("foo.bar",), ("foo", ""), ("foo", 1)])
+@pytest.mark.parametrize(
+    "kind", ["get", "put", "delete", "search", "list_prefix", "list_suffix"]
+)
+def test_batch_rejects_invalid_namespace_labels(
+    store: SqliteStore, namespace: tuple, kind: str
+) -> None:
+    """Ops passed straight to `batch` must not reach another namespace.
+
+    Namespaces are stored dot-joined, so `("foo.bar",)` flattens to the same
+    text as `("foo", "bar")`. `BaseStore` methods validate labels themselves,
+    but `batch` takes ops as given.
+    """
+    op = {
+        "get": GetOp(namespace, "key"),
+        "put": PutOp(namespace, "key", {"changed": True}),
+        "delete": PutOp(namespace, "key", None),
+        "search": SearchOp(namespace),
+        "list_prefix": ListNamespacesOp((MatchCondition("prefix", namespace),)),
+        "list_suffix": ListNamespacesOp((MatchCondition("suffix", namespace),)),
+    }[kind]
+    store.put(("foo", "bar"), "key", {"original": True})
+
+    with pytest.raises(InvalidNamespaceError):
+        store.batch([PutOp(("valid",), "key", {}), op])
+
+    item = store.get(("foo", "bar"), "key")
+    assert item is not None and item.value == {"original": True}
+    # The whole batch is rejected before any SQL runs.
+    assert store.get(("valid",), "key") is None
+
+
+def test_batch_allows_empty_search_prefix_and_listing_wildcards(
+    store: SqliteStore,
+) -> None:
+    store.put(("foo", "bar"), "key", {"v": 1})
+
+    found, listed = store.batch(
+        [
+            SearchOp(()),
+            ListNamespacesOp((MatchCondition("prefix", ("foo", "*")),)),
+        ]
+    )
+
+    assert [item.namespace for item in found] == [("foo", "bar")]
+    assert listed == [("foo", "bar")]

libs/checkpoint-sqlite/tests/test_writes_task_path_migration.py

@@ -0,0 +1,151 @@
+import sqlite3
+from collections.abc import Iterator
+from contextlib import closing
+from pathlib import Path
+
+import aiosqlite
+import pytest
+from langgraph.checkpoint.base import empty_checkpoint
+
+from langgraph.checkpoint.sqlite import SqliteSaver
+from langgraph.checkpoint.sqlite.aio import AsyncSqliteSaver
+
+WRITES_BEFORE_TASK_PATH = """
+CREATE TABLE writes (
+    thread_id TEXT NOT NULL,
+    checkpoint_ns TEXT NOT NULL DEFAULT '',
+    checkpoint_id TEXT NOT NULL,
+    task_id TEXT NOT NULL,
+    idx INTEGER NOT NULL,
+    channel TEXT NOT NULL,
+    type TEXT,
+    value BLOB,
+    PRIMARY KEY (thread_id, checkpoint_ns, checkpoint_id, task_id, idx)
+);
+INSERT INTO writes VALUES ('t', '', 'c', 'old-task', 0, 'ch', 'null', X'');
+"""
+
+
+@pytest.fixture
+def legacy_db(tmp_path: Path) -> Path:
+    db = tmp_path / "legacy.sqlite"
+    with sqlite3.connect(db) as conn:
+        conn.executescript(WRITES_BEFORE_TASK_PATH)
+    return db
+
+
+def test_setup_migrates_legacy_writes_table_repeatably(legacy_db: Path) -> None:
+    for _ in range(2):
+        with SqliteSaver.from_conn_string(str(legacy_db)) as saver:
+            saver.setup()
+            rows = saver.conn.execute(
+                "SELECT task_id, task_path FROM writes"
+            ).fetchall()
+            assert rows == [("old-task", "")]
+
+
+@pytest.mark.parametrize("fresh", [True, False], ids=["fresh", "legacy"])
+def test_put_writes_persists_task_path(
+    tmp_path: Path, legacy_db: Path, fresh: bool
+) -> None:
+    db = tmp_path / "fresh.sqlite" if fresh else legacy_db
+    with SqliteSaver.from_conn_string(str(db)) as saver:
+        config = saver.put(
+            {"configurable": {"thread_id": "t", "checkpoint_ns": ""}},
+            empty_checkpoint(),
+            {},
+            {},
+        )
+        saver.put_writes(config, [("ch", "v")], "task-1", "~__pregel_pull, node")
+        stored = saver.conn.execute(
+            "SELECT task_path FROM writes WHERE task_id = 'task-1'"
+        ).fetchall()
+    assert stored == [("~__pregel_pull, node",)]
+
+
+async def test_async_setup_migrates_legacy_writes_table_repeatably(
+    legacy_db: Path,
+) -> None:
+    for _ in range(2):
+        async with AsyncSqliteSaver.from_conn_string(str(legacy_db)) as saver:
+            await saver.setup()
+            config = await saver.aput(
+                {"configurable": {"thread_id": "t", "checkpoint_ns": ""}},
+                empty_checkpoint(),
+                {},
+                {},
+            )
+            await saver.aput_writes(
+                config, [("ch", "v")], "task-1", "~__pregel_pull, node"
+            )
+
+    async with aiosqlite.connect(legacy_db) as conn:
+        async with conn.execute(
+            "SELECT DISTINCT task_id, task_path FROM writes ORDER BY task_id"
+        ) as cur:
+            assert await cur.fetchall() == [
+                ("old-task", ""),
+                ("task-1", "~__pregel_pull, node"),
+            ]
+
+
+@pytest.fixture
+def busy_db(tmp_path: Path) -> Iterator[Path]:
+    db = tmp_path / "busy.sqlite"
+    with SqliteSaver.from_conn_string(str(db)) as saver:
+        saver.setup()
+    with closing(sqlite3.connect(db, isolation_level=None)) as writer:
+        writer.execute("BEGIN IMMEDIATE")
+        yield db
+        writer.execute("ROLLBACK")
+
+
+def test_setup_does_not_wait_on_another_writer(busy_db: Path) -> None:
+    with closing(sqlite3.connect(busy_db, timeout=0)) as conn:
+        SqliteSaver(conn).setup()
+
+
+async def test_async_setup_does_not_wait_on_another_writer(busy_db: Path) -> None:
+    async with aiosqlite.connect(busy_db, timeout=0) as conn:
+        await AsyncSqliteSaver(conn).setup()
+
+
+def _legacy_database_with_history(db: Path) -> dict:
+    root = empty_checkpoint()
+    root["channel_values"] = {"ch": "seed"}
+    root["channel_versions"] = {"ch": 1}
+    with SqliteSaver.from_conn_string(str(db)) as saver:
+        root_config = saver.put(
+            {"configurable": {"thread_id": "t", "checkpoint_ns": ""}},
+            root,
+            {},
+            {"ch": 1},
+        )
+        saver.put_writes(root_config, [("ch", "write")], "task", "~__pregel_pull, n")
+        child = saver.put(root_config, empty_checkpoint(), {}, {})
+        saver.conn.execute("ALTER TABLE writes DROP COLUMN task_path")
+        saver.conn.commit()
+    return child
+
+
+def test_read_only_legacy_database_still_reads_delta_history(tmp_path: Path) -> None:
+    db = tmp_path / "legacy.sqlite"
+    child = _legacy_database_with_history(db)
+
+    saver = SqliteSaver(sqlite3.connect(f"file:{db}?mode=ro", uri=True))
+    got = saver.get_delta_channel_history(config=child, channels=["ch"])
+
+    assert got["ch"] == {"seed": "seed", "writes": [("task", "ch", "write")]}
+
+
+async def test_async_read_only_legacy_database_still_reads_delta_history(
+    tmp_path: Path,
+) -> None:
+    db = tmp_path / "legacy.sqlite"
+    child = _legacy_database_with_history(db)
+
+    async with aiosqlite.connect(f"file:{db}?mode=ro", uri=True) as conn:
+        saver = AsyncSqliteSaver(conn)
+        got = await saver.aget_delta_channel_history(config=child, channels=["ch"])
+
+    assert got["ch"] == {"seed": "seed", "writes": [("task", "ch", "write")]}

libs/checkpoint-sqlite/uv.lock

@@ -285,7 +285,7 @@ wheels = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "4.2.0"
+version = "4.3.0"
 source = { editable = "../checkpoint" }
 dependencies = [
     { name = "langchain-core" },

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

@@ -162,6 +162,14 @@ class DeltaChannelHistory(TypedDict):
       Always present; possibly empty. Already filtered to one channel.
       Writes stored at the target checkpoint itself are pending for the
       next super-step and are excluded.
+
+      Within a single checkpoint, writes are ordered by `writes_sort_key`,
+      `(task_path, task_id, idx)`, which is the order live execution applies
+      a super-step's task writes in. `task_id` is a hash of the path, so
+      ordering by it permutes parallel tasks writing one channel, and
+      reducers need not be order-invariant. Writes stored without a
+      `task_path` (graph input, `update_state` and `Command` updates, rows
+      predating the column) sort first, by `task_id`.
     * `seed` — the stored value at the nearest ancestor whose
       `channel_values[ch]` is populated. Omitted if the walk reached the
       root without finding any stored value (consumer treats absence as
@@ -174,6 +182,20 @@ class DeltaChannelHistory(TypedDict):
     seed: NotRequired[Any]
 
 
+def writes_sort_key(
+    task_path: str, task_id: str = "", idx: int = 0
+) -> tuple[str, str, int]:
+    """Sort key for the writes of one super-step.
+
+    Live execution applies a super-step's tasks in this order, so a saver
+    that replays stored writes, as `get_delta_channel_history` does, must
+    sort them by it too, or an order-sensitive reducer rebuilds a different
+    value than the run produced. `task_path` is the string passed to
+    `put_writes`.
+    """
+    return (task_path, task_id, idx)
+
+
 class BaseCheckpointSaver(Generic[V]):
     """Base class for creating a graph checkpointer.
 
@@ -244,7 +266,8 @@ class BaseCheckpointSaver(Generic[V]):
             config: Configuration specifying which checkpoint to retrieve.
 
         Returns:
-            The requested checkpoint tuple, or `None` if not found.
+            The requested checkpoint tuple, or `None` if not found. Its
+                `pending_writes` must be in `writes_sort_key` order.
 
         Raises:
             NotImplementedError: Implement this method in your custom checkpoint saver.
@@ -434,7 +457,8 @@ class BaseCheckpointSaver(Generic[V]):
             config: Configuration specifying which checkpoint to retrieve.
 
         Returns:
-            The requested checkpoint tuple, or `None` if not found.
+            The requested checkpoint tuple, or `None` if not found. Its
+                `pending_writes` must be in `writes_sort_key` order.
 
         Raises:
             NotImplementedError: Implement this method in your custom checkpoint saver.
@@ -611,6 +635,10 @@ class BaseCheckpointSaver(Generic[V]):
         `PostgresSaver`) override for performance; the return contract is
         fixed here.
 
+        `PendingWrite` carries no `task_path`, so this default replays each
+        checkpoint's writes in `get_tuple`'s `pending_writes` order, which
+        `get_tuple` must return in `writes_sort_key` order.
+
         Args:
             config: Configuration identifying the target checkpoint.
             channels: Channel names to walk for. Empty → empty mapping.

libs/checkpoint/langgraph/checkpoint/memory/__init__.py

@@ -25,6 +25,7 @@ from langgraph.checkpoint.base import (
     SerializerProtocol,
     get_checkpoint_id,
     get_checkpoint_metadata,
+    writes_sort_key,
 )
 
 logger = logging.getLogger(__name__)
@@ -139,6 +140,15 @@ class InMemorySaver(
             result[k] = self.serde.loads_typed(vv)
         return result
 
+    def _ordered_writes(
+        self, thread_id: str, checkpoint_ns: str, checkpoint_id: str
+    ) -> list[tuple[str, str, tuple[str, bytes], str]]:
+        stored = self.writes.get((thread_id, checkpoint_ns, checkpoint_id), {})
+        return [
+            stored[k]
+            for k in sorted(stored, key=lambda k: writes_sort_key(stored[k][3], *k))
+        ]
+
     def get_delta_channel_history(
         self, *, config: RunnableConfig, channels: Sequence[str]
     ) -> Mapping[str, DeltaChannelHistory]:
@@ -160,8 +170,8 @@ class InMemorySaver(
             return {}
         thread_id = config["configurable"]["thread_id"]
         checkpoint_ns = config["configurable"].get("checkpoint_ns", "")
-        checkpoint_id = config["configurable"].get("checkpoint_id", "")
         ns_storage = self.storage.get(thread_id, {}).get(checkpoint_ns, {})
+        checkpoint_id = get_checkpoint_id(config) or max(ns_storage, default="")
 
         chain: list[str] = []
         target_entry = ns_storage.get(checkpoint_id)
@@ -198,9 +208,8 @@ class InMemorySaver(
                     blob_value_by_ch[ch] = self.serde.loads_typed(blob_entry)
                     terminated_here.add(ch)
 
-            step_writes = self.writes.get((thread_id, checkpoint_ns, cp_id), {})
-            for (_task_id, _idx), (tid, ch, serialized, _) in sorted(
-                step_writes.items(), reverse=True
+            for tid, ch, serialized, _ in reversed(
+                self._ordered_writes(thread_id, checkpoint_ns, cp_id)
             ):
                 if ch not in remaining:
                     continue
@@ -246,7 +255,7 @@ class InMemorySaver(
         if checkpoint_id := get_checkpoint_id(config):
             if saved := self.storage[thread_id][checkpoint_ns].get(checkpoint_id):
                 checkpoint, metadata, parent_checkpoint_id = saved
-                writes = self.writes[(thread_id, checkpoint_ns, checkpoint_id)].values()
+                writes = self._ordered_writes(thread_id, checkpoint_ns, checkpoint_id)
                 checkpoint_: Checkpoint = self.serde.loads_typed(checkpoint)
                 return CheckpointTuple(
                     config=config,
@@ -276,7 +285,7 @@ class InMemorySaver(
             if checkpoints := self.storage[thread_id][checkpoint_ns]:
                 checkpoint_id = max(checkpoints.keys())
                 checkpoint, metadata, parent_checkpoint_id = checkpoints[checkpoint_id]
-                writes = self.writes[(thread_id, checkpoint_ns, checkpoint_id)].values()
+                writes = self._ordered_writes(thread_id, checkpoint_ns, checkpoint_id)
                 checkpoint_ = self.serde.loads_typed(checkpoint)
                 return CheckpointTuple(
                     config={
@@ -379,9 +388,9 @@ class InMemorySaver(
                     elif limit is not None:
                         limit -= 1
 
-                    writes = self.writes[
-                        (thread_id, checkpoint_ns, checkpoint_id)
-                    ].values()
+                    writes = self._ordered_writes(
+                        thread_id, checkpoint_ns, checkpoint_id
+                    )
 
                     checkpoint_: Checkpoint = self.serde.loads_typed(checkpoint)
 

libs/checkpoint/langgraph/checkpoint/serde/jsonplus.py

@@ -55,6 +55,7 @@ logger = logging.getLogger(__name__)
 _MAX_WARNED_TYPES = 1000
 _warned_unregistered_types: set[tuple[str, str]] = set()
 _warned_blocked_types: set[tuple[str, str]] = set()
+_warned_unreconstructable_types: set[tuple[str, str]] = set()
 
 
 def _is_safe_json_type(id_list: list[str]) -> bool:
@@ -79,6 +80,27 @@ def _warn_once(
     logger.warning(msg, *args)
 
 
+def _reconstruction_fallback(tup: Any, exc: Exception) -> Any:
+    """Return the serialized payload of an object that could not be rebuilt.
+
+    Returning `None` here would silently erase the value from restored state.
+    """
+    try:
+        module, name, payload = tup[0], tup[1], tup[2]
+    except Exception:
+        return None
+    _warn_once(
+        _warned_unreconstructable_types,
+        (str(module), str(name)),
+        "Could not reconstruct %s.%s from checkpoint (%s); "
+        "returning its serialized data instead.",
+        module,
+        name,
+        type(exc).__name__,
+    )
+    return payload
+
+
 class JsonPlusSerializer(SerializerProtocol):
     """Serializer that uses ormsgpack, with optional fallbacks.
 
@@ -638,6 +660,7 @@ def _create_msgpack_ext_hook(
                 )
             )
         elif code == EXT_CONSTRUCTOR_SINGLE_ARG:
+            tup = None
             try:
                 tup = ormsgpack.unpackb(
                     data, ext_hook=ext_hook, option=ormsgpack.OPT_NON_STR_KEYS
@@ -649,9 +672,10 @@ def _create_msgpack_ext_hook(
                     return tup[2]
                 # module, name, arg
                 return getattr(importlib.import_module(tup[0]), tup[1])(tup[2])
-            except Exception:
-                return None
+            except Exception as exc:
+                return _reconstruction_fallback(tup, exc)
         elif code == EXT_CONSTRUCTOR_POS_ARGS:
+            tup = None
             try:
                 tup = ormsgpack.unpackb(
                     data, ext_hook=ext_hook, option=ormsgpack.OPT_NON_STR_KEYS
@@ -662,9 +686,10 @@ def _create_msgpack_ext_hook(
                     return _send_from_args(tup[2])
                 # module, name, args
                 return getattr(importlib.import_module(tup[0]), tup[1])(*tup[2])
-            except Exception:
-                return None
+            except Exception as exc:
+                return _reconstruction_fallback(tup, exc)
         elif code == EXT_CONSTRUCTOR_KW_ARGS:
+            tup = None
             try:
                 tup = ormsgpack.unpackb(
                     data, ext_hook=ext_hook, option=ormsgpack.OPT_NON_STR_KEYS
@@ -673,9 +698,10 @@ def _create_msgpack_ext_hook(
                     return tup[2]
                 # module, name, kwargs
                 return getattr(importlib.import_module(tup[0]), tup[1])(**tup[2])
-            except Exception:
-                return None
+            except Exception as exc:
+                return _reconstruction_fallback(tup, exc)
         elif code == EXT_METHOD_SINGLE_ARG:
+            tup = None
             try:
                 tup = ormsgpack.unpackb(
                     data, ext_hook=ext_hook, option=ormsgpack.OPT_NON_STR_KEYS
@@ -686,8 +712,8 @@ def _create_msgpack_ext_hook(
                 return getattr(
                     getattr(importlib.import_module(tup[0]), tup[1]), tup[3]
                 )(tup[2])
-            except Exception:
-                return None
+            except Exception as exc:
+                return _reconstruction_fallback(tup, exc)
         elif code == EXT_PYDANTIC_V1:
             try:
                 tup = ormsgpack.unpackb(

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

@@ -771,7 +771,12 @@ class BaseStore(ABC):
 
         Returns:
             The retrieved item or `None` if not found.
+
+        Raises:
+            InvalidNamespaceError: If a namespace label is empty, is not a string,
+                or contains a period (`.`).
         """
+        _validate_namespace_labels(namespace)
         return self.batch(
             [GetOp(namespace, str(key), _ensure_refresh(self.ttl_config, refresh_ttl))]
         )[0]
@@ -801,6 +806,10 @@ class BaseStore(ABC):
         Returns:
             List of items matching the search criteria.
 
+        Raises:
+            InvalidNamespaceError: If a `namespace_prefix` label is empty, is not a
+                string, or contains a period (`.`).
+
         ???+ example "Examples"
 
             Basic filtering:
@@ -840,6 +849,7 @@ class BaseStore(ABC):
                 Natural language search support depends on your store implementation
                 and requires proper embedding configuration.
         """
+        _validate_namespace_labels(namespace_prefix)
         return self.batch(
             [
                 SearchOp(
@@ -887,6 +897,11 @@ class BaseStore(ABC):
                 By default, the expiration timer refreshes on both read operations (get/search)
                 and write operations (put/update), whenever the item is included in the operation.
 
+        Raises:
+            InvalidNamespaceError: If the namespace is empty, its root label is
+                `"langgraph"`, or a label is empty, is not a string, or contains a
+                period (`.`).
+
         Note:
             Indexing support depends on your store implementation.
             If you do not initialize the store with indexing capabilities,
@@ -940,7 +955,12 @@ class BaseStore(ABC):
         Args:
             namespace: Hierarchical path for the item.
             key: Unique identifier within the namespace.
+
+        Raises:
+            InvalidNamespaceError: If a namespace label is empty, is not a string,
+                or contains a period (`.`).
         """
+        _validate_namespace_labels(namespace)
         self.batch([PutOp(namespace, str(key), None, ttl=None)])
 
     def list_namespaces(
@@ -969,6 +989,10 @@ class BaseStore(ABC):
             A list of namespace tuples that match the criteria. Each tuple represents a
                 full namespace path up to `max_depth`.
 
+        Raises:
+            InvalidNamespaceError: If a `prefix` or `suffix` label is empty, is not a
+                string, or contains a period (`.`).
+
         ???+ example "Examples":
 
             Setting `max_depth=3`. Given the namespaces:
@@ -984,6 +1008,8 @@ class BaseStore(ABC):
             # [("a", "b", "c"), ("a", "b", "d"), ("a", "b", "f")]
             ```
         """
+        _validate_namespace_labels(prefix or ())
+        _validate_namespace_labels(suffix or ())
         match_conditions = []
         if prefix:
             match_conditions.append(MatchCondition(match_type="prefix", path=prefix))
@@ -1013,7 +1039,12 @@ class BaseStore(ABC):
 
         Returns:
             The retrieved item or `None` if not found.
+
+        Raises:
+            InvalidNamespaceError: If a namespace label is empty, is not a string,
+                or contains a period (`.`).
         """
+        _validate_namespace_labels(namespace)
         return (
             await self.abatch(
                 [
@@ -1052,6 +1083,10 @@ class BaseStore(ABC):
         Returns:
             List of items matching the search criteria.
 
+        Raises:
+            InvalidNamespaceError: If a `namespace_prefix` label is empty, is not a
+                string, or contains a period (`.`).
+
         ???+ example "Examples"
 
             Basic filtering:
@@ -1091,6 +1126,7 @@ class BaseStore(ABC):
                 Natural language search support depends on your store implementation
                 and requires proper embedding configuration.
         """
+        _validate_namespace_labels(namespace_prefix)
         return (
             await self.abatch(
                 [
@@ -1140,6 +1176,11 @@ class BaseStore(ABC):
                 By default, the expiration timer refreshes on both read operations (get/search)
                 and write operations (put/update), whenever the item is included in the operation.
 
+        Raises:
+            InvalidNamespaceError: If the namespace is empty, its root label is
+                `"langgraph"`, or a label is empty, is not a string, or contains a
+                period (`.`).
+
         Note:
             Indexing support depends on your store implementation.
             If you do not initialize the store with indexing capabilities,
@@ -1201,7 +1242,12 @@ class BaseStore(ABC):
         Args:
             namespace: Hierarchical path for the item.
             key: Unique identifier within the namespace.
+
+        Raises:
+            InvalidNamespaceError: If a namespace label is empty, is not a string,
+                or contains a period (`.`).
         """
+        _validate_namespace_labels(namespace)
         await self.abatch([PutOp(namespace, str(key), None)])
 
     async def alist_namespaces(
@@ -1230,6 +1276,10 @@ class BaseStore(ABC):
             A list of namespace tuples that match the criteria. Each tuple represents a
                 full namespace path up to `max_depth`.
 
