chore(deps): bump langgraph-checkpoint to 4.2.0 / postgres 3.1.2 and delete the saver patch (#5734)

* chore(checkpoint): bump to checkpoint 4.2.0 and drop the stale saver patch

langgraph-checkpoint 4.2.0 fixes the write dropped after a full -> delta
migration (upstream langchain-ai/langgraph#8526) and keeps its own
InMemorySaver override, so the compatibility patch in checkpoint_patches.py
could neither detect the fix nor stand down: it read langgraph's version
while InMemorySaver ships in langgraph-checkpoint, and it would have kept
shadowing the upstream implementation on 4.2.0. The postgres release 3.1.2
locates plain-value delta seeds (upstream #8535).

- floor langgraph-checkpoint>=4.2.0,<5.0 in the harness and raise the postgres
  extra to >=3.1.2,<3.2; langgraph's own >=4.1.0 would otherwise let a
  resolver reintroduce the bug now that the patch is gone
- delete the patch, its version guard, and the three implementation-assertion
  tests; test_full_to_delta_migration_replays_on_same_thread stays as the gate
  and fails on 4.1.1 without the patch (verified by a one-off unpatch run)
- langgraph stays 1.2.9 and langgraph-checkpoint-sqlite stays 3.1.1

Verification: make lint; delta checkpointer/cache/worker-resume suites green
with the migration gate passing on memory and sqlite (postgres params skip
without TEST_POSTGRES_URI). The full make test run before the packaging-pin
fix below was 13 failed / 18523 passed; 12 of those failures reproduce on main
with the same environment (git stash baseline, identical failure sets), 7 of
them because the local config.yaml runs checkpoint_channel_mode: delta. The
remaining one, the postgres-extra string pin in tests/test_checkpointer.py, is
updated here.

Upstream status for the surrounding gaps: cache parity across off/cold/warm
states, postgres pagination (langchain-ai/langgraph#8448) and parallel-superstep
replay order (#8382) are still open upstream, as is the abandoned-branch fork
fix (#8548) that the delta resume linearization in runtime/runs/worker.py works
around, so that path stays.

* docs(changelog): keep checkpoint upgrade in Unreleased

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

CHANGELOG.md

@@ -2975,6 +2975,14 @@ This release closes that milestone with **765 merged pull requests**.
 
 ### Internal
 
+- **deps:** Raise `langgraph-checkpoint` to `>=4.2.0,<5.0` and
+  `langgraph-checkpoint-postgres` to `>=3.1.2,<3.2`, and drop the
+  `InMemorySaver` delta-history compatibility patch. Upstream 4.2.0 fixes the
+  first write dropped after a full → delta migration
+  (langchain-ai/langgraph#8526) and the postgres release locates plain-value
+  delta seeds (langchain-ai/langgraph#8535), so the dependency floor replaces
+  the patch; the full → delta migration contract test remains the gate.
+  `langgraph` and `langgraph-checkpoint-sqlite` are unchanged. ([#5734])
 - **tests:** Migrate frontend unit tests to rstest and run hook-level tests in
   a DOM environment. ([#3703], [#4453])
 - **tests:** Require explicit opt-in for live client tests. ([#4482])
@@ -4339,3 +4347,4 @@ with **180 merged pull requests** since the first 2.0 milestone tag.
 [#5578]: https://github.com/bytedance/deer-flow/pull/5578
 [#5611]: https://github.com/bytedance/deer-flow/pull/5611
 [#5673]: https://github.com/bytedance/deer-flow/pull/5673
+[#5734]: https://github.com/bytedance/deer-flow/pull/5734

