deer-flow/backend/tests/test_threads_router.py

import asyncio
import re
from contextlib import asynccontextmanager
from types import SimpleNamespace
from unittest.mock import AsyncMock, patch

import anyio
import pytest
from _router_auth_helpers import make_authed_test_app
from fastapi import FastAPI, HTTPException
from fastapi.testclient import TestClient
from langchain_core.messages import AIMessage, HumanMessage, ToolMessage
from langgraph.checkpoint.base import empty_checkpoint, uuid6
from langgraph.checkpoint.memory import InMemorySaver
from langgraph.store.memory import InMemoryStore
from langgraph.types import Overwrite

from app.gateway import services as gateway_services
from app.gateway.routers import thread_runs, threads
from deerflow.config.paths import Paths
from deerflow.persistence.engine import close_engine, get_session_factory, init_engine
from deerflow.persistence.projects import ProjectRepository
from deerflow.persistence.thread_meta import (
    PROJECT_FILTER_UNSET,
    THREAD_PINNED_METADATA_KEY,
    THREAD_PROJECT_METADATA_KEY,
    InvalidMetadataFilterError,
    ThreadMetaRepository,
    ThreadOwnershipConflictError,
)
from deerflow.persistence.thread_meta.memory import THREADS_NS, MemoryThreadMetaStore
from deerflow.runtime import ConflictError, ThreadOperationKind
from deerflow.runtime.checkpoint_state import CheckpointStateAccessor
from deerflow.runtime.user_context import reset_current_user, set_current_user

_ISO_TIMESTAMP_RE = re.compile(r"^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}")


class _PermissiveThreadMetaStore(MemoryThreadMetaStore):
    """Memory store that skips user-id filtering for router tests.

    Owner isolation is exercised separately in
    ``test_memory_thread_meta_isolation.py``. Router tests need to drive
    the FastAPI surface end-to-end with a single fixed app user, but the
    stub auth middleware in ``_router_auth_helpers`` stamps a fresh UUID
    on every request, so the production filtering would reject every
    pre-seeded record. Bypass that filter so the test can focus on the
    timestamp wire format.
    """

    async def _get_owned_record(self, thread_id, user_id, method_name):  # type: ignore[override]
        item = await self._store.aget(THREADS_NS, thread_id)
        return dict(item.value) if item is not None else None

    async def check_access(self, thread_id, user_id, *, require_existing=False):  # type: ignore[override]
        item = await self._store.aget(THREADS_NS, thread_id)
        if item is None:
            return not require_existing
        return True

    async def create(self, thread_id, *, assistant_id=None, user_id=None, display_name=None, metadata=None, project_id=None):  # type: ignore[override]
        return await super().create(thread_id, assistant_id=assistant_id, user_id=None, display_name=display_name, metadata=metadata, project_id=project_id)

    async def search(self, *, metadata=None, status=None, limit=100, offset=0, user_id=None, archived=None, project_id=PROJECT_FILTER_UNSET):  # type: ignore[override]
        return await super().search(metadata=metadata, status=status, limit=limit, offset=offset, user_id=None, archived=archived, project_id=project_id)


class _ThreadTestRunManager:
    def __init__(self):
        self.reservations: list[tuple[str, dict]] = []

    async def list_by_thread(self, _thread_id: str, *, user_id=None, limit: int = 100) -> list:
        return []

    @asynccontextmanager
    async def reserve_thread_operation(self, _thread_id: str, **_kwargs):
        self.reservations.append((_thread_id, _kwargs))
        yield


def _build_thread_app() -> tuple[FastAPI, InMemoryStore, InMemorySaver]:
    """Build a stub-authed FastAPI app wired with an in-memory ThreadMetaStore.

    The thread_store on ``app.state`` is a permissive subclass of
    ``MemoryThreadMetaStore`` so tests can drive ``/api/threads``
    end-to-end and pre-seed legacy records via the underlying BaseStore.

    Returns ``(app, store, checkpointer)`` for direct seeding/inspection.
    """
    app = make_authed_test_app()
    store = InMemoryStore()
    checkpointer = InMemorySaver()
    app.state.store = store
    app.state.checkpointer = checkpointer
    app.state.run_manager = _ThreadTestRunManager()
    app.state.thread_store = _PermissiveThreadMetaStore(store)
    app.include_router(threads.router)
    return app, store, checkpointer


def test_thread_response_excludes_internal_incarnation() -> None:
    response = threads.ThreadResponse.model_validate(
        {
            "thread_id": "thread-with-incarnation",
            "incarnation": "a" * 32,
        }
    )

    assert "incarnation" not in response.model_dump()


def test_compact_rejects_run_owned_by_another_worker(monkeypatch) -> None:
    """The HTTP guard must consult the shared store, not only local run memory."""
    from deerflow.runtime import RunManager, RunStatus
    from deerflow.runtime.runs.store.memory import MemoryRunStore

    app, _store, _checkpointer = _build_thread_app()
    run_store = MemoryRunStore()
    owner = RunManager(store=run_store, worker_id="worker-a")
    non_owner = RunManager(store=run_store, worker_id="worker-b")
    app.state.run_manager = non_owner
    monkeypatch.setattr(
        threads,
        "build_checkpoint_state_mutation_accessor",
        lambda *_args, **_kwargs: (SimpleNamespace(), None),
    )

    async def _seed_active_run() -> None:
        active = await owner.create_or_reject("thread-compact-race")
        await owner.set_status(active.run_id, RunStatus.running)

    asyncio.run(_seed_active_run())

    with TestClient(app) as client:
        created = client.post("/api/threads", json={"thread_id": "thread-compact-race"})
        assert created.status_code == 200, created.text
        response = client.post("/api/threads/thread-compact-race/compact", json={"force": True})

    assert response.status_code == 409
    assert response.json()["detail"] == "Thread has a run in flight. Compact after the run finishes."


def test_update_state_rejects_run_owned_by_another_worker(monkeypatch) -> None:
    """All out-of-run writes share the same durable thread-operation admission."""
    from deerflow.runtime import RunManager, RunStatus
    from deerflow.runtime.runs.store.memory import MemoryRunStore

    app, _store, _checkpointer = _build_thread_app()
    run_store = MemoryRunStore()
    owner = RunManager(store=run_store, worker_id="worker-a")
    app.state.run_manager = RunManager(store=run_store, worker_id="worker-b")
    accessor = SimpleNamespace(
        graph=None,
        aupdate=AsyncMock(side_effect=AssertionError("state write must not run")),
        aget=AsyncMock(),
    )
    monkeypatch.setattr(
        threads,
        "build_thread_checkpoint_state_mutation_accessor",
        AsyncMock(return_value=(accessor, {"configurable": {"thread_id": "thread-state-race"}})),
    )

    async def _seed_active_run() -> None:
        active = await owner.create_or_reject("thread-state-race")
        await owner.set_status(active.run_id, RunStatus.running)

    asyncio.run(_seed_active_run())

    with TestClient(app) as client:
        created = client.post("/api/threads", json={"thread_id": "thread-state-race"})
        assert created.status_code == 200, created.text
        response = client.post(
            "/api/threads/thread-state-race/state",
            json={"values": {"title": "must not write"}},
        )

    assert response.status_code == 409
    assert response.json()["detail"] == "Thread has a run in flight. Update state after the run finishes."
    accessor.aupdate.assert_not_awaited()


class _RawStateAccessor:
    def __init__(self, checkpointer: InMemorySaver):
        self.checkpointer = checkpointer

    @staticmethod
    def _snapshot(checkpoint_tuple, fallback_config):
        if checkpoint_tuple is None:
            return SimpleNamespace(
                values={},
                config=fallback_config,
                parent_config=None,
                metadata={},
                next=(),
                tasks=(),
                created_at=None,
            )
        checkpoint = checkpoint_tuple.checkpoint or {}
        metadata = checkpoint_tuple.metadata or {}
        return SimpleNamespace(
            values=dict(checkpoint.get("channel_values", {})),
            config=checkpoint_tuple.config,
            parent_config=checkpoint_tuple.parent_config,
            metadata=metadata,
            next=(),
            tasks=(),
            created_at=checkpoint.get("ts") or metadata.get("created_at"),
        )

    async def aget(self, config):
        checkpoint_tuple = await self.checkpointer.aget_tuple(config)
        return self._snapshot(checkpoint_tuple, config)

    async def ahistory(self, config, *, limit=None):
        snapshots = []
        async for checkpoint_tuple in self.checkpointer.alist(config, limit=limit):
            snapshots.append(self._snapshot(checkpoint_tuple, config))
        return snapshots

    async def aupdate(self, config, values, *, as_node=None):
        checkpoint_tuple = await self.checkpointer.aget_tuple(config)
        checkpoint = dict(checkpoint_tuple.checkpoint if checkpoint_tuple is not None else empty_checkpoint())
        channel_values = dict(checkpoint.get("channel_values", {}))
        channel_values.update({key: value.value if isinstance(value, Overwrite) else value for key, value in values.items()})
        checkpoint["channel_values"] = channel_values
        channel_versions = dict(checkpoint.get("channel_versions", {}))
        new_versions = {}
        for key in values:
            current_version = channel_versions.get(key)
            next_version = current_version + 1 if isinstance(current_version, int) else 1
            channel_versions[key] = next_version
            new_versions[key] = next_version
        checkpoint["channel_versions"] = channel_versions
        checkpoint["id"] = str(uuid6())
        metadata = dict(checkpoint_tuple.metadata if checkpoint_tuple is not None else {})
        metadata.update(
            {
                "source": "update",
                "step": metadata.get("step", -1) + 1,
                "writes": {as_node: values},
            }
        )
        write_config = {
            "configurable": {
                "thread_id": config["configurable"]["thread_id"],
                "checkpoint_ns": config["configurable"].get("checkpoint_ns", ""),
            }
        }
        return await self.checkpointer.aput(write_config, checkpoint, metadata, new_versions)


@pytest.fixture(autouse=True)
def _patch_checkpoint_state_builder(monkeypatch):
    def _builder(request, *, thread_id, assistant_id=None, checkpoint_id=None):
        config = {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}
        if checkpoint_id is not None:
            config["configurable"]["checkpoint_id"] = checkpoint_id
        return _RawStateAccessor(request.app.state.checkpointer), config

    def _mutation_builder(request, *, thread_id, as_node, checkpoint_id=None, state_schema=None):
        config = {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}
        if checkpoint_id is not None:
            config["configurable"]["checkpoint_id"] = checkpoint_id
        return _RawStateAccessor(request.app.state.checkpointer), config

    async def _read_boundary(request, *, thread_id, checkpoint_id=None):
        return _builder(request, thread_id=thread_id, checkpoint_id=checkpoint_id)

    async def _mutation_boundary(request, *, thread_id, as_node, checkpoint_id=None):
        return _mutation_builder(request, thread_id=thread_id, as_node=as_node, checkpoint_id=checkpoint_id)

    async def _abuild(request, *, thread_id, assistant_id=None, checkpoint_id=None):
        return _builder(request, thread_id=thread_id, assistant_id=assistant_id, checkpoint_id=checkpoint_id)

    monkeypatch.setattr(threads, "abuild_checkpoint_state_accessor", _abuild)
    monkeypatch.setattr(threads, "build_checkpoint_state_mutation_accessor", _mutation_builder)
    monkeypatch.setattr(threads, "build_thread_checkpoint_state_accessor", _read_boundary)
    monkeypatch.setattr(threads, "build_thread_checkpoint_state_mutation_accessor", _mutation_boundary)
    monkeypatch.setattr(thread_runs, "build_thread_checkpoint_state_accessor", _read_boundary)


class _FakeStateAccessor:
    def __init__(self, snapshot: SimpleNamespace):
        self.snapshot = snapshot

    async def aget(self, config):
        return self.snapshot

    async def ahistory(self, config, *, limit=None):
        return [self.snapshot][:limit]


def _materialized_snapshot() -> SimpleNamespace:
    return SimpleNamespace(
        values={
            "messages": [
                HumanMessage(id="h1", content="question"),
                AIMessage(id="a1", content="answer"),
            ]
        },
        config={
            "configurable": {
                "thread_id": "thread-1",
                "checkpoint_ns": "",
                "checkpoint_id": "ckpt-2",
            }
        },
        parent_config={"configurable": {"checkpoint_id": "ckpt-1"}},
        metadata={"step": 2},
        next=(),
        tasks=(),
        created_at=None,
    )


async def _write_checkpoint(
    checkpointer: InMemorySaver,
    thread_id: str,
    checkpoint_id: str,
    messages: list[object],
    *,
    step: int,
    metadata: dict | None = None,
    parent_config: dict | None = None,
) -> dict:
    checkpoint = empty_checkpoint()
    checkpoint["id"] = checkpoint_id
    checkpoint["channel_values"] = {"messages": messages}
    checkpoint["channel_versions"] = {"messages": step}
    checkpoint_metadata = {
        "step": step,
        "source": "loop",
        "writes": {"test": {"messages": messages}},
        "parents": {},
        "created_at": f"2026-07-05T00:00:0{step}+00:00",
    }
    checkpoint_metadata.update(metadata or {})
    return await checkpointer.aput(
        parent_config or {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}},
        checkpoint,
        checkpoint_metadata,
        {"messages": step},
    )


def test_delete_thread_data_removes_thread_directory(tmp_path):
    paths = Paths(tmp_path)
    thread_dir = paths.thread_dir("thread-cleanup")
    workspace = paths.sandbox_work_dir("thread-cleanup")
    uploads = paths.sandbox_uploads_dir("thread-cleanup")
    outputs = paths.sandbox_outputs_dir("thread-cleanup")

    for directory in [workspace, uploads, outputs]:
        directory.mkdir(parents=True, exist_ok=True)
    (workspace / "notes.txt").write_text("hello", encoding="utf-8")
    (uploads / "report.pdf").write_bytes(b"pdf")
    (outputs / "result.json").write_text("{}", encoding="utf-8")