+        Raises:
+            InvalidNamespaceError: If a `prefix` or `suffix` label is empty, is not a
+                string, or contains a period (`.`).
+
         ???+ example "Examples"
 
             Setting `max_depth=3` with existing namespaces:
@@ -1245,6 +1295,8 @@ class BaseStore(ABC):
             # Returns: [("a", "b", "c"), ("a", "b", "d"), ("a", "b", "f")]
             ```
         """
+        _validate_namespace_labels(prefix or ())
+        _validate_namespace_labels(suffix or ())
         match_conditions = []
         if prefix:
             match_conditions.append(MatchCondition(match_type="prefix", path=prefix))
@@ -1263,6 +1315,14 @@ class BaseStore(ABC):
 def _validate_namespace(namespace: tuple[str, ...]) -> None:
     if not namespace:
         raise InvalidNamespaceError("Namespace cannot be empty.")
+    _validate_namespace_labels(namespace)
+    if namespace[0] == "langgraph":
+        raise InvalidNamespaceError(
+            f'Root label for namespace cannot be "langgraph". Got: {namespace}'
+        )
+
+
+def _validate_namespace_labels(namespace: tuple[str, ...]) -> None:
     for label in namespace:
         if not isinstance(label, str):
             raise InvalidNamespaceError(
@@ -1277,10 +1337,27 @@ def _validate_namespace(namespace: tuple[str, ...]) -> None:
             raise InvalidNamespaceError(
                 f"Namespace labels cannot be empty strings. Got {label} in {namespace}"
             )
-    if namespace[0] == "langgraph":
-        raise InvalidNamespaceError(
-            f'Root label for namespace cannot be "langgraph". Got: {namespace}'
-        )
+
+
+def validate_op_namespace(op: Op) -> None:
+    """Validate the namespace labels an op carries before a store executes it.
+
+    `BaseStore` methods check labels before batching, but ops passed directly to
+    `batch`/`abatch` skip those methods. Stores that serialize namespaces as
+    delimited text should call this for every op they execute, so a label such
+    as `"foo.bar"` cannot address the namespace `("foo", "bar")`.
+
+    Raises:
+        InvalidNamespaceError: If a label is empty, is not a string, or contains
+            a period (`.`).
+    """
+    if isinstance(op, (GetOp, PutOp)):
+        _validate_namespace_labels(op.namespace)
+    elif isinstance(op, SearchOp):
+        _validate_namespace_labels(op.namespace_prefix)
+    elif isinstance(op, ListNamespacesOp):
+        for condition in op.match_conditions or ():
+            _validate_namespace_labels(condition.path)
 
 
 def _ensure_refresh(
@@ -1319,4 +1396,5 @@ __all__ = [
     "ensure_embeddings",
     "tokenize_path",
     "get_text_at_path",
+    "validate_op_namespace",
 ]

libs/checkpoint/langgraph/store/base/batch.py

@@ -25,6 +25,7 @@ from langgraph.store.base import (
     _ensure_refresh,
     _ensure_ttl,
     _validate_namespace,
+    _validate_namespace_labels,
 )
 
 F = TypeVar("F", bound=Callable)
@@ -86,6 +87,7 @@ class AsyncBatchedBaseStore(BaseStore):
         *,
         refresh_ttl: bool | None = None,
     ) -> Item | None:
+        _validate_namespace_labels(namespace)
         self._ensure_task()
         fut = self._loop.create_future()
         self._aqueue.put_nowait(
@@ -111,6 +113,7 @@ class AsyncBatchedBaseStore(BaseStore):
         offset: int = 0,
         refresh_ttl: bool | None = None,
     ) -> list[SearchItem]:
+        _validate_namespace_labels(namespace_prefix)
         self._ensure_task()
         fut = self._loop.create_future()
         self._aqueue.put_nowait(
@@ -155,6 +158,7 @@ class AsyncBatchedBaseStore(BaseStore):
         namespace: tuple[str, ...],
         key: str,
     ) -> None:
+        _validate_namespace_labels(namespace)
         self._ensure_task()
         fut = self._loop.create_future()
         self._aqueue.put_nowait((fut, PutOp(namespace, key, None)))
@@ -169,6 +173,8 @@ class AsyncBatchedBaseStore(BaseStore):
         limit: int = 100,
         offset: int = 0,
     ) -> list[tuple[str, ...]]:
+        _validate_namespace_labels(prefix or ())
+        _validate_namespace_labels(suffix or ())
         self._ensure_task()
         fut = self._loop.create_future()
         match_conditions = []

libs/checkpoint/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "langgraph-checkpoint"
-version = "4.2.0"
+version = "4.3.0"
 description = "Library with base interfaces for LangGraph checkpoint savers."
 authors = []
 requires-python = ">=3.10"

libs/checkpoint/tests/test_conformance_delta.py

@@ -1,37 +0,0 @@
-"""Run delta-channel conformance capabilities against InMemorySaver."""
-
-from __future__ import annotations
-
-import pytest
-
-conformance = pytest.importorskip(
-    "langgraph.checkpoint.conformance",
-    reason="langgraph-checkpoint-conformance not installed",
-)
-
-
-@pytest.mark.asyncio
-async def test_delta_channel_conformance():
-    # Imported inside the test: the module-level importorskip above is what
-    # makes these safe, so they cannot move to the top of the file.
-    from langgraph.checkpoint.conformance import validate  # noqa: PLC0415
-    from langgraph.checkpoint.conformance.initializer import (  # noqa: PLC0415
-        checkpointer_test,
-    )
-
-    from langgraph.checkpoint.memory import InMemorySaver  # noqa: PLC0415
-
-    @checkpointer_test(name="InMemorySaver")
-    async def mem_saver():
-        yield InMemorySaver()
-
-    report = await validate(
-        mem_saver,
-        capabilities={
-            "delta_channel_history",
-        },
-    )
-    for cap, result in report.results.items():
-        if result.passed is False:
-            details = "\n".join(result.failures or [])
-            pytest.fail(f"Capability {cap} failed:\n{details}")

libs/checkpoint/tests/test_jsonplus.py

@@ -7,6 +7,7 @@ import pickle
 import re
 import sys
 import tempfile
+import types
 import uuid
 from collections import deque
 from datetime import date, datetime, time, timezone
@@ -33,12 +34,16 @@ from langgraph.checkpoint.serde.event_hooks import (
     register_serde_event_listener,
 )
 from langgraph.checkpoint.serde.jsonplus import (
+    EXT_CONSTRUCTOR_KW_ARGS,
+    EXT_CONSTRUCTOR_POS_ARGS,
+    EXT_CONSTRUCTOR_SINGLE_ARG,
     EXT_METHOD_SINGLE_ARG,
     InvalidModuleError,
     JsonPlusSerializer,
     _msgpack_enc,
     _msgpack_ext_hook_to_json,
     _warned_blocked_types,
+    _warned_unreconstructable_types,
     _warned_unregistered_types,
 )
 from langgraph.store.base import Item
@@ -821,6 +826,7 @@ def _reset_warned_types() -> None:
     # a fresh slate and assertions about warning emission are stable.
     _warned_unregistered_types.clear()
     _warned_blocked_types.clear()
+    _warned_unreconstructable_types.clear()
 
 
 def test_msgpack_pydantic_warns_by_default(caplog: pytest.LogCaptureFixture) -> None:
@@ -1230,3 +1236,58 @@ def test_msgpack_nested_pydantic_serializes_as_dict(
     # No blocking should occur - inner is serialized as dict, not ext
     assert "blocked" not in caplog.text.lower()
     assert result == obj
+
+
+def test_msgpack_dataclass_from_removed_module_restores_payload(
+    monkeypatch: pytest.MonkeyPatch, caplog: pytest.LogCaptureFixture
+) -> None:
+    @dataclasses.dataclass
+    class SavedObject:
+        value: int
+
+    SavedObject.__module__ = "removed_module"
+    module = types.ModuleType("removed_module")
+    module.SavedObject = SavedObject
+    monkeypatch.setitem(sys.modules, "removed_module", module)
+    serde = JsonPlusSerializer(
+        allowed_msgpack_modules=[("removed_module", "SavedObject")]
+    )
+    dumped = serde.dumps_typed({"state": SavedObject(123)})
+    assert serde.loads_typed(dumped) == {"state": SavedObject(123)}
+
+    monkeypatch.delitem(sys.modules, "removed_module")
+    caplog.set_level(logging.WARNING, logger="langgraph.checkpoint.serde.jsonplus")
+
+    assert serde.loads_typed(dumped) == {"state": {"value": 123}}
+    assert (
+        "could not reconstruct removed_module.savedobject from checkpoint "
+        "(modulenotfounderror)" in caplog.text.lower()
+    )
+
+
+@pytest.mark.parametrize(
+    ("code", "tup", "expected"),
+    [
+        (EXT_CONSTRUCTOR_SINGLE_ARG, ("missing_module", "Thing", "x"), "x"),
+        (EXT_CONSTRUCTOR_POS_ARGS, ("missing_module", "Thing", [1, 2]), [1, 2]),
+        (
+            EXT_CONSTRUCTOR_KW_ARGS,
+            ("missing_module", "Thing", {"value": 123}),
+            {"value": 123},
+        ),
+        (
+            EXT_METHOD_SINGLE_ARG,
+            ("datetime", "datetime", "not-a-date", "fromisoformat"),
+            "not-a-date",
+        ),
+    ],
+)
+def test_msgpack_failed_reconstruction_returns_payload(
+    code: int, tup: tuple, expected: object
+) -> None:
+    serde = JsonPlusSerializer(allowed_msgpack_modules=True)
+    payload = ormsgpack.packb(
+        ormsgpack.Ext(code, _msgpack_enc(tup)), option=ormsgpack.OPT_NON_STR_KEYS
+    )
+
+    assert serde.loads_typed(("msgpack", payload)) == expected

libs/checkpoint/tests/test_memory.py

@@ -420,6 +420,19 @@ class TestInMemorySaverDeltaChannel:
         assert "seed" not in result
         assert result["writes"] == []
 
+    def test_get_channel_writes_without_checkpoint_id_reads_the_latest(self) -> None:
+        saver = InMemorySaver()
+        thread: RunnableConfig = {
+            "configurable": {"thread_id": "t1", "checkpoint_ns": ""}
+        }
+        parent = saver.put(thread, empty_checkpoint(), {}, {})
+        saver.put_writes(parent, [("messages", "hi")], "task1")
+        saver.put(parent, empty_checkpoint(), {}, {})
+
+        result = saver.get_delta_channel_history(config=thread, channels=["messages"])
+
+        assert result == {"messages": {"writes": [("task1", "messages", "hi")]}}
+
 
 class TestBaseFallbackGetChannelWrites:
     """Exercises the `BaseCheckpointSaver.get_delta_channel_history` default

libs/checkpoint/tests/test_store.py

@@ -13,10 +13,14 @@ from langgraph.store.base import (
     GetOp,
     InvalidNamespaceError,
     Item,
+    ListNamespacesOp,
+    MatchCondition,
     Op,
     PutOp,
     Result,
+    SearchOp,
     get_text_at_path,
+    validate_op_namespace,
 )
 from langgraph.store.base.batch import AsyncBatchedBaseStore
 from langgraph.store.memory import InMemoryStore
@@ -528,6 +532,127 @@ async def test_cannot_put_empty_namespace() -> None:
     assert (await async_store.aget(("valid", "namespace"), "key")) is None
 
 
+INVALID_NAMESPACES = [("foo.bar",), ("foo", ""), (123,)]
+NAMESPACE_METHODS = ["get", "delete", "search", "prefix", "suffix"]
+
+
+@pytest.mark.parametrize("namespace", INVALID_NAMESPACES)
+@pytest.mark.parametrize("method", NAMESPACE_METHODS)
+def test_rejects_invalid_namespace_labels(
+    mocker: MockerFixture, namespace: tuple, method: str
+) -> None:
+    store = InMemoryStore()
+    batch = mocker.spy(InMemoryStore, "batch")
+    call = {
+        "get": lambda: store.get(namespace, "key"),
+        "delete": lambda: store.delete(namespace, "key"),
+        "search": lambda: store.search(namespace),
+        "prefix": lambda: store.list_namespaces(prefix=namespace),
+        "suffix": lambda: store.list_namespaces(suffix=namespace),
+    }[method]
+
+    with pytest.raises(InvalidNamespaceError):
+        call()
+
+    batch.assert_not_called()
+
+
+@pytest.mark.parametrize("batched", [False, True])
+@pytest.mark.parametrize("namespace", INVALID_NAMESPACES)
+@pytest.mark.parametrize("method", NAMESPACE_METHODS)
+async def test_async_rejects_invalid_namespace_labels(
+    mocker: MockerFixture, batched: bool, namespace: tuple, method: str
+) -> None:
+    # The batched store must reject before queueing: a failure inside the
+    # shared `abatch` would fail every op queued alongside this one.
+    store = MockAsyncBatchedStore() if batched else InMemoryStore()
+    # `MockAsyncBatchedStore` dispatches through `InMemoryStore.batch`.
+    batch = mocker.spy(InMemoryStore, "batch")
+    abatch = mocker.spy(InMemoryStore, "abatch")
+    call = {
+        "get": lambda: store.aget(namespace, "key"),
+        "delete": lambda: store.adelete(namespace, "key"),
+        "search": lambda: store.asearch(namespace),
+        "prefix": lambda: store.alist_namespaces(prefix=namespace),
+        "suffix": lambda: store.alist_namespaces(suffix=namespace),
+    }[method]
+
+    with pytest.raises(InvalidNamespaceError):
+        await call()
+
+    batch.assert_not_called()
+    abatch.assert_not_called()
+
+
+def test_search_and_listing_keep_empty_prefixes_and_wildcards() -> None:
+    store = InMemoryStore()
+    store.put(("tenant", "a_%"), "key", {"v": 1})
+    store.put(("tenant", "b", "child"), "key", {"v": 1})
+
+    assert len(store.search(())) == 2
+    assert [item.namespace for item in store.search(("tenant", "a_%"))] == [
+        ("tenant", "a_%")
+    ]
+    assert sorted(store.list_namespaces(prefix=("tenant", "*"), suffix=("*",))) == [
+        ("tenant", "a_%"),
+        ("tenant", "b", "child"),
+    ]
+
+
+@pytest.mark.parametrize("batched", [False, True])
+async def test_async_search_and_listing_keep_empty_prefixes_and_wildcards(
+    batched: bool,
+) -> None:
+    store = MockAsyncBatchedStore() if batched else InMemoryStore()
+    await store.aput(("tenant", "a_%"), "key", {"v": 1})
+    await store.aput(("tenant", "b", "child"), "key", {"v": 1})
+
+    assert len(await store.asearch(())) == 2
+    assert [item.namespace for item in await store.asearch(("tenant", "a_%"))] == [
+        ("tenant", "a_%")
+    ]
+    assert sorted(
+        await store.alist_namespaces(prefix=("tenant", "*"), suffix=("*",))
+    ) == [("tenant", "a_%"), ("tenant", "b", "child")]
+
+
+@pytest.mark.parametrize("namespace", INVALID_NAMESPACES)
+@pytest.mark.parametrize(
+    "kind", ["get", "put", "delete", "search", "list_prefix", "list_suffix"]
+)
+def test_validate_op_namespace_rejects_invalid_labels(
+    namespace: tuple, kind: str
+) -> None:
+    op = {
+        "get": GetOp(namespace, "key"),
+        "put": PutOp(namespace, "key", {"v": 1}),
+        "delete": PutOp(namespace, "key", None),
+        "search": SearchOp(namespace),
+        "list_prefix": ListNamespacesOp((MatchCondition("prefix", namespace),)),
+        "list_suffix": ListNamespacesOp((MatchCondition("suffix", namespace),)),
+    }[kind]
+
+    with pytest.raises(InvalidNamespaceError):
+        validate_op_namespace(op)
+
+
+def test_validate_op_namespace_allows_empty_prefix_and_wildcards() -> None:
+    for op in (
+        SearchOp(()),
+        ListNamespacesOp(),
+        ListNamespacesOp(
+            (
+                MatchCondition("prefix", ("tenant", "*")),
+                MatchCondition("suffix", ("*",)),
+            )
+        ),
+        GetOp(("tenant", "a_%"), "key"),
+        # Write-only rules belong to `put`, not to op validation.
+        PutOp(("langgraph", "x"), "key", {"v": 1}),
+    ):
+        validate_op_namespace(op)
+
+
 async def test_async_batch_store_deduplication(mocker: MockerFixture) -> None:
     abatch = mocker.spy(InMemoryStore, "batch")
     store = MockAsyncBatchedStore()

libs/checkpoint/uv.lock

@@ -301,7 +301,7 @@ wheels = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "4.2.0"
+version = "4.3.0"
 source = { editable = "." }
 dependencies = [
     { name = "langchain-core" },

libs/cli/langgraph_cli/__init__.py

@@ -1 +1 @@
-__version__ = "0.4.32"
+__version__ = "0.4.33"

libs/cli/langgraph_cli/deploy.py

@@ -32,7 +32,7 @@ from langgraph_cli.host_backend import (
     HostBackendError,
     SourceName,
 )
-from langgraph_cli.image_reference import ImageReference
+from langgraph_cli.image_reference import DIGEST_SEPARATOR, ImageReference
 from langgraph_cli.progress import Progress
 from langgraph_cli.util import warn_non_wolfi_distro
 
@@ -624,6 +624,41 @@ def format_deployments_table(deployments: Sequence[dict[str, object]]) -> str:
     return "\n".join(lines)
 
 
+def _extract_listener_namespaces(listener: dict[str, object]) -> str:
+    compute_config = listener.get("compute_config")
+    namespaces = (
+        compute_config.get("k8s_namespaces")
+        if isinstance(compute_config, dict)
+        else None
+    )
+    if isinstance(namespaces, list) and namespaces:
+        return ", ".join(str(namespace) for namespace in namespaces)
+    return "-"
+
+
+def format_listeners_table(listeners: Sequence[dict[str, object]]) -> str:
+    headers = ("Listener ID", "Compute ID", "Namespaces")
+    rows = [
+        (
+            str(listener.get("id", "-") or "-"),
+            str(listener.get("compute_id", "-") or "-"),
+            _extract_listener_namespaces(listener),
+        )
+        for listener in listeners
+    ]
+    widths = [
+        max(len(headers[index]), *(len(row[index]) for row in rows))
+        for index in range(len(headers))
+    ]
+
+    def format_row(row: Sequence[str]) -> str:
+        return "  ".join(value.ljust(widths[index]) for index, value in enumerate(row))
+
+    lines = [format_row(headers), format_row(tuple("-" * width for width in widths))]
+    lines.extend(format_row(row) for row in rows)
+    return "\n".join(lines)
+
+
 def format_revisions_table(revisions: Sequence[dict[str, object]]) -> str:
     headers = ("Revision ID", "Status", "Created At")
     latest_deployed_seen = False
@@ -1544,9 +1579,9 @@ def _ensure_customer_registry_source(existing: ExistingDeployment) -> None:
     if existing.source != _CUSTOMER_REGISTRY_SOURCE:
         raise click.UsageError(
             f"Deployment {existing.id} was not created from an external image "
-            "and cannot be updated with --push-to. Run without --push-to to keep "
-            "its current build mode, or use a different --name to create a new "
-            "deployment."
+            "and cannot be updated with --push-to or --image-uri. Run without "
+            "either flag to keep its current build mode, or use a different "
+            "--name to create a new deployment."
         )
 
 
@@ -1599,9 +1634,22 @@ class RemoteBuildSource:
 
 
 @dataclass(frozen=True, slots=True)
-class CustomerRegistrySource:
+class BuildAndPush:
     reference: ImageReference
     prebuilt_image: str | None
+
+
+@dataclass(frozen=True, slots=True)
+class PublishedImage:
+    image_uri: str
+
+
+ImageSource = BuildAndPush | PublishedImage
+
+
+@dataclass(frozen=True, slots=True)
+class CustomerRegistrySource:
+    image: ImageSource
     requested_placement: RequestedPlacement
 
     def run(self, ctx: DeployContext) -> DeployOutcome:
@@ -1686,16 +1734,22 @@ class CustomerRegistrySource:
         )
 
     def _publish(self, ctx: DeployContext, step: int) -> tuple[str, int]:
-        image = str(self.reference)
+        if isinstance(self.image, PublishedImage):
+            return self.image.image_uri, step
+        image = str(self.image.reference)
         with Runner() as runner:
-            if self.prebuilt_image:
-                _log_deploy_step(step, f"Validating image {self.prebuilt_image}")
+            if self.image.prebuilt_image:
+                _log_deploy_step(step, f"Validating image {self.image.prebuilt_image}")
                 _validate_prebuilt_image(
-                    runner, self.prebuilt_image, verbose=ctx.verbose
+                    runner, self.image.prebuilt_image, verbose=ctx.verbose
                 )
                 runner.run(
                     subp_exec(
-                        "docker", "tag", self.prebuilt_image, image, verbose=ctx.verbose
+                        "docker",
+                        "tag",
+                        self.image.prebuilt_image,
+                        image,
+                        verbose=ctx.verbose,
                     )
                 )
             else:
@@ -1733,20 +1787,35 @@ def _push_reference(push_to: str, tag: str | None) -> ImageReference:
     return reference.with_tag(normalize_image_tag(tag or _DEFAULT_IMAGE_TAG))
 
 
+def _validate_image_uri(image_uri: str) -> str:
+    value = image_uri.strip()
+    if not value:
+        raise click.UsageError("--image-uri must not be empty.")
+    if DIGEST_SEPARATOR not in value:
+        raise click.UsageError(
+            "--image-uri must pin a digest, e.g. "
+            f"repository{DIGEST_SEPARATOR}<sha256 hex>. Kubernetes can cache "
+            "images by tag, so redeploying a mutable tag may silently keep "
+            "running the previous image."
+        )
+    return value
+
+
 def _select_source(
     *,
     push_to: str | None,
     image: str | None,
+    image_uri: str | None,
     image_name: str | None,
     tag: str | None,
     remote_build_flag: bool | None,
     placement: RequestedPlacement,
     selector: DeploymentSelector,
 ) -> DeploymentSource:
-    if push_to is None and placement.requested:
+    if push_to is None and image_uri is None and placement.requested:
         raise click.UsageError(
             "--listener-id and --k8s-namespace only apply when creating a "
-            "deployment with --push-to."
+            "deployment with --push-to or --image-uri."
         )
     if placement.requested and isinstance(selector, ById):
         raise click.UsageError(
@@ -1754,6 +1823,19 @@ def _select_source(
             "they cannot be set for an existing --deployment-id. Drop them, or "
             "create a new deployment with --name."
         )
+    if image_uri is not None:
+        if push_to is not None:
+            raise click.UsageError("--image-uri cannot be combined with --push-to.")
+        if image is not None:
+            raise click.UsageError("--image-uri cannot be combined with --image.")
+        if tag is not None:
+            raise click.UsageError("--image-uri cannot be combined with --tag.")
+        if remote_build_flag is not None:
+            raise click.UsageError("--image-uri cannot be combined with --remote.")
+        return CustomerRegistrySource(
+            image=PublishedImage(_validate_image_uri(image_uri)),
+            requested_placement=placement,
+        )
     if push_to is not None:
         if remote_build_flag is True:
             raise click.UsageError("--push-to cannot be combined with --remote.")
@@ -1761,8 +1843,7 @@ def _select_source(
         if image is None:
             _require_local_docker()
         return CustomerRegistrySource(
-            reference=reference,
-            prebuilt_image=image,
+            image=BuildAndPush(reference=reference, prebuilt_image=image),
             requested_placement=placement,
         )
     if image and remote_build_flag is True:
@@ -2075,19 +2156,30 @@ def _deploy_base_options(
                     "Give the tag here or with --tag (default: latest)."
                 ),
             ),
+            click.option(
+                "--image-uri",
+                help=(
+                    "Deploy an image that's already in a registry you manage, "
+                    "without building, retagging, or pushing anything. For "
+                    "self-hosted and hybrid LangSmith. Give the full reference, "
+                    "e.g. 123456789.dkr.ecr.us-east-1.amazonaws.com/agents/"
+                    "my-agent:v1.2.3 or ...@sha256:<digest>. Cannot be combined "
+                    "with --push-to, --image, --tag, or --remote."
+                ),
+            ),
             click.option(
                 "--listener-id",
                 help=(
                     "Listener that will run the deployment, for workspaces that "
                     "deploy through a listener in your own cluster. Only used when "
-                    "creating a deployment with --push-to."
+                    "creating a deployment with --push-to or --image-uri."
                 ),
             ),
             click.option(
                 "--k8s-namespace",
                 help=(
                     "Kubernetes namespace the listener deploys into. Only used when "
-                    "creating a deployment with --push-to."
+                    "creating a deployment with --push-to or --image-uri."
                 ),
             ),
             click.option(
@@ -2200,6 +2292,7 @@ def _deploy_cmd(
     image_name: str | None,
     image: str | None,
     push_to: str | None,
+    image_uri: str | None,
     listener_id: str | None,
     k8s_namespace: str | None,
     tag: str | None,
@@ -2273,6 +2366,7 @@ def _deploy_cmd(
     source = _select_source(
         push_to=push_to,
         image=image,
+        image_uri=image_uri,
         image_name=image_name,
         tag=tag,
         remote_build_flag=remote_build_flag,
@@ -2408,6 +2502,41 @@ def deploy_list(
     click.echo(format_deployments_table(deployments))
 
 
+# ---------------------------------------------------------------------------
+# deploy listeners
+# ---------------------------------------------------------------------------
+
+
+@deploy.group(
+    "listeners",
+    cls=NestedHelpGroup,
+    help="[Beta] Inspect listeners available to this workspace.",
+)
+def deploy_listeners() -> None:
+    pass
+
+
+@OPT_HOST_API_KEY
+@OPT_HOST_URL
+@deploy_listeners.command(
+    "list",
+    help=(
+        "[Beta] List listeners available to this workspace.\n\n"
+        "Pass a listener's id to `langgraph deploy --push-to ... "
+        "--listener-id <id>` to deploy through it."
+    ),
+)
+def deploy_listeners_list(api_key: str | None, host_url: str | None) -> None:
+    client = _create_host_backend_client(host_url, api_key)
+    listeners = _call_host_backend_with_optional_tenant(
+        client, lambda c: c.list_listeners()
+    )
+    if not listeners:
+        click.echo("No listeners found for this workspace.")
+        return
+    click.echo(format_listeners_table(listeners))
+
+
 # ---------------------------------------------------------------------------
 # deploy revisions
 # ---------------------------------------------------------------------------

libs/cli/tests/unit_tests/cli/test_cli.py

@@ -453,6 +453,88 @@ def test_deploy_list_command_no_results(monkeypatch) -> None:
     assert result.output.strip() == "No deployments found."
 