CHANGELOG_zh.md

@@ -2225,6 +2225,13 @@
 
 ### 内部改进
 
+- **依赖：** `langgraph-checkpoint` 下限提升到 `>=4.2.0,<5.0`，
+  `langgraph-checkpoint-postgres` 提升到 `>=3.1.2,<3.2`，并移除
+  `InMemorySaver` delta-history 兼容补丁。上游 4.2.0 修复了 full → delta
+  迁移后首条写入丢失（langchain-ai/langgraph#8526），postgres 新版本能定位
+  plain-value delta 种子（langchain-ai/langgraph#8535），因此由依赖下限取代
+  补丁；full → delta 迁移合约测试保留为门禁。`langgraph` 与
+  `langgraph-checkpoint-sqlite` 不变。 ([#5734])
 - **测试：** 前端单元测试迁移到 rstest，并在 DOM 环境运行 hook 级测试。([#3703]、[#4453])
 - **测试：** live client 测试要求显式 opt-in。([#4482])
 - **测试：** LLM 错误测试替身不再复用共享 `FakeError`。([#4744])
@@ -3527,3 +3534,4 @@ DeerFlow 2.0 是围绕"超级智能体"框架的彻底重写，核心包含子
 [#5578]: https://github.com/bytedance/deer-flow/pull/5578
 [#5611]: https://github.com/bytedance/deer-flow/pull/5611
 [#5673]: https://github.com/bytedance/deer-flow/pull/5673
+[#5734]: https://github.com/bytedance/deer-flow/pull/5734

backend/packages/harness/deerflow/checkpoint_patches.py

@@ -6,99 +6,33 @@ imported from ``deerflow.agents.thread_state`` without pulling in the heavy
 machinery). Anchored from ``deerflow.agents.thread_state`` so every process
 that builds a DeerFlow graph (gateway, workers, in-process LangGraph
 runtime, tests) runs with the fixes in place.
+
+One patch remains: ``BinaryOperatorAggregate`` unwrapping an ``Overwrite``
+first write into an empty (MISSING) channel (#4380). The former
+``InMemorySaver`` delta-history patch was removed: upstream fixed the dropped
+first post-migration write in ``langgraph-checkpoint`` 4.2.0 (upstream #8526)
+while keeping its own override, so a behavioural probe cannot see the fix.
+The harness dependency floor (``langgraph-checkpoint>=4.2.0``) is what keeps
+that bug out, and
+``tests/test_delta_channel_checkpointers.py::test_full_to_delta_migration_replays_on_same_thread``
+is the regression gate that fails when the fix is absent. Do not re-add a
+version-guarded saver patch: the guard that used to live here read
+``langgraph``'s version, but ``InMemorySaver`` ships in the independently
+released ``langgraph-checkpoint`` distribution.
 """
 
 from __future__ import annotations
 
-import importlib.metadata
 import logging
 from collections.abc import Sequence
 from typing import Any
 
 from langgraph.channels.binop import BinaryOperatorAggregate
-from langgraph.checkpoint.base import BaseCheckpointSaver
-from langgraph.checkpoint.memory import InMemorySaver
 from langgraph.errors import ErrorCode, InvalidUpdateError, create_error_message
 from langgraph.types import Overwrite
-from packaging.version import Version
 
 logger = logging.getLogger(__name__)
 