    assert thread_dir.exists()

    response = threads._delete_thread_data("thread-cleanup", paths=paths)

    assert response.success is True
    assert not thread_dir.exists()


def test_delete_thread_data_is_idempotent_for_missing_directory(tmp_path):
    paths = Paths(tmp_path)

    response = threads._delete_thread_data("missing-thread", paths=paths)

    assert response.success is True
    assert not paths.thread_dir("missing-thread").exists()


def test_delete_thread_data_rejects_invalid_thread_id(tmp_path):
    paths = Paths(tmp_path)

    with pytest.raises(HTTPException) as exc_info:
        threads._delete_thread_data("../escape", paths=paths)

    assert exc_info.value.status_code == 422
    assert "Invalid thread_id" in exc_info.value.detail


def test_delete_thread_route_cleans_thread_directory(tmp_path):
    from deerflow.runtime.user_context import get_effective_user_id

    paths = Paths(tmp_path)
    user_id = get_effective_user_id()
    thread_dir = paths.thread_dir("thread-route", user_id=user_id)
    paths.sandbox_work_dir("thread-route", user_id=user_id).mkdir(parents=True, exist_ok=True)
    (paths.sandbox_work_dir("thread-route", user_id=user_id) / "notes.txt").write_text("hello", encoding="utf-8")

    app = make_authed_test_app()
    app.state.run_manager = _ThreadTestRunManager()
    app.include_router(threads.router)

    with patch("app.gateway.routers.threads.get_paths", return_value=paths):
        with TestClient(app) as client:
            response = client.delete("/api/threads/thread-route")

    assert response.status_code == 200
    assert response.json() == {"success": True, "message": "Deleted local thread data for thread-route"}
    assert not thread_dir.exists()


def test_delete_thread_route_closes_browser_session(tmp_path):
    """Deleting a thread tears down its live browser session so a later caller
    who reuses the id cannot inherit the retained page/cookies."""
    paths = Paths(tmp_path)

    app = make_authed_test_app()
    app.state.run_manager = _ThreadTestRunManager()
    app.include_router(threads.router)

    manager = SimpleNamespace(close_session=AsyncMock(return_value=True))
    with (
        patch("app.gateway.routers.threads.get_paths", return_value=paths),
        patch(
            "deerflow.community.browser_automation.get_browser_session_manager",
            return_value=manager,
        ),
    ):
        with TestClient(app) as client:
            response = client.delete("/api/threads/thread-browser")

    assert response.status_code == 200
    manager.close_session.assert_awaited_once_with("thread-browser")


def test_delete_thread_route_rejects_invalid_thread_id(tmp_path):
    paths = Paths(tmp_path)

    app = make_authed_test_app()
    app.include_router(threads.router)

    with patch("app.gateway.routers.threads.get_paths", return_value=paths):
        with TestClient(app) as client:
            response = client.delete("/api/threads/../escape")

    assert response.status_code == 404


def test_delete_thread_route_cleans_legacy_metadata_without_resolving_unsafe_path():
    app, store, _checkpointer = _build_thread_app()
    legacy_thread_id = "legacy.thread"

    asyncio.run(
        store.aput(
            THREADS_NS,
            legacy_thread_id,
            {
                "thread_id": legacy_thread_id,
                "status": "idle",
                "created_at": "",
                "updated_at": "",
                "metadata": {},
            },
        )
    )

    with (
        patch(
            "app.gateway.routers.threads._delete_thread_data",
            side_effect=AssertionError("legacy thread ID must not reach filesystem cleanup"),
        ),
        TestClient(app) as client,
    ):
        response = client.delete(f"/api/threads/{legacy_thread_id}")

    assert response.status_code == 200
    assert "Skipped local data cleanup" in response.json()["message"]
    assert asyncio.run(store.aget(THREADS_NS, legacy_thread_id)) is None


def test_delete_thread_route_reserves_exclusive_thread_operation():
    app, store, _checkpointer = _build_thread_app()
    asyncio.run(
        store.aput(
            THREADS_NS,
            "thread-delete-reservation",
            {
                "thread_id": "thread-delete-reservation",
                "status": "idle",
                "created_at": "",
                "updated_at": "",
                "metadata": {},
            },
        )
    )

    with TestClient(app) as client:
        response = client.delete("/api/threads/thread-delete-reservation")

    assert response.status_code == 200
    assert len(app.state.run_manager.reservations) == 1
    reserved_user_id = app.state.run_manager.reservations[0][1]["user_id"]
    assert app.state.run_manager.reservations == [
        (
            "thread-delete-reservation",
            {
                "kind": ThreadOperationKind.delete,
                "user_id": reserved_user_id,
            },
        )
    ]
    assert reserved_user_id is not None


def test_delete_thread_route_rejects_active_thread_operation_without_deleting_metadata():
    class RejectingRunManager(_ThreadTestRunManager):
        @asynccontextmanager
        async def reserve_thread_operation(self, _thread_id: str, **_kwargs):
            raise ConflictError("Thread already has active work")
            yield  # pragma: no cover - required by asynccontextmanager

    app, store, _checkpointer = _build_thread_app()
    app.state.run_manager = RejectingRunManager()
    asyncio.run(
        store.aput(
            THREADS_NS,
            "thread-active-delete",
            {
                "thread_id": "thread-active-delete",
                "status": "idle",
                "created_at": "",
                "updated_at": "",
                "metadata": {},
            },
        )
    )

    with TestClient(app) as client:
        response = client.delete("/api/threads/thread-active-delete")

    assert response.status_code == 409
    assert asyncio.run(store.aget(THREADS_NS, "thread-active-delete")) is not None


def test_branch_thread_route_rejects_concurrent_source_operation_without_creating_child():
    class RejectingRunManager(_ThreadTestRunManager):
        @asynccontextmanager
        async def reserve_thread_operation(self, _thread_id: str, **_kwargs):
            raise ConflictError("Thread already has active work")
            yield  # pragma: no cover - required by asynccontextmanager

    app, store, _checkpointer = _build_thread_app()
    app.state.run_manager = RejectingRunManager()
    asyncio.run(
        store.aput(
            THREADS_NS,
            "thread-active-branch",
            {
                "thread_id": "thread-active-branch",
                "user_id": None,
                "status": "idle",
                "created_at": "",
                "updated_at": "",
                "metadata": {},
            },
        )
    )

    with TestClient(app) as client:
        response = client.post(
            "/api/threads/thread-active-branch/branches",
            json={"message_id": "ai-1", "message_ids": ["ai-1"]},
        )

    assert response.status_code == 409
    assert response.json()["detail"] == "Thread has work in flight. Branch it after the work finishes."
    children = asyncio.run(app.state.thread_store.search(metadata={"branch_parent_thread_id": "thread-active-branch"}, user_id=None))
    assert children == []


def test_legacy_thread_metadata_mutation_is_rejected():
    app, store, _checkpointer = _build_thread_app()
    legacy_thread_id = "legacy.thread"

    asyncio.run(
        store.aput(
            THREADS_NS,
            legacy_thread_id,
            {
                "thread_id": legacy_thread_id,
                "status": "idle",
                "created_at": "",
                "updated_at": "",
                "metadata": {"original": True},
            },
        )
    )

    with TestClient(app) as client:
        response = client.patch(
            f"/api/threads/{legacy_thread_id}",
            json={"metadata": {"mutated": True}},
        )

    assert response.status_code == 422
    record = asyncio.run(store.aget(THREADS_NS, legacy_thread_id))
    assert record is not None
    assert record.value["metadata"] == {"original": True}


def test_delete_thread_data_returns_generic_500_error(tmp_path):
    paths = Paths(tmp_path)

    with (
        patch.object(paths, "delete_thread_dir", side_effect=OSError("/secret/path")),
        patch.object(threads.logger, "exception") as log_exception,
    ):
        with pytest.raises(HTTPException) as exc_info:
            threads._delete_thread_data("thread-cleanup", paths=paths)

    assert exc_info.value.status_code == 500
    assert exc_info.value.detail == "Failed to delete local thread data."
    assert "/secret/path" not in exc_info.value.detail
    log_exception.assert_called_once_with("Failed to delete thread data for %s", "thread-cleanup")


# ── Server-reserved metadata key stripping ──────────────────────────────────


def test_strip_reserved_metadata_removes_user_id():
    """Client-supplied user_id is dropped to prevent reflection attacks."""
    out = threads._strip_reserved_metadata({"user_id": "victim-id", "title": "ok"})
    assert out == {"title": "ok"}


def test_strip_reserved_metadata_passes_through_safe_keys():
    """Non-reserved keys are preserved verbatim."""
    md = {"title": "ok", "tags": ["a", "b"], "custom": {"x": 1}}
    assert threads._strip_reserved_metadata(md) == md


def test_strip_reserved_metadata_empty_input():
    """Empty / None metadata returns same object — no crash."""
    assert threads._strip_reserved_metadata({}) == {}


def test_strip_reserved_metadata_strips_all_reserved_keys():
    out = threads._strip_reserved_metadata({"user_id": "x", "keep": "me"})
    assert out == {"keep": "me"}


# ---------------------------------------------------------------------------
# ISO 8601 timestamp contract (issue #2594)
# ---------------------------------------------------------------------------
#
# Threads endpoints document ``created_at`` / ``updated_at`` as ISO
# timestamps and that is the format LangGraph Platform uses
# (``langgraph_sdk.schema.Thread.created_at: datetime`` JSON-encodes to
# ISO 8601). The tests below pin that contract end-to-end and also
# exercise the ``coerce_iso`` healing path for legacy unix-timestamp
# records written by older Gateway versions.


def test_create_thread_returns_iso_timestamps() -> None:
    app, _store, _checkpointer = _build_thread_app()

    with TestClient(app) as client:
        response = client.post("/api/threads", json={"metadata": {}})

    assert response.status_code == 200, response.text
    body = response.json()
    assert _ISO_TIMESTAMP_RE.match(body["created_at"]), body["created_at"]
    assert _ISO_TIMESTAMP_RE.match(body["updated_at"]), body["updated_at"]
    assert body["created_at"] == body["updated_at"]


@pytest.mark.parametrize(
    "thread_id",
    ["", "thread.with.dot", "../escape", "x" * 65],
)
def test_create_thread_rejects_invalid_explicit_thread_id_before_persistence(thread_id: str) -> None:
    app, store, checkpointer = _build_thread_app()

    with TestClient(app) as client:
        response = client.post("/api/threads", json={"thread_id": thread_id})

    assert response.status_code == 422
    assert asyncio.run(store.asearch(THREADS_NS)) == []
    assert not checkpointer.storage


def test_create_thread_preserves_valid_explicit_thread_id() -> None:
    app, _store, _checkpointer = _build_thread_app()

    with TestClient(app) as client:
        response = client.post("/api/threads", json={"thread_id": "caller_thread-1"})

    assert response.status_code == 200
    assert response.json()["thread_id"] == "caller_thread-1"


def test_create_thread_returns_existing_when_insert_loses_race() -> None:
    """A concurrent create that loses the INSERT race stays idempotent.

    The idempotency ``get`` check and the ``create`` INSERT are not atomic:
    a competing request for the same ``thread_id`` can commit in between, and
    the SQL-backed store then rejects ours on the duplicate primary key. The
    endpoint documents idempotency ("returns the existing record when
    ``thread_id`` already exists"), so it must surface the now-present row
    rather than turning the integrity error into an HTTP 500.
    """
    from sqlalchemy.exc import IntegrityError

    app, store, _checkpointer = _build_thread_app()

    class _RacingThreadMetaStore(_PermissiveThreadMetaStore):
        """First create loses the race: the row is committed by a competing
        request, then our INSERT fails with an integrity violation."""

        def __init__(self, backing):
            super().__init__(backing)
            self._raised = False

        async def create(self, thread_id, *, assistant_id=None, user_id=None, display_name=None, metadata=None, project_id=None):  # type: ignore[override]
            if not self._raised:
                self._raised = True
                await super().create(
                    thread_id,
                    assistant_id=assistant_id,
                    user_id=user_id,
                    display_name=display_name,
                    metadata=metadata,
                    project_id=project_id,
                )
                raise IntegrityError(
                    "INSERT INTO threads_meta",
                    {},
                    Exception("UNIQUE constraint failed: threads_meta.thread_id"),
                )
            return await super().create(
                thread_id,
                assistant_id=assistant_id,
                user_id=user_id,
                display_name=display_name,
                metadata=metadata,
                project_id=project_id,
            )

    app.state.thread_store = _RacingThreadMetaStore(store)

    with TestClient(app) as client:
        response = client.post(
            "/api/threads",
            json={"thread_id": "race-thread", "metadata": {"k": "v"}},
        )

    assert response.status_code == 200, response.text
    body = response.json()
    assert body["thread_id"] == "race-thread"
    assert body["metadata"] == {"k": "v"}


def test_insert_race_recovery_claims_unscoped_row_for_trusted_owner() -> None:
    """The insert-race recovery mirrors the fast path's owner reconciliation.