 
+def test_deploy_listeners_list_command(monkeypatch) -> None:
+    runner = CliRunner()
+    captured: dict[str, str] = {}
+
+    class FakeClient:
+        def __init__(self, host_url: str, api_key: str, tenant_id: str | None = None):
+            captured["host_url"] = host_url
+            captured["api_key"] = api_key
+            captured["tenant_id"] = tenant_id or ""
+
+        def list_listeners(self):
+            return [
+                {
+                    "id": "listener-1",
+                    "compute_id": "prod-cluster",
+                    "compute_config": {"k8s_namespaces": ["agents"]},
+                },
+                {
+                    "id": "listener-2",
+                    "compute_id": "multi-cluster",
+                    "compute_config": {"k8s_namespaces": ["agents", "agents-staging"]},
+                },
+            ]
+
+    monkeypatch.setattr(deploy_module, "HostBackendClient", FakeClient)
+
+    result = runner.invoke(
+        cli,
+        [
+            "deploy",
+            "listeners",
+            "list",
+            "--api-key",
+            "test-key",
+            "--host-url",
+            "https://api.example.com",
+        ],
+    )
+
+    assert result.exit_code == 0, result.output
+    assert captured == {
+        "host_url": "https://api.example.com",
+        "api_key": "test-key",
+        "tenant_id": "",
+    }
+    assert "Listener ID" in result.output
+    assert "Compute ID" in result.output
+    assert "Namespaces" in result.output
+    assert "listener-1" in result.output
+    assert "prod-cluster" in result.output
+    assert "agents, agents-staging" in result.output
+
+
+def test_deploy_listeners_list_command_no_results(monkeypatch) -> None:
+    runner = CliRunner()
+
+    class FakeClient:
+        def __init__(self, host_url: str, api_key: str, tenant_id: str | None = None):
+            pass
+
+        def list_listeners(self):
+            return []
+
+    monkeypatch.setattr(deploy_module, "HostBackendClient", FakeClient)
+
+    result = runner.invoke(
+        cli,
+        [
+            "deploy",
+            "listeners",
+            "list",
+            "--api-key",
+            "test-key",
+            "--host-url",
+            "https://api.example.com",
+        ],
+    )
+
+    assert result.exit_code == 0, result.output
+    assert result.output.strip() == "No listeners found for this workspace."
+
+
 def test_deploy_revisions_list_command(monkeypatch) -> None:
     runner = CliRunner()
     captured: dict[str, str] = {}

libs/cli/tests/unit_tests/cli/test_deploy_command.py

@@ -695,6 +695,106 @@ def test_push_to_with_deployment_id_fetches_the_deployment_once(
     ]
 
 
+def test_image_uri_creates_an_external_deployment_without_any_docker_work(
+    deploy_project: DeployProject,
+) -> None:
+    result = deploy_project.run("--image-uri", EXTERNAL_DIGEST)
+
+    assert result.exit_code == 0, result.output
+    assert deploy_project.docker.verbs() == []
+    assert deploy_project.timeline == [LIST_DEPLOYMENTS, CREATE_DEPLOYMENT]
+    assert deploy_project.control_plane.bodies[CREATE_DEPLOYMENT][
+        "source_revision_config"
+    ] == {"image_uri": EXTERNAL_DIGEST}
+
+
+def test_image_uri_updates_an_existing_external_deployment_without_any_docker_work(
+    deploy_project: DeployProject,
+) -> None:
+    deploy_project.control_plane.existing_deployments = [
+        {"id": "dep-ext", "name": "my-app", "source": "external_docker"}
+    ]
+
+    result = deploy_project.run("--image-uri", EXTERNAL_DIGEST)
+
+    assert result.exit_code == 0, result.output
+    assert deploy_project.docker.verbs() == []
+    assert deploy_project.timeline == [LIST_DEPLOYMENTS, _patch("dep-ext")]
+    assert deploy_project.control_plane.bodies[_patch("dep-ext")] == {
+        "source_revision_config": {"image_uri": EXTERNAL_DIGEST},
+        "secrets": [],
+        "tracked_packages": TRACKED_PACKAGES,
+    }
+
+
+def test_image_uri_places_a_new_deployment_on_the_only_listener(
+    deploy_project: DeployProject,
+) -> None:
+    deploy_project.control_plane.listeners = [LISTENER]
+
+    result = deploy_project.run(
+        "--image-uri", EXTERNAL_DIGEST, host_url=CLOUD_CONTROL_PLANE_URL
+    )
+
+    assert result.exit_code == 0, result.output
+    assert deploy_project.docker.verbs() == []
+    assert deploy_project.control_plane.bodies[CREATE_DEPLOYMENT]["source_config"] == {
+        "resource_spec": {},
+        "listener_id": LISTENER_ID,
+        "listener_config": {"k8s_namespace": "agents"},
+    }
+
+
+def test_image_uri_rejects_a_non_external_deployment_before_any_docker_work(
+    deploy_project: DeployProject,
+) -> None:
+    deploy_project.control_plane.existing_deployments = [
+        {"id": "dep-cli", "name": "my-app", "source": "internal_docker"}
+    ]
+
+    result = deploy_project.run("--image-uri", EXTERNAL_DIGEST)
+
+    assert result.exit_code != 0
+    assert "cannot be updated with --push-to or --image-uri" in result.output
+    assert deploy_project.docker.verbs() == []
+
+
+@pytest.mark.parametrize(
+    ("args", "message"),
+    [
+        pytest.param(
+            ("--image-uri", EXTERNAL_DIGEST, "--push-to", PUSH_REPOSITORY),
+            "--image-uri cannot be combined with --push-to.",
+            id="with_push_to",
+        ),
+        pytest.param(
+            ("--image-uri", EXTERNAL_DIGEST, "--image", "local/app:dev"),
+            "--image-uri cannot be combined with --image.",
+            id="with_image",
+        ),
+        pytest.param(
+            ("--image-uri", EXTERNAL_DIGEST, "--tag", "v2"),
+            "--image-uri cannot be combined with --tag.",
+            id="with_tag",
+        ),
+        pytest.param(
+            ("--image-uri", EXTERNAL_DIGEST, "--remote"),
+            "--image-uri cannot be combined with --remote.",
+            id="with_remote",
+        ),
+    ],
+)
+def test_image_uri_conflicting_flags_are_rejected_before_any_docker_work(
+    deploy_project: DeployProject, args: tuple[str, ...], message: str
+) -> None:
+    result = deploy_project.run(*args)
+
+    assert result.exit_code != 0
+    assert message in result.output
+    assert deploy_project.docker.verbs() == []
+    assert deploy_project.timeline == []
+
+
 def test_invalid_tag_fails_before_any_control_plane_call(
     deploy_project: DeployProject,
 ) -> None:

libs/cli/tests/unit_tests/test_deploy_helpers.py

@@ -13,6 +13,7 @@ import pytest
 
 import langgraph_cli.deploy as deploy_mod
 from langgraph_cli.deploy import (
+    BuildAndPush,
     ById,
     ByName,
     CustomerRegistrySource,
@@ -21,6 +22,7 @@ from langgraph_cli.deploy import (
     Listener,
     ManagedRegistrySource,
     OnListener,
+    PublishedImage,
     RemoteBuildSource,
     RequestedPlacement,
     Unplaced,
@@ -614,6 +616,7 @@ class TestSelectSource:
     OPTIONS = {
         "push_to": None,
         "image": None,
+        "image_uri": None,
         "image_name": None,
         "tag": None,
         "remote_build_flag": None,
@@ -629,8 +632,10 @@ class TestSelectSource:
                 {"push_to": REPOSITORY},
                 True,
                 CustomerRegistrySource(
-                    reference=ImageReference(REPOSITORY, "latest"),
-                    prebuilt_image=None,
+                    image=BuildAndPush(
+                        reference=ImageReference(REPOSITORY, "latest"),
+                        prebuilt_image=None,
+                    ),
                     requested_placement=RequestedPlacement(),
                 ),
                 id="push_to_selects_the_external_source_with_the_default_tag",
@@ -639,8 +644,10 @@ class TestSelectSource:
                 {"push_to": f"{REPOSITORY}:v2"},
                 True,
                 CustomerRegistrySource(
-                    reference=ImageReference(REPOSITORY, "v2"),
-                    prebuilt_image=None,
+                    image=BuildAndPush(
+                        reference=ImageReference(REPOSITORY, "v2"),
+                        prebuilt_image=None,
+                    ),
                     requested_placement=RequestedPlacement(),
                 ),
                 id="push_to_keeps_a_tag_given_in_the_reference",
@@ -649,8 +656,10 @@ class TestSelectSource:
                 {"push_to": REPOSITORY, "tag": "v3"},
                 True,
                 CustomerRegistrySource(
-                    reference=ImageReference(REPOSITORY, "v3"),
-                    prebuilt_image=None,
+                    image=BuildAndPush(
+                        reference=ImageReference(REPOSITORY, "v3"),
+                        prebuilt_image=None,
+                    ),
                     requested_placement=RequestedPlacement(),
                 ),
                 id="tag_flag_composes_with_push_to",
@@ -659,8 +668,10 @@ class TestSelectSource:
                 {"push_to": REPOSITORY, "image": "app:dev"},
                 False,
                 CustomerRegistrySource(
-                    reference=ImageReference(REPOSITORY, "latest"),
-                    prebuilt_image="app:dev",
+                    image=BuildAndPush(
+                        reference=ImageReference(REPOSITORY, "latest"),
+                        prebuilt_image="app:dev",
+                    ),
                     requested_placement=RequestedPlacement(),
                 ),
                 id="prebuilt_image_is_retagged_for_push_to_without_docker_checks",
@@ -672,12 +683,44 @@ class TestSelectSource:
                 },
                 True,
                 CustomerRegistrySource(
-                    reference=ImageReference(REPOSITORY, "latest"),
-                    prebuilt_image=None,
+                    image=BuildAndPush(
+                        reference=ImageReference(REPOSITORY, "latest"),
+                        prebuilt_image=None,
+                    ),
                     requested_placement=RequestedPlacement("listener-1", "agents"),
                 ),
                 id="push_to_carries_the_requested_placement",
             ),
+            pytest.param(
+                {"image_uri": f"{REPOSITORY}@sha256:abc123"},
+                True,
+                CustomerRegistrySource(
+                    image=PublishedImage(f"{REPOSITORY}@sha256:abc123"),
+                    requested_placement=RequestedPlacement(),
+                ),
+                id="image_uri_selects_the_published_image_source_by_digest",
+            ),
+            pytest.param(
+                {"image_uri": f"  {REPOSITORY}@sha256:abc123  "},
+                False,
+                CustomerRegistrySource(
+                    image=PublishedImage(f"{REPOSITORY}@sha256:abc123"),
+                    requested_placement=RequestedPlacement(),
+                ),
+                id="image_uri_needs_no_local_docker_and_is_trimmed",
+            ),
+            pytest.param(
+                {
+                    "image_uri": f"{REPOSITORY}@sha256:abc123",
+                    "placement": RequestedPlacement("listener-1", "agents"),
+                },
+                False,
+                CustomerRegistrySource(
+                    image=PublishedImage(f"{REPOSITORY}@sha256:abc123"),
+                    requested_placement=RequestedPlacement("listener-1", "agents"),
+                ),
+                id="image_uri_carries_the_requested_placement",
+            ),
             pytest.param(
                 {"remote_build_flag": True},
                 True,
@@ -763,6 +806,46 @@ class TestSelectSource:
                 "only apply when creating a deployment with --push-to",
                 id="namespace_without_push_to",
             ),
+            pytest.param(
+                {"image_uri": REPOSITORY, "push_to": REPOSITORY},
+                "--image-uri cannot be combined with --push-to.",
+                id="image_uri_with_push_to",
+            ),
+            pytest.param(
+                {"image_uri": REPOSITORY, "image": "app:dev"},
+                "--image-uri cannot be combined with --image.",
+                id="image_uri_with_image",
+            ),
+            pytest.param(
+                {"image_uri": REPOSITORY, "tag": "v2"},
+                "--image-uri cannot be combined with --tag.",
+                id="image_uri_with_tag",
+            ),
+            pytest.param(
+                {"image_uri": REPOSITORY, "remote_build_flag": True},
+                "--image-uri cannot be combined with --remote.",
+                id="image_uri_with_remote",
+            ),
+            pytest.param(
+                {"image_uri": ""},
+                "--image-uri must not be empty.",
+                id="image_uri_empty",
+            ),
+            pytest.param(
+                {"image_uri": "   "},
+                "--image-uri must not be empty.",
+                id="image_uri_blank",
+            ),
+            pytest.param(
+                {"image_uri": f"{REPOSITORY}:v1.2.3"},
+                "--image-uri must pin a digest",
+                id="image_uri_with_a_mutable_tag",
+            ),
+            pytest.param(
+                {"image_uri": REPOSITORY},
+                "--image-uri must pin a digest",
+                id="image_uri_without_any_tag_or_digest",
+            ),
         ],
     )
     def test_conflicting_flags_are_rejected(self, monkeypatch, flags, message):
@@ -1164,6 +1247,7 @@ def test_a_deployment_id_with_listener_flags_is_refused_without_probing_docker(
         _select_source(
             push_to="registry.example.com/app",
             image=None,
+            image_uri=None,
             image_name=None,
             tag=None,
             remote_build_flag=None,

libs/cli/tests/unit_tests/test_util.py

@@ -3,6 +3,7 @@ from unittest.mock import patch
 from langgraph_cli.deploy import (
     _extract_deployment_url,
     format_deployments_table,
+    format_listeners_table,
     format_revisions_table,
 )
 from langgraph_cli.util import clean_empty_lines, warn_non_wolfi_distro
@@ -255,3 +256,34 @@ def test_format_revisions_table():
     assert "rev-456" in output
     assert "rev-789" in output
     assert "REPLACED" in output
+
+
+def test_format_listeners_table():
+    output = format_listeners_table(
+        [
+            {
+                "id": "listener-1",
+                "compute_id": "prod-cluster",
+                "compute_config": {"k8s_namespaces": ["agents"]},
+            },
+            {
+                "id": "listener-2",
+                "compute_id": "multi-cluster",
+                "compute_config": {"k8s_namespaces": ["agents", "agents-staging"]},
+            },
+            {
+                "id": "listener-3",
+                "compute_id": "broken-cluster",
+            },
+        ]
+    )
+    assert "Listener ID" in output
+    assert "Compute ID" in output
+    assert "Namespaces" in output
+    assert "listener-1" in output
+    assert "prod-cluster" in output
+    assert "agents" in output
+    assert "listener-2" in output
+    assert "agents, agents-staging" in output
+    assert "listener-3" in output
+    assert "broken-cluster" in output

libs/langgraph/langgraph/errors.py

@@ -28,6 +28,7 @@ __all__ = (
     "ParentCommand",
     "EmptyInputError",
     "TaskNotFound",
+    "is_invalid_resume",
 )
 
 
@@ -239,3 +240,21 @@ class NodeTimeoutError(Exception):
         self.kind = kind
         self.idle_timeout = idle_timeout
         self.run_timeout = run_timeout
+
+
+_INVALID_RESUME = "_langgraph_invalid_resume"
+
+
+def _mark_invalid_resume(error: BaseException) -> None:
+    setattr(error, _INVALID_RESUME, True)
+
+
+def is_invalid_resume(error: BaseException) -> bool:
+    """Whether `error` was raised because a resume value didn't match `response_schema`.
+
+    `interrupt()` raises a `pydantic.ValidationError` in that case. `ToolNode` uses
+    this to tell it apart from invalid tool arguments when a tool calls `interrupt()`
+    or runs a graph that does, so the resume fails and the interrupt can be answered
+    again.
+    """
+    return getattr(error, _INVALID_RESUME, False) is True

libs/langgraph/langgraph/pregel/_algo.py

@@ -27,6 +27,7 @@ from langgraph.checkpoint.base import (
     Checkpoint,
     PendingWrite,
     V,
+    writes_sort_key,
 )
 from langgraph.store.base import BaseStore
 from xxhash import xxh3_128_hexdigest
@@ -251,9 +252,7 @@ def apply_writes(
         Set of channels that were updated in this step.
     """
     # sort tasks on path, to ensure deterministic order for update application
-    # any path parts after the 3rd are ignored for sorting
-    # (we use them for eg. task ids which aren't good for sorting)
-    tasks = sorted(tasks, key=lambda t: task_path_str(t.path[:3]))
+    tasks = sorted(tasks, key=lambda t: writes_sort_key(task_path_str(t.path)))
     # if no task has triggers this is applying writes from the null task only
     # so we don't do anything other than update the channels written to
     bump_step = any(t.triggers for t in tasks)

libs/langgraph/langgraph/pregel/_checkpoint.py

@@ -1,8 +1,9 @@
 from __future__ import annotations
 
 import uuid
-from collections.abc import Callable, Iterable, Mapping
+from collections.abc import Callable, Iterable, Mapping, Sequence
 from datetime import datetime, timezone
+from inspect import signature
 from typing import Any, Literal, cast
 
 from langchain_core.runnables import RunnableConfig
@@ -25,11 +26,13 @@ from langgraph._internal._constants import (
     CONFIG_KEY_CHECKPOINT_ID,
     NS_END,
     NS_SEP,
+    NULL_TASK_ID,
     PUSH,
     SNAPSHOT_BUMPS,
 )
 from langgraph._internal._typing import MISSING
 from langgraph.channels.base import BaseChannel
+from langgraph.channels.binop import _get_overwrite
 from langgraph.channels.delta import DeltaChannel
 from langgraph.managed.base import ManagedValueMapping, ManagedValueSpec
 
@@ -49,15 +52,38 @@ def empty_checkpoint() -> Checkpoint:
     )
 
 
+def put_writes_accepts_task_path(put_writes: Callable[..., Any]) -> bool:
+    """Whether a saver's `put_writes` or `aput_writes` takes `task_path`.
+
+    Savers written before the parameter existed don't, so it is passed only
+    when this is true.
+    """
+    return signature(put_writes).parameters.get("task_path") is not None
+
+
 def exit_delta_task_id(step: int, task_id: str) -> str:
     """Synthetic task id for exit-mode DeltaChannel writes.
 
     Embeds the superstep in the first UUID group so `ORDER BY task_id, idx`
     preserves chronological order while remaining a valid RFC UUID (required by
-    Postgres `checkpoint_writes.task_id uuid` columns).
+    Postgres `checkpoint_writes.task_id uuid` columns). Never `NULL_TASK_ID`:
+    readers apply writes under it as the anchor checkpoint's own pending writes.
     """
     parts = str(uuid.UUID(task_id)).split("-")
-    return f"{step:08d}-{parts[1]}-{parts[2]}-{parts[3]}-{parts[4]}"
+    synthetic = f"{step:08d}-{parts[1]}-{parts[2]}-{parts[3]}-{parts[4]}"
+    if synthetic == NULL_TASK_ID:
+        return f"{step:08d}-0000-0000-0000-000000000001"
+    return synthetic
+
+
+def exit_delta_late_task_id(step: int, task_id: str) -> str:
+    """Synthetic task id for exit-mode writes of a superstep after the anchor's own.
+
+    Sorts after every real task id, in step order, so replay keeps them after
+    the anchor's own superstep whether a saver orders by task path or task id.
+    """
+    parts = str(uuid.UUID(task_id)).split("-")
+    return f"ffffffff-{step >> 16:04x}-{step & 0xFFFF:04x}-{parts[3]}-{parts[4]}"
 
 
 def delta_channels_to_snapshot(
@@ -127,6 +153,23 @@ def delta_channels_with_pending_writes(
     }
 
 
+def delta_channels_overwritten(
+    specs: Mapping[str, Any], writes: Iterable[tuple[str, Any]]
+) -> set[str]:
+    """Return the names of the DeltaChannels that `writes` set with an `Overwrite`.
+
+    `update_state` saves a full snapshot of these channels in the checkpoint it
+    creates, like the loop does when a node returns an `Overwrite`. Otherwise,
+    reading the channel later starts from an older snapshot and replays the
+    writes the `Overwrite` threw away.
+    """
+    return {
+        ch
+        for ch, value in writes
+        if isinstance(specs.get(ch), DeltaChannel) and _get_overwrite(value)[0]
+    }
+
+
 def checkpoint_superseded(
     saver: BaseCheckpointSaver, config: RunnableConfig, saved: CheckpointTuple
 ) -> bool:
@@ -231,6 +274,7 @@ def create_checkpoint(
     get_next_version: GetNextVersion | None = None,
     channels_to_snapshot: set[str] | None = None,
     stored_versions: ChannelVersions | None = None,
+    trigger_to_nodes: Mapping[str, Sequence[str]] | None = None,
 ) -> Checkpoint:
     """Build a new Checkpoint from the previous one and live channel state.
 
@@ -289,7 +333,9 @@ def create_checkpoint(
         id=id or str(uuid6(clock_seq=step)),
         channel_values=values,
         channel_versions=channel_versions,
-        versions_seen=_mark_bumps_seen(checkpoint["versions_seen"], bumped),
+        versions_seen=_mark_bumps_seen(
+            checkpoint["versions_seen"], bumped, trigger_to_nodes or {}
+        ),
         updated_channels=None if updated_channels is None else sorted(updated_channels),
     )
 
@@ -297,19 +343,27 @@ def create_checkpoint(
 def _mark_bumps_seen(
     versions_seen: dict[str, ChannelVersions],
     bumped: Mapping[str, tuple[Any, Any]],
+    trigger_to_nodes: Mapping[str, Sequence[str]],
 ) -> dict[str, ChannelVersions]:
     """Advance whoever had seen a bumped channel's old version to the new one.
 
     A bump that only stores a snapshot is not a write. Left unseen, it would
-    re-fire `interrupt_before` and rerun the channel's subscribers. For each
-    entry it advances, `SNAPSHOT_BUMPS` keeps the new version and the one the
-    node really read, so `versions_seen_without_bumps` can put the read back.
+    re-fire `interrupt_before` and rerun the channel's subscribers. A channel
+    bumped from no version was never written, so it also goes to the
+    subscribers that never ran: they have no entry, and would start on the bump.
+    For each entry it advances, `SNAPSHOT_BUMPS` keeps the new version and the
+    one the node really read, so `versions_seen_without_bumps` can put the read
+    back.
     """
     if not bumped:
         return versions_seen
     out = dict(versions_seen)
+    for k, (old, _) in bumped.items():
+        if old is None:
+            for node in trigger_to_nodes.get(k, ()):
+                out.setdefault(node, {})
     marks = dict(versions_seen.get(SNAPSHOT_BUMPS, {}))
-    for node, seen in versions_seen.items():
+    for node, seen in out.items():
         if node == SNAPSHOT_BUMPS:
             continue
         for k, (old, new) in bumped.items():

libs/langgraph/langgraph/pregel/_loop.py

@@ -12,7 +12,6 @@ from contextlib import (
     ExitStack,
 )
 from datetime import datetime, timezone
-from inspect import signature
 from types import TracebackType
 from typing import (
     Any,
@@ -20,6 +19,7 @@ from typing import (
     TypeVar,
     cast,
 )
+from uuid import UUID, uuid5
 
 from langchain_core.callbacks import AsyncParentRunManager, ParentRunManager
 from langchain_core.runnables import RunnableConfig
@@ -106,7 +106,9 @@ from langgraph.pregel._checkpoint import (
     delta_channels_to_snapshot,
     delta_channels_with_pending_writes,
     empty_checkpoint,
+    exit_delta_late_task_id,
     exit_delta_task_id,
+    put_writes_accepts_task_path,
 )
 from langgraph.pregel._executor import (
     AsyncBackgroundExecutor,
@@ -190,6 +192,7 @@ class PregelLoop:
         Callable[
             [
                 concurrent.futures.Future | None,
+                Sequence[Any],
                 RunnableConfig,
                 Checkpoint,
                 str,
@@ -203,11 +206,13 @@ class PregelLoop:
     submit: Submit
     channels: Mapping[str, BaseChannel]
     # Futures from `checkpointer.put_writes` calls that produced delta-channel
-    # writes. `_checkpointer_put_after_previous` drains this list (swap to a
-    # local `futs` then reset to `[]` and wait/gather) before putting the
-    # next checkpoint, so a checkpoint never becomes durable before the
-    # writes that produced it. Initialised to `[]` in both sync and async
-    # `__enter__`; stays `None` only when no checkpointer.
+    # writes. `_put_checkpoint` hands this list to the save it submits, which
+    # waits for them first, so a checkpoint never becomes durable before the
+    # writes that produced it. If a write or the previous save failed, the
+    # save fails too: a DeltaChannel is rebuilt from its writes along the
+    # parent chain, so a checkpoint saved past either gap reads back short
+    # for good. Initialised to `[]` in both sync and async `__enter__`;
+    # stays `None` only when no checkpointer.
     _delta_write_futs: list[Any] | None = None
 
     # Same pattern as `_delta_write_futs` but for error-handler writes.
@@ -221,10 +226,18 @@ class PregelLoop:
     # `after_tick`). At exit, `_put_exit_delta_writes` filters out channels
     # that will snapshot, then persists the rest under an anchor parent.
     # `None` when not in exit mode (so the capture sites are no-ops).
-    # Each tuple is `(step, task_id, channel, value)` — `step` drives the
-    # synthetic step-prefixed task_id used to preserve chronological order
-    # under the saver's `ORDER BY task_id, idx` sorting.
-    _exit_delta_writes: list[tuple[int, str, str, Any]] | None = None
+    # Each tuple is `(step, task_id, task_path, channel, value)`; see
+    # `_put_exit_delta_writes` for how they are ordered.
+    _exit_delta_writes: list[tuple[int, str, str, str, Any]] | None = None
+
+    # The (task_id, channel) pairs whose delta writes are stored on the loaded
+    # checkpoint, which a resume addressed by `checkpoint_id` can rerun; this
+    # run's `Command` delta writes, kept apart from the NULL_TASK_ID writes
+    # loaded with the checkpoint; and the checkpoint's own superstep, the
+    # first one this run ticks.
+    _stored_delta_writes: set[tuple[str, str]]
+    _exit_command_writes: list[tuple[str, Any]]
+    _exit_first_step: int | None = None
 