-_PATCH_FLAG = "_deerflow_delta_history_patched"
-# The patch was authored and verified against langgraph 1.2.9
-# (langgraph/checkpoint/memory/__init__.py::InMemorySaver.get_delta_channel_history).
-# On any newer LangGraph the override must be re-inspected before keeping the
-# patch: if upstream fixed or removed it, this module must stand down.
-_PATCH_VALIDATED_LANGGRAPH_VERSION = Version("1.2.9")
-
-
-def _get_delta_channel_history_via_base(self: Any, *, config: Any, channels: Any) -> Any:
-    return BaseCheckpointSaver.get_delta_channel_history(self, config=config, channels=channels)
-
-
-async def _aget_delta_channel_history_via_base(self: Any, *, config: Any, channels: Any) -> Any:
-    return await BaseCheckpointSaver.aget_delta_channel_history(self, config=config, channels=channels)
-
-
-def _upstream_override_present() -> bool:
-    """True while InMemorySaver still ships its own (buggy) override."""
-    return (
-        getattr(InMemorySaver, "get_delta_channel_history", None) is not None
-        and InMemorySaver.get_delta_channel_history is not BaseCheckpointSaver.get_delta_channel_history
-        and InMemorySaver.aget_delta_channel_history is not BaseCheckpointSaver.aget_delta_channel_history
-    )
-
-
-def ensure_inmemory_delta_history_patch() -> None:
-    """Fix InMemorySaver dropping writes on full -> delta migrated threads.
-
-    ``InMemorySaver.get_delta_channel_history`` overrides the base walk with a
-    single-pass version that, upon reaching the first checkpoint carrying a
-    non-empty plain-value blob for a channel, skips that checkpoint's *own*
-    pending writes as "subsumed" by the blob. That is only true when the blob
-    was written by that same checkpoint. When the version was carried forward
-    from an older ancestor - exactly the first superstep after a full -> delta
-    migration, where the input write lands on a checkpoint still referencing
-    the pre-delta blob version - those pending writes postdate the blob and
-    are silently dropped: the first message appended after migration vanishes
-    from materialized state.
-
-    Both the base implementation (used by the SQLite savers) and the Postgres
-    override collect the terminating checkpoint's writes *before* treating its
-    blob as the seed, which is the correct order. This patch delegates
-    InMemorySaver to the base implementation - one ``get_tuple`` per ancestor
-    instead of a single fused walk, which is fine for dict-backed storage.
-
-    Idempotent. Guarded: stands down when the upstream override disappears or
-    the assignment fails, and warns once LangGraph moves past the validated
-    version so the patch is re-inspected instead of silently overriding an
-    upstream fix. Remove once LangGraph fixes the override upstream (no
-    upstream issue exists yet; re-check ``InMemorySaver.get_delta_channel_history``
-    on every langgraph upgrade).
-    """
-    if getattr(InMemorySaver, _PATCH_FLAG, False):
-        return
-    try:
-        langgraph_version = Version(importlib.metadata.version("langgraph"))
-    except Exception:
-        langgraph_version = _PATCH_VALIDATED_LANGGRAPH_VERSION
-    if langgraph_version > _PATCH_VALIDATED_LANGGRAPH_VERSION:
-        logger.warning(
-            "langgraph %s is newer than the version (%s) the InMemorySaver delta-history patch was validated against; re-inspect the upstream override before relying on the patch.",
-            langgraph_version,
-            _PATCH_VALIDATED_LANGGRAPH_VERSION,
-        )
-    try:
-        if not _upstream_override_present():
-            # Upstream removed its override (fixed or refactored): the base
-            # implementation is already in use, nothing to patch.
-            return
-        InMemorySaver.get_delta_channel_history = _get_delta_channel_history_via_base  # type: ignore[method-assign]
-        InMemorySaver.aget_delta_channel_history = _aget_delta_channel_history_via_base  # type: ignore[method-assign]
-        setattr(InMemorySaver, _PATCH_FLAG, True)
-    except (AttributeError, TypeError):
-        logger.warning("Failed to apply the InMemorySaver delta-history patch; leaving the upstream implementation untouched.", exc_info=True)
-
 
 _BINOP_PATCH_FLAG = "_deerflow_overwrite_first_write_patched"
 _unpatched_binop_update = BinaryOperatorAggregate.update
@@ -188,5 +122,4 @@ def ensure_binop_overwrite_first_write_patch() -> None:
         logger.warning("Failed to apply the BinaryOperatorAggregate Overwrite first-write patch; leaving the upstream implementation untouched.", exc_info=True)
 