    When a competing request commits a legacy unscoped (``user_id=None``) row
    between our idempotency read and our insert, and our insert then loses the
    duplicate-key race, a trusted internal owner must still claim the row rather
    than return it unowned — otherwise ownership of the same thread would depend
    on whether the fast path or the recovery path resolved it.
    """
    import asyncio

    from sqlalchemy.exc import IntegrityError

    from app.gateway.auth_disabled import AUTH_SOURCE_INTERNAL
    from app.gateway.internal_auth import INTERNAL_OWNER_USER_ID_HEADER_NAME, INTERNAL_SYSTEM_ROLE

    store = InMemoryStore()
    checkpointer = InMemorySaver()

    class _RacingOwnerStore(MemoryThreadMetaStore):
        """Our insert loses to a competing create that already wrote an
        unscoped row, exactly the interleaving the recovery path exists for."""

        async def create(self, thread_id, *, assistant_id=None, user_id=None, display_name=None, metadata=None, project_id=None):  # type: ignore[override]
            # The competing request commits its (owner-less) row here, then our
            # insert loses the primary-key race.
            await super().create(thread_id, user_id=None, metadata=metadata, project_id=project_id)
            raise IntegrityError(
                "INSERT INTO threads_meta",
                {},
                Exception("UNIQUE constraint failed: threads_meta.thread_id"),
            )

    thread_store = _RacingOwnerStore(store)
    request = SimpleNamespace(
        headers={INTERNAL_OWNER_USER_ID_HEADER_NAME: "owner-1"},
        state=SimpleNamespace(user=SimpleNamespace(id="default", system_role=INTERNAL_SYSTEM_ROLE), auth_source=AUTH_SOURCE_INTERNAL),
        app=SimpleNamespace(state=SimpleNamespace(checkpointer=checkpointer, thread_store=thread_store)),
    )

    async def _scenario():
        response = await threads.create_thread(
            threads.ThreadCreateRequest(thread_id="channel-thread", metadata={"k": "v"}),
            request,
        )
        owner_row = await thread_store.get("channel-thread", user_id="owner-1")
        unscoped_lookup = await thread_store.get("channel-thread", user_id=None)
        return response, owner_row, unscoped_lookup

    response, owner_row, unscoped_lookup = asyncio.run(_scenario())

    assert response.thread_id == "channel-thread"
    # Recovery claimed the legacy row for the trusted owner, same as the fast path.
    assert owner_row is not None
    assert owner_row["user_id"] == "owner-1"
    assert unscoped_lookup["user_id"] == "owner-1"


def test_fast_path_concurrent_trusted_claims_have_one_winner() -> None:
    thread_store = MemoryThreadMetaStore(InMemoryStore())

    async def _scenario():
        await thread_store.create("legacy-fast-race", user_id=None)
        owners = ("owner-a", "owner-b")
        outcomes = await asyncio.gather(
            *(
                threads._resolve_existing_thread(
                    thread_store,
                    "legacy-fast-race",
                    owner,
                    {"user_id": owner},
                )
                for owner in owners
            )
        )
        return owners, outcomes, await thread_store.get("legacy-fast-race", user_id=None)

    owners, outcomes, final_record = asyncio.run(_scenario())

    winners = [owner for owner, outcome in zip(owners, outcomes, strict=True) if outcome is not None]
    assert winners == [final_record["user_id"]]
    assert final_record["user_id"] in owners


def test_fast_path_trusted_claim_does_not_take_over_owned_row() -> None:
    thread_store = MemoryThreadMetaStore(InMemoryStore())

    async def _scenario():
        await thread_store.create("already-owned", user_id="owner-a")
        outcome = await threads._resolve_existing_thread(
            thread_store,
            "already-owned",
            "owner-b",
            {"user_id": "owner-b"},
        )
        return outcome, await thread_store.get("already-owned", user_id=None)

    outcome, final_record = asyncio.run(_scenario())

    assert outcome is None
    assert final_record["user_id"] == "owner-a"


def test_insert_race_concurrent_trusted_claims_have_one_winner() -> None:
    from sqlalchemy.exc import IntegrityError

    from app.gateway.auth_disabled import AUTH_SOURCE_INTERNAL
    from app.gateway.internal_auth import INTERNAL_OWNER_USER_ID_HEADER_NAME, INTERNAL_SYSTEM_ROLE

    class _ConcurrentInsertRaceStore(MemoryThreadMetaStore):
        def __init__(self):
            super().__init__(InMemoryStore())
            self._create_arrivals = 0
            self._create_lock = asyncio.Lock()
            self._legacy_row_committed = asyncio.Event()

        async def create(self, thread_id, *, assistant_id=None, user_id=None, display_name=None, metadata=None, project_id=None):  # type: ignore[override]
            async with self._create_lock:
                self._create_arrivals += 1
                if self._create_arrivals == 2:
                    await super().create(thread_id, user_id=None, metadata=metadata)
                    self._legacy_row_committed.set()
            await self._legacy_row_committed.wait()
            raise IntegrityError(
                "INSERT INTO threads_meta",
                {},
                Exception("UNIQUE constraint failed: threads_meta.thread_id"),
            )

    thread_store = _ConcurrentInsertRaceStore()
    checkpointer = InMemorySaver()

    def _request(owner):
        return SimpleNamespace(
            headers={INTERNAL_OWNER_USER_ID_HEADER_NAME: owner},
            state=SimpleNamespace(user=SimpleNamespace(id="default", system_role=INTERNAL_SYSTEM_ROLE), auth_source=AUTH_SOURCE_INTERNAL),
            app=SimpleNamespace(state=SimpleNamespace(checkpointer=checkpointer, thread_store=thread_store)),
        )

    async def _scenario():
        owners = ("owner-a", "owner-b")
        outcomes = await asyncio.gather(
            *(
                threads.create_thread(
                    threads.ThreadCreateRequest(thread_id="legacy-insert-race"),
                    _request(owner),
                )
                for owner in owners
            ),
            return_exceptions=True,
        )
        return owners, outcomes, await thread_store.get("legacy-insert-race", user_id=None)

    owners, outcomes, final_record = asyncio.run(_scenario())

    winners = [owner for owner, outcome in zip(owners, outcomes, strict=True) if isinstance(outcome, threads.ThreadResponse)]
    failures = [outcome for outcome in outcomes if isinstance(outcome, HTTPException)]
    assert winners == [final_record["user_id"]]
    assert final_record["user_id"] in owners
    assert len(failures) == 1
    assert failures[0].status_code == 500


def test_create_thread_maps_memory_owner_conflict_to_404() -> None:
    app, _store, _checkpointer = _build_thread_app()
    app.state.thread_store = SimpleNamespace(
        get=AsyncMock(return_value=None),
        create=AsyncMock(side_effect=ThreadOwnershipConflictError("foreign-thread")),
    )

    with TestClient(app) as client:
        response = client.post("/api/threads", json={"thread_id": "foreign-thread"})

    assert response.status_code == 404
    assert response.json()["detail"] == "Thread not found"


def test_create_thread_does_not_swallow_non_integrity_errors() -> None:
    """A non-race insert failure must surface as 500, even when a row now exists.

    The recovery path only rescues the duplicate-key ``IntegrityError`` race; an
    arbitrary failure that happens to coincide with an existing row must not be
    silently returned as a 200 (previously the broad ``except`` did exactly that).
    """
    app, store, _checkpointer = _build_thread_app()

    class _BrokenAfterWriteStore(_PermissiveThreadMetaStore):
        async def create(self, thread_id, *, assistant_id=None, user_id=None, display_name=None, metadata=None):  # type: ignore[override]
            # A row exists after this call, but the insert failed for a reason
            # unrelated to the idempotency race.
            await super().create(thread_id, metadata=metadata)
            raise RuntimeError("unexpected store failure")

    app.state.thread_store = _BrokenAfterWriteStore(store)

    with TestClient(app) as client:
        response = client.post("/api/threads", json={"thread_id": "broken-thread", "metadata": {}})

    assert response.status_code == 500, response.text


def test_put_goal_creates_missing_thread_checkpoint_and_returns_goal() -> None:
    app, _store, _checkpointer = _build_thread_app()

    with TestClient(app) as client:
        response = client.put(
            "/api/threads/goal-thread/goal",
            json={"objective": "Finish the feature and make all tests pass"},
        )
        state_response = client.get("/api/threads/goal-thread/state")

    assert response.status_code == 200, response.text
    body = response.json()
    assert body["goal"]["objective"] == "Finish the feature and make all tests pass"
    assert body["goal"]["status"] == "active"
    assert body["goal"]["continuation_count"] == 0
    assert body["goal"]["max_continuations"] == 8
    assert state_response.status_code == 200, state_response.text
    assert state_response.json()["values"]["goal"]["objective"] == "Finish the feature and make all tests pass"


def test_goal_status_and_clear_round_trip() -> None:
    app, _store, _checkpointer = _build_thread_app()

    with TestClient(app) as client:
        set_response = client.put(
            "/api/threads/goal-thread/goal",
            json={"objective": "Ship it", "max_continuations": 3},
        )
        get_response = client.get("/api/threads/goal-thread/goal")
        clear_response = client.delete("/api/threads/goal-thread/goal")
        after_clear_response = client.get("/api/threads/goal-thread/goal")
        state_response = client.get("/api/threads/goal-thread/state")

    assert set_response.status_code == 200, set_response.text
    assert get_response.status_code == 200, get_response.text
    assert get_response.json()["goal"]["objective"] == "Ship it"
    assert get_response.json()["goal"]["max_continuations"] == 3
    assert clear_response.status_code == 200, clear_response.text
    assert clear_response.json()["goal"] is None
    assert after_clear_response.status_code == 200, after_clear_response.text
    assert after_clear_response.json()["goal"] is None
    assert "goal" not in state_response.json()["values"]


def test_goal_mutations_reject_run_owned_by_another_worker() -> None:
    """PUT and DELETE goal writes share the durable thread-operation boundary."""
    from deerflow.runtime import RunManager, RunStatus
    from deerflow.runtime.runs.store.memory import MemoryRunStore

    app, _store, _checkpointer = _build_thread_app()
    run_store = MemoryRunStore()
    owner = RunManager(store=run_store, worker_id="worker-a")
    app.state.run_manager = RunManager(store=run_store, worker_id="worker-b")
    thread_id = "thread-goal-race"

    async def _seed_active_run() -> None:
        active = await owner.create_or_reject(thread_id)
        await owner.set_status(active.run_id, RunStatus.running)

    with TestClient(app) as client:
        created = client.post("/api/threads", json={"thread_id": thread_id})
        assert created.status_code == 200, created.text
        initial_goal = client.put(
            f"/api/threads/{thread_id}/goal",
            json={"objective": "Original goal"},
        )
        assert initial_goal.status_code == 200, initial_goal.text
        assert client.portal is not None
        client.portal.call(_seed_active_run)
        put_response = client.put(
            f"/api/threads/{thread_id}/goal",
            json={"objective": "Must not be written"},
        )
        delete_response = client.delete(f"/api/threads/{thread_id}/goal")
        goal_response = client.get(f"/api/threads/{thread_id}/goal")

    assert put_response.status_code == 409, put_response.text
    assert delete_response.status_code == 409, delete_response.text
    assert goal_response.status_code == 200, goal_response.text
    assert goal_response.json()["goal"]["objective"] == "Original goal"


def test_internal_owner_header_assigns_thread_to_owner() -> None:
    import asyncio

    from app.gateway.auth_disabled import AUTH_SOURCE_INTERNAL
    from app.gateway.internal_auth import INTERNAL_OWNER_USER_ID_HEADER_NAME, INTERNAL_SYSTEM_ROLE

    store = InMemoryStore()
    checkpointer = InMemorySaver()
    thread_store = MemoryThreadMetaStore(store)
    request = SimpleNamespace(
        headers={INTERNAL_OWNER_USER_ID_HEADER_NAME: "owner-1"},
        state=SimpleNamespace(user=SimpleNamespace(id="default", system_role=INTERNAL_SYSTEM_ROLE), auth_source=AUTH_SOURCE_INTERNAL),
        app=SimpleNamespace(state=SimpleNamespace(checkpointer=checkpointer, thread_store=thread_store)),
    )

    async def _scenario():
        response = await threads.create_thread(
            threads.ThreadCreateRequest(thread_id="channel-thread", metadata={}),
            request,
        )
        owner_row = await thread_store.get("channel-thread", user_id="owner-1")
        internal_row = await thread_store.get("channel-thread", user_id="default")
        return response, owner_row, internal_row

    response, owner_row, internal_row = asyncio.run(_scenario())

    assert response.thread_id == "channel-thread"
    assert owner_row is not None
    assert owner_row["user_id"] == "owner-1"
    assert internal_row is None


def test_goal_thread_creation_uses_internal_owner_header() -> None:
    import asyncio

    from app.gateway.auth_disabled import AUTH_SOURCE_INTERNAL
    from app.gateway.internal_auth import INTERNAL_OWNER_USER_ID_HEADER_NAME, INTERNAL_SYSTEM_ROLE

    store = InMemoryStore()
    checkpointer = InMemorySaver()
    thread_store = MemoryThreadMetaStore(store)
    request = SimpleNamespace(
        headers={INTERNAL_OWNER_USER_ID_HEADER_NAME: "owner-1"},
        state=SimpleNamespace(user=SimpleNamespace(id="default", system_role=INTERNAL_SYSTEM_ROLE), auth_source=AUTH_SOURCE_INTERNAL),
        app=SimpleNamespace(state=SimpleNamespace(checkpointer=checkpointer, thread_store=thread_store)),
    )

    async def _scenario():
        await threads._ensure_thread_for_goal("channel-goal-thread", request)
        owner_row = await thread_store.get("channel-goal-thread", user_id="owner-1")
        internal_row = await thread_store.get("channel-goal-thread", user_id="default")
        owner_threads = await thread_store.search(user_id="owner-1")
        return owner_row, internal_row, owner_threads

    owner_row, internal_row, owner_threads = asyncio.run(_scenario())

    assert owner_row is not None
    assert owner_row["user_id"] == "owner-1"
    assert internal_row is None
    assert [thread["thread_id"] for thread in owner_threads] == ["channel-goal-thread"]


def test_get_thread_returns_iso_for_legacy_unix_record() -> None:
    """A thread record written by older versions stores ``time.time()``
    floats. ``get_thread`` must transparently surface them as ISO so the
    frontend's ``new Date(...)`` parser does not break.
    """
    app, store, checkpointer = _build_thread_app()

    legacy_thread_id = "legacy-thread"
    legacy_ts = "1777252410.411327"