     # Delta channels that must snapshot at the next checkpoint, whatever their
     # cadence counters say:
@@ -257,6 +270,9 @@ class PregelLoop:
     # `_put_exit_delta_writes` uses this to decide between anchoring on
     # the existing parent (True) or creating a lazy stub (False).
     _has_persisted_parent: bool = False
+    # True iff `__enter__` loaded the thread's latest checkpoint, not one a
+    # `checkpoint_id` addressed, so nothing has been built on it yet.
+    _loaded_latest: bool = False
 
     managed: ManagedValueMapping
     checkpoint: Checkpoint
@@ -669,10 +685,6 @@ class PregelLoop:
             self.status = "done"
             return False
 
-        if self.control is not None and self.control.drain_requested:
-            self.status = "draining"
-            return False
-
         # if there are pending writes from a previous loop, apply them
         if self._reapplies_pending_writes and self.checkpoint_pending_writes:
             self._reapply_writes_to_succeeded_nodes(self.tasks)
@@ -685,6 +697,13 @@ class PregelLoop:
             self.status = "interrupt_before"
             raise GraphInterrupt()
 
+        # stop before running the next tasks if a drain was requested. after
+        # the breakpoint check: a resume passes the next step's breakpoints,
+        # so draining in front of one would skip it
+        if self.control is not None and self.control.drain_requested:
+            self.status = "draining"
+            return False
+
         # produce debug output
         self._emit("tasks", map_debug_tasks, self.tasks.values())
 
@@ -737,9 +756,25 @@ class PregelLoop:
             )
         # capture delta-channel writes for exit-mode accumulator before clearing
         if self._exit_delta_writes is not None:
+            # On the first tick the pending writes still hold the ones loaded
+            # with the checkpoint, which are already stored on it.
+            first = self._exit_first_step is None
+            if first:
+                self._exit_first_step = self.step
+                self._exit_delta_writes.extend(
+                    (self.step, NULL_TASK_ID, "", ch, v)
+                    for ch, v in self._exit_command_writes
+                )
             for tid, ch, v in self.checkpoint_pending_writes:
-                if isinstance(self.specs.get(ch), DeltaChannel):
-                    self._exit_delta_writes.append((self.step, tid, ch, v))
+                if not isinstance(self.specs.get(ch), DeltaChannel):
+                    continue
+                if first and (
+                    tid == NULL_TASK_ID or (tid, ch) in self._stored_delta_writes
+                ):
+                    continue
+                task = self.tasks.get(tid)
+                path = task_path_str(task.path) if task else ""
+                self._exit_delta_writes.append((self.step, tid, path, ch, v))
         # clear pending writes
         self.checkpoint_pending_writes.clear()
         # only replay (re-execute) done tasks on the first tick
@@ -860,6 +895,12 @@ class PregelLoop:
     def _first(
         self, *, input_keys: str | Sequence[str], updated_channels: set[str] | None
     ) -> set[str] | None:
+        self._stored_delta_writes = {
+            (tid, ch)
+            for tid, ch, _ in self.checkpoint_pending_writes
+            if tid != NULL_TASK_ID and isinstance(self.specs.get(ch), DeltaChannel)
+        }
+        self._exit_command_writes = []
         # Resuming from a previous checkpoint requires two things:
         # 1. A prior checkpoint exists (channel_versions is non-empty)
         # 2. The input signals continuation (not a fresh run with new input)
@@ -977,6 +1018,12 @@ class PregelLoop:
                     carried.extend((tid, c, v) for c, v in ws)
                 else:
                     self.put_writes(tid, ws)
+                    if self._exit_delta_writes is not None and tid == NULL_TASK_ID:
+                        self._exit_command_writes.extend(
+                            (c, v)
+                            for c, v in ws
+                            if isinstance(self.specs.get(c), DeltaChannel)
+                        )
             self._delta_channels_forced_snapshot.update(
                 delta_channels_with_pending_writes(self.specs, carried)
             )
@@ -1074,17 +1121,29 @@ class PregelLoop:
             if self._exit_delta_writes is not None:
                 for c, v in input_writes:
                     if isinstance(self.specs.get(c), DeltaChannel):
-                        self._exit_delta_writes.append((self.step, NULL_TASK_ID, c, v))
-            # Persist delta-channel input writes so sub-freq inputs are
-            # recoverable via ancestor walk (mirrors the Command input path).
+                        self._exit_delta_writes.append(
+                            (self.step, NULL_TASK_ID, "", c, v)
+                        )
+            # A DeltaChannel reads its input from the writes stored on the
+            # checkpoint this run starts from, under a task id of their own:
+            # readers apply a checkpoint's NULL_TASK_ID writes as its own state.
+            # A new thread has no checkpoint to store them on, and one a
+            # `checkpoint_id` addressed may have children that would read them,
+            # so then the input checkpoint snapshots the channel instead.
             if self.durability != "exit":
                 delta_input = [
                     (c, v)
                     for c, v in input_writes
                     if isinstance(self.specs.get(c), DeltaChannel)
                 ]
-                if delta_input:
-                    self.put_writes(NULL_TASK_ID, delta_input)
+                if delta_input and self._has_persisted_parent and self._loaded_latest:
+                    self.put_writes(
+                        str(uuid5(UUID(self.checkpoint["id"]), INPUT)), delta_input
+                    )
+                else:
+                    self._delta_channels_forced_snapshot.update(
+                        c for c, _ in delta_input
+                    )
             # save input checkpoint
             self.updated_channels = updated_channels
             self._put_checkpoint({"source": "input"})
@@ -1214,6 +1273,7 @@ class PregelLoop:
             else None,
             channels_to_snapshot=channels_to_snapshot,
             stored_versions=self.checkpoint_previous_versions,
+            trigger_to_nodes=self.trigger_to_nodes,
         )
         for k in channels_to_snapshot:
             new_counters[k] = (0, 0)
@@ -1260,12 +1320,17 @@ class PregelLoop:
             )
             self.checkpoint_previous_versions = channel_versions
 
+            # Take this checkpoint's writes now: saves run in the background
+            # and can start out of order, so a save that took them itself
+            # could get another checkpoint's writes.
+            delta_write_futs, self._delta_write_futs = self._delta_write_futs, []
             # save it, without blocking
             # if there's a previous checkpoint save in progress, wait for it
             # ensuring checkpointers receive checkpoints in order
             self._put_checkpoint_fut = self.submit(
                 self._checkpointer_put_after_previous,
                 getattr(self, "_put_checkpoint_fut", None),
+                delta_write_futs,
                 self.checkpoint_config,
                 copy_checkpoint(self.checkpoint),
                 self.checkpoint_metadata,
@@ -1309,9 +1374,7 @@ class PregelLoop:
         )
 
         pending = [
-            (step, tid, ch, v)
-            for (step, tid, ch, v) in self._exit_delta_writes
-            if ch not in channels_to_snapshot
+            w for w in self._exit_delta_writes if w[3] not in channels_to_snapshot
         ]
         if not pending:
             return
@@ -1337,6 +1400,7 @@ class PregelLoop:
             self._put_checkpoint_fut = self.submit(
                 self._checkpointer_put_after_previous,
                 getattr(self, "_put_checkpoint_fut", None),
+                (),
                 stub_put_config,
                 stub_cp,
                 {"step": -2},
@@ -1346,11 +1410,21 @@ class PregelLoop:
             # sees the stub as its parent.
             self.checkpoint_config = anchor_config
 
-        # Step-prefixed synthetic task_id preserves chronological superstep
-        # order under the saver's ORDER BY task_id, idx sorting.
-        grouped: dict[tuple[int, str], list[tuple[str, Any]]] = {}
-        for step, tid, ch, v in pending:
-            grouped.setdefault((step, tid), []).append((ch, v))
+        # The checkpoint's own superstep keeps its real task paths, so it
+        # interleaves with the writes a resume loaded from it. Its task ids stay
+        # synthetic: under the real id, a run whose final checkpoint fails to
+        # save would leave the resumed task looking done to the next resume.
+        # Later supersteps sort after every real task path and task id, in step
+        # order, so this holds whether a saver orders by path or by id.
+        grouped: dict[tuple[str, str], list[tuple[str, Any]]] = {}
+        for step, tid, path, ch, v in pending:
+            if tid == NULL_TASK_ID:
+                key = (exit_delta_task_id(step, tid), "")
+            elif step == self._exit_first_step:
+                key = (exit_delta_task_id(step, tid), path)
+            else:
+                key = (exit_delta_late_task_id(step, tid), f"~~{step:010d}{path}")
+            grouped.setdefault(key, []).append((ch, v))
         anchor_write_config = patch_configurable(
             anchor_config,
             {
@@ -1360,22 +1434,21 @@ class PregelLoop:
                 CONFIG_KEY_CHECKPOINT_ID: anchor_config[CONF][CONFIG_KEY_CHECKPOINT_ID],
             },
         )
-        for (step, tid), entries in grouped.items():
-            synth_tid = exit_delta_task_id(step, tid)
+        for (tid, path), entries in grouped.items():
             if self.checkpointer_put_writes_accepts_task_path:
                 fut = self.submit(
                     self.checkpointer_put_writes,
                     anchor_write_config,
                     entries,
-                    synth_tid,
-                    "",
+                    tid,
+                    path,
                 )
             else:
                 fut = self.submit(
                     self.checkpointer_put_writes,
                     anchor_write_config,
                     entries,
-                    synth_tid,
+                    tid,
                 )
             if self._delta_write_futs is not None:
                 self._delta_write_futs.append(fut)
@@ -1584,8 +1657,7 @@ class SyncPregelLoop(PregelLoop, AbstractContextManager):
             self.checkpointer_get_next_version = checkpointer.get_next_version
             self.checkpointer_put_writes = checkpointer.put_writes
             self.checkpointer_put_writes_accepts_task_path = (
-                signature(checkpointer.put_writes).parameters.get("task_path")
-                is not None
+                put_writes_accepts_task_path(checkpointer.put_writes)
             )
         else:
             self.checkpointer_get_next_version = increment
@@ -1596,21 +1668,19 @@ class SyncPregelLoop(PregelLoop, AbstractContextManager):
     def _checkpointer_put_after_previous(
         self,
         prev: concurrent.futures.Future | None,
+        delta_write_futs: Sequence[concurrent.futures.Future],
         config: RunnableConfig,
         checkpoint: Checkpoint,
         metadata: CheckpointMetadata,
         new_versions: ChannelVersions,
     ) -> RunnableConfig:
-        if self._delta_write_futs:
-            futs, self._delta_write_futs = self._delta_write_futs, []
-            concurrent.futures.wait(futs)
-        try:
-            if prev is not None:
-                prev.result()
-        finally:
-            cast(BaseCheckpointSaver, self.checkpointer).put(
-                config, checkpoint, metadata, new_versions
-            )
+        for fut in delta_write_futs:
+            fut.result()
+        if prev is not None:
+            prev.result()
+        cast(BaseCheckpointSaver, self.checkpointer).put(
+            config, checkpoint, metadata, new_versions
+        )
 
     def match_cached_writes(self) -> Sequence[PregelExecutableTask]:
         if self.cache is None:
@@ -1722,6 +1792,7 @@ class SyncPregelLoop(PregelLoop, AbstractContextManager):
             # Normal case: fetch the most recent checkpoint for this
             # graph/thread. Returns None on first invocation.
             saved = self.checkpointer.get_tuple(self.checkpoint_config)
+            self._loaded_latest = True
 
         # Capture before the synthetic-empty fallback below overwrites `saved`.
         # `_put_exit_delta_writes` uses this on first run (no persisted parent)
@@ -1840,8 +1911,7 @@ class AsyncPregelLoop(PregelLoop, AbstractAsyncContextManager):
             self.checkpointer_get_next_version = checkpointer.get_next_version
             self.checkpointer_put_writes = checkpointer.aput_writes
             self.checkpointer_put_writes_accepts_task_path = (
-                signature(checkpointer.aput_writes).parameters.get("task_path")
-                is not None
+                put_writes_accepts_task_path(checkpointer.aput_writes)
             )
         else:
             self.checkpointer_get_next_version = increment
@@ -1852,23 +1922,19 @@ class AsyncPregelLoop(PregelLoop, AbstractAsyncContextManager):
     async def _checkpointer_put_after_previous(
         self,
         prev: asyncio.Task | None,
+        delta_write_futs: Sequence[asyncio.Future],
         config: RunnableConfig,
         checkpoint: Checkpoint,
         metadata: CheckpointMetadata,
         new_versions: ChannelVersions,
     ) -> RunnableConfig:
-        # Drain DeltaChannel write futures before committing the checkpoint so
-        # ancestor walks never see a checkpoint without its backing writes.
-        if self._delta_write_futs:
-            futs, self._delta_write_futs = self._delta_write_futs, []
-            await asyncio.gather(*futs)
-        try:
-            if prev is not None:
-                await prev
-        finally:
-            await cast(BaseCheckpointSaver, self.checkpointer).aput(
-                config, checkpoint, metadata, new_versions
-            )
+        if delta_write_futs:
+            await asyncio.gather(*delta_write_futs)
+        if prev is not None:
+            await prev
+        await cast(BaseCheckpointSaver, self.checkpointer).aput(
+            config, checkpoint, metadata, new_versions
+        )
 
     async def amatch_cached_writes(self) -> Sequence[PregelExecutableTask]:
         if self.cache is None:
@@ -1983,6 +2049,7 @@ class AsyncPregelLoop(PregelLoop, AbstractAsyncContextManager):
             # Normal case: fetch the most recent checkpoint for this
             # graph/thread. Returns None on first invocation.
             saved = await self.checkpointer.aget_tuple(self.checkpoint_config)
+            self._loaded_latest = True
 
         # Capture before the synthetic-empty fallback below overwrites `saved`.
         # `_put_exit_delta_writes` uses this on first run (no persisted parent)

libs/langgraph/langgraph/pregel/main.py

@@ -126,6 +126,7 @@ from langgraph.pregel._algo import (
     apply_writes,
     local_read,
     prepare_next_tasks,
+    task_path_str,
 )
 from langgraph.pregel._call import identifier
 from langgraph.pregel._checkpoint import (
@@ -136,9 +137,11 @@ from langgraph.pregel._checkpoint import (
     copy_checkpoint,
     create_checkpoint,
     create_checkpoint_plan_for_update_state_api,
+    delta_channels_overwritten,
     delta_channels_with_pending_writes,
     empty_checkpoint,
     get_updated_channels_from_tasks,
+    put_writes_accepts_task_path,
     versions_seen_without_bumps,
 )
 from langgraph.pregel._draw import draw_graph
@@ -150,6 +153,7 @@ from langgraph.pregel._loop import (
 from langgraph.pregel._messages import (
     StreamMessagesHandler,
     StreamMessagesHandlerV2,
+    ensure_message_ids,
 )
 from langgraph.pregel._read import DEFAULT_BOUND, PregelNode
 from langgraph.pregel._retry import RetryPolicy
@@ -1764,6 +1768,7 @@ class Pregel(
                     get_next_version=checkpointer.get_next_version,
                     channels_to_snapshot=channels_to_snapshot,
                     stored_versions=checkpoint_previous_versions,
+                    trigger_to_nodes=self.trigger_to_nodes,
                 )
                 next_config = checkpointer.put(
                     checkpoint_config,
@@ -1786,6 +1791,22 @@ class Pregel(
                     )
 
                 if input_writes := deque(map_input(self.input_channels, values)):
+                    _store_or_fork_delta_writes(
+                        checkpointer,
+                        config,
+                        saved,
+                        checkpoint_config,
+                        self.channels,
+                        [
+                            (
+                                str(uuid5(UUID(checkpoint["id"]), INPUT)),
+                                input_writes,
+                                None,
+                            )
+                        ],
+                        fork_pending,
+                        is_first=is_first,
+                    )
                     updated_channels = apply_writes(
                         checkpoint,
                         channels,
@@ -1793,6 +1814,9 @@ class Pregel(
                         checkpointer.get_next_version,
                         self.trigger_to_nodes,
                     )
+                    fork_pending |= delta_channels_overwritten(
+                        self.channels, input_writes
+                    )
 
                     # apply input write to channels
                     next_step = (
@@ -1820,6 +1844,7 @@ class Pregel(
                         get_next_version=checkpointer.get_next_version,
                         channels_to_snapshot=channels_to_snapshot,
                         stored_versions=checkpoint_previous_versions,
+                        trigger_to_nodes=self.trigger_to_nodes,
                     )
                     next_config = checkpointer.put(
                         checkpoint_config,
@@ -1831,13 +1856,6 @@ class Pregel(
                         ),
                     )
 
-                    # store the writes
-                    checkpointer.put_writes(
-                        next_config,
-                        input_writes,
-                        str(uuid5(UUID(checkpoint["id"]), INPUT)),
-                    )
-
                     return patch_checkpoint_map(
                         next_config, saved.metadata if saved else None
                     )
@@ -1983,13 +2001,13 @@ class Pregel(
             run_tasks: list[PregelTaskWrites] = []
             run_task_ids: list[str] = []
 
-            for as_node, values, provided_task_id in valid_updates:
+            for i, (as_node, values, provided_task_id) in enumerate(valid_updates):
                 # create task to run all writers of the chosen node
                 writers = self.nodes[as_node].flat_writers
                 if not writers:
                     raise InvalidUpdateError(f"Node {as_node} has no writers")
                 writes: deque[tuple[str, Any]] = deque()
-                task = PregelTaskWrites((), as_node, writes, [INTERRUPT])
+                task = PregelTaskWrites((INTERRUPT, i), as_node, writes, [INTERRUPT])
                 # get the task ids that were prepared for this node
                 # if a task id was provided in the StateUpdate, we use it
                 # otherwise, we use the next available task id
@@ -1997,7 +2015,7 @@ class Pregel(
                 task_id = provided_task_id or (
                     prepared_task_ids.popleft()
                     if prepared_task_ids
-                    else str(uuid5(UUID(checkpoint["id"]), INTERRUPT))
+                    else _update_task_id(checkpoint["id"], i)
                 )
                 run_tasks.append(task)
                 run_task_ids.append(task_id)
@@ -2031,27 +2049,22 @@ class Pregel(
                     ),
                 )
             updated_channels = get_updated_channels_from_tasks(run_tasks)
-            # The base's other children replay whatever is stored on it, so an
-            # edit of an older checkpoint stores none of its writes there: the
-            # checkpoint written here carries them, its delta channels
-            # snapshotted. Later supersteps address the checkpoint just written.
-            if (
-                is_first
-                and saved is not None
-                and checkpoint_superseded(checkpointer, config, saved)
-            ):
-                fork_pending.update(
-                    ch
-                    for ch in updated_channels
-                    if isinstance(self.channels.get(ch), DeltaChannel)
-                )
-            elif saved is not None:
-                for task_id, task in zip(run_task_ids, run_tasks):
-                    channel_writes = [w for w in task.writes if w[0] != PUSH]
-                    if channel_writes:
-                        checkpointer.put_writes(
-                            checkpoint_config, channel_writes, task_id
-                        )
+            fork_pending |= delta_channels_overwritten(
+                self.channels, (w for t in run_tasks for w in t.writes)
+            )
+            _store_or_fork_delta_writes(
+                checkpointer,
+                config,
+                saved,
+                checkpoint_config,
+                self.channels,
+                [
+                    (task_id, [w for w in task.writes if w[0] != PUSH], task)
+                    for task_id, task in zip(run_task_ids, run_tasks)
+                ],
+                fork_pending,
+                is_first=is_first,
+            )
             apply_writes(
                 checkpoint,
                 channels,
@@ -2081,6 +2094,7 @@ class Pregel(
                 else None,
                 channels_to_snapshot=channels_to_snapshot,
                 stored_versions=checkpoint_previous_versions,
+                trigger_to_nodes=self.trigger_to_nodes,
             )
             next_config = checkpointer.put(
                 checkpoint_config,
@@ -2253,6 +2267,7 @@ class Pregel(
                     get_next_version=checkpointer.get_next_version,
                     channels_to_snapshot=channels_to_snapshot,
                     stored_versions=checkpoint_previous_versions,
+                    trigger_to_nodes=self.trigger_to_nodes,
                 )
                 next_config = await checkpointer.aput(
                     checkpoint_config,
@@ -2275,6 +2290,22 @@ class Pregel(
                     )
 
                 if input_writes := deque(map_input(self.input_channels, values)):
+                    await _astore_or_fork_delta_writes(
+                        checkpointer,
+                        config,
+                        saved,
+                        checkpoint_config,
+                        self.channels,
+                        [
+                            (
+                                str(uuid5(UUID(checkpoint["id"]), INPUT)),
+                                input_writes,
+                                None,
+                            )
+                        ],
+                        fork_pending,
+                        is_first=is_first,
+                    )
                     updated_channels = apply_writes(
                         checkpoint,
                         channels,
@@ -2282,6 +2313,9 @@ class Pregel(
                         checkpointer.get_next_version,
                         self.trigger_to_nodes,
                     )
+                    fork_pending |= delta_channels_overwritten(
+                        self.channels, input_writes
+                    )
 
                     # apply input write to channels
                     next_step = (
@@ -2309,6 +2343,7 @@ class Pregel(
                         get_next_version=checkpointer.get_next_version,
                         channels_to_snapshot=channels_to_snapshot,
                         stored_versions=checkpoint_previous_versions,
+                        trigger_to_nodes=self.trigger_to_nodes,
                     )
                     next_config = await checkpointer.aput(
                         checkpoint_config,
@@ -2320,13 +2355,6 @@ class Pregel(
                         ),
                     )
 
-                    # store the writes
-                    await checkpointer.aput_writes(
-                        next_config,
-                        input_writes,
-                        str(uuid5(UUID(checkpoint["id"]), INPUT)),
-                    )
-
                     return patch_checkpoint_map(
                         next_config, saved.metadata if saved else None
                     )
@@ -2471,13 +2499,13 @@ class Pregel(
             run_tasks: list[PregelTaskWrites] = []
             run_task_ids: list[str] = []
 
-            for as_node, values, provided_task_id in valid_updates:
+            for i, (as_node, values, provided_task_id) in enumerate(valid_updates):
                 # create task to run all writers of the chosen node
                 writers = self.nodes[as_node].flat_writers
                 if not writers:
                     raise InvalidUpdateError(f"Node {as_node} has no writers")
                 writes: deque[tuple[str, Any]] = deque()
-                task = PregelTaskWrites((), as_node, writes, [INTERRUPT])
+                task = PregelTaskWrites((INTERRUPT, i), as_node, writes, [INTERRUPT])
                 # get the task ids that were prepared for this node
                 # if a task id was provided in the StateUpdate, we use it
                 # otherwise, we use the next available task id
@@ -2485,7 +2513,7 @@ class Pregel(
                 task_id = provided_task_id or (
                     prepared_task_ids.popleft()
                     if prepared_task_ids
-                    else str(uuid5(UUID(checkpoint["id"]), INTERRUPT))
+                    else _update_task_id(checkpoint["id"], i)
                 )
                 run_tasks.append(task)
                 run_task_ids.append(task_id)
@@ -2519,27 +2547,22 @@ class Pregel(
                     ),
                 )
             updated_channels = get_updated_channels_from_tasks(run_tasks)
-            # The base's other children replay whatever is stored on it, so an
-            # edit of an older checkpoint stores none of its writes there: the
-            # checkpoint written here carries them, its delta channels
-            # snapshotted. Later supersteps address the checkpoint just written.
-            if (
-                is_first
-                and saved is not None
-                and await acheckpoint_superseded(checkpointer, config, saved)
-            ):
-                fork_pending.update(
-                    ch
-                    for ch in updated_channels
-                    if isinstance(self.channels.get(ch), DeltaChannel)
-                )
-            elif saved is not None:
-                for task_id, task in zip(run_task_ids, run_tasks):
-                    channel_writes = [w for w in task.writes if w[0] != PUSH]
-                    if channel_writes:
-                        await checkpointer.aput_writes(
-                            checkpoint_config, channel_writes, task_id
-                        )
+            fork_pending |= delta_channels_overwritten(
+                self.channels, (w for t in run_tasks for w in t.writes)
+            )
+            await _astore_or_fork_delta_writes(
+                checkpointer,
+                config,
+                saved,
+                checkpoint_config,
+                self.channels,
+                [
+                    (task_id, [w for w in task.writes if w[0] != PUSH], task)
+                    for task_id, task in zip(run_task_ids, run_tasks)
+                ],
+                fork_pending,
+                is_first=is_first,
+            )
             apply_writes(
                 checkpoint,
                 channels,
@@ -2569,6 +2592,7 @@ class Pregel(
                 else None,
                 channels_to_snapshot=channels_to_snapshot,
                 stored_versions=checkpoint_previous_versions,
+                trigger_to_nodes=self.trigger_to_nodes,
             )
             next_config = await checkpointer.aput(
                 checkpoint_config,
@@ -3706,16 +3730,15 @@ class Pregel(
         config: RunnableConfig | None = None,
         *,
         version: Literal["v1", "v2", "v3"] = "v2",
-        interrupt_before: All | Sequence[str] | None = None,
-        interrupt_after: All | Sequence[str] | None = None,
-        control: RunControl | None = None,
         transformers: Sequence[Callable[[tuple[str, ...]], Any]] | None = None,
         **kwargs: Any,
     ) -> Any:
         """Stream events from this graph.
 