 
-ensure_inmemory_delta_history_patch()
 ensure_binop_overwrite_first_write_patch()

backend/packages/harness/deerflow/runtime/AGENTS.md

@@ -241,7 +241,7 @@ the number of required IDs, whichever is larger; missing exact runs use targeted
 **Where things live**:
 - `runtime/checkpoint_mode.py` — mode + snapshot-frequency freeze, marker injection, delta detection, compatibility gate, both error types
 - `runtime/checkpoint_state.py` — `CheckpointStateAccessor`, `build_state_mutation_graph`, `RollbackPoint`
-- `checkpoint_patches.py` (package root) — checkpoint-machinery patches: delta-history folding for `InMemorySaver` (delegating to the base walk), stable message IDs across materialization, upstream first-write drop fix, and `BinaryOperatorAggregate` unwrapping an `Overwrite` first write into an empty (MISSING) channel — Union-typed reducer channels (`sandbox`/`goal`/`todos`/`promoted`) have no constructible default, so a replace-style write into a fresh branch thread or a never-written channel stored the wrapper literally and crashed the next consumer (#4380; probe-guarded, stands down if upstream fixes it)
+- `checkpoint_patches.py` (package root) — the one remaining patch: `BinaryOperatorAggregate` unwrapping an `Overwrite` first write into an empty channel (#4380; probe-guarded). The `InMemorySaver` delta-history patch is gone: `langgraph-checkpoint` 4.2.0 fixed that write loss upstream (#8526) while keeping its override, so the dependency floor plus the full → delta migration contract test are the gate — never re-add a version-guarded saver patch.
 - `agents/thread_state.py` — `ThreadState`/`DeltaThreadState`, `delta_messages_field` / `DELTA_MESSAGES_FIELD` (`DeltaChannel` at the configured `snapshot_frequency`, default 10), schema adaptation helpers
 - `runtime/context_compaction.py` — compaction via accessor + mutation graph (reference consumer). Runs stamp their effective agent into server-owned checkpoint metadata; manual compaction uses that binding—not request `agent_name`—for memory policy and bucket. Missing/invalid legacy bindings and unreadable agent configs fail closed by skipping the optional flush while compaction may continue with the default model; a missing pre-binding checkpoint emits a warning so the skipped write is observable.
 - `runtime/checkpoint_cache/` + `runtime/checkpointer/cached_saver.py` — delta-mode checkpoint history cache; checkpoint state reads MUST go through `CheckpointStateAccessor`, and the checkpointer may be a `CachedHistorySaver` wrapper — never rely on concrete saver types

backend/packages/harness/pyproject.toml

@@ -46,6 +46,12 @@ dependencies = [
     "ddgs>=9.10.0",
     "duckdb>=1.4.4",
     "langchain-google-genai>=4.2.1",
+    # Floor matters: the InMemorySaver delta-history patch was removed once
+    # 4.2.0 fixed the dropped first post-migration write upstream (#8526) and
+    # kept its own override, so a 4.1.x resolution would silently reintroduce
+    # the bug. langgraph's own constraint (langgraph-checkpoint>=4.1.0) does
+    # not exclude that version.
+    "langgraph-checkpoint>=4.2.0,<5.0",
     "langgraph-checkpoint-sqlite>=3.1.1,<3.2",
     "langgraph-sdk>=0.1.51",
     "sqlalchemy[asyncio]>=2.0,<3.0",
@@ -73,7 +79,9 @@ groundroute = []
 ollama = ["langchain-ollama>=0.3.0"]
 postgres = [
     "asyncpg>=0.29",
-    "langgraph-checkpoint-postgres>=3.1.1,<3.2",
+    # 3.1.2 finds plain-value delta seeds (upstream #8535); 3.1.1 walks past
+    # them to the thread root instead.
+    "langgraph-checkpoint-postgres>=3.1.2,<3.2",
     "psycopg[binary]>=3.3.3",
     "psycopg-pool>=3.3.0",
 ]

backend/tests/test_checkpointer.py

@@ -208,7 +208,7 @@ class TestHarnessPackaging:
         assert "postgres" in optional_dependencies
         assert optional_dependencies["postgres"] == [
             "asyncpg>=0.29",
-            "langgraph-checkpoint-postgres>=3.1.1,<3.2",
+            "langgraph-checkpoint-postgres>=3.1.2,<3.2",
             "psycopg[binary]>=3.3.3",
             "psycopg-pool>=3.3.0",
         ]