    async def _seed() -> None:
        await store.aput(
            THREADS_NS,
            legacy_thread_id,
            {
                "thread_id": legacy_thread_id,
                "status": "idle",
                "created_at": legacy_ts,
                "updated_at": legacy_ts,
                "metadata": {},
            },
        )
        from langgraph.checkpoint.base import empty_checkpoint

        await checkpointer.aput(
            {"configurable": {"thread_id": legacy_thread_id, "checkpoint_ns": ""}},
            empty_checkpoint(),
            {"step": -1, "source": "input", "writes": None, "parents": {}},
            {},
        )

    import asyncio

    asyncio.run(_seed())

    with TestClient(app) as client:
        response = client.get(f"/api/threads/{legacy_thread_id}")

    assert response.status_code == 200, response.text
    body = response.json()
    assert _ISO_TIMESTAMP_RE.match(body["created_at"]), body["created_at"]
    assert _ISO_TIMESTAMP_RE.match(body["updated_at"]), body["updated_at"]


def test_latest_thread_readers_use_materialized_snapshot_values() -> None:
    app, store, checkpointer = _build_thread_app()
    thread_id = "thread-1"

    async def _seed() -> None:
        await store.aput(
            THREADS_NS,
            thread_id,
            {
                "thread_id": thread_id,
                "status": "idle",
                "created_at": "2026-07-18T00:00:00+00:00",
                "updated_at": "2026-07-18T00:00:00+00:00",
                "metadata": {},
            },
        )
        await checkpointer.aput(
            {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}},
            empty_checkpoint(),
            {"step": 2, "source": "loop", "writes": {}, "parents": {}},
            {},
        )

    asyncio.run(_seed())
    accessor = _FakeStateAccessor(_materialized_snapshot())
    thread_accessor = AsyncMock(return_value=(accessor, {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}))

    with (
        patch(
            "app.gateway.routers.threads.abuild_checkpoint_state_accessor",
            new=AsyncMock(return_value=(accessor, {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}})),
        ),
        patch(
            "app.gateway.routers.threads.build_thread_checkpoint_state_accessor",
            new=thread_accessor,
        ),
        TestClient(app) as client,
    ):
        thread_response = client.get(f"/api/threads/{thread_id}")
        state_response = client.get(f"/api/threads/{thread_id}/state")
        history_response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert thread_response.status_code == 200, thread_response.text
    assert state_response.status_code == 200, state_response.text
    assert history_response.status_code == 200, history_response.text
    assert [message["id"] for message in thread_response.json()["values"]["messages"]] == ["h1", "a1"]
    assert [message["id"] for message in state_response.json()["values"]["messages"]] == ["h1", "a1"]
    assert [message["id"] for message in history_response.json()[0]["values"]["messages"]] == ["h1", "a1"]
    assert [call.kwargs["thread_id"] for call in thread_accessor.await_args_list] == [thread_id, thread_id]


def test_get_thread_status_uses_raw_pending_writes_for_materialized_checkpoint() -> None:
    app, store, _checkpointer = _build_thread_app()
    thread_id = "thread-1"

    async def _seed() -> None:
        await store.aput(
            THREADS_NS,
            thread_id,
            {
                "thread_id": thread_id,
                "status": "idle",
                "created_at": "2026-07-18T00:00:00+00:00",
                "updated_at": "2026-07-18T00:00:00+00:00",
                "metadata": {},
            },
        )

    asyncio.run(_seed())
    requested_configs = []

    class _AdvancingCheckpointer:
        async def aget_tuple(self, config):
            requested_configs.append(config)
            checkpoint_id = config.get("configurable", {}).get("checkpoint_id")
            return SimpleNamespace(
                pending_writes=[] if checkpoint_id == "ckpt-2" else [("task-old", "__error__", "stale")],
            )

    app.state.checkpointer = _AdvancingCheckpointer()
    snapshot = _materialized_snapshot()
    accessor = _FakeStateAccessor(snapshot)

    with (
        patch(
            "app.gateway.routers.threads.abuild_checkpoint_state_accessor",
            new=AsyncMock(return_value=(accessor, {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}})),
        ),
        TestClient(app) as client,
    ):
        response = client.get(f"/api/threads/{thread_id}")

    assert response.status_code == 200, response.text
    assert response.json()["status"] == "idle"
    assert requested_configs == [snapshot.config]


@pytest.mark.parametrize("stored_status", ["running", "error"])
def test_get_thread_preserves_metadata_status_without_checkpoint(stored_status: str) -> None:
    app, store, _checkpointer = _build_thread_app()
    thread_id = "thread-without-checkpoint"

    async def _seed() -> None:
        await store.aput(
            THREADS_NS,
            thread_id,
            {
                "thread_id": thread_id,
                "status": stored_status,
                "created_at": "2026-07-18T00:00:00+00:00",
                "updated_at": "2026-07-18T00:00:00+00:00",
                "metadata": {},
            },
        )

    asyncio.run(_seed())
    snapshot = SimpleNamespace(
        values={},
        config={"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}},
        parent_config=None,
        metadata={},
        next=(),
        tasks=(),
        created_at=None,
    )
    accessor = _FakeStateAccessor(snapshot)

    with (
        patch(
            "app.gateway.routers.threads.abuild_checkpoint_state_accessor",
            new=AsyncMock(return_value=(accessor, snapshot.config)),
        ),
        TestClient(app) as client,
    ):
        response = client.get(f"/api/threads/{thread_id}")

    assert response.status_code == 200, response.text
    assert response.json()["status"] == stored_status


@pytest.mark.parametrize("key", [THREAD_PINNED_METADATA_KEY, "deerflow_archived"])
def test_patch_thread_pin_returns_iso_and_preserves_updated_at(key) -> None:
    """A pin/unpin PATCH must not bump ``updated_at``.

    Pinning or unpinning a chat does not represent conversation activity.
    Timestamps are still surfaced as ISO via ``coerce_iso``.
    """
    app, store, _checkpointer = _build_thread_app()
    thread_id = "patch-target"

    legacy_created = "1777000000.000000"
    legacy_updated = "1777000000.000000"

    async def _seed() -> None:
        await store.aput(
            THREADS_NS,
            thread_id,
            {
                "thread_id": thread_id,
                "status": "idle",
                "created_at": legacy_created,
                "updated_at": legacy_updated,
                "metadata": {"k": "v0"},
            },
        )

    import asyncio

    asyncio.run(_seed())

    with TestClient(app) as client:
        response = client.patch(
            f"/api/threads/{thread_id}",
            json={"metadata": {key: True}},
        )

    assert response.status_code == 200, response.text
    body = response.json()
    assert _ISO_TIMESTAMP_RE.match(body["created_at"]), body["created_at"]
    assert _ISO_TIMESTAMP_RE.match(body["updated_at"]), body["updated_at"]
    # ``touch=False`` preserves the original ``updated_at``; both timestamps
    # derive from the same legacy value, so they coerce to the same ISO string.
    assert body["updated_at"] == body["created_at"]
    assert body["metadata"] == {"k": "v0", key: True}


def test_patch_thread_non_pin_metadata_bumps_updated_at() -> None:
    """The public metadata PATCH endpoint still bumps recency by default."""
    app, store, _checkpointer = _build_thread_app()
    thread_id = "patch-target"

    legacy_created = "946684800.000000"
    legacy_updated = "946684800.000000"

    async def _seed() -> None:
        await store.aput(
            THREADS_NS,
            thread_id,
            {
                "thread_id": thread_id,
                "status": "idle",
                "created_at": legacy_created,
                "updated_at": legacy_updated,
                "metadata": {"k": "v0"},
            },
        )

    import asyncio

    asyncio.run(_seed())

    with TestClient(app) as client:
        response = client.patch(f"/api/threads/{thread_id}", json={"metadata": {"k": "v1"}})

    assert response.status_code == 200, response.text
    body = response.json()
    assert _ISO_TIMESTAMP_RE.match(body["updated_at"]), body["updated_at"]
    assert body["updated_at"] != body["created_at"]
    assert body["metadata"] == {"k": "v1"}


def test_search_threads_normalizes_legacy_unix_seconds_to_iso() -> None:
    """``MemoryThreadMetaStore`` may hold legacy ``time.time()`` floats
    written by older Gateway versions. ``/search`` must surface them as
    ISO via ``coerce_iso`` so the frontend's ``new Date(...)`` parser
    does not break.
    """
    app, store, _checkpointer = _build_thread_app()

    async def _seed() -> None:
        # Legacy unix-second float (the literal value from issue #2594).
        await store.aput(
            THREADS_NS,
            "legacy",
            {
                "thread_id": "legacy",
                "status": "idle",
                "created_at": 1777000000.0,
                "updated_at": 1777000000.0,
                "metadata": {},
            },
        )
        # Modern ISO string, slightly later.
        await store.aput(
            THREADS_NS,
            "modern",
            {
                "thread_id": "modern",
                "status": "idle",
                "created_at": "2026-04-27T00:00:00+00:00",
                "updated_at": "2026-04-27T00:00:00+00:00",
                "metadata": {},
            },
        )

    import asyncio

    asyncio.run(_seed())

    with TestClient(app) as client:
        response = client.post("/api/threads/search", json={"limit": 10})

    assert response.status_code == 200, response.text
    items = response.json()
    assert {item["thread_id"] for item in items} == {"legacy", "modern"}
    for item in items:
        assert _ISO_TIMESTAMP_RE.match(item["created_at"]), item
        assert _ISO_TIMESTAMP_RE.match(item["updated_at"]), item


def test_search_threads_returns_pinned_threads_before_newer_unpinned_threads() -> None:
    app, store, _checkpointer = _build_thread_app()

    async def _seed() -> None:
        await store.aput(
            THREADS_NS,
            "newer-unpinned",
            {
                "thread_id": "newer-unpinned",
                "status": "idle",
                "created_at": "2026-07-01T00:00:00+00:00",
                "updated_at": "2026-07-20T00:00:00+00:00",
                "metadata": {},
            },
        )
        await store.aput(
            THREADS_NS,
            "older-pinned",
            {
                "thread_id": "older-pinned",
                "status": "idle",
                "created_at": "2026-06-01T00:00:00+00:00",
                "updated_at": "2026-06-01T00:00:00+00:00",
                "metadata": {THREAD_PINNED_METADATA_KEY: True},
            },
        )

    import asyncio

    asyncio.run(_seed())

    with TestClient(app) as client:
        response = client.post("/api/threads/search", json={"limit": 1})

    assert response.status_code == 200, response.text
    assert [item["thread_id"] for item in response.json()] == ["older-pinned"]


def test_memory_thread_meta_store_writes_iso_on_create() -> None:
    """``MemoryThreadMetaStore.create`` must emit ISO so newly created
    threads serialize correctly without depending on the router's
    ``coerce_iso`` heal path.
    """
    import asyncio

    store = InMemoryStore()
    repo = MemoryThreadMetaStore(store)

    async def _scenario() -> dict:
        await repo.create("fresh", user_id=None, metadata={"a": 1})
        record = (await store.aget(THREADS_NS, "fresh")).value
        return record

    record = asyncio.run(_scenario())
    assert _ISO_TIMESTAMP_RE.match(record["created_at"]), record
    assert _ISO_TIMESTAMP_RE.match(record["updated_at"]), record


def test_get_thread_state_returns_iso_for_legacy_checkpoint_metadata() -> None:
    """Checkpoints written by older Gateway versions stored
    ``created_at`` as a unix-second float in their metadata. The
    ``/state`` endpoint must surface that value as ISO so the frontend's
    ``new Date(...)`` parser does not break — same root cause as the
    thread-record bug fixed in #2594, but on the checkpoint side.
    """
    app, _store, checkpointer = _build_thread_app()
    thread_id = "legacy-state"

    async def _seed() -> None:
        from langgraph.checkpoint.base import empty_checkpoint

        await checkpointer.aput(
            {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}},
            empty_checkpoint(),
            {"step": -1, "source": "input", "writes": None, "parents": {}, "created_at": 1777252410.411327},
            {},
        )

    import asyncio

    asyncio.run(_seed())

    with TestClient(app) as client:
        response = client.get(f"/api/threads/{thread_id}/state")

    assert response.status_code == 200, response.text
    body = response.json()
    assert _ISO_TIMESTAMP_RE.match(body["created_at"]), body["created_at"]
    assert _ISO_TIMESTAMP_RE.match(body["checkpoint"]["ts"]), body["checkpoint"]


def test_get_thread_history_returns_iso_for_legacy_checkpoint_metadata() -> None:
    """``/history`` walks ``checkpointer.alist`` and emits one entry per
    checkpoint. Each entry's ``created_at`` must come out as ISO even if
    older checkpoints stored a unix-second float in their metadata.
    """
    app, _store, checkpointer = _build_thread_app()
    thread_id = "legacy-history"

    async def _seed() -> None:
        from langgraph.checkpoint.base import empty_checkpoint

        await checkpointer.aput(
            {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}},
            empty_checkpoint(),
            {"step": -1, "source": "input", "writes": None, "parents": {}, "created_at": 1777252410.411327},
            {},
        )

    import asyncio

    asyncio.run(_seed())

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    entries = response.json()
    assert entries, "expected at least one history entry"
    for entry in entries:
        assert _ISO_TIMESTAMP_RE.match(entry["created_at"]), entry


def test_get_thread_history_associates_tool_messages_from_checkpoint_turn() -> None:
    app, _store, checkpointer = _build_thread_app()
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=AsyncMock(return_value={}))
    thread_id = "history-tool-run"
    messages = [
        HumanMessage(id="human-1", content="Use a tool", additional_kwargs={"run_id": "run-1"}),
        AIMessage(
            id="ai-1",
            content="Calling tool",
            tool_calls=[{"name": "lookup", "args": {}, "id": "call-1"}],
        ),
        ToolMessage(id="tool-1", content="result", tool_call_id="call-1"),
        AIMessage(id="ai-2", content="Done"),
    ]

    asyncio.run(
        _write_checkpoint(
            checkpointer,
            thread_id,
            "checkpoint-tool-run",
            messages,
            step=1,
            metadata={"run_durations": {"run-1": 4}},
        )
    )