-        For `version="v1"` / `"v2"`, yields `StreamEvent` dicts (see
-        `Runnable.stream_events`). For `version="v3"`, returns a
+        For `version="v1"` / `"v2"`, delegates to
+        `Runnable.(a)stream_events`; synchronous v1/v2 event streaming is
+        not implemented in langchain-core, so use `astream_events` for
+        those versions. For `version="v3"`, returns a
         `GraphRunStream` whose typed projections the caller drives by
         iterating — no background thread.
 
@@ -3745,20 +3768,27 @@ class Pregel(
             config: Optional runnable config.
             version: Streaming-event schema version. `"v3"` selects the
                 content-block-centric streaming protocol.
-            interrupt_before: Nodes to interrupt before, if any. Only
-                used for `version="v3"`.
-            interrupt_after: Nodes to interrupt after, if any. Only
-                used for `version="v3"`.
+            interrupt_before: Nodes to interrupt before, if any.
+                Honored on every version that can run; type-checked
+                only on the `version="v3"` overloads.
+            interrupt_after: Nodes to interrupt after, if any. Honored
+                on every version that can run; type-checked only on
+                the `version="v3"` overloads.
             control: Optional run control used to request cooperative
-                drain. Only used for `version="v3"`.
+                drain. Honored on every version that can run;
+                type-checked only on the `version="v3"` overloads.
             transformers: Extra transformer classes or configured
                 factories appended after compile-time
                 `stream_transformers`. Factories are called as
                 `factory(scope)` so they can propagate to subgraph
                 scopes. Only used for `version="v3"`.
-            **kwargs: For `version="v1"`/`"v2"`, forwarded to
-                `Runnable.stream_events`. For `version="v3"`, forwarded
-                to the underlying `stream(...)` call (e.g. `context`,
+            **kwargs: For `version="v1"`/`"v2"` on `astream_events`,
+                forwarded to `Runnable.astream_events`, which passes
+                them through to `astream` — so execution kwargs such as
+                `context`, `durability`, `interrupt_before`,
+                `interrupt_after` and `control` are honored on every
+                version that can run. For `version="v3"`, forwarded to the
+                underlying `stream(...)` call (e.g. `context`,
                 `durability`, `output_keys`, `print_mode`, `debug`).
                 `stream_mode` and `subgraphs` are not accepted under
                 `version="v3"` and raise `TypeError` if supplied; v3
@@ -3766,16 +3796,15 @@ class Pregel(
 
         Returns:
             For `version="v3"`, a `GraphRunStream` the caller iterates
-            to drive the run. Otherwise an `Iterator[StreamEvent]`.
+            to drive the run. For `version="v1"`/`"v2"`,
+            `astream_events` yields `StreamEvent` dicts; the synchronous
+            v1/v2 path is not implemented in langchain-core.
         """
         if version == "v3":
             _reject_v3_invariant_kwargs(kwargs)
             return self._pregel_stream_v3(
                 input,
                 config,
-                interrupt_before=interrupt_before,
-                interrupt_after=interrupt_after,
-                control=control,
                 transformers=transformers,
                 **kwargs,
             )
@@ -3811,9 +3840,6 @@ class Pregel(
         config: RunnableConfig | None = None,
         *,
         version: Literal["v1", "v2", "v3"] = "v2",
-        interrupt_before: All | Sequence[str] | None = None,
-        interrupt_after: All | Sequence[str] | None = None,
-        control: RunControl | None = None,
         transformers: Sequence[Callable[[tuple[str, ...]], Any]] | None = None,
         **kwargs: Any,
     ) -> AsyncIterator[StreamEvent] | Awaitable[Any]:
@@ -3836,9 +3862,6 @@ class Pregel(
             return self._apregel_stream_v3(
                 input,
                 config,
-                interrupt_before=interrupt_before,
-                interrupt_after=interrupt_after,
-                control=control,
                 transformers=transformers,
                 **kwargs,
             )
@@ -4237,6 +4260,109 @@ class Pregel(
         await self.cache.aclear(namespaces)
 
 
+def _task_path_kwarg(put_writes: Callable[..., Any], task: PregelTaskWrites) -> dict:
+    """Pass the task's path to savers whose `put_writes` takes one.
+
+    Savers that replay a checkpoint's writes in task path order then give back
+    updates applied together in the order they were given.
+    """
+    if not put_writes_accepts_task_path(put_writes):
+        return {}
+    return {"task_path": task_path_str(task.path)}
+
+
+_UpdateWrites = Sequence[tuple[str, Sequence[tuple[str, Any]], PregelTaskWrites | None]]
+
+
+def _delta_writes(
+    channels: Mapping[str, BaseChannel | ManagedValueSpec], writes: _UpdateWrites
+) -> list[tuple[str, Any]]:
+    """Give the update's DeltaChannel writes message ids, as the loop's
+    `put_writes` does, so every read of them returns the same ids."""
+    delta = [
+        (ch, value)
+        for _, task_writes, _ in writes
+        for ch, value in task_writes
+        if isinstance(channels.get(ch), DeltaChannel)
+    ]
+    for _, value in delta:
+        ensure_message_ids(value)
+    return delta
+
+
+def _store_or_fork_delta_writes(
+    checkpointer: BaseCheckpointSaver,
+    config: RunnableConfig,
+    saved: CheckpointTuple | None,
+    checkpoint_config: RunnableConfig,
+    channels: Mapping[str, BaseChannel | ManagedValueSpec],
+    writes: _UpdateWrites,
+    fork_pending: set[str],
+    *,
+    is_first: bool,
+) -> None:
+    """Save an update's writes where its DeltaChannels will read them.
+
+    A DeltaChannel rebuilds its value from the writes saved on a checkpoint's
+    ancestors, so the writes go on the checkpoint the update builds on. If the
+    thread already moved past that checkpoint, its other children would read
+    them too, so the new checkpoint snapshots those channels instead. `writes`
+    holds `(task_id, writes, task)` per task; `task` is `None` for input.
+    """
+    delta = _delta_writes(channels, writes)
+    if saved is None:
+        return
+    if is_first and checkpoint_superseded(checkpointer, config, saved):
+        fork_pending.update(ch for ch, _ in delta)
+        return
+    for task_id, task_writes, task in writes:
+        if task_writes:
+            checkpointer.put_writes(
+                checkpoint_config,
+                task_writes,
+                task_id,
+                **(_task_path_kwarg(checkpointer.put_writes, task) if task else {}),
+            )
+
+
+async def _astore_or_fork_delta_writes(
+    checkpointer: BaseCheckpointSaver,
+    config: RunnableConfig,
+    saved: CheckpointTuple | None,
+    checkpoint_config: RunnableConfig,
+    channels: Mapping[str, BaseChannel | ManagedValueSpec],
+    writes: _UpdateWrites,
+    fork_pending: set[str],
+    *,
+    is_first: bool,
+) -> None:
+    """Async `_store_or_fork_delta_writes`."""
+    delta = _delta_writes(channels, writes)
+    if saved is None:
+        return
+    if is_first and await acheckpoint_superseded(checkpointer, config, saved):
+        fork_pending.update(ch for ch, _ in delta)
+        return
+    for task_id, task_writes, task in writes:
+        if task_writes:
+            await checkpointer.aput_writes(
+                checkpoint_config,
+                task_writes,
+                task_id,
+                **(_task_path_kwarg(checkpointer.aput_writes, task) if task else {}),
+            )
+
+
+def _update_task_id(checkpoint_id: str, i: int) -> str:
+    """Task id for the `i`th update of a superstep that has no task to reuse.
+
+    Savers keep one write per `(task_id, idx)`, so updates sharing an id lose
+    all but the first one's writes, which a `DeltaChannel` replays from. The
+    first update keeps the id a lone update has always had.
+    """
+    return str(uuid5(UUID(checkpoint_id), INTERRUPT if i == 0 else f"{INTERRUPT}:{i}"))
+
+
 def _trigger_to_nodes(nodes: dict[str, PregelNode]) -> Mapping[str, Sequence[str]]:
     """Index from a trigger to nodes that depend on it."""
     trigger_to_nodes: defaultdict[str, list[str]] = defaultdict(list)

libs/langgraph/langgraph/types.py

@@ -20,7 +20,7 @@ from warnings import warn
 from langchain_core.messages import AnyMessage
 from langchain_core.runnables import Runnable, RunnableConfig
 from langgraph.checkpoint.base import BaseCheckpointSaver, CheckpointMetadata
-from pydantic import TypeAdapter
+from pydantic import TypeAdapter, ValidationError
 from typing_extensions import (
     NotRequired,
     TypeAliasType,
@@ -882,6 +882,16 @@ class Command(Generic[N], ToolOutputMixin):
     PARENT: ClassVar[Literal["__parent__"]] = "__parent__"
 
 
+def _validate_resume(adapter: TypeAdapter[Any], value: Any) -> Any:
+    from langgraph.errors import _mark_invalid_resume
+
+    try:
+        return adapter.validate_python(value)
+    except ValidationError as exc:
+        _mark_invalid_resume(exc)
+        raise
+
+
 @overload
 def interrupt(value: Any, *, response_schema: type[ResponseT]) -> ResponseT: ...
 
@@ -989,6 +999,7 @@ def interrupt(
     Raises:
         GraphInterrupt: On the first invocation within the node, halts execution and surfaces the provided value to the client.
         pydantic.ValidationError: When a resume value does not match a Pydantic model, `TypedDict`, or dataclass `response_schema`.
+            Nothing is saved, so the interrupt can be answered again. `is_invalid_resume` identifies it.
     """
     from langgraph._internal._constants import (
         CONFIG_KEY_CHECKPOINT_NS,
@@ -1012,14 +1023,14 @@ def interrupt(
     if scratchpad.resume:
         if idx < len(scratchpad.resume):
             v = scratchpad.resume[idx]
-            validated = adapter.validate_python(v) if adapter else v
+            validated = _validate_resume(adapter, v) if adapter else v
             conf[CONFIG_KEY_SEND]([(RESUME, scratchpad.resume[: idx + 1])])
             return validated
     # find current resume value
     v = scratchpad.get_null_resume(True)
     if v is not None:
         assert len(scratchpad.resume) == idx, (scratchpad.resume, idx)
-        validated = adapter.validate_python(v) if adapter else v
+        validated = _validate_resume(adapter, v) if adapter else v
         scratchpad.resume.append(v)
         conf[CONFIG_KEY_SEND]([(RESUME, scratchpad.resume)])
         return validated

libs/langgraph/pyproject.toml

@@ -25,7 +25,7 @@ classifiers = [
 ]
 dependencies = [
     "langchain-core>=1.4.7,<2",
-    "langgraph-checkpoint>=4.1.0,<5.0.0",
+    "langgraph-checkpoint>=4.3.0,<5.0.0",
     "langgraph-sdk>=0.4.6,<0.5.0",
     "langgraph-prebuilt>=1.1.0,<1.2.0",
     "xxhash>=3.5.0",

libs/langgraph/tests/test_delta_channel_exit_mode.py

@@ -6,19 +6,23 @@ channel), lazy stub creation when no parent exists, and proper read-path
 reconstruction via ancestor walks.
 """
 
+import operator
 import uuid
 from typing import Annotated, Any
 
 import pytest
 from langchain_core.messages import AIMessage, HumanMessage
+from langgraph.checkpoint.base import BaseCheckpointSaver
 from langgraph.checkpoint.memory import InMemorySaver
 from langgraph.checkpoint.serde.types import _DeltaSnapshot
 from typing_extensions import TypedDict
 
+from langgraph._internal._constants import NULL_TASK_ID
 from langgraph.channels.delta import DeltaChannel
 from langgraph.graph import START, StateGraph
 from langgraph.graph.message import _messages_delta_reducer
 from langgraph.pregel._checkpoint import exit_delta_task_id
+from langgraph.types import Command, Durability, interrupt
 
 pytestmark = pytest.mark.anyio
 
@@ -35,6 +39,7 @@ def test_exit_delta_task_id_is_valid_uuid_and_ordered() -> None:
     assert id1.split("-")[0] == "00000001"
     assert id7.split("-")[0] == "00000007"
     assert id1.endswith("-0270-bf16-1ef8-fb321bef9f3d")
+    assert exit_delta_task_id(0, NULL_TASK_ID) != NULL_TASK_ID
 
     with pytest.raises(ValueError):
         uuid.UUID(f"00000001-{tid}")
@@ -389,3 +394,234 @@ async def test_exit_snapshot_then_tail_deltas() -> None:
     assert "seed-msg" in contents
     assert "tail-msg" in contents
     assert contents.index("seed-msg") < contents.index("tail-msg")
+
+
+def _append(current: list, writes: list) -> list:
+    out = list(current)
+    for write in writes:
+        out.extend(write)
+    return out
+
+
+class _ResumeState(TypedDict):
+    log: Annotated[list, DeltaChannel(_append)]
+    plain: Annotated[list, operator.add]
+
+
+def _both(marker: str) -> dict:
+    return {"log": [marker], "plain": [marker]}
+
+
+def _ask(marker: str) -> Any:
+    def ask(state: _ResumeState) -> dict:
+        interrupt("approve?")
+        return _both(marker)
+
+    return ask
+
+
+@pytest.mark.parametrize("addressed", [False, True])
+def test_resume_after_a_parallel_interrupt_replays_in_live_order(
+    sync_checkpointer: BaseCheckpointSaver, durability: Durability, addressed: bool
+) -> None:
+    builder = StateGraph(_ResumeState)
+    builder.add_node("done", lambda state: _both("done"))
+    builder.add_node("ask", _ask("ask"))
+    builder.add_node("after", lambda state: _both("after"))
+    builder.add_edge(START, "done")
+    builder.add_edge(START, "ask")
+    builder.add_edge("ask", "after")
+    graph = builder.compile(checkpointer=sync_checkpointer)
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke(_both("in"), config, durability=durability)
+    head = graph.get_state(config).config
+
+    graph.invoke(
+        Command(resume="yes"), head if addressed else config, durability=durability
+    )
+
+    state = graph.get_state(config)
+    assert state.values["log"] == state.values["plain"]
+    assert sorted(state.values["log"]) == ["after", "ask", "done", "in"]
+
+
+def test_resume_with_a_command_update_replays_its_write_once(
+    sync_checkpointer: BaseCheckpointSaver, durability: Durability
+) -> None:
+    builder = StateGraph(_ResumeState)
+    builder.add_node("done", lambda state: _both("done"))
+    builder.add_node("ask", _ask("ask"))
+    builder.add_edge(START, "done")
+    builder.add_edge(START, "ask")
+    graph = builder.compile(checkpointer=sync_checkpointer)
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke(_both("in"), config, durability=durability)
+
+    graph.invoke(
+        Command(resume="yes", update=_both("cmd")), config, durability=durability
+    )
+
+    state = graph.get_state(config)
+    assert state.values["log"] == state.values["plain"] == ["in", "cmd", "ask", "done"]
+
+
+def test_command_update_on_an_input_checkpoint_matches_a_plain_channel(
+    sync_checkpointer: BaseCheckpointSaver, durability: Durability
+) -> None:
+    builder = StateGraph(_ResumeState)
+    builder.add_node("node", lambda state: _both("node"))
+    builder.add_edge(START, "node")
+    graph = builder.compile(checkpointer=sync_checkpointer)
+    config = {"configurable": {"thread_id": "t"}}
+    graph.update_state(config, _both("in"), as_node="__input__")
+
+    graph.invoke(Command(update=_both("cmd")), config, durability=durability)
+
+    history = list(graph.get_state_history(config))
+    assert [s.values.get("log", []) for s in history] == [
+        s.values.get("plain", []) for s in history
+    ]
+    replayed = graph.invoke(None, history[-1].config, durability=durability)
+    assert replayed["log"] == replayed["plain"]
+
+
+def test_exit_command_update_on_a_new_thread_matches_a_plain_channel(
+    sync_checkpointer: BaseCheckpointSaver,
+) -> None:
+    builder = StateGraph(_ResumeState)
+    builder.add_node("node", lambda state: _both("node"))
+    builder.add_edge(START, "node")
+    graph = builder.compile(checkpointer=sync_checkpointer)
+    config = {"configurable": {"thread_id": "t"}}
+
+    graph.invoke(Command(update=_both("cmd")), config, durability="exit")
+
+    history = list(graph.get_state_history(config))
+    assert [s.values.get("log", []) for s in history] == [
+        s.values.get("plain", []) for s in history
+    ]
+
+
+class _FlagState(_ResumeState, total=False):
+    extra: Annotated[list, DeltaChannel(_append)]
+    flag: bool
+
+
+def test_addressed_resume_keeps_a_rerun_tasks_write_to_a_new_channel(
+    sync_checkpointer: BaseCheckpointSaver, durability: Durability
+) -> None:
+    def done(state: _FlagState) -> dict:
+        return {**_both("done"), **({"extra": ["new"]} if state.get("flag") else {})}
+
+    builder = StateGraph(_FlagState)
+    builder.add_node("done", done)
+    builder.add_node("ask", _ask("ask"))
+    builder.add_edge(START, "done")
+    builder.add_edge(START, "ask")
+    graph = builder.compile(checkpointer=sync_checkpointer)
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke(_both("in"), config, durability=durability)
+    head = graph.get_state(config).config
+
+    live = graph.invoke(
+        Command(resume="yes", update={"flag": True}), head, durability=durability
+    )
+
+    state = graph.get_state(config)
+    assert live["extra"] == state.values["extra"] == ["new"]
+    assert state.values["log"] == state.values["plain"]
+
+
+def test_resume_interleaves_the_resumed_superstep_by_task_path(
+    sync_checkpointer: BaseCheckpointSaver, durability: Durability
+) -> None:
+    builder = StateGraph(_ResumeState)
+    builder.add_node("z_done", lambda state: _both("z"))
+    builder.add_node("a_asks", _ask("a"))
+    builder.add_edge(START, "z_done")
+    builder.add_edge(START, "a_asks")
+    graph = builder.compile(checkpointer=sync_checkpointer)
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke(_both("in"), config, durability=durability)
+
+    graph.invoke(Command(resume="yes"), config, durability=durability)
+
+    state = graph.get_state(config)
+    assert state.values["log"] == state.values["plain"] == ["in", "a", "z"]
+
+
+class _TaskIdOrderSaver(InMemorySaver):
+    """Replays each checkpoint's writes by task id, as savers without task path
+    ordering do."""
+
+    def get_tuple(self, config: Any) -> Any:
+        tup = super().get_tuple(config)
+        if tup and tup.pending_writes:
+            tup = tup._replace(pending_writes=sorted(tup.pending_writes))
+        return tup
+
+    get_delta_channel_history = BaseCheckpointSaver.get_delta_channel_history
+
+
+def test_exit_run_replays_supersteps_in_order_on_a_task_id_ordered_saver() -> None:
+    builder = StateGraph(_ResumeState)
+    builder.add_node("a", lambda state: _both("a"))
+    builder.add_node("b", lambda state: _both("b"))
+    builder.add_edge(START, "a")
+    builder.add_edge("a", "b")
+    graph = builder.compile(checkpointer=_TaskIdOrderSaver())
+    config = {"configurable": {"thread_id": "t"}}
+
+    graph.invoke(_both("in"), config, durability="exit")
+
+    assert graph.get_state(config).values["log"] == ["in", "a", "b"]
+
+
+def test_exit_resume_replays_supersteps_in_order_on_a_task_id_ordered_saver() -> None:
+    builder = StateGraph(_ResumeState)
+    builder.add_node("ask", _ask("ask"))
+    builder.add_node("after", lambda state: _both("after"))
+    builder.add_edge(START, "ask")
+    builder.add_edge("ask", "after")
+    graph = builder.compile(checkpointer=_TaskIdOrderSaver())
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke(_both("in"), config, durability="exit")
+
+    graph.invoke(Command(resume="yes"), config, durability="exit")
+
+    assert graph.get_state(config).values["log"] == ["in", "ask", "after"]
+
+
+class _FailingPutSaver(InMemorySaver):
+    fail = False
+
+    def put(
+        self, config: Any, checkpoint: Any, metadata: Any, new_versions: Any
+    ) -> Any:
+        if self.fail:
+            raise RuntimeError("final checkpoint lost")
+        return super().put(config, checkpoint, metadata, new_versions)
+
+
+def test_exit_resume_retried_after_its_final_checkpoint_fails_reruns_the_resumed_task() -> (
+    None
+):
+    saver = _FailingPutSaver()
+    builder = StateGraph(_ResumeState)
+    builder.add_node("done", lambda state: _both("done"))
+    builder.add_node("ask", _ask("ask"))
+    builder.add_edge(START, "done")
+    builder.add_edge(START, "ask")
+    graph = builder.compile(checkpointer=saver)
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke(_both("in"), config, durability="exit")
+    saver.fail = True
+    with pytest.raises(RuntimeError, match="final checkpoint lost"):
+        graph.invoke(Command(resume="yes"), config, durability="exit")
+    saver.fail = False
+
+    graph.invoke(Command(resume="yes"), config, durability="exit")
+
+    state = graph.get_state(config)
+    assert state.values["log"] == state.values["plain"]
+    assert sorted(state.values["plain"]) == ["ask", "done", "in"]

libs/langgraph/tests/test_delta_channel_fork.py

@@ -740,20 +740,6 @@ def _build_deferred_after_interrupt(checkpointer: BaseCheckpointSaver) -> Any:
     return builder.compile(checkpointer=checkpointer, interrupt_after=["a"])
 