backend/tests/test_delta_channel_checkpointers.py

@@ -318,54 +318,3 @@ async def test_non_delta_writers_preserve_delta_messages_and_markers(saver_env:
     assert checkpoint_tuple_uses_delta(latest_tuple)
     assert latest_tuple.metadata.get(CHECKPOINT_MODE_METADATA_KEY) == "delta"
     assert latest_tuple.metadata.get("run_durations", {}).get("run-1") == 7
-
-
-# ---------------------------------------------------------------------------
-# InMemorySaver delta-history patch guards (deerflow.checkpoint_patches)
-# ---------------------------------------------------------------------------
-
-
-def test_inmemory_delta_history_patch_is_active() -> None:
-    """The compatibility patch must be applied in every test/app process."""
-    from langgraph.checkpoint.memory import InMemorySaver
-
-    from deerflow import checkpoint_patches
-
-    assert getattr(InMemorySaver, checkpoint_patches._PATCH_FLAG, False) is True
-    assert InMemorySaver.get_delta_channel_history is checkpoint_patches._get_delta_channel_history_via_base
-    assert InMemorySaver.aget_delta_channel_history is checkpoint_patches._aget_delta_channel_history_via_base
-
-
-def test_inmemory_delta_history_patch_stands_down_without_upstream_override(monkeypatch) -> None:
-    """If upstream removes its (buggy) override, the patch must not reinstall."""
-    from langgraph.checkpoint.memory import InMemorySaver
-
-    from deerflow import checkpoint_patches
-
-    monkeypatch.setattr(checkpoint_patches, "_upstream_override_present", lambda: False)
-    monkeypatch.delattr(InMemorySaver, checkpoint_patches._PATCH_FLAG, raising=False)
-    sentinel = object()
-    monkeypatch.setattr(InMemorySaver, "get_delta_channel_history", sentinel)
-
-    checkpoint_patches.ensure_inmemory_delta_history_patch()
-
-    assert getattr(InMemorySaver, checkpoint_patches._PATCH_FLAG, False) is False
-    assert InMemorySaver.get_delta_channel_history is sentinel
-
-
-def test_inmemory_delta_history_patch_warns_on_unvalidated_langgraph(monkeypatch, caplog) -> None:
-    """A langgraph newer than the validated version must log a re-inspection warning."""
-    import logging
-
-    from langgraph.checkpoint.memory import InMemorySaver
-
-    from deerflow import checkpoint_patches
-
-    monkeypatch.setattr(checkpoint_patches.importlib.metadata, "version", lambda _name: "99.0.0")
-    monkeypatch.setattr(checkpoint_patches, "_upstream_override_present", lambda: False)
-    monkeypatch.delattr(InMemorySaver, checkpoint_patches._PATCH_FLAG, raising=False)
-
-    with caplog.at_level(logging.WARNING, logger=checkpoint_patches.__name__):
-        checkpoint_patches.ensure_inmemory_delta_history_patch()
-
-    assert any("newer than the version" in record.message for record in caplog.records)

backend/uv.lock

@@ -954,6 +954,7 @@ dependencies = [
     { name = "langfuse" },
     { name = "langgraph" },
     { name = "langgraph-api" },
+    { name = "langgraph-checkpoint" },
     { name = "langgraph-checkpoint-sqlite" },
     { name = "langgraph-cli" },
     { name = "langgraph-runtime-inmem" },
@@ -1042,7 +1043,8 @@ requires-dist = [
     { name = "langfuse", specifier = ">=3.4.1" },
     { name = "langgraph", specifier = ">=1.2.9,<1.3" },
     { name = "langgraph-api", specifier = ">=0.8.1" },
-    { name = "langgraph-checkpoint-postgres", marker = "extra == 'postgres'", specifier = ">=3.1.1,<3.2" },
+    { name = "langgraph-checkpoint", specifier = ">=4.2.0,<5.0" },
+    { name = "langgraph-checkpoint-postgres", marker = "extra == 'postgres'", specifier = ">=3.1.2,<3.2" },
     { name = "langgraph-checkpoint-sqlite", specifier = ">=3.1.1,<3.2" },
     { name = "langgraph-cli", specifier = ">=0.4.24" },
     { name = "langgraph-runtime-inmem", specifier = ">=0.30.0" },
@@ -2231,20 +2233,20 @@ wheels = [
 