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    history_messages = response.json()[0]["values"]["messages"]
    assert [message.get("run_id") for message in history_messages[1:]] == ["run-1", "run-1", "run-1"]

    # #4152: turn_duration belongs to the run, not to every AI message in it —
    # only the run's last AI message ("Done") gets stamped, not the
    # tool-calling one that precedes it.
    ai_messages = [message for message in history_messages if message["type"] == "ai"]
    assert len(ai_messages) == 2
    assert "turn_duration" not in (ai_messages[0].get("additional_kwargs") or {})
    assert ai_messages[1]["additional_kwargs"]["turn_duration"] == 4


def test_get_thread_history_fast_path_skips_runs_already_in_checkpoint_metadata() -> None:
    """A checkpoint can carry metadata for some runs but not others (e.g. the
    latest run just completed and hasn't been persisted yet). Only the
    missing run should trigger the event-store/run-manager correlation
    fallback; the already-migrated run must not re-query it."""
    app, _store, checkpointer = _build_thread_app()
    thread_id = "history-partial-migration"
    messages = [
        HumanMessage(id="human-1", content="First", additional_kwargs={"run_id": "run-migrated"}),
        AIMessage(id="ai-1", content="First answer"),
        HumanMessage(id="human-2", content="Second", additional_kwargs={"run_id": "run-pending"}),
        AIMessage(id="ai-2", content="Second answer"),
    ]
    asyncio.run(
        _write_checkpoint(
            checkpointer,
            thread_id,
            "checkpoint-partial",
            messages,
            step=1,
            metadata={
                "run_durations": {"run-migrated": 4},
                "run_message_ids": {"ai-1": "run-migrated"},
            },
        )
    )

    async def list_by_thread(_: str, *, user_id=None, limit: int = 100) -> list[SimpleNamespace]:
        return [
            SimpleNamespace(
                run_id="run-pending",
                created_at="2026-07-05T00:00:00+00:00",
                updated_at="2026-07-05T00:00:06+00:00",
            ),
        ]

    lookup_calls: list[set[str]] = []

    async def find_latest_ai_message_run_ids(thread: str, message_ids: set[str], *, user_id=None) -> dict[str, str]:
        assert thread == thread_id
        assert message_ids == {"ai-2"}
        lookup_calls.append(message_ids)
        return {}

    app.state.run_manager = SimpleNamespace(
        list_by_thread=list_by_thread,
        reserve_thread_operation=app.state.run_manager.reserve_thread_operation,
    )
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=find_latest_ai_message_run_ids)

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    history_messages = response.json()[0]["values"]["messages"]
    assert history_messages[1]["additional_kwargs"]["turn_duration"] == 4
    assert history_messages[3]["additional_kwargs"]["turn_duration"] == 6
    # The missing ID is checked once for the response and once after write
    # admission; the already migrated ID is absent from both lookups.
    assert lookup_calls == [{"ai-2"}, {"ai-2"}]


def test_get_thread_history_backfills_exact_mapping_when_durations_already_exist() -> None:
    """Duration metadata alone does not prove exact message attribution.

    A pre-#4949 checkpoint can already carry every run duration while lacking
    ``run_message_ids``.  The history read must still consult the event index;
    otherwise the synthesized human-boundary run becomes permanent.
    """
    app, _store, checkpointer = _build_thread_app()
    thread_id = "history-duration-without-attribution"
    messages = [
        HumanMessage(id="human-1", content="Question", additional_kwargs={"run_id": "boundary-run"}),
        AIMessage(id="ai-1", content="Answer"),
    ]
    asyncio.run(
        _write_checkpoint(
            checkpointer,
            thread_id,
            "00000000-0000-6000-8000-000000000010",
            messages,
            step=1,
            metadata={"run_durations": {"boundary-run": 3, "exact-run": 7}},
        )
    )

    lookup_calls: list[set[str]] = []

    async def find_latest_ai_message_run_ids(_: str, message_ids: set[str], *, user_id=None) -> dict[str, str]:
        lookup_calls.append(message_ids)
        return {"ai-1": "exact-run"}

    async def list_by_thread(_: str, *, user_id=None, limit: int = 100) -> list[SimpleNamespace]:
        return []

    app.state.run_manager = SimpleNamespace(
        list_by_thread=list_by_thread,
        reserve_thread_operation=app.state.run_manager.reserve_thread_operation,
    )
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=find_latest_ai_message_run_ids)

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    ai_message = response.json()[0]["values"]["messages"][1]
    assert ai_message["run_id"] == "exact-run"
    assert ai_message["additional_kwargs"]["turn_duration"] == 7
    assert lookup_calls == [{"ai-1"}, {"ai-1"}]

    latest = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}))
    assert latest is not None
    assert latest.metadata["run_message_ids"] == {"ai-1": "exact-run"}


def test_get_thread_history_preserves_boundary_fallback_after_complete_partial_lookup() -> None:
    """A complete lookup may legitimately find no event for old messages.

    Pre-event-store checkpoints still rely on the human turn boundary.  A
    partial result therefore corrects the IDs it can prove and preserves that
    compatibility fallback for IDs that are definitively absent.
    """
    app, _store, checkpointer = _build_thread_app()
    thread_id = "history-partial-exact-attribution"
    messages = [
        HumanMessage(id="human-1", content="First", additional_kwargs={"run_id": "boundary-1"}),
        AIMessage(id="ai-1", content="First answer"),
        HumanMessage(id="human-2", content="Second", additional_kwargs={"run_id": "boundary-2"}),
        AIMessage(id="ai-2", content="Second answer"),
    ]
    asyncio.run(_write_checkpoint(checkpointer, thread_id, "00000000-0000-6000-8000-000000000011", messages, step=1))

    lookup_calls: list[set[str]] = []

    async def find_latest_ai_message_run_ids(_: str, message_ids: set[str], *, user_id=None) -> dict[str, str]:
        lookup_calls.append(message_ids)
        if message_ids == {"ai-1", "ai-2"}:
            return {"ai-1": "exact-1"}
        assert message_ids == {"ai-2"}
        return {}

    async def list_by_thread(_: str, *, user_id=None, limit: int = 100) -> list[SimpleNamespace]:
        return [
            SimpleNamespace(
                run_id="exact-1",
                created_at="2026-07-05T00:00:00+00:00",
                updated_at="2026-07-05T00:00:07+00:00",
            ),
            SimpleNamespace(
                run_id="boundary-2",
                created_at="2026-07-05T00:00:00+00:00",
                updated_at="2026-07-05T00:00:03+00:00",
            ),
        ]

    app.state.run_manager = SimpleNamespace(
        list_by_thread=list_by_thread,
        reserve_thread_operation=app.state.run_manager.reserve_thread_operation,
    )
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=find_latest_ai_message_run_ids)

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    first_ai, second_ai = [message for message in response.json()[0]["values"]["messages"] if message["type"] == "ai"]
    assert first_ai["run_id"] == "exact-1"
    assert first_ai["additional_kwargs"]["turn_duration"] == 7
    assert second_ai["run_id"] == "boundary-2"
    assert second_ai["additional_kwargs"]["turn_duration"] == 3

    latest = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}))
    assert latest is not None
    assert latest.metadata["run_message_ids"] == {"ai-1": "exact-1", "ai-2": "boundary-2"}
    assert latest.metadata["run_durations"] == {"boundary-2": 3, "exact-1": 7}
    assert lookup_calls == [{"ai-1", "ai-2"}, {"ai-1", "ai-2"}]


def test_get_thread_history_removes_synthesized_boundary_when_exact_lookup_is_incomplete() -> None:
    """Unsafe pagination removes only attribution it cannot prove."""
    from deerflow.runtime.events.store.base import IncompleteMessageRunLookupError

    app, _store, checkpointer = _build_thread_app()
    thread_id = "history-incomplete-exact-attribution"
    messages = [
        HumanMessage(id="human-1", content="Proven question", additional_kwargs={"run_id": "proven-run"}),
        AIMessage(id="ai-1", content="Proven answer"),
        HumanMessage(id="human-2", content="Legacy question", additional_kwargs={"run_id": "boundary-run"}),
        AIMessage(id="ai-2", content="Legacy answer"),
    ]
    asyncio.run(
        _write_checkpoint(
            checkpointer,
            thread_id,
            "00000000-0000-6000-8000-000000000012",
            messages,
            step=1,
            metadata={
                "run_durations": {"proven-run": 4},
                "run_message_ids": {"ai-1": "proven-run"},
            },
        )
    )

    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=AsyncMock(side_effect=IncompleteMessageRunLookupError("Run event lookup could not form a safe backward cursor")))

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    first_ai, second_ai = [message for message in response.json()[0]["values"]["messages"] if message["type"] == "ai"]
    assert first_ai["run_id"] == "proven-run"
    assert first_ai["additional_kwargs"]["turn_duration"] == 4
    assert "run_id" not in second_ai
    assert "turn_duration" not in (second_ai.get("additional_kwargs") or {})
    assert app.state.run_manager.reservations == []


def test_get_thread_history_caches_complete_boundary_attribution() -> None:
    """A complete audit, including a negative event result, is a one-time scan."""
    app, _store, checkpointer = _build_thread_app()
    thread_id = "history-sparse-exact-attribution"
    messages = [
        HumanMessage(id="human-1", content="Question", additional_kwargs={"run_id": "boundary-run"}),
        AIMessage(id="ai-1", content="Answer"),
    ]
    asyncio.run(_write_checkpoint(checkpointer, thread_id, "00000000-0000-6000-8000-000000000013", messages, step=1))

    lookup_calls: list[set[str]] = []

    async def find_latest_ai_message_run_ids(_: str, message_ids: set[str], *, user_id=None) -> dict[str, str]:
        assert message_ids == {"ai-1"}
        lookup_calls.append(message_ids)
        return {}

    async def list_by_thread(_: str, *, user_id=None, limit: int = 100) -> list[SimpleNamespace]:
        return [
            SimpleNamespace(
                run_id="boundary-run",
                created_at="2026-07-05T00:00:00+00:00",
                updated_at="2026-07-05T00:00:03+00:00",
            )
        ]

    app.state.run_manager = SimpleNamespace(
        list_by_thread=list_by_thread,
        reserve_thread_operation=app.state.run_manager.reserve_thread_operation,
    )
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=find_latest_ai_message_run_ids)

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})
        second_response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    ai_message = response.json()[0]["values"]["messages"][1]
    assert ai_message["run_id"] == "boundary-run"
    assert ai_message["additional_kwargs"]["turn_duration"] == 3
    assert second_response.status_code == 200, second_response.text
    assert lookup_calls == [{"ai-1"}, {"ai-1"}]

    latest = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}))
    assert latest is not None
    assert latest.metadata["run_durations"] == {"boundary-run": 3}
    assert latest.metadata["run_message_ids"] == {"ai-1": "boundary-run"}


def test_get_thread_history_revalidates_boundary_fallback_after_reservation() -> None:
    """A run may flush its exact event before the metadata task is admitted.

    The foreground lookup can exhaust the event log while the run's journal is
    still buffered. If the background task acquires its checkpoint reservation
    only after that run flushes and releases the thread, persisting the earlier
    human-boundary fallback would make the temporary miss permanent.
    """
    app, _store, checkpointer = _build_thread_app()
    thread_id = "history-fallback-reservation-race"
    messages = [
        HumanMessage(
            id="human-1",
            content="Question",
            additional_kwargs={"run_id": "boundary-run"},
        ),
        AIMessage(id="ai-1", content="Answer"),
    ]
    asyncio.run(
        _write_checkpoint(
            checkpointer,
            thread_id,
            "00000000-0000-6000-8000-000000000014",
            messages,
            step=1,
        )
    )

    event_visible = False
    lookup_visibility: list[bool] = []

    async def find_latest_ai_message_run_ids(
        _: str,
        message_ids: set[str],
        *,
        user_id=None,
    ) -> dict[str, str]:
        assert message_ids == {"ai-1"}
        lookup_visibility.append(event_visible)
        return {"ai-1": "exact-run"} if event_visible else {}

    class RunManager(_ThreadTestRunManager):
        async def list_by_thread(
            self,
            _thread_id: str,
            *,
            user_id=None,
            limit: int = 100,
        ) -> list[SimpleNamespace]:
            runs = [
                SimpleNamespace(
                    run_id="boundary-run",
                    created_at="2026-07-05T00:00:00+00:00",
                    updated_at="2026-07-05T00:00:03+00:00",
                )
            ]
            if event_visible:
                runs.append(
                    SimpleNamespace(
                        run_id="exact-run",
                        created_at="2026-07-05T00:00:00+00:00",
                        updated_at="2026-07-05T00:00:07+00:00",
                    )
                )
            return runs