 
-@pytest.mark.parametrize(
-    "durability",
-    [
-        "sync",
-        "async",
-        pytest.param(
-            "exit",
-            marks=pytest.mark.xfail(
-                reason="exit durability stores a resumed run's loaded writes twice",
-                strict=True,
-            ),
-        ),
-    ],
-)
 def test_resume_on_an_interrupted_head_consumes_its_writes_without_a_snapshot(
     sync_checkpointer: BaseCheckpointSaver, durability: Durability
 ) -> None:

libs/langgraph/tests/test_delta_channel_parallel_order.py

@@ -0,0 +1,126 @@
+"""`DeltaChannel` replay must apply parallel writes in the order `invoke` did."""
+
+import asyncio
+from typing import Annotated, Any
+
+import pytest
+from langgraph.checkpoint.base import BaseCheckpointSaver
+from typing_extensions import TypedDict
+
+from langgraph.channels.delta import DeltaChannel
+from langgraph.graph import END, START, StateGraph
+from langgraph.types import Send
+
+pytestmark = pytest.mark.anyio
+
+# Sorted, because live execution applies PULL tasks in node-name order.
+FAN_OUT_NAMES = ["a", "b", "c", "d", "e", "f", "g", "h"]
+SEND_ARGS = [f"send-{i:02d}" for i in range(12)]
+
+
+def _append_reducer(current: list, updates: list) -> list:
+    return [*current, *(x for u in updates for x in u)]
+
+
+def _build_fan_out_graph(checkpointer: BaseCheckpointSaver) -> Any:
+    class State(TypedDict):
+        items: Annotated[
+            list, DeltaChannel(_append_reducer, list, snapshot_frequency=10_000)
+        ]
+
+    def make_node(label: str) -> Any:
+        return lambda state: {"items": [label]}
+
+    builder = StateGraph(State)
+    for name in FAN_OUT_NAMES:
+        builder.add_node(name, make_node(name))
+        builder.add_edge(START, name)
+        builder.add_edge(name, END)
+    return builder.compile(checkpointer=checkpointer)
+
+
+def _build_send_fan_out_graph(checkpointer: BaseCheckpointSaver) -> Any:
+    class State(TypedDict):
+        items: Annotated[
+            list, DeltaChannel(_append_reducer, list, snapshot_frequency=10_000)
+        ]
+
+    builder = StateGraph(State)
+    builder.add_node("worker", lambda arg: {"items": [arg]})
+    builder.add_conditional_edges(
+        START, lambda state: [Send("worker", n) for n in SEND_ARGS]
+    )
+    builder.add_edge("worker", END)
+    return builder.compile(checkpointer=checkpointer)
+
+
+async def test_get_state_matches_live_send_order(
+    async_checkpointer: BaseCheckpointSaver,
+) -> None:
+    graph = _build_send_fan_out_graph(async_checkpointer)
+    config = {"configurable": {"thread_id": "1"}}
+
+    live = (await graph.ainvoke({"items": []}, config))["items"]
+    replayed = (await graph.aget_state(config)).values["items"]
+
+    assert live == SEND_ARGS
+    assert replayed == live
+
+
+async def test_get_state_matches_live_invoke_order(
+    async_checkpointer: BaseCheckpointSaver,
+) -> None:
+    graph = _build_fan_out_graph(async_checkpointer)
+    config = {"configurable": {"thread_id": "1"}}
+
+    live = (await graph.ainvoke({"items": []}, config))["items"]
+    replayed = (await graph.aget_state(config)).values["items"]
+
+    assert live == FAN_OUT_NAMES
+    assert replayed == live
+
+
+async def test_sync_get_state_on_async_saver_matches_live_order(
+    async_checkpointer: BaseCheckpointSaver,
+) -> None:
+    graph = _build_fan_out_graph(async_checkpointer)
+    config = {"configurable": {"thread_id": "1"}}
+
+    live = (await graph.ainvoke({"items": []}, config))["items"]
+    replayed = (await asyncio.to_thread(graph.get_state, config)).values["items"]
+
+    assert replayed == live
+
+
+async def test_continuing_thread_preserves_committed_prefix(
+    async_checkpointer: BaseCheckpointSaver,
+) -> None:
+    graph = _build_fan_out_graph(async_checkpointer)
+    config = {"configurable": {"thread_id": "1"}}
+
+    first = (await graph.ainvoke({"items": []}, config))["items"]
+    second = (await graph.ainvoke({"items": []}, config))["items"]
+
+    assert second == first + first
+    assert (await graph.aget_state(config)).values["items"] == second
+
+
+async def test_state_history_reports_live_order_at_every_step(
+    async_checkpointer: BaseCheckpointSaver,
+) -> None:
+    runs = 3
+    graph = _build_fan_out_graph(async_checkpointer)
+    config = {"configurable": {"thread_id": "1"}}
+    for _ in range(runs):
+        await graph.ainvoke({"items": []}, config)
+    live = FAN_OUT_NAMES * runs
+
+    seen = [
+        s.values["items"]
+        async for s in graph.aget_state_history(config)
+        if "items" in s.values
+    ]
+
+    assert max(map(len, seen)) == len(live)
+    for values in seen:
+        assert values == live[: len(values)], f"{values} is not a prefix of {live}"

libs/langgraph/tests/test_delta_channel_run_input.py

@@ -0,0 +1,103 @@
+"""A run's input to a DeltaChannel input channel reads back on the checkpoints
+built from it, and on no others."""
+
+import pytest
+from langgraph.checkpoint.memory import InMemorySaver
+
+from langgraph.channels.binop import BinaryOperatorAggregate
+from langgraph.channels.delta import DeltaChannel
+from langgraph.channels.last_value import LastValue
+from langgraph.pregel import NodeBuilder, Pregel
+from langgraph.types import Durability
+
+pytestmark = pytest.mark.anyio
+
+
+def _sorted_extend(current: list, writes: list) -> list:
+    return sorted([*current, *(item for write in writes for item in write)])
+
+
+def _delta_input_graph() -> Pregel:
+    node = NodeBuilder().subscribe_only("go").do(lambda _: [2]).write_to("log", "plain")
+    return Pregel(
+        nodes={"n": node},
+        channels={
+            "log": DeltaChannel(_sorted_extend),
+            "plain": BinaryOperatorAggregate(list, lambda a, b: sorted(a + b)),
+            "go": LastValue(int),
+        },
+        input_channels=["log", "plain", "go"],
+        output_channels=["log", "plain"],
+        checkpointer=InMemorySaver(),
+    )
+
+
+def test_each_run_input_reads_back_on_its_own_checkpoints(
+    durability: Durability,
+) -> None:
+    graph = _delta_input_graph()
+    config = {"configurable": {"thread_id": "t"}}
+
+    graph.invoke({"log": [0], "plain": [0], "go": 1}, config, durability=durability)
+    graph.invoke({"log": [5], "plain": [5], "go": 1}, config, durability=durability)
+
+    for state in graph.get_state_history(config):
+        assert state.values.get("log", []) == state.values.get("plain", [])
+
+
+async def test_each_run_input_reads_back_on_its_own_checkpoints_async(
+    durability: Durability,
+) -> None:
+    graph = _delta_input_graph()
+    config = {"configurable": {"thread_id": "t"}}
+
+    await graph.ainvoke(
+        {"log": [0], "plain": [0], "go": 1}, config, durability=durability
+    )
+    await graph.ainvoke(
+        {"log": [5], "plain": [5], "go": 1}, config, durability=durability
+    )
+
+    async for state in graph.aget_state_history(config):
+        assert state.values.get("log", []) == state.values.get("plain", [])
+
+
+OTHER_BRANCH_INPUTS = pytest.mark.parametrize(
+    "other_branch_input",
+    [{"go": 1}, {"log": [5], "plain": [5], "go": 1}],
+    ids=["other-branch-without-delta-input", "other-branch-with-delta-input"],
+)
+
+
+@OTHER_BRANCH_INPUTS
+def test_run_input_from_an_older_checkpoint_stays_out_of_its_other_branch(
+    durability: Durability, other_branch_input: dict
+) -> None:
+    graph = _delta_input_graph()
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke({"go": 1}, config, durability=durability)
+    older = graph.get_state(config).config
+    graph.invoke(other_branch_input, config, durability=durability)
+
+    graph.invoke({"log": [7], "plain": [7], "go": 1}, older, durability=durability)
+
+    for state in graph.get_state_history(config):
+        assert state.values.get("log", []) == state.values.get("plain", [])
+
+
+@OTHER_BRANCH_INPUTS
+async def test_run_input_from_an_older_checkpoint_stays_out_of_its_other_branch_async(
+    durability: Durability, other_branch_input: dict
+) -> None:
+    graph = _delta_input_graph()
+    config = {"configurable": {"thread_id": "t"}}
+    await graph.ainvoke({"go": 1}, config, durability=durability)
+    older = (await graph.aget_state(config)).config
+    await graph.ainvoke(other_branch_input, config, durability=durability)
+
+    await graph.ainvoke(
+        {"log": [7], "plain": [7], "go": 1}, older, durability=durability
+    )
+
+    async for state in graph.aget_state_history(config):
+        assert state.values.get("log", []) == state.values.get("plain", [])

libs/langgraph/tests/test_delta_channel_seal_subscribers.py

@@ -0,0 +1,78 @@
+import pytest
+from langgraph.checkpoint.memory import InMemorySaver
+
+from langgraph.channels.delta import DeltaChannel
+from langgraph.channels.last_value import LastValue
+from langgraph.pregel import NodeBuilder, Pregel
+
+pytestmark = pytest.mark.anyio
+
+CONFIG = {"configurable": {"thread_id": "t"}}
+
+
+def _extend(current: list, writes: list) -> list:
+    return [*current, *(item for write in writes for item in write)]
+
+
+def _graph(reads: list) -> Pregel:
+    writer = NodeBuilder().subscribe_only("a").do(lambda _: [1]).write_to("d")
+    reader = NodeBuilder().subscribe_only("d").do(lambda d: reads.append(list(d)))
+    return Pregel(
+        nodes={"writer": writer, "reader": reader},
+        channels={"a": LastValue(str), "d": DeltaChannel(_extend)},
+        input_channels="a",
+        output_channels=["d"],
+        checkpointer=InMemorySaver(),
+    )
+
+
+def test_an_input_update_from_before_the_first_write_starts_only_the_writer() -> None:
+    reads: list = []
+    graph = _graph(reads)
+    graph.invoke("go", CONFIG)
+    first = next(
+        s.config for s in graph.get_state_history(CONFIG) if s.metadata["step"] == -1
+    )
+
+    fork = graph.update_state(first, {"a": "go"}, as_node="__input__")
+
+    assert graph.get_state(fork).next == ("writer",)
+    graph.invoke(None, fork)
+    assert reads == [[1], [1]]
+
+
+def test_a_replay_from_before_the_first_write_forks_with_only_the_writer_next() -> None:
+    reads: list = []
+    graph = _graph(reads)
+    graph.invoke("go", CONFIG)
+    first = next(
+        s.config for s in graph.get_state_history(CONFIG) if s.metadata["step"] == -1
+    )
+
+    graph.invoke(None, first, durability="sync")
+
+    fork = next(
+        s for s in graph.get_state_history(CONFIG) if s.metadata["source"] == "fork"
+    )
+    assert fork.next == ("writer",)
+    graph.invoke(None, fork.config)
+    assert reads == [[1], [1], [1]]
+
+
+async def test_an_ainput_update_from_before_the_first_write_starts_only_the_writer() -> (
+    None
+):
+    reads: list = []
+    graph = _graph(reads)
+    await graph.ainvoke("go", CONFIG)
+    first = [
+        s.config
+        async for s in graph.aget_state_history(CONFIG)
+        if s.metadata["step"] == -1
+    ][0]
+
+    fork = await graph.aupdate_state(first, {"a": "go"}, as_node="__input__")
+
+    assert (await graph.aget_state(fork)).next == ("writer",)
+    await graph.ainvoke(None, fork)
+    assert reads == [[1], [1]]

libs/langgraph/tests/test_delta_channel_update_overwrite.py

@@ -0,0 +1,110 @@
+"""An `Overwrite` through `update_state` snapshots its DeltaChannel on the
+checkpoint the update saves, as a node's `Overwrite` does on the loop's."""
+
+from typing import Annotated, Any
+
+import pytest
+from langchain_core.messages import HumanMessage
+from langgraph.checkpoint.memory import InMemorySaver
+from langgraph.checkpoint.serde.types import _DeltaSnapshot
+from typing_extensions import TypedDict
+
+from langgraph.channels.delta import DeltaChannel
+from langgraph.channels.last_value import LastValue
+from langgraph.graph import START, StateGraph
+from langgraph.graph.message import _messages_delta_reducer
+from langgraph.pregel import NodeBuilder, Pregel
+from langgraph.types import Overwrite
+
+pytestmark = pytest.mark.anyio
+
+
+class _State(TypedDict):
+    messages: Annotated[list, DeltaChannel(_messages_delta_reducer)]
+
+
+def _messages_graph(saver: InMemorySaver) -> Any:
+    builder = StateGraph(_State)
+    builder.add_node("model", lambda state: {})
+    builder.add_edge(START, "model")
+    return builder.compile(checkpointer=saver)
+
+
+def _extend(current: list, writes: list) -> list:
+    return [*current, *(item for write in writes for item in write)]
+
+
+def _delta_input_graph(saver: InMemorySaver) -> Pregel:
+    node = NodeBuilder().subscribe_only("go").do(lambda _: [2]).write_to("log")
+    return Pregel(
+        nodes={"n": node},
+        channels={"log": DeltaChannel(_extend), "go": LastValue(int)},
+        input_channels=["log", "go"],
+        output_channels=["log"],
+        checkpointer=saver,
+    )
+
+
+def test_update_state_with_an_overwrite_snapshots_the_channel() -> None:
+    saver = InMemorySaver()
+    graph = _messages_graph(saver)
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke({"messages": [HumanMessage(content="a", id="1")]}, config)
+
+    graph.update_state(
+        config,
+        {"messages": Overwrite([HumanMessage(content="b", id="2")])},
+        as_node="model",
+    )
+
+    head = saver.get_tuple(config)
+    assert head is not None
+    assert isinstance(head.checkpoint["channel_values"].get("messages"), _DeltaSnapshot)
+    assert [m.content for m in graph.get_state(config).values["messages"]] == ["b"]
+
+
+async def test_aupdate_state_with_an_overwrite_snapshots_the_channel() -> None:
+    saver = InMemorySaver()
+    graph = _messages_graph(saver)
+    config = {"configurable": {"thread_id": "t"}}
+    await graph.ainvoke({"messages": [HumanMessage(content="a", id="1")]}, config)
+
+    await graph.aupdate_state(
+        config,
+        {"messages": Overwrite([HumanMessage(content="b", id="2")])},
+        as_node="model",
+    )
+
+    head = await saver.aget_tuple(config)
+    assert head is not None
+    assert isinstance(head.checkpoint["channel_values"].get("messages"), _DeltaSnapshot)
+    values = (await graph.aget_state(config)).values
+    assert [m.content for m in values["messages"]] == ["b"]
+
+
+def test_update_state_as_input_with_an_overwrite_snapshots_the_channel() -> None:
+    saver = InMemorySaver()
+    graph = _delta_input_graph(saver)
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke({"log": [0], "go": 1}, config)
+
+    graph.update_state(config, {"log": Overwrite([1])}, as_node="__input__")
+
+    head = saver.get_tuple(config)
+    assert head is not None
+    assert isinstance(head.checkpoint["channel_values"].get("log"), _DeltaSnapshot)
+    assert graph.get_state(config).values["log"] == [1]
+
+
+async def test_aupdate_state_as_input_with_an_overwrite_snapshots_the_channel() -> None:
+    saver = InMemorySaver()
+    graph = _delta_input_graph(saver)
+    config = {"configurable": {"thread_id": "t"}}
+    await graph.ainvoke({"log": [0], "go": 1}, config)
+
+    await graph.aupdate_state(config, {"log": Overwrite([1])}, as_node="__input__")
+
+    head = await saver.aget_tuple(config)
+    assert head is not None
+    assert isinstance(head.checkpoint["channel_values"].get("log"), _DeltaSnapshot)
+    assert (await graph.aget_state(config)).values["log"] == [1]

libs/langgraph/tests/test_delta_channel_update_state.py

@@ -20,23 +20,28 @@ from typing import Annotated, Any
 
 import pytest
 from langchain_core.messages import HumanMessage
+from langgraph.checkpoint.base import BaseCheckpointSaver
 from langgraph.checkpoint.memory import InMemorySaver
 from langgraph.checkpoint.serde.types import _DeltaSnapshot
 from typing_extensions import TypedDict
 
+from langgraph.channels.binop import BinaryOperatorAggregate
 from langgraph.channels.delta import DeltaChannel
+from langgraph.channels.last_value import LastValue
 from langgraph.graph import START, StateGraph
 from langgraph.graph.message import _messages_delta_reducer
-from langgraph.types import StateUpdate
+from langgraph.pregel import NodeBuilder, Pregel
+from langgraph.types import StateSnapshot, StateUpdate
 
 pytestmark = pytest.mark.anyio
 
 
 def _build_graph(
-    checkpointer: InMemorySaver,
+    checkpointer: BaseCheckpointSaver,
     *,
     two_nodes: bool = False,
     snapshot_frequency: int = 1000,
+    interrupt_before: list[str] | None = None,
 ) -> Any:
     """Compile a minimal DeltaChannel-backed `messages` graph.
 
@@ -63,7 +68,7 @@ def _build_graph(
         builder.set_finish_point("assistant")
     else:
         builder.set_finish_point("model")
-    return builder.compile(checkpointer=checkpointer)
+    return builder.compile(checkpointer=checkpointer, interrupt_before=interrupt_before)
 
 
 # ---------------------------------------------------------------------------
@@ -304,15 +309,14 @@ def test_bulk_update_state_multi_task_per_superstep_delta_channel() -> None:
     that each call `put_writes`. Guards the regression where moving
     `put_writes` outside the per-task loop would persist only the last
     task's writes.
-
-    Explicit `task_id`s are required to disambiguate writes belonging to
-    different `StateUpdate`s targeting the same node — otherwise both share
-    the deterministic interrupt-derived id and collide in the saver.
     """
 
     saver = InMemorySaver()
     graph = _build_graph(saver)
     config = {"configurable": {"thread_id": "bulk-multi-task"}}
+    graph.invoke({"messages": [HumanMessage(content="hi", id="hi")]}, config)
+    base = saver.get_tuple(config)
+    assert base is not None
 
     graph.bulk_update_state(
         config,
@@ -332,13 +336,155 @@ def test_bulk_update_state_multi_task_per_superstep_delta_channel() -> None:
         ],
     )
 
+    stored = saver.get_tuple(base.config)
+    assert stored is not None
+    assert {task_id for task_id, _, _ in stored.pending_writes or []} == {
+        "task-1",
+        "task-2",
+    }, "explicit task ids must key the stored writes"
     state = graph.get_state(config)
     contents = [m.content for m in state.values["messages"]]
     ids = [m.id for m in state.values["messages"]]
-    assert sorted(contents) == ["first", "second"], (
+    assert sorted(contents) == ["first", "hi", "second"], (
         f"both updates' writes must persist; got {contents}"
     )
-    assert sorted(ids) == ["m1", "m2"]
+    assert sorted(ids) == ["hi", "m1", "m2"]
+
+
+def _update(content: str, as_node: str) -> StateUpdate:
+    return StateUpdate(
+        values={"messages": [HumanMessage(content=content, id=content)]},
+        as_node=as_node,
+    )
+
+
+def _contents(state: StateSnapshot) -> list[str]:
+    return [m.content for m in state.values["messages"]]
+
+
+def test_bulk_update_state_keeps_every_update_without_task_ids(
+    sync_checkpointer: BaseCheckpointSaver,
+) -> None:
+    graph = _build_graph(sync_checkpointer, two_nodes=True)
+    config = {"configurable": {"thread_id": "bulk-no-task-ids"}}
+    graph.invoke({"messages": [HumanMessage(content="hi", id="hi")]}, config)
+
+    graph.bulk_update_state(
+        config,
+        [
+            [
+                _update("first", "model"),
+                _update("second", "model"),
+                _update("third", "assistant"),
+            ]
+        ],
+    )
+
+    contents = _contents(graph.get_state(config))
+    assert sorted(contents) == ["first", "hi", "second", "third"], (
+        f"every update's writes must persist; got {contents}"
+    )
+
+
+async def test_abulk_update_state_keeps_every_update_without_task_ids(
+    async_checkpointer: BaseCheckpointSaver,
+) -> None:
+    graph = _build_graph(async_checkpointer, two_nodes=True)
+    config = {"configurable": {"thread_id": "bulk-no-task-ids"}}
+    await graph.ainvoke({"messages": [HumanMessage(content="hi", id="hi")]}, config)
+
+    await graph.abulk_update_state(
+        config,
+        [
+            [
+                _update("first", "model"),
+                _update("second", "model"),
+                _update("third", "assistant"),
+            ]
+        ],
+    )
+
+    contents = _contents(await graph.aget_state(config))
+    assert sorted(contents) == ["first", "hi", "second", "third"], (
+        f"every update's writes must persist; got {contents}"
+    )
+
+
+def test_bulk_update_state_keeps_every_update_next_to_a_pending_task(
+    sync_checkpointer: BaseCheckpointSaver,
+) -> None:
+    graph = _build_graph(
+        sync_checkpointer, two_nodes=True, interrupt_before=["assistant"]
+    )
+    config = {"configurable": {"thread_id": "bulk-pending-task"}}
+    graph.invoke({"messages": [HumanMessage(content="hi", id="hi")]}, config)
+    assert graph.get_state(config).next == ("assistant",)
+
+    graph.bulk_update_state(
+        config,
+        [
+            [
+                _update("first", "assistant"),
+                _update("second", "model"),
+                _update("third", "model"),
+            ]
+        ],
+    )
+
+    contents = _contents(graph.get_state(config))
+    assert sorted(contents) == ["first", "hi", "second", "third"], (
+        f"every update's writes must persist; got {contents}"
+    )
+
+
+class _TaskPathOrderSaver(InMemorySaver):
+    """Replays each checkpoint's writes by `(task_path, task_id, idx)`."""
+
+    def get_tuple(self, config: Any) -> Any:
+        tup = super().get_tuple(config)
+        if tup is None or not tup.pending_writes:
+            return tup
+        conf = tup.config["configurable"]
+        stored = self.writes[
+            (conf["thread_id"], conf["checkpoint_ns"], conf["checkpoint_id"])
+        ]
+        rows = sorted(
+            zip(stored.items(), tup.pending_writes),
+            key=lambda row: (row[0][1][3], *row[0][0]),
+        )
+        return tup._replace(pending_writes=[write for _, write in rows])
+
+    get_delta_channel_history = BaseCheckpointSaver.get_delta_channel_history
+    aget_delta_channel_history = BaseCheckpointSaver.aget_delta_channel_history
+
+
+GIVEN = ["u1", "u2", "u3", "u4", "u5", "u6"]
+
+
+def _updates_in_given_order() -> list[list[StateUpdate]]:
+    return [
+        [_update(c, "assistant" if i % 2 else "model") for i, c in enumerate(GIVEN)]
+    ]
+
+
+def test_bulk_update_state_replays_updates_in_the_order_given() -> None:
+    graph = _build_graph(_TaskPathOrderSaver(), two_nodes=True)
+    config = {"configurable": {"thread_id": "bulk-order"}}
+    graph.invoke({"messages": [HumanMessage(content="hi", id="hi")]}, config)
+
+    graph.bulk_update_state(config, _updates_in_given_order())
+
+    assert _contents(graph.get_state(config)) == ["hi", *GIVEN]
+
+
+async def test_abulk_update_state_replays_updates_in_the_order_given() -> None:
+    graph = _build_graph(_TaskPathOrderSaver(), two_nodes=True)
+    config = {"configurable": {"thread_id": "bulk-order"}}
+    await graph.ainvoke({"messages": [HumanMessage(content="hi", id="hi")]}, config)
+
+    await graph.abulk_update_state(config, _updates_in_given_order())
+
+    assert _contents(await graph.aget_state(config)) == ["hi", *GIVEN]
 
 
 # ---------------------------------------------------------------------------
@@ -395,3 +541,189 @@ def test_update_state_that_snapshots_keeps_a_deferred_node_pending() -> None:
 
     assert [m.content for m in final["messages"]] == ["s", "a", "u", "b"]
     assert graph.get_state(config).next == ()
+
+
+def _sorted_extend(current: list, writes: list) -> list:
+    return sorted([*current, *(item for write in writes for item in write)])
+
+
+def _delta_input_graph(snapshot_frequency: int = 1000) -> Any:
+    node = NodeBuilder().subscribe_only("go").do(lambda _: [2]).write_to("log", "plain")
+    return Pregel(
+        nodes={"n": node},
+        channels={
+            "log": DeltaChannel(_sorted_extend, snapshot_frequency=snapshot_frequency),
+            "plain": BinaryOperatorAggregate(list, lambda a, b: sorted(a + b)),
+            "go": LastValue(int),
+        },
+        input_channels=["log", "plain", "go"],
+        output_channels=["log", "plain"],
+        checkpointer=InMemorySaver(),
+    )
+
+
+@pytest.mark.parametrize("snapshot_frequency", [1, 2])
+def test_update_as_input_reads_back_on_its_checkpoint_and_after_the_next_run(
+    snapshot_frequency: int,
+) -> None:
+    graph = _delta_input_graph(snapshot_frequency)
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke({"log": [0], "plain": [0], "go": 1}, config)
+
+    graph.update_state(config, {"log": [1], "plain": [1], "go": 1}, as_node="__input__")
+    after_update = graph.get_state(config).values
+    graph.invoke(None, config)
+    after_run = graph.get_state(config).values
+
+    assert after_update["log"] == after_update["plain"]
+    assert after_run["log"] == after_run["plain"]
+
+
+@pytest.mark.parametrize("snapshot_frequency", [1, 2])
+async def test_aupdate_as_input_reads_back_on_its_checkpoint_and_after_the_next_run(
+    snapshot_frequency: int,
+) -> None:
+    graph = _delta_input_graph(snapshot_frequency)
+    config = {"configurable": {"thread_id": "t"}}
+    await graph.ainvoke({"log": [0], "plain": [0], "go": 1}, config)
+
+    await graph.aupdate_state(
+        config, {"log": [1], "plain": [1], "go": 1}, as_node="__input__"
+    )
+    after_update = (await graph.aget_state(config)).values
+    await graph.ainvoke(None, config)
+    after_run = (await graph.aget_state(config)).values
+
+    assert after_update["log"] == after_update["plain"]
+    assert after_run["log"] == after_run["plain"]
+
+
+def test_update_as_input_to_an_older_checkpoint_stays_out_of_its_other_branch() -> None:
+    graph = _delta_input_graph()
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke({"go": 1}, config)
+    older = graph.get_state(config).config
+    graph.invoke({"go": 1}, config)
+    other_branch = graph.get_state(config)
+
+    edited = graph.update_state(
+        older, {"log": [1], "plain": [1], "go": 1}, as_node="__input__"
+    )
+
+    values = graph.get_state(edited).values
+    assert values["log"] == values["plain"]
+    assert graph.get_state(other_branch.config).values == other_branch.values
+
+
+async def test_aupdate_as_input_to_an_older_checkpoint_stays_out_of_its_other_branch() -> (
+    None
+):
+    graph = _delta_input_graph()
+    config = {"configurable": {"thread_id": "t"}}
+    await graph.ainvoke({"go": 1}, config)
+    older = (await graph.aget_state(config)).config
+    await graph.ainvoke({"go": 1}, config)
+    other_branch = await graph.aget_state(config)
+
+    edited = await graph.aupdate_state(
+        older, {"log": [1], "plain": [1], "go": 1}, as_node="__input__"
+    )
+
+    values = (await graph.aget_state(edited)).values
+    assert values["log"] == values["plain"]
+    assert (await graph.aget_state(other_branch.config)).values == other_branch.values
+
+
+def _message_ids(graph: Any, config: dict) -> list[str | None]:
+    return [m.id for m in graph.get_state(config).values["messages"]]
+
+
+async def _amessage_ids(graph: Any, config: dict) -> list[str | None]:
+    return [m.id for m in (await graph.aget_state(config)).values["messages"]]
+
+
+def _messages_input_graph() -> Any:
+    node = (
+        NodeBuilder()
+        .subscribe_only("go")
+        .do(lambda _: [HumanMessage("n", id="n")])
+        .write_to("messages")
+    )
+    return Pregel(
+        nodes={"n": node},
+        channels={
+            "messages": DeltaChannel(_messages_delta_reducer),
+            "go": LastValue(int),
+        },
+        input_channels=["messages", "go"],
+        output_channels=["messages"],
+        checkpointer=InMemorySaver(),
+    )
+
+
+def test_update_state_gives_a_message_an_id_that_every_read_keeps() -> None:
+    graph = _build_graph(InMemorySaver())
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke({"messages": [HumanMessage("a", id="a")]}, config)
+
+    graph.update_state(config, {"messages": [HumanMessage("b")]})
+
+    first, second = _message_ids(graph, config), _message_ids(graph, config)
+    assert first[-1] is not None
+    assert first == second
+
+
+async def test_aupdate_state_gives_a_message_an_id_that_every_read_keeps() -> None:
+    graph = _build_graph(InMemorySaver())
+    config = {"configurable": {"thread_id": "t"}}
+    await graph.ainvoke({"messages": [HumanMessage("a", id="a")]}, config)
+
+    await graph.aupdate_state(config, {"messages": [HumanMessage("b")]})
+
+    first, second = (
+        await _amessage_ids(graph, config),
+        await _amessage_ids(graph, config),
+    )
+    assert first[-1] is not None
+    assert first == second
+
+
+def test_update_state_on_an_older_checkpoint_gives_a_message_an_id() -> None:
+    graph = _build_graph(InMemorySaver())
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke({"messages": [HumanMessage("a", id="a")]}, config)
+    older = graph.get_state(config).config
+    graph.invoke({"messages": [HumanMessage("c", id="c")]}, config)
+
+    branch = graph.update_state(older, {"messages": [HumanMessage("b")]})
+
+    assert _message_ids(graph, branch)[-1] is not None
+
+
+def test_update_as_input_gives_a_message_an_id_that_every_read_keeps() -> None:
+    graph = _messages_input_graph()
+    config = {"configurable": {"thread_id": "t"}}
+    graph.invoke({"messages": [HumanMessage("a", id="a")], "go": 1}, config)
+
+    graph.update_state(config, {"messages": [HumanMessage("b")]}, as_node="__input__")
+
+    first, second = _message_ids(graph, config), _message_ids(graph, config)
+    assert first[-1] is not None
+    assert first == second
+
+
+async def test_aupdate_as_input_gives_a_message_an_id_that_every_read_keeps() -> None:
+    graph = _messages_input_graph()
+    config = {"configurable": {"thread_id": "t"}}
+    await graph.ainvoke({"messages": [HumanMessage("a", id="a")], "go": 1}, config)
+
+    await graph.aupdate_state(
+        config, {"messages": [HumanMessage("b")]}, as_node="__input__"
+    )
+
+    first, second = (
+        await _amessage_ids(graph, config),
+        await _amessage_ids(graph, config),
+    )
+    assert first[-1] is not None
+    assert first == second