 [[package]]
 name = "langgraph-checkpoint"
-version = "4.1.1"
+version = "4.2.0"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "langchain-core" },
     { name = "ormsgpack" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/83/47/886af6f886f0bff2273164a45f008694e48a96ff3cd25ff0228f2aa9480e/langgraph_checkpoint-4.1.1.tar.gz", hash = "sha256:6c2bdb530c91f91d7d9c1bd100925d0fc4f498d418c17f3587d1526279482a25", size = 184020, upload-time = "2026-05-22T16:57:38.503Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/dc/e1/089c4c9e0a2fec7f883f82ae8e6a727138d50074cfeb6644bc2d13b1019b/langgraph_checkpoint-4.2.0.tar.gz", hash = "sha256:51a593b6bee684b0818e5d6e58e28ab340c6db7794575056ce7bd1b746a84ed7", size = 180239, upload-time = "2026-08-07T20:05:03.756Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/bd/b4/71425e3e38be92611300b9cc5e46a5bf98ab23f5ea8a75b73d02a2f1413c/langgraph_checkpoint-4.1.1-py3-none-any.whl", hash = "sha256:25d29144b082827218e7bc3f1e9b0566a4bb007895cd6cc26f66a8428739f56e", size = 56212, upload-time = "2026-05-22T16:57:37.203Z" },
+    { url = "https://files.pythonhosted.org/packages/05/71/3b475f09bd57d3a5649792c66353312b4432afd843f301739dfcebd157f0/langgraph_checkpoint-4.2.0-py3-none-any.whl", hash = "sha256:0547fd228935a0b758865de3a3d6d7a2537c308895d0f9ab092ce9151b5da942", size = 56833, upload-time = "2026-08-07T20:05:02.655Z" },
 ]
 
 [[package]]
 name = "langgraph-checkpoint-postgres"
-version = "3.1.1"
+version = "3.1.2"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "langgraph-checkpoint" },
@@ -2252,9 +2254,9 @@ dependencies = [
     { name = "psycopg" },
     { name = "psycopg-pool" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/06/92/1e8959f8cd1b56e672fde3227f6fd642be85af6c5fd662d73921074aa39d/langgraph_checkpoint_postgres-3.1.1.tar.gz", hash = "sha256:d320e147ddad8c374cd546df0b52b532dd54d0541dd9fd23fc738cbd5de76f41", size = 150413, upload-time = "2026-07-30T19:15:39.014Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/9d/52/6e732f7bf702ef4918b64ea4107e7da21d4276b808f9a651fe34be9b0abe/langgraph_checkpoint_postgres-3.1.2.tar.gz", hash = "sha256:1cd404803ff895a2b79f3ac04ce92b775e6b999715f8333fce674c6d927bba95", size = 155091, upload-time = "2026-08-07T20:40:00.049Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/03/32/ba457698a48a0e18d786caa770033067049fbe36d6846f8e50f13b594b51/langgraph_checkpoint_postgres-3.1.1-py3-none-any.whl", hash = "sha256:6e353aecd8150de144fef8e51a49076f58b7d6830d4cf51392b7ad4d79832ba7", size = 50778, upload-time = "2026-07-30T19:15:37.405Z" },
+    { url = "https://files.pythonhosted.org/packages/0f/62/8899c9f4d9b97d5b3eb0c07c13cdf5f63342f15f5ef93eaf3477958df602/langgraph_checkpoint_postgres-3.1.2-py3-none-any.whl", hash = "sha256:6a7e38ef16985b54e356cba7bdaf447943aae33d5aaf290026c593bb6b4a6264", size = 52084, upload-time = "2026-08-07T20:39:58.994Z" },
 ]
 
 [[package]]