        @asynccontextmanager
        async def reserve_thread_operation(self, _thread_id: str, **kwargs):
            nonlocal event_visible
            self.reservations.append((_thread_id, kwargs))
            event_visible = True
            yield

    app.state.run_manager = RunManager()
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=find_latest_ai_message_run_ids)

    with TestClient(app) as client:
        response = client.post(
            f"/api/threads/{thread_id}/history",
            json={"limit": 10},
        )

    assert response.status_code == 200, response.text
    response_ai = response.json()[0]["values"]["messages"][1]
    assert response_ai["run_id"] == "boundary-run"
    assert response_ai["additional_kwargs"]["turn_duration"] == 3
    assert lookup_visibility == [False, True]

    latest = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}))
    assert latest is not None
    assert latest.metadata["run_message_ids"] == {"ai-1": "exact-run"}
    assert latest.metadata["run_durations"]["exact-run"] == 7


def test_get_thread_history_revalidates_exact_attribution_after_reservation() -> None:
    """A newer exact event must replace the foreground mapping before persistence."""
    app, _store, checkpointer = _build_thread_app()
    thread_id = "history-exact-reservation-race"
    messages = [
        HumanMessage(
            id="human-1",
            content="Question",
            additional_kwargs={"run_id": "boundary-run"},
        ),
        AIMessage(id="ai-1", content="Answer"),
    ]
    asyncio.run(
        _write_checkpoint(
            checkpointer,
            thread_id,
            "00000000-0000-6000-8000-000000000015",
            messages,
            step=1,
        )
    )

    admitted = False
    lookup_states: list[bool] = []

    async def find_latest_ai_message_run_ids(
        _: str,
        message_ids: set[str],
        *,
        user_id=None,
    ) -> dict[str, str]:
        assert message_ids == {"ai-1"}
        lookup_states.append(admitted)
        return {"ai-1": "new-run" if admitted else "old-run"}

    class RunManager(_ThreadTestRunManager):
        async def list_by_thread(
            self,
            _thread_id: str,
            *,
            user_id=None,
            limit: int = 100,
        ) -> list[SimpleNamespace]:
            runs = [
                SimpleNamespace(
                    run_id="old-run",
                    created_at="2026-07-05T00:00:00+00:00",
                    updated_at="2026-07-05T00:00:04+00:00",
                )
            ]
            if admitted:
                runs.append(
                    SimpleNamespace(
                        run_id="new-run",
                        created_at="2026-07-05T00:00:00+00:00",
                        updated_at="2026-07-05T00:00:08+00:00",
                    )
                )
            return runs

        @asynccontextmanager
        async def reserve_thread_operation(self, _thread_id: str, **kwargs):
            nonlocal admitted
            self.reservations.append((_thread_id, kwargs))
            admitted = True
            yield

    app.state.run_manager = RunManager()
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=find_latest_ai_message_run_ids)

    with TestClient(app) as client:
        response = client.post(
            f"/api/threads/{thread_id}/history",
            json={"limit": 10},
        )

    assert response.status_code == 200, response.text
    response_ai = response.json()[0]["values"]["messages"][1]
    assert response_ai["run_id"] == "old-run"
    assert response_ai["additional_kwargs"]["turn_duration"] == 4
    assert lookup_states == [False, True]

    latest = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}))
    assert latest is not None
    assert latest.metadata["run_message_ids"] == {"ai-1": "new-run"}
    assert latest.metadata["run_durations"]["new-run"] == 8


def test_get_thread_history_recomputes_duration_after_reservation() -> None:
    """A final run row must replace a stale foreground duration before persistence."""
    app, _store, checkpointer = _build_thread_app()
    thread_id = "history-duration-reservation-race"
    messages = [
        HumanMessage(
            id="human-1",
            content="Question",
            additional_kwargs={"run_id": "run-1"},
        ),
        AIMessage(id="ai-1", content="Answer"),
    ]
    asyncio.run(
        _write_checkpoint(
            checkpointer,
            thread_id,
            "00000000-0000-6000-8000-000000000016",
            messages,
            step=1,
        )
    )

    admitted = False
    lookup_states: list[bool] = []

    async def find_latest_ai_message_run_ids(
        _: str,
        message_ids: set[str],
        *,
        user_id=None,
    ) -> dict[str, str]:
        assert message_ids == {"ai-1"}
        lookup_states.append(admitted)
        return {"ai-1": "run-1"}

    class RunManager(_ThreadTestRunManager):
        async def list_by_thread(
            self,
            _thread_id: str,
            *,
            user_id=None,
            limit: int = 100,
        ) -> list[SimpleNamespace]:
            return [
                SimpleNamespace(
                    run_id="run-1",
                    created_at="2026-07-05T00:00:00+00:00",
                    updated_at=("2026-07-05T00:00:09+00:00" if admitted else "2026-07-05T00:00:03+00:00"),
                )
            ]

        @asynccontextmanager
        async def reserve_thread_operation(self, _thread_id: str, **kwargs):
            nonlocal admitted
            self.reservations.append((_thread_id, kwargs))
            admitted = True
            yield

    app.state.run_manager = RunManager()
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=find_latest_ai_message_run_ids)

    with TestClient(app) as client:
        response = client.post(
            f"/api/threads/{thread_id}/history",
            json={"limit": 10},
        )

    assert response.status_code == 200, response.text
    response_ai = response.json()[0]["values"]["messages"][1]
    assert response_ai["run_id"] == "run-1"
    assert response_ai["additional_kwargs"]["turn_duration"] == 3
    assert lookup_states == [False, True]

    latest = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}))
    assert latest is not None
    assert latest.metadata["run_message_ids"] == {"ai-1": "run-1"}
    assert latest.metadata["run_durations"]["run-1"] == 9


def test_get_thread_history_backfills_legacy_durations_with_exact_event_run_id() -> None:
    app, _store, checkpointer = _build_thread_app()
    thread_id = "legacy-history-run-id"
    messages = [
        HumanMessage(id="human-1", content="Question", additional_kwargs={"run_id": "boundary-run"}),
        AIMessage(id="ai-1", content="Answer"),
        ToolMessage(id="tool-1", content="result", tool_call_id="call-1"),
    ]
    asyncio.run(_write_checkpoint(checkpointer, thread_id, "00000000-0000-6000-8000-000000000001", messages, step=1))

    async def list_by_thread(_: str, *, user_id=None, limit: int = 100) -> list[SimpleNamespace]:
        return [
            SimpleNamespace(
                run_id="boundary-run",
                created_at="2026-07-05T00:00:00+00:00",
                updated_at="2026-07-05T00:00:03+00:00",
            ),
            SimpleNamespace(
                run_id="exact-run",
                created_at="2026-07-05T00:00:00+00:00",
                updated_at="2026-07-05T00:00:07+00:00",
            ),
        ]

    list_messages_calls: list[str] = []

    async def find_latest_ai_message_run_ids(thread: str, message_ids: set[str], *, user_id=None) -> dict[str, str]:
        assert message_ids == {"ai-1"}
        list_messages_calls.append(thread)
        return {"ai-1": "exact-run"}

    reservation_owner = app.state.run_manager
    app.state.run_manager = SimpleNamespace(
        list_by_thread=list_by_thread,
        reserve_thread_operation=reservation_owner.reserve_thread_operation,
    )
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=find_latest_ai_message_run_ids)

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})
        second_response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    entry = response.json()[0]
    history_messages = entry["values"]["messages"]
    assert history_messages[1]["run_id"] == "exact-run"
    assert history_messages[1]["additional_kwargs"]["turn_duration"] == 7
    assert history_messages[2]["run_id"] == "boundary-run"
    assert "run_durations" not in entry["metadata"]
    assert list_messages_calls == [thread_id, thread_id]
    assert len(reservation_owner.reservations) == 1
    reserved_thread_id, reservation_kwargs = reservation_owner.reservations[0]
    assert reserved_thread_id == thread_id
    assert reservation_kwargs["kind"] is ThreadOperationKind.checkpoint_write
    assert isinstance(reservation_kwargs["user_id"], str)

    assert second_response.status_code == 200, second_response.text
    second_history_messages = second_response.json()[0]["values"]["messages"]
    assert second_history_messages[1]["run_id"] == "exact-run"
    assert second_history_messages[1]["additional_kwargs"]["turn_duration"] == 7

    latest = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}))
    assert latest is not None
    assert latest.metadata["run_durations"] == {"exact-run": 7}
    assert latest.metadata["run_message_ids"] == {"ai-1": "exact-run"}


def test_get_thread_history_finds_ai_event_beyond_ten_thousand_newer_events() -> None:
    """#4949: no arbitrary page cap may turn an old exact run into a boundary run."""
    from deerflow.runtime.events.store.memory import MemoryRunEventStore

    app, _store, checkpointer = _build_thread_app()
    thread_id = "legacy-history-run-id-paginated"
    messages = [
        HumanMessage(id="human-1", content="Question", additional_kwargs={"run_id": "boundary-run"}),
        AIMessage(id="ai-1", content="Answer"),
    ]
    asyncio.run(_write_checkpoint(checkpointer, thread_id, "00000000-0000-6000-8000-000000000002", messages, step=1))

    async def list_by_thread(_: str, *, user_id=None, limit: int = 100) -> list[SimpleNamespace]:
        return [
            SimpleNamespace(
                run_id="boundary-run",
                created_at="2026-07-05T00:00:00+00:00",
                updated_at="2026-07-05T00:00:03+00:00",
            ),
            SimpleNamespace(
                run_id="exact-run",
                created_at="2026-07-05T00:00:00+00:00",
                updated_at="2026-07-05T00:00:07+00:00",
            ),
        ]

    event_store = MemoryRunEventStore()
    events = [
        {
            "thread_id": thread_id,
            "run_id": "exact-run",
            "event_type": "llm.ai.response",
            "category": "message",
            "content": {"type": "ai", "id": "ai-1"},
        },
        *[
            {
                "thread_id": thread_id,
                "run_id": "noise-run",
                "event_type": "llm.ai.response",
                "category": "message",
                "content": {"type": "ai", "id": f"noise-{index}"},
            }
            for index in range(10_000)
        ],
    ]
    asyncio.run(event_store.put_batch(events))
    event_store.find_latest_ai_message_run_ids = AsyncMock(wraps=event_store.find_latest_ai_message_run_ids)

    app.state.run_manager = SimpleNamespace(
        list_by_thread=list_by_thread,
        reserve_thread_operation=app.state.run_manager.reserve_thread_operation,
    )
    app.state.run_event_store = event_store

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    history_messages = response.json()[0]["values"]["messages"]
    assert history_messages[1]["run_id"] == "exact-run"
    assert history_messages[1]["additional_kwargs"]["turn_duration"] == 7
    assert event_store.find_latest_ai_message_run_ids.await_count == 2


def test_get_thread_history_sizes_initial_run_page_to_required_attributions() -> None:
    """A long thread should batch-hydrate its common migration path."""
    app, _store, checkpointer = _build_thread_app()
    thread_id = "legacy-history-run-page-sizing"
    run_count = 101
    messages = []
    runs = []
    message_run_ids: dict[str, str] = {}
    for index in range(run_count):
        boundary_run_id = f"boundary-{index}"
        exact_run_id = f"exact-{index}"
        message_id = f"ai-{index}"
        messages.extend(
            [
                HumanMessage(id=f"human-{index}", content=f"Question {index}", additional_kwargs={"run_id": boundary_run_id}),
                AIMessage(id=message_id, content=f"Answer {index}"),
            ]
        )
        message_run_ids[message_id] = exact_run_id
        runs.append(
            SimpleNamespace(
                run_id=exact_run_id,
                created_at="2026-07-05T00:00:00+00:00",
                updated_at="2026-07-05T00:00:05+00:00",
            )
        )

    asyncio.run(_write_checkpoint(checkpointer, thread_id, "00000000-0000-6000-8000-000000000020", messages, step=1))

    list_limits: list[int] = []

    async def list_by_thread(_: str, *, user_id=None, limit: int = 100) -> list[SimpleNamespace]:
        list_limits.append(limit)
        return runs[:limit]

    async def get(run_id: str, *, user_id=None) -> SimpleNamespace | None:
        return next((run for run in runs if run.run_id == run_id), None)

    get_mock = AsyncMock(side_effect=get)

    async def find_latest_ai_message_run_ids(_: str, message_ids: set[str], *, user_id=None) -> dict[str, str]:
        assert message_ids == set(message_run_ids)
        return message_run_ids

    app.state.run_manager = SimpleNamespace(
        list_by_thread=list_by_thread,
        get=get_mock,
        reserve_thread_operation=app.state.run_manager.reserve_thread_operation,
    )
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=find_latest_ai_message_run_ids)

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    ai_messages = [message for message in response.json()[0]["values"]["messages"] if message["type"] == "ai"]
    assert len(ai_messages) == run_count
    assert ai_messages[-1]["additional_kwargs"]["turn_duration"] == 5
    assert list_limits == [run_count, run_count]
    get_mock.assert_not_awaited()


def test_get_thread_history_fetches_exact_run_older_than_default_run_page() -> None:
    """The event index may resolve a run outside RunManager's newest-100 page."""
    app, _store, checkpointer = _build_thread_app()
    thread_id = "legacy-history-old-exact-run"
    messages = [
        HumanMessage(id="human-1", content="Question", additional_kwargs={"run_id": "boundary-run"}),
        AIMessage(id="ai-1", content="Answer"),
    ]
    asyncio.run(_write_checkpoint(checkpointer, thread_id, "00000000-0000-6000-8000-000000000003", messages, step=1))

    boundary_run = SimpleNamespace(
        run_id="boundary-run",
        created_at="2026-07-05T00:00:00+00:00",
        updated_at="2026-07-05T00:00:03+00:00",
    )
    exact_run = SimpleNamespace(
        run_id="old-exact-run",
        created_at="2026-06-01T00:00:00+00:00",
        updated_at="2026-06-01T00:00:09+00:00",
    )
    get_calls: list[str] = []

    async def list_by_thread(_: str, *, user_id=None, limit: int = 100) -> list[SimpleNamespace]:
        assert limit == 100
        return [boundary_run]

    async def get(run_id: str, *, user_id=None) -> SimpleNamespace | None:
        get_calls.append(run_id)
        return exact_run if run_id == exact_run.run_id else None

    async def find_latest_ai_message_run_ids(_: str, message_ids: set[str], *, user_id=None) -> dict[str, str]:
        assert message_ids == {"ai-1"}
        return {"ai-1": exact_run.run_id}

    app.state.run_manager = SimpleNamespace(
        list_by_thread=list_by_thread,
        get=get,
        reserve_thread_operation=app.state.run_manager.reserve_thread_operation,
    )
    app.state.run_event_store = SimpleNamespace(find_latest_ai_message_run_ids=find_latest_ai_message_run_ids)