libs/langgraph/tests/test_delta_channel_write_failures.py

@@ -0,0 +1,168 @@
+"""A checkpoint must never be saved without the `DeltaChannel` writes it reads."""
+
+import operator
+import threading
+from typing import Annotated, Any
+
+import pytest
+from langgraph.checkpoint.memory import InMemorySaver
+from typing_extensions import TypedDict
+
+from langgraph.channels.delta import DeltaChannel
+from langgraph.graph import START, StateGraph
+from langgraph.types import Durability
+
+pytestmark = pytest.mark.anyio
+
+INPUT = {"log": [], "plain": []}
+FINAL = {"log": ["a", "b", "c"], "plain": ["a", "b", "c"]}
+
+# Exit mode saves nothing before the failed write, so its retry starts over.
+RETRIES = [
+    pytest.param("sync", None, id="sync"),
+    pytest.param("async", None, id="async"),
+    pytest.param("exit", INPUT, id="exit"),
+]
+
+
+def _append(current: list, writes: list) -> list:
+    return [*current, *(item for write in writes for item in write)]
+
+
+class _State(TypedDict):
+    log: Annotated[list, DeltaChannel(_append)]
+    plain: Annotated[list, operator.add]
+
+
+class _FailsTheWriteOfBOnce(InMemorySaver):
+    failed = False
+
+    def _fail_once(self, writes: Any) -> None:
+        if not self.failed and ("log", ["b"]) in writes:
+            self.failed = True
+            raise ConnectionError("b's write was not saved")
+
+    def put_writes(
+        self, config: Any, writes: Any, task_id: str, task_path: str = ""
+    ) -> None:
+        self._fail_once(writes)
+        super().put_writes(config, writes, task_id, task_path)
+
+    async def aput_writes(
+        self, config: Any, writes: Any, task_id: str, task_path: str = ""
+    ) -> None:
+        self._fail_once(writes)
+        await super().aput_writes(config, writes, task_id, task_path)
+
+
+class _FailsTheSaveAfterAOnce(InMemorySaver):
+    failed = False
+
+    def _fail_once(self, checkpoint: Any) -> None:
+        if not self.failed and checkpoint["channel_values"].get("plain") == ["a"]:
+            self.failed = True
+            raise ConnectionError("the checkpoint after a was not saved")
+
+    def put(
+        self, config: Any, checkpoint: Any, metadata: Any, new_versions: Any
+    ) -> Any:
+        self._fail_once(checkpoint)
+        return super().put(config, checkpoint, metadata, new_versions)
+
+    async def aput(
+        self, config: Any, checkpoint: Any, metadata: Any, new_versions: Any
+    ) -> Any:
+        self._fail_once(checkpoint)
+        return await super().aput(config, checkpoint, metadata, new_versions)
+
+
+def _a_then_b_then_c(saver: InMemorySaver) -> Any:
+    builder = StateGraph(_State)
+    for name in "abc":
+        builder.add_node(
+            name, lambda state, name=name: {"log": [name], "plain": [name]}
+        )
+    builder.add_edge(START, "a")
+    builder.add_edge("a", "b")
+    builder.add_edge("b", "c")
+    return builder.compile(checkpointer=saver)
+
+
+@pytest.mark.parametrize(("durability", "retry_input"), RETRIES)
+def test_a_failed_delta_write_is_rerun_not_lost(
+    durability: Durability, retry_input: dict | None
+) -> None:
+    graph = _a_then_b_then_c(_FailsTheWriteOfBOnce())
+    config = {"configurable": {"thread_id": "t"}}
+
+    with pytest.raises(ConnectionError):
+        graph.invoke(INPUT, config, durability=durability)
+    for state in graph.get_state_history(config):
+        assert state.values.get("log", []) == state.values.get("plain", [])
+
+    graph.invoke(retry_input, config, durability=durability)
+    assert graph.get_state(config).values == FINAL
+
+
+@pytest.mark.parametrize(("durability", "retry_input"), RETRIES)
+async def test_a_failed_delta_write_is_rerun_not_lost_async(
+    durability: Durability, retry_input: dict | None
+) -> None:
+    graph = _a_then_b_then_c(_FailsTheWriteOfBOnce())
+    config = {"configurable": {"thread_id": "t"}}
+
+    with pytest.raises(ConnectionError):
+        await graph.ainvoke(INPUT, config, durability=durability)
+    async for state in graph.aget_state_history(config):
+        assert state.values.get("log", []) == state.values.get("plain", [])
+
+    await graph.ainvoke(retry_input, config, durability=durability)
+    assert (await graph.aget_state(config)).values == FINAL
+
+
+@pytest.mark.parametrize("durability", ["sync", "async"])
+def test_a_failed_checkpoint_save_is_rerun_not_built_on(
+    durability: Durability,
+) -> None:
+    graph = _a_then_b_then_c(_FailsTheSaveAfterAOnce())
+    config = {"configurable": {"thread_id": "t"}}
+
+    with pytest.raises(ConnectionError):
+        graph.invoke(INPUT, config, durability=durability)
+    for state in graph.get_state_history(config):
+        assert state.values.get("log", []) == state.values.get("plain", [])
+
+    graph.invoke(None, config, durability=durability)
+    assert graph.get_state(config).values == FINAL
+
+
+@pytest.mark.parametrize("durability", ["sync", "async"])
+async def test_a_failed_checkpoint_save_is_rerun_not_built_on_async(
+    durability: Durability,
+) -> None:
+    graph = _a_then_b_then_c(_FailsTheSaveAfterAOnce())
+    config = {"configurable": {"thread_id": "t"}}
+
+    with pytest.raises(ConnectionError):
+        await graph.ainvoke(INPUT, config, durability=durability)
+    async for state in graph.aget_state_history(config):
+        assert state.values.get("log", []) == state.values.get("plain", [])
+
+    await graph.ainvoke(None, config, durability=durability)
+    assert (await graph.aget_state(config)).values == FINAL
+
+
+def test_a_delta_graph_finishes_on_a_single_background_thread() -> None:
+    graph = _a_then_b_then_c(InMemorySaver())
+    config = {"configurable": {"thread_id": "t"}, "max_concurrency": 1}
+    result: dict = {}
+    run = threading.Thread(
+        target=lambda: result.update(graph.invoke(INPUT, config, durability="async")),
+        daemon=True,
+    )
+
+    run.start()
+    run.join(timeout=10)
+
+    assert not run.is_alive(), "invoke hung"
+    assert result == FINAL

libs/langgraph/tests/test_interruption.py

@@ -6,6 +6,7 @@ from langgraph.checkpoint.base import BaseCheckpointSaver
 from pydantic import BaseModel, ValidationError
 from typing_extensions import TypedDict
 
+from langgraph.errors import is_invalid_resume
 from langgraph.graph import END, START, StateGraph
 from langgraph.types import Command, Durability, Interrupt, interrupt
 from tests.any_str import AnyStr
@@ -202,14 +203,22 @@ def test_interrupt_response_schema_rejects_invalid_resume(
     def resume(value: dict[str, Any]) -> Command:
         return Command(resume=value if resume_style == "null" else {pending.id: value})
 
-    with pytest.raises(ValidationError, match="approved"):
+    with pytest.raises(ValidationError, match="approved") as exc_info:
         graph.invoke(resume({"approved": "nope"}), config)
+    assert is_invalid_resume(exc_info.value)
 
     assert graph.invoke(resume({"approved": False}), config) == {
         "answer": Decision(approved=False)
     }
 
 
+def test_is_invalid_resume_ignores_other_errors() -> None:
+    with pytest.raises(ValidationError) as exc_info:
+        Decision.model_validate({"approved": "nope"})
+    assert not is_invalid_resume(exc_info.value)
+    assert not is_invalid_resume(ValueError("nope"))
+
+
 @pytest.mark.parametrize("resume_style", ["null", "id_map"])
 def test_interrupt_response_schema_invalid_resume_after_earlier_interrupt(
     sync_checkpointer: BaseCheckpointSaver, resume_style: str

libs/langgraph/tests/test_runtime.py

@@ -248,6 +248,95 @@ def test_drain_from_subgraph_can_resume_parent() -> None:
     }
 
 
+class _BreakpointState(TypedDict, total=False):
+    first: str
+    second: str
+
+
+def _drain_before_breakpoint_builder(
+    second_runs: list[str],
+) -> StateGraph[_BreakpointState]:
+    def first(state: _BreakpointState, runtime: Runtime) -> _BreakpointState:
+        runtime.control.request_drain("rollout")
+        return {"first": "done"}
+
+    def second(state: _BreakpointState) -> _BreakpointState:
+        second_runs.append("second")
+        return {"second": "done"}
+
+    builder = StateGraph(_BreakpointState)
+    builder.add_node("first", first)
+    builder.add_node("second", second)
+    builder.add_edge(START, "first")
+    builder.add_edge("first", "second")
+    return builder
+
+
+@pytest.mark.parametrize("at_compile", [True, False])
+def test_drain_before_interrupt_before_stops_at_breakpoint(at_compile: bool) -> None:
+    # A resume passes the next step's breakpoints, so a drain right before a
+    # breakpoint has to stop there instead, or the resumed run skips it.
+    second_runs: list[str] = []
+    breakpoints = {"interrupt_before": ["second"]}
+    compiled = _drain_before_breakpoint_builder(second_runs).compile(
+        checkpointer=MemorySaver(), **(breakpoints if at_compile else {})
+    )
+    run_kwargs = {} if at_compile else breakpoints
+    config = {"configurable": {"thread_id": "drain-breakpoint"}}
+
+    assert compiled.invoke({}, config, control=RunControl(), **run_kwargs) == {
+        "first": "done"
+    }
+    assert compiled.get_state(config).next == ("second",)
+    assert second_runs == []
+
+    assert compiled.invoke(None, config, **run_kwargs) == {
+        "first": "done",
+        "second": "done",
+    }
+    assert second_runs == ["second"]
+
+
+def test_drain_before_subgraph_interrupt_before_stops_at_breakpoint() -> None:
+    second_runs: list[str] = []
+    child = _drain_before_breakpoint_builder(second_runs).compile(
+        interrupt_before=["second"]
+    )
+    parent = StateGraph(_BreakpointState)
+    parent.add_node("child", child)
+    parent.add_edge(START, "child")
+    compiled = parent.compile(checkpointer=MemorySaver())
+    config = {"configurable": {"thread_id": "drain-subgraph-breakpoint"}}
+
+    compiled.invoke({}, config, control=RunControl())
+    state = compiled.get_state(config, subgraphs=True)
+    assert state.next == ("child",)
+    assert state.tasks[0].state.next == ("second",)
+    assert second_runs == []
+
+    assert compiled.invoke(None, config) == {"first": "done", "second": "done"}
+    assert second_runs == ["second"]
+
+
+@pytest.mark.anyio
+async def test_drain_before_interrupt_before_stops_at_breakpoint_async() -> None:
+    second_runs: list[str] = []
+    compiled = _drain_before_breakpoint_builder(second_runs).compile(
+        checkpointer=MemorySaver(), interrupt_before=["second"]
+    )
+    config = {"configurable": {"thread_id": "drain-breakpoint-async"}}
+
+    assert await compiled.ainvoke({}, config, control=RunControl()) == {"first": "done"}
+    assert (await compiled.aget_state(config)).next == ("second",)
+    assert second_runs == []
+
+    assert await compiled.ainvoke(None, config) == {
+        "first": "done",
+        "second": "done",
+    }
+    assert second_runs == ["second"]
+
+
 @pytest.mark.anyio
 async def test_drain_requested_in_terminal_step_finishes_normally_async() -> None:
     class State(TypedDict, total=False):

libs/langgraph/tests/test_stream_events_v3_kwarg_forwarding.py

@@ -8,20 +8,33 @@ caller kwargs to the inner ``(a)stream`` call but rejects ``stream_mode`` and
 ``subgraphs`` since v3 owns them (``stream_mode`` is built from the
 transformer mux; ``subgraphs`` is forced True so nested namespaces flow
 through scoped muxes).
+
+A second regression is pinned here: #7677 (first released in 1.2.0a3)
+declared `interrupt_before` / `interrupt_after` / `control` as named
+parameters on the `Pregel.stream_events` / `astream_events` dispatchers
+but forwarded them only on the v3 branch, silently dropping them on v1/v2
+(where they had reached `(a)stream` through `**kwargs` before).
+`TestAstreamKwargsForwardedOnEveryVersion` and friends pin that they
+reach `(a)stream` on every version, with the v1/v2 passthrough semantics
+restored (exactly what the caller passed, including an explicit `None`)
+and v3's explicit-default semantics preserved.
 """
 
 from __future__ import annotations
 
 import sys
+from collections.abc import AsyncIterator, Callable
 from dataclasses import dataclass
 from typing import Any
 
 import pytest
+from langgraph.checkpoint.memory import InMemorySaver
 from typing_extensions import TypedDict
 
 from langgraph.constants import END, START
+from langgraph.errors import GraphDrained
 from langgraph.graph import StateGraph
-from langgraph.runtime import Runtime
+from langgraph.runtime import RunControl, Runtime
 
 NEEDS_CONTEXTVARS = pytest.mark.skipif(
     sys.version_info < (3, 11),
@@ -106,3 +119,274 @@ class TestKwargForwardingAsync:
                 version="v3",
                 subgraphs=False,
             )
+
+
+_KWARG_NAMES = ("control", "interrupt_before", "interrupt_after")
+
+
+def _build_two_step_graph(
+    first: Callable[[_State], dict[str, Any]] | None = None,
+) -> Any:
+    """A `first -> second` graph with a checkpointer, for interrupt/drain tests."""
+
+    def default_first(state: _State) -> dict[str, Any]:
+        return {"message": state["message"] + " first"}
+
+    def second(state: _State) -> dict[str, Any]:
+        return {"message": state["message"] + " second"}
+
+    builder = StateGraph(_State)
+    builder.add_node("first", first or default_first)
+    builder.add_node("second", second)
+    builder.add_edge(START, "first")
+    builder.add_edge("first", "second")
+    builder.add_edge("second", END)
+    return builder.compile(checkpointer=InMemorySaver())
+
+
+async def _drive_astream_events(
+    graph: Any, config: dict[str, Any], version: str, **kwargs: Any
+) -> None:
+    """Consume an astream_events run for `version` to completion."""
+    if version == "v3":
+        run = await graph.astream_events(
+            {"message": "hi"}, config, version="v3", **kwargs
+        )
+        await run.output()
+    else:
+        async for _ in graph.astream_events(
+            {"message": "hi"}, config, version=version, **kwargs
+        ):
+            pass
+
+
+@pytest.mark.anyio
+@pytest.mark.filterwarnings("ignore:astream_events version='v1' is deprecated")
+@pytest.mark.parametrize("version", ["v1", "v2", "v3"])
+class TestAstreamKwargsForwardedOnEveryVersion:
+    """`interrupt_before`/`interrupt_after`/`control` reach `astream` on every
+    version.
+
+    Regression test for #7677 (first released in 1.2.0a3): the dispatchers
+    captured these parameters as named arguments but forwarded them only on
+    the v3 branch, silently dropping them on v1/v2.
+    """
+
+    async def test_interrupt_before(self, version: str) -> None:
+        graph = _build_two_step_graph()
+        config = {"configurable": {"thread_id": "ib"}}
+        await _drive_astream_events(graph, config, version, interrupt_before=["second"])
+        state = await graph.aget_state(config)
+        assert state.next == ("second",)
+        assert state.values == {"message": "hi first"}
+
+    async def test_interrupt_after(self, version: str) -> None:
+        graph = _build_two_step_graph()
+        config = {"configurable": {"thread_id": "ia"}}
+        await _drive_astream_events(graph, config, version, interrupt_after=["first"])
+        state = await graph.aget_state(config)
+        assert state.next == ("second",)
+        assert state.values == {"message": "hi first"}
+
+    async def test_pre_drained_control(self, version: str) -> None:
+        graph = _build_two_step_graph()
+        config = {"configurable": {"thread_id": "drain"}}
+        control = RunControl()
+        control.request_drain("sigterm")
+        with pytest.raises(GraphDrained, match="sigterm"):
+            await _drive_astream_events(graph, config, version, control=control)
+
+
+class TestStreamEventsV3SyncInterrupts:
+    """Sync v3 static interrupts reach `stream()` after the kwargs rewire."""
+
+    @pytest.mark.parametrize(
+        ("kwarg", "node"),
+        [("interrupt_before", "second"), ("interrupt_after", "first")],
+    )
+    def test_static_interrupt(self, kwarg: str, node: str) -> None:
+        graph = _build_two_step_graph()
+        config = {"configurable": {"thread_id": "sync"}}
+        run = graph.stream_events(
+            {"message": "hi"}, config, version="v3", **{kwarg: [node]}
+        )
+        list(run.values)
+        state = graph.get_state(config)
+        assert state.next == ("second",)
+        assert state.values == {"message": "hi first"}
+
+
+@pytest.mark.anyio
+@pytest.mark.filterwarnings("ignore:astream_events version='v1' is deprecated")
+@pytest.mark.parametrize("version", ["v1", "v2", "v3"])
+class TestAstreamMidRunDrain:
+    """A drain requested from inside a node propagates out of `astream_events`.
+
+    This is the graceful-shutdown scenario: `request_drain()` called while
+    the run is in flight (e.g. from a signal handler), with v1/v2 running
+    inside core's event-stream task. The caller's own `RunControl` is used
+    (the drain reason proves identity), `GraphDrained` propagates to the
+    consumer, and the checkpoint keeps the pending step.
+    """
+
+    async def test_drain_requested_inside_first_node(self, version: str) -> None:
+        control = RunControl()
+
+        def first(state: _State) -> dict[str, Any]:
+            control.request_drain("sigterm-mid")
+            return {"message": state["message"] + " first"}
+
+        graph = _build_two_step_graph(first)
+        config = {"configurable": {"thread_id": "midrun"}}
+
+        with pytest.raises(GraphDrained, match="sigterm-mid"):
+            await _drive_astream_events(graph, config, version, control=control)
+        state = await graph.aget_state(config)
+        assert state.next == ("second",)
+        assert state.values == {"message": "hi first"}
+
+
+def _record_astream_kwargs(graph: Any) -> list[dict[str, Any]]:
+    """Patch `graph.astream` to record the kwargs each call receives."""
+    received: list[dict[str, Any]] = []
+    original = graph.astream
+
+    async def recording_astream(
+        input: Any, config: Any = None, **kwargs: Any
+    ) -> AsyncIterator[Any]:
+        received.append(kwargs)
+        async for chunk in original(input, config, **kwargs):
+            yield chunk
+
+    graph.astream = recording_astream  # type: ignore[method-assign]
+    return received
+
+
+@pytest.mark.anyio
+@pytest.mark.filterwarnings("ignore:astream_events version='v1' is deprecated")
+@pytest.mark.parametrize("version", ["v1", "v2"])
+class TestAstreamV1V2KwargsPassthrough:
+    """v1/v2 forward to `astream` exactly what the caller passed.
+
+    Pre-#7677 semantics: an explicit `None` is forwarded as `None`, and an
+    omitted argument is not forwarded at all (so an override's own default
+    would apply).
+    """
+
+    @pytest.mark.parametrize("name", _KWARG_NAMES)
+    async def test_passed_values_reach_astream(self, version: str, name: str) -> None:
+        graph = _build_two_step_graph()
+        received = _record_astream_kwargs(graph)
+        value: Any = RunControl() if name == "control" else ["second"]
+        await _drive_astream_events(
+            graph, {"configurable": {"thread_id": "rec"}}, version, **{name: value}
+        )
+        assert len(received) == 1
+        assert received[0][name] == value
+        if name == "control":
+            assert received[0][name] is value
+
+    @pytest.mark.parametrize("name", _KWARG_NAMES)
+    async def test_explicit_none_is_forwarded(self, version: str, name: str) -> None:
+        graph = _build_two_step_graph()
+        received = _record_astream_kwargs(graph)
+        await _drive_astream_events(
+            graph, {"configurable": {"thread_id": "rec-none"}}, version, **{name: None}
+        )
+        assert len(received) == 1
+        assert received[0][name] is None
+
+    @pytest.mark.parametrize("name", _KWARG_NAMES)
+    async def test_omitted_values_are_absent(self, version: str, name: str) -> None:
+        graph = _build_two_step_graph()
+        received = _record_astream_kwargs(graph)
+        await _drive_astream_events(
+            graph, {"configurable": {"thread_id": "rec-omit"}}, version
+        )
+        assert len(received) == 1
+        assert name not in received[0]
+
+
+@pytest.mark.anyio
+class TestAstreamV3KwargsDefaults:
+    """v3 keeps its since-inception explicit-default semantics (#7519).
+
+    Omitted `interrupt_before`/`interrupt_after`/`control` are supplied to
+    `astream` as `None`; passed values are forwarded as-is.
+    """
+
+    async def test_omitted_values_arrive_as_none(self) -> None:
+        graph = _build_two_step_graph()
+        received = _record_astream_kwargs(graph)
+        await _drive_astream_events(
+            graph, {"configurable": {"thread_id": "v3-rec"}}, "v3"
+        )
+        assert len(received) == 1
+        assert received[0]["control"] is None
+        assert received[0]["interrupt_before"] is None
+        assert received[0]["interrupt_after"] is None
+
+    @pytest.mark.parametrize("name", _KWARG_NAMES)
+    async def test_passed_values_reach_astream(self, name: str) -> None:
+        graph = _build_two_step_graph()
+        received = _record_astream_kwargs(graph)
+        value: Any = RunControl() if name == "control" else ["second"]
+        await _drive_astream_events(
+            graph, {"configurable": {"thread_id": "v3-rec-2"}}, "v3", **{name: value}
+        )
+        assert len(received) == 1
+        assert received[0][name] == value
+        if name == "control":
+            assert received[0][name] is value
+
+
+def _record_stream_kwargs(graph: Any) -> list[dict[str, Any]]:
+    """Patch `graph.stream` to record the kwargs each call receives."""
+    received: list[dict[str, Any]] = []
+    original = graph.stream
+
+    def recording_stream(input: Any, config: Any = None, **kwargs: Any) -> Any:
+        received.append(kwargs)
+        yield from original(input, config, **kwargs)
+
+    graph.stream = recording_stream  # type: ignore[method-assign]
+    return received
+
+
+def _drive_stream_events_v3(graph: Any, config: dict[str, Any], **kwargs: Any) -> None:
+    """Consume a sync v3 stream_events run to completion."""
+    run = graph.stream_events({"message": "hi"}, config, version="v3", **kwargs)
+    list(run.values)
+
+
+class TestStreamEventsV3SyncKwargsDefaults:
+    """Sync v3 keeps its since-inception explicit-default semantics (#7519).
+
+    Mirror of `TestAstreamV3KwargsDefaults`: omitted
+    `interrupt_before`/`interrupt_after`/`control` are supplied to `stream`
+    as `None`; passed values are forwarded as-is. Pins the sync helper
+    against a kwargs-only "simplification" that would change subclass
+    default handling.
+    """
+
+    def test_omitted_values_arrive_as_none(self) -> None:
+        graph = _build_two_step_graph()
+        received = _record_stream_kwargs(graph)
+        _drive_stream_events_v3(graph, {"configurable": {"thread_id": "s-rec"}})
+        assert len(received) == 1
+        assert received[0]["control"] is None
+        assert received[0]["interrupt_before"] is None
+        assert received[0]["interrupt_after"] is None
+
+    @pytest.mark.parametrize("name", _KWARG_NAMES)
+    def test_passed_values_reach_stream(self, name: str) -> None:
+        graph = _build_two_step_graph()
+        received = _record_stream_kwargs(graph)
+        value: Any = RunControl() if name == "control" else ["second"]
+        _drive_stream_events_v3(
+            graph, {"configurable": {"thread_id": "s-rec-2"}}, **{name: value}
+        )
+        assert len(received) == 1
+        assert received[0][name] == value
+        if name == "control":
+            assert received[0][name] is value

libs/langgraph/uv.lock

@@ -1217,6 +1217,20 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/38/64/285f20a31679bf547b75602702f7800e74dbabae36ef324f716c02804753/jupyter-1.1.1-py2.py3-none-any.whl", hash = "sha256:7a59533c22af65439b24bbe60373a4e95af8f16ac65a6c00820ad378e3f7cc83", size = 2657, upload-time = "2024-08-30T07:15:47.045Z" },
 ]
 