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    history_messages = response.json()[0]["values"]["messages"]
    assert history_messages[1]["run_id"] == exact_run.run_id
    assert history_messages[1]["additional_kwargs"]["turn_duration"] == 9
    assert get_calls == [exact_run.run_id, exact_run.run_id]


def test_get_thread_history_injects_turn_duration_once_per_run() -> None:
    """#4152: ``/history`` replays checkpoint messages on reload, so it must
    stamp ``turn_duration`` the same way the message endpoints do — once per
    run, on that run's last AI message — even when a run produced several AI
    messages."""
    from unittest.mock import AsyncMock, MagicMock

    from deerflow.runtime import RunRecord

    def _run(run_id: str, seconds: int) -> RunRecord:
        return RunRecord(
            run_id=run_id,
            thread_id="history-durations",
            assistant_id=None,
            status="success",
            on_disconnect="cancel",
            created_at="2026-06-20T10:00:00Z",
            updated_at=f"2026-06-20T10:00:{seconds:02d}Z",
        )

    app, _store, checkpointer = _build_thread_app()
    thread_id = "history-durations"

    messages = [
        HumanMessage(id="human-1", content="Hello", additional_kwargs={"run_id": "run-1"}),
        AIMessage(id="ai-1a", content="Before tools"),
        AIMessage(id="ai-1b", content="Final answer"),
        HumanMessage(id="human-2", content="Again", additional_kwargs={"run_id": "run-2"}),
        AIMessage(id="ai-2", content="Second answer"),
    ]
    asyncio.run(_write_checkpoint(checkpointer, thread_id, "0001", messages, step=1))

    run_manager = AsyncMock()
    run_manager.list_by_thread = AsyncMock(return_value=[_run("run-1", 5), _run("run-2", 9)])
    run_manager.reserve_thread_operation = _ThreadTestRunManager().reserve_thread_operation
    event_store = MagicMock()
    event_store.find_latest_ai_message_run_ids = AsyncMock(return_value={})
    app.state.run_manager = run_manager
    app.state.run_event_store = event_store

    with TestClient(app) as client:
        response = client.post(f"/api/threads/{thread_id}/history", json={"limit": 10})

    assert response.status_code == 200, response.text
    replayed = response.json()[0]["values"]["messages"]

    assert "turn_duration" not in (replayed[0].get("additional_kwargs") or {})
    assert "turn_duration" not in (replayed[1].get("additional_kwargs") or {})
    assert replayed[2]["additional_kwargs"]["turn_duration"] == 5
    assert "turn_duration" not in (replayed[3].get("additional_kwargs") or {})
    assert replayed[4]["additional_kwargs"]["turn_duration"] == 9


# ── branch threads from completed assistant turns ─────────────────────────────


def test_branch_thread_can_prepare_regenerate_without_branch_run_events() -> None:
    app, _store, checkpointer = _build_thread_app()
    app.include_router(thread_runs.router)
    source_thread_id = "source-regenerate"
    source_run_id = "source-run"

    async def list_messages(_thread_id: str, *, limit: int, **_kwargs) -> list[dict]:
        assert limit == thread_runs.REGENERATE_HISTORY_SCAN_LIMIT
        return []

    async def list_by_thread(_thread_id: str, *, user_id=None, limit: int = 100) -> list:
        return []

    app.state.run_event_store = SimpleNamespace(list_messages=list_messages)
    app.state.run_manager.list_by_thread = list_by_thread

    human = HumanMessage(id="human-1", content="Question", additional_kwargs={"run_id": source_run_id})
    ai = AIMessage(id="ai-1", content="Answer")

    with TestClient(app) as client:
        created = client.post("/api/threads", json={"thread_id": source_thread_id, "metadata": {}})
        assert created.status_code == 200, created.text

        initial = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}}))
        assert initial is not None
        after_human = asyncio.run(
            _write_checkpoint(
                checkpointer,
                source_thread_id,
                str(uuid6()),
                [human],
                step=1,
                parent_config=initial.config,
            )
        )
        asyncio.run(
            _write_checkpoint(
                checkpointer,
                source_thread_id,
                str(uuid6()),
                [human, ai],
                step=2,
                parent_config=after_human,
            )
        )

        branch_response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "ai-1", "message_ids": ["ai-1"]},
        )
        assert branch_response.status_code == 200, branch_response.text
        branch_thread_id = branch_response.json()["thread_id"]

        prepare_response = client.post(
            f"/api/threads/{branch_thread_id}/runs/regenerate/prepare",
            json={"message_id": "ai-1"},
        )

    assert prepare_response.status_code == 200, prepare_response.text
    prepared = prepare_response.json()
    assert prepared["target_run_id"] == source_run_id
    branch_base_id = prepared["checkpoint"]["checkpoint_id"]
    assert prepared["input"]["messages"][0]["id"] == "human-1"
    assert prepared["input"]["messages"][0]["content"] == [{"type": "text", "text": "Question"}]

    branch_base = asyncio.run(
        checkpointer.aget_tuple(
            {
                "configurable": {
                    "thread_id": branch_thread_id,
                    "checkpoint_ns": "",
                    "checkpoint_id": branch_base_id,
                }
            }
        )
    )
    assert branch_base is not None
    assert branch_base.checkpoint.get("channel_values", {}).get("messages", []) == []


def test_branch_thread_from_older_assistant_turn_creates_truncated_thread() -> None:
    app, store, checkpointer = _build_thread_app()
    source_thread_id = "source-thread"

    human_1 = HumanMessage(id="human-1", content="First question")
    ai_1 = AIMessage(id="ai-1", content="First answer")
    human_2 = HumanMessage(id="human-2", content="Second question")
    ai_2 = AIMessage(id="ai-2", content="Second answer")
    human_3 = HumanMessage(id="human-3", content="Third question")
    ai_3 = AIMessage(id="ai-3", content="Third answer")

    async def _seed(parent_config: dict) -> dict:
        after_human_1 = await _write_checkpoint(checkpointer, source_thread_id, str(uuid6()), [human_1], step=1, parent_config=parent_config)
        after_ai_1 = await _write_checkpoint(checkpointer, source_thread_id, str(uuid6()), [human_1, ai_1], step=2, parent_config=after_human_1)
        after_human_2 = await _write_checkpoint(
            checkpointer,
            source_thread_id,
            str(uuid6()),
            [human_1, ai_1, human_2],
            step=3,
            parent_config=after_ai_1,
        )
        after_ai_2 = await _write_checkpoint(
            checkpointer,
            source_thread_id,
            str(uuid6()),
            [human_1, ai_1, human_2, ai_2],
            step=4,
            parent_config=after_human_2,
        )
        after_human_3 = await _write_checkpoint(
            checkpointer,
            source_thread_id,
            str(uuid6()),
            [human_1, ai_1, human_2, ai_2, human_3],
            step=5,
            parent_config=after_ai_2,
        )
        await _write_checkpoint(
            checkpointer,
            source_thread_id,
            str(uuid6()),
            [human_1, ai_1, human_2, ai_2, human_3, ai_3],
            step=6,
            parent_config=after_human_3,
        )
        return after_ai_2

    with TestClient(app) as client:
        created = client.post("/api/threads", json={"thread_id": source_thread_id, "metadata": {}, "assistant_id": "agent"})
        assert created.status_code == 200, created.text
        initial = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}}))
        assert initial is not None
        target_checkpoint_config = asyncio.run(_seed(initial.config))
        asyncio.run(
            store.aput(
                THREADS_NS,
                source_thread_id,
                {
                    "thread_id": source_thread_id,
                    "assistant_id": "agent",
                    "user_id": None,
                    "status": "idle",
                    "created_at": "2026-07-05T00:00:00Z",
                    "updated_at": "2026-07-05T00:00:00Z",
                    "display_name": "Original chat",
                    "metadata": {},
                },
            )
        )

        response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "ai-2", "message_ids": ["ai-2"]},
        )
        assert response.status_code == 200, response.text
        body = response.json()
        new_thread_id = body["thread_id"]
        sibling_response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "ai-2", "message_ids": ["ai-2"]},
        )
        assert sibling_response.status_code == 200, sibling_response.text
        sibling_thread_id = sibling_response.json()["thread_id"]
        explicit_collision_response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "ai-2", "message_ids": ["ai-2"], "title": "Original chat (4)"},
        )
        assert explicit_collision_response.status_code == 200, explicit_collision_response.text
        explicit_collision_thread_id = explicit_collision_response.json()["thread_id"]
        after_explicit_response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "ai-2", "message_ids": ["ai-2"]},
        )
        assert after_explicit_response.status_code == 200, after_explicit_response.text
        after_explicit_thread_id = after_explicit_response.json()["thread_id"]
        nested_response = client.post(
            f"/api/threads/{new_thread_id}/branches",
            json={"message_id": "ai-2", "message_ids": ["ai-2"]},
        )
        assert nested_response.status_code == 200, nested_response.text
        nested_thread_id = nested_response.json()["thread_id"]
        rename_response = client.post(
            f"/api/threads/{new_thread_id}/state",
            json={"values": {"title": "Report Q4"}},
        )
        assert rename_response.status_code == 200, rename_response.text
        renamed_branch_response = client.post(
            f"/api/threads/{new_thread_id}/branches",
            json={"message_id": "ai-2", "message_ids": ["ai-2"]},
        )
        assert renamed_branch_response.status_code == 200, renamed_branch_response.text
        renamed_branch_thread_id = renamed_branch_response.json()["thread_id"]
        explicit_response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "ai-2", "message_ids": ["ai-2"], "title": "Deliberate branch title"},
        )
        assert explicit_response.status_code == 200, explicit_response.text
        explicit_thread_id = explicit_response.json()["thread_id"]
        state_response = client.get(f"/api/threads/{new_thread_id}/state")
        sibling_state_response = client.get(f"/api/threads/{sibling_thread_id}/state")
        explicit_collision_state_response = client.get(f"/api/threads/{explicit_collision_thread_id}/state")
        after_explicit_state_response = client.get(f"/api/threads/{after_explicit_thread_id}/state")
        nested_state_response = client.get(f"/api/threads/{nested_thread_id}/state")
        renamed_branch_state_response = client.get(f"/api/threads/{renamed_branch_thread_id}/state")
        explicit_state_response = client.get(f"/api/threads/{explicit_thread_id}/state")
        search_response = client.post("/api/threads/search", json={"limit": 10})

    assert body["parent_thread_id"] == source_thread_id
    assert body["parent_checkpoint_id"] == target_checkpoint_config["configurable"]["checkpoint_id"]
    assert body["branched_from_message_id"] == "ai-2"
    assert body["workspace_clone_mode"] == "skipped_historical_turn"

    assert state_response.status_code == 200, state_response.text
    state_values = state_response.json()["values"]
    messages = state_values["messages"]
    assert [message["id"] for message in messages] == ["human-1", "ai-1", "human-2", "ai-2"]
    assert "Third answer" not in [message.get("content") for message in messages]
    assert state_values["title"] == "Report Q4"
    assert sibling_state_response.status_code == 200, sibling_state_response.text
    assert sibling_state_response.json()["values"]["title"] == "Original chat (3)"
    assert explicit_collision_state_response.status_code == 200, explicit_collision_state_response.text
    assert explicit_collision_state_response.json()["values"]["title"] == "Original chat (4)"
    assert after_explicit_state_response.status_code == 200, after_explicit_state_response.text
    assert after_explicit_state_response.json()["values"]["title"] == "Original chat (5)"
    assert nested_state_response.status_code == 200, nested_state_response.text
    assert nested_state_response.json()["values"]["title"] == "Original chat (3)"
    assert renamed_branch_state_response.status_code == 200, renamed_branch_state_response.text
    assert renamed_branch_state_response.json()["values"]["title"] == "Report Q4 (2)"
    assert explicit_state_response.status_code == 200, explicit_state_response.text
    assert explicit_state_response.json()["values"]["title"] == "Deliberate branch title"
    assert search_response.status_code == 200, search_response.text
    branch_entry = next(item for item in search_response.json() if item["thread_id"] == new_thread_id)
    assert branch_entry["values"]["title"] == "Report Q4"
    assert "branch_title_sequence" not in branch_entry["metadata"]
    sibling_entry = next(item for item in search_response.json() if item["thread_id"] == sibling_thread_id)
    assert sibling_entry["values"]["title"] == "Original chat (3)"
    assert sibling_entry["metadata"]["branch_title_sequence"] == 3
    explicit_collision_entry = next(item for item in search_response.json() if item["thread_id"] == explicit_collision_thread_id)
    assert explicit_collision_entry["values"]["title"] == "Original chat (4)"
    assert "branch_title_sequence" not in explicit_collision_entry["metadata"]
    after_explicit_entry = next(item for item in search_response.json() if item["thread_id"] == after_explicit_thread_id)
    assert after_explicit_entry["values"]["title"] == "Original chat (5)"
    assert after_explicit_entry["metadata"]["branch_title_sequence"] == 5
    nested_entry = next(item for item in search_response.json() if item["thread_id"] == nested_thread_id)
    assert nested_entry["values"]["title"] == "Original chat (3)"
    renamed_branch_entry = next(item for item in search_response.json() if item["thread_id"] == renamed_branch_thread_id)
    assert renamed_branch_entry["values"]["title"] == "Report Q4 (2)"
    assert renamed_branch_entry["metadata"]["branch_title_sequence"] == 2
    explicit_entry = next(item for item in search_response.json() if item["thread_id"] == explicit_thread_id)
    assert explicit_entry["values"]["title"] == "Deliberate branch title"
    assert "branch_title_sequence" not in explicit_entry["metadata"]
    branch_reservations = [reservation for reservation in app.state.run_manager.reservations if reservation[1]["kind"] == ThreadOperationKind.branch]
    assert len(branch_reservations) == 7


def test_branch_thread_uses_materialized_history_and_overwrites_fresh_seed(monkeypatch) -> None:
    app, _store, _checkpointer = _build_thread_app()
    source_thread_id = "source-materialized"
    messages = [
        HumanMessage(id="h1", content="First question"),
        AIMessage(id="a1", content="First answer"),
        HumanMessage(id="h2", content="Second question"),
        AIMessage(id="a2", content="Second answer"),
    ]