+[[package]]
+name = "jupyter-builder"
+version = "1.2.3"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "jupyter-core" },
+    { name = "tomli", marker = "python_full_version < '3.11'" },
+    { name = "traitlets" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/75/3e/56f593e6a664cd14d441724654ce8243f3cac7d3e45867cf084749c8bc75/jupyter_builder-1.2.3.tar.gz", hash = "sha256:01aba6794eb9b19e0e29ae21137ca60ba4135c70347d4b9f664a586822b8c809", size = 1024218, upload-time = "2026-09-04T18:54:09.411Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/84/aa/be79e87c50698673f196d0633fc1664607da2289f9688d1de7a1c9db9e71/jupyter_builder-1.2.3-py3-none-any.whl", hash = "sha256:c5ea5a7190c2a7b082494abade98eece1b2b5bd5dbd7d610606cbcd10a1d08b3", size = 947541, upload-time = "2026-09-04T18:54:07.644Z" },
+]
+
 [[package]]
 name = "jupyter-client"
 version = "8.8.0"
@@ -1342,28 +1356,28 @@ wheels = [
 
 [[package]]
 name = "jupyterlab"
-version = "4.5.10"
+version = "4.6.4"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "async-lru" },
     { name = "httpx" },
     { name = "ipykernel" },
     { name = "jinja2" },
+    { name = "jupyter-builder" },
     { name = "jupyter-core" },
     { name = "jupyter-lsp" },
     { name = "jupyter-server" },
     { name = "jupyterlab-server" },
     { name = "notebook-shim" },
     { name = "packaging" },
-    { name = "setuptools" },
     { name = "tomli", marker = "python_full_version < '3.11'" },
     { name = "tornado" },
     { name = "traitlets" },
     { name = "typing-extensions", marker = "python_full_version < '3.12'" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/74/24/621aa20ec0d2fe72f52095bda0fc1be7738ac21aabe4129ff623140d5cdf/jupyterlab-4.5.10.tar.gz", hash = "sha256:77e8d80b78be59b2eaba2154562e21caa6e79c2f1281d6f486584f7144ee2f47", size = 23998879, upload-time = "2026-07-21T12:43:27.324Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/33/8d/995cc142f6083346b35e7d3eadc5a6717ee89ce64ea53577010ac493bc3c/jupyterlab-4.6.4.tar.gz", hash = "sha256:404f49b081819378524886c9db66dba57a5565981eff885830df1baba3a17df5", size = 28335647, upload-time = "2026-09-21T15:25:18.779Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/9f/c9/940f95f17ee4e413ad252bf8d4f2ee9a341f18cfeda87775fef3d7847321/jupyterlab-4.5.10-py3-none-any.whl", hash = "sha256:5967ca61e692e67a2f30b5a2b901c941dc6ce56c0b0e357bc6d34fed5ec095f6", size = 12452502, upload-time = "2026-07-21T12:43:23.542Z" },
+    { url = "https://files.pythonhosted.org/packages/3b/e4/072bc0d3c6d45d414062a06af7ee81c02a2c12d769c358ec9919f9995ffd/jupyterlab-4.6.4-py3-none-any.whl", hash = "sha256:15b13f991d3985129c797eb84d9949eeb8b6615e14b444868e642411f2c418b2", size = 17171596, upload-time = "2026-09-21T15:25:14.123Z" },
 ]
 
 [[package]]
@@ -1623,7 +1637,7 @@ wheels = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "4.2.0"
+version = "4.3.0"
 source = { editable = "../checkpoint" }
 dependencies = [
     { name = "langchain-core" },
@@ -2146,18 +2160,19 @@ wheels = [
 
 [[package]]
 name = "notebook"
-version = "7.5.7"
+version = "7.6.3"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
+    { name = "jupyter-builder" },
     { name = "jupyter-server" },
     { name = "jupyterlab" },
     { name = "jupyterlab-server" },
     { name = "notebook-shim" },
     { name = "tornado" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/3e/c4/f71f8716f2903e9e817a47f534b9fd84831e155e2acb32c26691c8e06243/notebook-7.5.7.tar.gz", hash = "sha256:d6d59288a25303b25e1dcb71e9b017ec3a785f7d92f38b9bc288ca1970d5b0a8", size = 14171612, upload-time = "2026-06-04T18:33:45.224Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/42/ac/aedb759dc683dcd129f6c75271bab5eb23020b0f7969163c726343718e1e/notebook-7.6.3.tar.gz", hash = "sha256:e2c08e469c0ae20bb0b3214f0ab77e79653317a2f8e5b34c10361c66874a5b50", size = 5501618, upload-time = "2026-09-21T18:07:24.261Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/e1/4d/b3347f7073a377273531efe4ffc738fc910e93718fd2838c7ebf6736c6af/notebook-7.5.7-py3-none-any.whl", hash = "sha256:1f95f79d117e47d20b5555b5c85a397d2cfecf136978aaab767cf0314b09165b", size = 14583767, upload-time = "2026-06-04T18:33:40.987Z" },
+    { url = "https://files.pythonhosted.org/packages/a1/f7/907b98438cf00bdc4e296570058f29a347214bb42338a48e3b7eae58ae2a/notebook-7.6.3-py3-none-any.whl", hash = "sha256:ad7e0eb765fba836cd4a2ab0c7a3a26cde1d91665fbf6f533b6ae7b2de6d88d2", size = 5548452, upload-time = "2026-09-21T18:07:21.563Z" },
 ]
 
 [[package]]

libs/prebuilt/langgraph/prebuilt/tool_node.py

@@ -99,6 +99,14 @@ if TYPE_CHECKING:
     from langgraph.runtime import Runtime
     from pydantic_core import ErrorDetails
 
+try:
+    from langgraph.errors import is_invalid_resume
+except ImportError:  # `langgraph` before `is_invalid_resume` never marks resume errors
+
+    def is_invalid_resume(error: BaseException) -> bool:
+        return False
+
+
 # right now we use a dict as the default, can change this to AgentState, but depends
 # on if this lives in LangChain or LangGraph... ideally would have some typed
 # messages key
@@ -957,6 +965,11 @@ class ToolNode(RunnableCallable):
             try:
                 response = tool.invoke(call_args, config)
             except ValidationError as exc:
+                if is_invalid_resume(exc):
+                    # An `interrupt()` in this tool, or in a graph it ran, got a resume
+                    # value that doesn't match its `response_schema`. That's not a bad
+                    # tool argument: fail the run so the interrupt can be answered again.
+                    raise
                 # Filter out errors for injected arguments
                 injected = self._injected_args.get(call["name"])
                 filtered_errors = _filter_validation_errors(exc, injected)
@@ -982,6 +995,10 @@ class ToolNode(RunnableCallable):
         except GraphBubbleUp:
             raise
         except Exception as e:
+            # The model can't fix a resume value that doesn't match an interrupt's
+            # `response_schema`, so no `handle_tool_errors` setting handles it.
+            if is_invalid_resume(e):
+                raise
             # Determine which exception types are handled
             handled_types: tuple[type[Exception], ...]
             if isinstance(self._handle_tool_errors, type) and issubclass(
@@ -1053,9 +1070,13 @@ class ToolNode(RunnableCallable):
         # Call wrapper with request and execute callable
         try:
             return self._wrap_tool_call(tool_request, execute)
+        except GraphBubbleUp:
+            # Interrupts always propagate, as they do without a wrapper.
+            raise
         except Exception as e:
-            # Wrapper threw an exception
-            if not self._handle_tool_errors:
+            # Wrapper threw an exception. The model can't fix a resume value that
+            # doesn't match an interrupt's `response_schema`, so it's never handled.
+            if not self._handle_tool_errors or is_invalid_resume(e):
                 raise
             # Convert to error message
             content = _handle_tool_error(e, flag=self._handle_tool_errors)
@@ -1104,6 +1125,11 @@ class ToolNode(RunnableCallable):
             try:
                 response = await tool.ainvoke(call_args, config)
             except ValidationError as exc:
+                if is_invalid_resume(exc):
+                    # An `interrupt()` in this tool, or in a graph it ran, got a resume
+                    # value that doesn't match its `response_schema`. That's not a bad
+                    # tool argument: fail the run so the interrupt can be answered again.
+                    raise
                 # Filter out errors for injected arguments
                 injected = self._injected_args.get(call["name"])
                 filtered_errors = _filter_validation_errors(exc, injected)
@@ -1129,6 +1155,10 @@ class ToolNode(RunnableCallable):
         except GraphBubbleUp:
             raise
         except Exception as e:
+            # The model can't fix a resume value that doesn't match an interrupt's
+            # `response_schema`, so no `handle_tool_errors` setting handles it.
+            if is_invalid_resume(e):
+                raise
             # Determine which exception types are handled
             handled_types: tuple[type[Exception], ...]
             if isinstance(self._handle_tool_errors, type) and issubclass(
@@ -1208,9 +1238,13 @@ class ToolNode(RunnableCallable):
             # None check was performed above already
             self._wrap_tool_call = cast("ToolCallWrapper", self._wrap_tool_call)
             return self._wrap_tool_call(tool_request, _sync_execute)
+        except GraphBubbleUp:
+            # Interrupts always propagate, as they do without a wrapper.
+            raise
         except Exception as e:
-            # Wrapper threw an exception
-            if not self._handle_tool_errors:
+            # Wrapper threw an exception. The model can't fix a resume value that
+            # doesn't match an interrupt's `response_schema`, so it's never handled.
+            if not self._handle_tool_errors or is_invalid_resume(e):
                 raise
             # Convert to error message
             content = _handle_tool_error(e, flag=self._handle_tool_errors)

libs/prebuilt/tests/test_tool_node.py

@@ -25,6 +25,7 @@ from langchain_core.runnables.config import RunnableConfig
 from langchain_core.tools import BaseTool, InjectedToolArg, ToolException
 from langchain_core.tools import tool as dec_tool
 from langchain_core.tools.base import InjectedToolCallId
+from langgraph.checkpoint.base import BaseCheckpointSaver
 from langgraph.config import get_stream_writer
 from langgraph.errors import GraphBubbleUp, GraphInterrupt
 from langgraph.graph import START, MessagesState, StateGraph
@@ -32,8 +33,8 @@ from langgraph.graph.message import REMOVE_ALL_MESSAGES, add_messages
 from langgraph.runtime import ExecutionInfo, ServerInfo
 from langgraph.store.base import BaseStore
 from langgraph.store.memory import InMemoryStore
-from langgraph.types import Command, Send
-from pydantic import BaseModel
+from langgraph.types import Command, Send, interrupt
+from pydantic import BaseModel, ValidationError
 from pydantic.v1 import BaseModel as BaseModelV1
 from typing_extensions import TypedDict
 
@@ -626,6 +627,149 @@ def test_tool_node_node_interrupt() -> None:
             assert exc_info.value == "foo"
 
 
+class _Approval(BaseModel):
+    approved: bool
+
+
+class _AskState(TypedDict, total=False):
+    answer: str
+
+
+def _approval_graph():
+    """A graph that asks a human for approval with a typed interrupt."""
+
+    def ask(state: _AskState) -> _AskState:
+        approval = interrupt("Approve?", response_schema=_Approval)
+        return {"answer": f"approved={approval.approved}"}
+
+    return StateGraph(_AskState).add_node("ask", ask).add_edge(START, "ask").compile()
+
+
+def _ask_human_call() -> dict[str, list[AnyMessage]]:
+    call = ToolCall(name="ask_human", args={}, id="call_1")
+    return {"messages": [AIMessage("", tool_calls=[call])]}
+
+
+def _handle_any(e):  # no annotation: handles every error
+    return "handled"
+
+
+# A bad answer to an interrupt must fail the run whatever `handle_tool_errors` is,
+# including settings that cover `ValidationError` (a `ValueError`), with or without
+# a wrapper. `create_agent` always runs tools through a wrapper (its middleware).
+_TOOL_NODES = pytest.mark.parametrize(
+    ("wrapped", "handle_tool_errors"),
+    [
+        (wrapped, handler)
+        for wrapped in (False, True)
+        for handler in (None, True, (ValueError,), _handle_any)
+    ],
+    ids=[
+        f"{wrapped}-{handler}"
+        for wrapped in ("plain", "wrapped")
+        for handler in ("default", "handle_true", "handle_value_error", "untyped")
+    ],
+)
+# The interrupt either runs in a graph the tool starts (a subagent) or in the tool.
+_SHAPE = pytest.mark.parametrize("nested", [True, False], ids=["nested", "direct"])
+
+
+@_TOOL_NODES
+@_SHAPE
+def test_tool_node_reraises_invalid_resume(
+    sync_checkpointer: BaseCheckpointSaver,
+    wrapped: bool,
+    nested: bool,
+    handle_tool_errors: Any,
+) -> None:
+    asker = _approval_graph()
+
+    @dec_tool
+    def ask_human() -> str:
+        """Ask a human for approval."""
+        if nested:
+            return asker.invoke({})["answer"]
+        approval = interrupt("Approve?", response_schema=_Approval)
+        return f"approved={approval.approved}"
+
+    def pass_through(request, handler):
+        return handler(request)
+
+    errors = (
+        {} if handle_tool_errors is None else {"handle_tool_errors": handle_tool_errors}
+    )
+    graph = (
+        StateGraph(MessagesState)
+        .add_node(
+            "tools",
+            ToolNode(
+                [ask_human], wrap_tool_call=pass_through if wrapped else None, **errors
+            ),
+        )
+        .add_edge(START, "tools")
+        .compile(checkpointer=sync_checkpointer)
+    )
+    config: RunnableConfig = {"configurable": {"thread_id": "1"}}
+    [pending] = graph.invoke(_ask_human_call(), config)["__interrupt__"]
+
+    # A bad answer isn't a bad tool argument: the run fails without saving, so
+    # the same interrupt can be answered again.
+    with pytest.raises(ValidationError, match="approved"):
+        graph.invoke(Command(resume={pending.id: {"approved": "maybe"}}), config)
+    assert [i.id for i in graph.get_state(config).interrupts] == [pending.id]
+
+    result = graph.invoke(Command(resume={pending.id: {"approved": True}}), config)
+    assert result["messages"][-1].content == "approved=True"
+
+
+@_TOOL_NODES
+@_SHAPE
+async def test_tool_node_reraises_invalid_resume_async(
+    async_checkpointer: BaseCheckpointSaver,
+    wrapped: bool,
+    nested: bool,
+    handle_tool_errors: Any,
+) -> None:
+    asker = _approval_graph()
+
+    @dec_tool
+    async def ask_human() -> str:
+        """Ask a human for approval."""
+        if nested:
+            return (await asker.ainvoke({}))["answer"]
+        approval = interrupt("Approve?", response_schema=_Approval)
+        return f"approved={approval.approved}"
+
+    async def pass_through(request, handler):
+        return await handler(request)
+
+    errors = (
+        {} if handle_tool_errors is None else {"handle_tool_errors": handle_tool_errors}
+    )
+    graph = (
+        StateGraph(MessagesState)
+        .add_node(
+            "tools",
+            ToolNode(
+                [ask_human], awrap_tool_call=pass_through if wrapped else None, **errors
+            ),
+        )
+        .add_edge(START, "tools")
+        .compile(checkpointer=async_checkpointer)
+    )
+    config: RunnableConfig = {"configurable": {"thread_id": "1"}}
+    [pending] = (await graph.ainvoke(_ask_human_call(), config))["__interrupt__"]
+
+    with pytest.raises(ValidationError, match="approved"):
+        await graph.ainvoke(Command(resume={pending.id: {"approved": "maybe"}}), config)
+    state = await graph.aget_state(config)
+    assert [i.id for i in state.interrupts] == [pending.id]
+
+    resume = Command(resume={pending.id: {"approved": True}})
+    result = await graph.ainvoke(resume, config)
+    assert result["messages"][-1].content == "approved=True"
+
+
 @pytest.mark.parametrize("input_type", ["dict", "tool_calls"])
 async def test_tool_node_command(input_type: str) -> None:
 

libs/prebuilt/uv.lock

@@ -370,7 +370,7 @@ test = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "4.2.0"
+version = "4.3.0"
 source = { editable = "../checkpoint" }
 dependencies = [
     { name = "langchain-core" },

libs/sdk-py/integration/Dockerfile

@@ -22,18 +22,23 @@ RUN pip install --no-cache-dir \
     "langchain>=1.3.0" \
     "deepagents>=0.6.2"
 
-# Swap the published langgraph *core* for this monorepo's local copy, so the
-# server executes the langgraph under test rather than the latest release.
+# Swap the published langgraph *core* and *checkpoint* for this monorepo's
+# local copies, so the server executes the langgraph under test rather than the
+# latest release.
 # We keep the rest of the base image (langgraph-api, runtime, Go core server)
 # on `latest` — that still surfaces upstream regressions — but the core the
 # server runs is now the PR's, which is what lets this suite catch core
 # regressions (e.g. ensure_config / runtime changes) before they're published.
-# `--no-deps` keeps the base image's already-compatible
-# checkpoint/prebuilt/sdk; we only replace core. The local source comes from
-# the `langgraph_src` additional build context (see docker-compose.yml).
+# Checkpoint goes with core because core can need a checkpoint API from the
+# same release. `--no-deps` keeps the base image's already-compatible
+# prebuilt/sdk. The local sources come from the `checkpoint_src` and
+# `langgraph_src` additional build contexts (see docker-compose.yml).
+COPY --from=checkpoint_src pyproject.toml README.md LICENSE /opt/checkpoint-src/
+COPY --from=checkpoint_src langgraph /opt/checkpoint-src/langgraph/
 COPY --from=langgraph_src pyproject.toml README.md LICENSE /opt/langgraph-src/
 COPY --from=langgraph_src langgraph /opt/langgraph-src/langgraph/
-RUN pip install --no-cache-dir --force-reinstall --no-deps /opt/langgraph-src
+RUN pip install --no-cache-dir --force-reinstall --no-deps \
+    /opt/checkpoint-src /opt/langgraph-src
 
 # Project graphs + registration config.
 COPY graph/ /app/graph/

libs/sdk-py/integration/docker-compose.yml

@@ -38,16 +38,17 @@ services:
     # see ./Dockerfile. The base image bundles langgraph-api +
     # langgraph_runtime_postgres + langgraph_license + the Go core-server;
     # on top we add graph deps (deepagents), the graph files, and this
-    # monorepo's local langgraph *core* (so the server runs the code under
-    # test, not the released langgraph).
+    # monorepo's local langgraph *core* and *checkpoint* (so the server runs
+    # the code under test, not the released langgraph).
     build:
       context: .
       dockerfile: Dockerfile
       additional_contexts:
-        # The monorepo's local langgraph core (libs/langgraph), installed over
-        # the base image so the server runs the langgraph under test. See the
-        # Dockerfile for why.
+        # The monorepo's local langgraph core (libs/langgraph) and checkpoint
+        # (libs/checkpoint), installed over the base image so the server runs
+        # the langgraph under test. See the Dockerfile for why.
         langgraph_src: ../../langgraph
+        checkpoint_src: ../../checkpoint
     image: langgraph-v3-integration-api:local
     depends_on:
       postgres:

libs/sdk-py/langgraph_sdk/_async/stream.py

@@ -1972,7 +1972,7 @@ class AsyncThreadStream:
                 # Mark that we have observed an active run so thread.output
                 # knows a run exists (handles reattach without run.start).
                 self._run_seen = True
-            elif phase in ("completed", "failed"):
+            elif _is_root_terminal_lifecycle(event):
                 # Why: interrupts describe current-run state. Clear on terminal
                 # lifecycle so a subsequent run.respond() can't fire against a
                 # stale prior-run interrupt_id. Acquire `_interrupts_lock` so

libs/sdk-py/langgraph_sdk/_sync/stream.py

@@ -35,7 +35,11 @@ from langgraph_sdk.stream.decoders import (
     validate_interleave_channels,
 )
 from langgraph_sdk.stream.subscription import compute_union_filter, infer_channel
-from langgraph_sdk.stream.sync_controller import SyncStreamController, _SyncSubscription
+from langgraph_sdk.stream.sync_controller import (
+    SyncStreamController,
+    _is_root_terminal_lifecycle,
+    _SyncSubscription,
+)
 from langgraph_sdk.stream.transport import (
     SyncEventStreamHandle,
     SyncProtocolSseTransport,
@@ -1614,7 +1618,7 @@ class SyncThreadStream:
             phase = data.get("event") if isinstance(data, dict) else None
             if phase in ("started", "running"):
                 self._run_seen = True
-            elif phase in ("completed", "failed"):
+            elif _is_root_terminal_lifecycle(event):
                 self.interrupted = False
                 self.interrupts = []
                 run_done = self._run_done

libs/sdk-py/tests/streaming/test_lifecycle_watcher.py

@@ -15,6 +15,7 @@ from langgraph_sdk.stream.transport import EventStreamHandle, ProtocolSseTranspo
 from streaming._events import (
     input_requested_event,
     lifecycle_completed_event,
+    lifecycle_errored_event,
     lifecycle_event,
 )
 from streaming._fake_server import FakeServer, _StreamScript
@@ -115,6 +116,25 @@ async def test_terminal_lifecycle_clears_interrupts():
     assert thread.interrupts == []
 
 
+async def test_subgraph_completed_event_does_not_end_run():
+    fake = FakeServer()
+    fake.script(
+        [
+            lifecycle_completed_event(seq=0, namespace=["child:1"]),
+            lifecycle_errored_event(seq=1, error="root failed"),
+        ]
+    )
+    asgi = httpx.ASGITransport(app=fake.app)
+    async with httpx.AsyncClient(transport=asgi, base_url="http://test") as raw:
+        threads = ThreadsClient(HttpClient(raw))
+        async with threads.stream(thread_id="t-1", assistant_id="agent") as thread:
+            run_done = thread._run_done
+            assert run_done is not None
+            terminal = await asyncio.wait_for(run_done, timeout=2.0)
+    assert terminal.status == "errored", "a subgraph's completed event ended the run"
+    assert "root failed" in str(terminal.error)
+
+
 async def test_lifecycle_error_captured_for_output():
     """Lifecycle error terminal state is captured in _run_done with error set."""
     fake = FakeServer()

libs/sdk-py/tests/streaming/test_sync_thread_stream.py

@@ -27,6 +27,7 @@ from streaming._events import (
     checkpoints_event,
     custom_event,
     lifecycle_completed_event,
+    lifecycle_errored_event,
     lifecycle_event,
     lifecycle_started_event,
     message_finish_event,
@@ -475,6 +476,23 @@ def test_sync_lifecycle_watcher_reconnects_with_since_after_transport_drop():
     assert fake.stream_request_bodies[1]["since"] == 1
 
 
+def test_sync_subgraph_completed_event_does_not_end_run():
+    fake = SyncFakeServer()
+    fake.script(
+        [
+            lifecycle_completed_event(seq=1, namespace=["child:1"]),
+            lifecycle_errored_event(seq=2, error="root failed"),
+        ]
+    )
+    with httpx.Client(transport=fake.transport, base_url="http://test") as raw:
+        threads = SyncThreadsClient(SyncHttpClient(raw))
+        with threads.stream(thread_id="existing", assistant_id="agent") as thread:
+            terminal = thread._wait_for_run_done()
+
+    assert terminal.status == "errored", "a subgraph's completed event ended the run"
+    assert "root failed" in str(terminal.error)
+
+
 def test_sync_threads_stream_accepts_websocket_transport_option():
     with httpx.Client(base_url="http://test") as raw:
         threads = SyncThreadsClient(SyncHttpClient(raw))

libs/sdk-py/uv.lock

@@ -385,7 +385,7 @@ test = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "4.2.0"
+version = "4.3.0"
 source = { editable = "../checkpoint" }
 dependencies = [
     { name = "langchain-core" },