    def snapshot(checkpoint_id: str, materialized_messages: list[object], *, parent_id: str | None = None) -> SimpleNamespace:
        return SimpleNamespace(
            values={"messages": materialized_messages, "title": "Materialized title"},
            config={
                "configurable": {
                    "thread_id": source_thread_id,
                    "checkpoint_ns": "",
                    "checkpoint_id": checkpoint_id,
                }
            },
            metadata={"step": int(checkpoint_id[-1])},
            parent_config=(
                {
                    "configurable": {
                        "thread_id": source_thread_id,
                        "checkpoint_ns": "",
                        "checkpoint_id": parent_id,
                    }
                }
                if parent_id is not None
                else None
            ),
        )

    source_accessor = SimpleNamespace()
    source_history = [
        snapshot("ckpt-2", messages, parent_id="ckpt-1"),
        snapshot("ckpt-1", messages[:2], parent_id="ckpt-0"),
        snapshot("ckpt-0", []),
    ]
    branch_updates: list[tuple[dict, dict, str | None]] = []

    async def source_ahistory(config, *, limit=None):
        assert config["configurable"]["thread_id"] == source_thread_id
        assert limit == threads._BRANCH_HISTORY_RAW_SCAN_LIMIT
        return source_history

    async def source_aget(config):
        checkpoint_id = config["configurable"]["checkpoint_id"]
        return next(item for item in source_history if item.config["configurable"]["checkpoint_id"] == checkpoint_id)

    async def branch_aupdate(config, values, *, as_node=None):
        branch_updates.append((config, values, as_node))
        return {
            "configurable": {
                "thread_id": config["configurable"]["thread_id"],
                "checkpoint_ns": "",
                "checkpoint_id": f"branch-{len(branch_updates)}",
            }
        }

    source_accessor.ahistory = source_ahistory
    source_accessor.aget = source_aget
    branch_accessor = SimpleNamespace(aupdate=branch_aupdate)

    async def build_accessor(_request, *, thread_id, assistant_id=None, checkpoint_id=None):
        assert thread_id == source_thread_id
        return source_accessor, {
            "configurable": {
                "thread_id": source_thread_id,
                "checkpoint_ns": "",
            }
        }

    def build_mutation_accessor(_request, *, thread_id, as_node, checkpoint_id=None, state_schema=None):
        return branch_accessor, {
            "configurable": {
                "thread_id": thread_id,
                "checkpoint_ns": "",
            }
        }

    monkeypatch.setattr(threads, "abuild_checkpoint_state_accessor", AsyncMock(side_effect=build_accessor))
    monkeypatch.setattr(threads, "build_checkpoint_state_mutation_accessor", build_mutation_accessor)

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "metadata": {}, "assistant_id": "agent"},
        )
        assert created.status_code == 200, created.text
        response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "a1", "message_ids": ["a1"]},
        )

    assert response.status_code == 200, response.text
    body = response.json()
    assert body["parent_checkpoint_id"] == "ckpt-1"
    assert len(branch_updates) == 2
    replay_config, replay_values, replay_node = branch_updates[0]
    assert isinstance(replay_values["messages"], Overwrite)
    assert replay_values["messages"].value == []
    assert replay_config["configurable"]["thread_id"] == body["thread_id"]
    assert replay_config["metadata"]["source"] == "branch"
    assert replay_node == "branch"

    head_config, head_values, head_node = branch_updates[1]
    assert isinstance(head_values["messages"], Overwrite)
    assert [message.id for message in head_values["messages"].value] == ["h1", "a1"]
    assert head_config["configurable"]["checkpoint_id"] == "branch-1"
    assert head_config["metadata"]["source"] == "branch"
    assert head_node == "branch"


@pytest.mark.parametrize(
    ("include_replay_base", "expected_message_ids"),
    [
        (True, [[], ["h1", "a1"]]),
        (False, [["h1", "a1"]]),
    ],
    ids=["chronological-replay-base", "legacy-single-checkpoint"],
)
def test_branch_thread_preserves_unlinked_legacy_histories(
    monkeypatch,
    include_replay_base: bool,
    expected_message_ids: list[list[str]],
) -> None:
    app, _store, _checkpointer = _build_thread_app()
    source_thread_id = "source-unlinked"
    messages = [
        HumanMessage(id="h1", content="Question"),
        AIMessage(id="a1", content="Answer"),
    ]

    def snapshot(checkpoint_id: str, snapshot_messages: list[object], *, duration_only: bool = False) -> SimpleNamespace:
        return SimpleNamespace(
            values={"messages": snapshot_messages},
            config={
                "configurable": {
                    "thread_id": source_thread_id,
                    "checkpoint_ns": "",
                    "checkpoint_id": checkpoint_id,
                }
            },
            metadata={"writes": {"runtime_run_duration": 1}} if duration_only else {},
            parent_config=None,
        )

    source_history = [snapshot("ckpt-1", messages)]
    if include_replay_base:
        source_history.extend(
            [
                snapshot("ckpt-duration", [], duration_only=True),
                snapshot("ckpt-0", []),
            ]
        )

    history_limits: list[int | None] = []

    async def source_ahistory(config, *, limit=None):
        assert config["configurable"]["thread_id"] == source_thread_id
        history_limits.append(limit)
        return source_history

    async def unexpected_lineage_read(_config):
        raise AssertionError("unlinked checkpoints must use chronological history")

    branch_updates: list[dict] = []

    async def branch_aupdate(config, values, *, as_node=None):
        assert as_node == "branch"
        branch_updates.append(values)
        return {
            "configurable": {
                "thread_id": config["configurable"]["thread_id"],
                "checkpoint_ns": "",
                "checkpoint_id": f"branch-{len(branch_updates)}",
            }
        }

    source_accessor = SimpleNamespace(ahistory=source_ahistory, aget=unexpected_lineage_read)
    branch_accessor = SimpleNamespace(aupdate=branch_aupdate)

    async def build_accessor(_request, *, thread_id, assistant_id=None, checkpoint_id=None):
        assert thread_id == source_thread_id
        return source_accessor, {
            "configurable": {
                "thread_id": source_thread_id,
                "checkpoint_ns": "",
            }
        }

    def build_mutation_accessor(_request, *, thread_id, as_node, checkpoint_id=None, state_schema=None):
        return branch_accessor, {
            "configurable": {
                "thread_id": thread_id,
                "checkpoint_ns": "",
            }
        }

    monkeypatch.setattr(threads, "abuild_checkpoint_state_accessor", AsyncMock(side_effect=build_accessor))
    monkeypatch.setattr(threads, "build_checkpoint_state_mutation_accessor", build_mutation_accessor)

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "metadata": {}, "assistant_id": "agent"},
        )
        assert created.status_code == 200, created.text
        response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "a1", "message_ids": ["a1"]},
        )

    assert response.status_code == 200, response.text
    assert response.json()["parent_checkpoint_id"] == "ckpt-1"
    assert [[message.id for message in update["messages"].value] for update in branch_updates] == expected_message_ids
    assert history_limits == [
        threads._BRANCH_HISTORY_RAW_SCAN_LIMIT,
        threads._BRANCH_HISTORY_RAW_SCAN_LIMIT,
        threads._BRANCH_HISTORY_RAW_SCAN_LIMIT,
    ]


def test_branch_history_scans_budget_for_duration_only_checkpoints() -> None:
    target = SimpleNamespace(
        values={
            "messages": [
                HumanMessage(id="h1", content="Question"),
                AIMessage(id="a1", content="Answer"),
            ]
        },
        config={
            "configurable": {
                "thread_id": "source-duration-budget",
                "checkpoint_ns": "",
                "checkpoint_id": "target",
            }
        },
        metadata={},
    )
    duration_only = [
        SimpleNamespace(
            values={"messages": []},
            config={
                "configurable": {
                    "thread_id": "source-duration-budget",
                    "checkpoint_ns": "",
                    "checkpoint_id": f"duration-{index}",
                }
            },
            metadata={"writes": {"runtime_run_duration": index}},
        )
        for index in range(threads._BRANCH_HISTORY_SCAN_LIMIT)
    ]
    history = [*duration_only, target]
    limits: list[int | None] = []

    async def ahistory(_config, *, limit=None):
        limits.append(limit)
        return history[:limit]

    accessor = SimpleNamespace(ahistory=ahistory)
    config = {"configurable": {"thread_id": "source-duration-budget", "checkpoint_ns": ""}}

    found = asyncio.run(threads._find_branch_checkpoint(accessor, config, {"a1"}))
    targets_latest = asyncio.run(threads._branch_targets_latest_turn(accessor, config, {"a1"}))

    assert found is target
    assert targets_latest is True
    assert limits == [threads._BRANCH_HISTORY_RAW_SCAN_LIMIT, threads._BRANCH_HISTORY_RAW_SCAN_LIMIT]


def test_branch_thread_real_mutation_graph_finishes_without_scheduling(monkeypatch) -> None:
    app, _store, _checkpointer = _build_thread_app()
    app.state.checkpoint_channel_mode = "delta"
    source_thread_id = "source-real-branch"
    messages = [
        HumanMessage(id="h1", content="First question"),
        AIMessage(id="a1", content="First answer"),
        HumanMessage(id="h2", content="Second question"),
        AIMessage(id="a2", content="Second answer"),
    ]

    def snapshot(checkpoint_id: str, materialized_messages: list[object], *, parent_id: str | None = None) -> SimpleNamespace:
        return SimpleNamespace(
            values={"messages": materialized_messages},
            config={
                "configurable": {
                    "thread_id": source_thread_id,
                    "checkpoint_ns": "",
                    "checkpoint_id": checkpoint_id,
                }
            },
            metadata={},
            parent_config=(
                {
                    "configurable": {
                        "thread_id": source_thread_id,
                        "checkpoint_ns": "",
                        "checkpoint_id": parent_id,
                    }
                }
                if parent_id is not None
                else None
            ),
        )

    source_history = [
        snapshot("ckpt-2", messages, parent_id="ckpt-1"),
        snapshot("ckpt-1", messages[:2], parent_id="ckpt-0"),
        snapshot("ckpt-0", []),
    ]
    source_accessor = SimpleNamespace(
        ahistory=AsyncMock(return_value=source_history),
        aget=AsyncMock(side_effect=lambda config: next(item for item in source_history if item.config["configurable"]["checkpoint_id"] == config["configurable"]["checkpoint_id"])),
    )

    async def source_builder(_request, *, thread_id, assistant_id=None, checkpoint_id=None):
        if thread_id != source_thread_id:
            raise AssertionError("fresh branches must use the dedicated mutation graph")
        return source_accessor, {
            "configurable": {
                "thread_id": source_thread_id,
                "checkpoint_ns": "",
            }
        }

    real_mutation_builder = gateway_services.build_checkpoint_state_mutation_accessor
    monkeypatch.setattr(threads, "abuild_checkpoint_state_accessor", AsyncMock(side_effect=source_builder))
    monkeypatch.setattr(
        threads,
        "build_checkpoint_state_mutation_accessor",
        real_mutation_builder,
        raising=False,
    )

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "metadata": {}, "assistant_id": "agent"},
        )
        assert created.status_code == 200, created.text
        response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "a1", "message_ids": ["a1"]},
        )

    assert response.status_code == 200, response.text
    new_thread_id = response.json()["thread_id"]
    accessor, config = real_mutation_builder(
        SimpleNamespace(app=app),
        thread_id=new_thread_id,
        as_node="branch",
    )
    branch_snapshot = asyncio.run(accessor.aget(config))
    assert [message.id for message in branch_snapshot.values["messages"]] == ["h1", "a1"]
    assert branch_snapshot.next == ()
    assert branch_snapshot.metadata["deerflow_branch"] is True
    assert branch_snapshot.metadata["branch_parent_checkpoint_id"] == "ckpt-1"


def _wire_extension_agent(monkeypatch, app, checkpointer, mode):
    """Stub only the infra context + assistant factory; keep builders real.

    The production resolution path stays live: thread record -> assistant_id
    -> resolve_agent_factory -> effective graph (base schema for ``mode`` plus
    a non-identity reducer channel contributed by AgentMiddleware.state_schema).
    """
    import operator
    from typing import Annotated, NotRequired, TypedDict

    from langchain.agents import create_agent
    from langchain.agents.middleware import AgentMiddleware
    from langchain_core.language_models.fake_chat_models import FakeMessagesListChatModel

    from deerflow.agents.thread_state import get_thread_state_schema

    class ExtensionState(TypedDict):
        ext_list: NotRequired[Annotated[list[str], operator.add]]

    class ExtensionMiddleware(AgentMiddleware):
        state_schema = ExtensionState

    app.state.checkpoint_channel_mode = mode
    model = FakeMessagesListChatModel(responses=[AIMessage(content="ok")])

    def custom_factory(*, config=None):
        return create_agent(model, middleware=[ExtensionMiddleware()], state_schema=get_thread_state_schema(mode))

    def default_factory(*, config=None):
        return create_agent(model, state_schema=get_thread_state_schema(mode))

    def selective_factory(assistant_id):
        # Only the thread's recorded assistant yields the extension graph;
        # unresolved assistant_id must materialize with the default schema so
        # the tests actually guard the resolution boundary.
        return custom_factory if assistant_id == "extension-agent" else default_factory

    ctx = SimpleNamespace(checkpointer=checkpointer, store=None, checkpoint_channel_mode=mode, app_config=None)
    monkeypatch.setattr(gateway_services, "get_run_context", lambda _request: ctx)
    monkeypatch.setattr(gateway_services, "resolve_agent_factory", selective_factory)
    monkeypatch.setattr(threads, "abuild_checkpoint_state_accessor", gateway_services.abuild_checkpoint_state_accessor)
    monkeypatch.setattr(threads, "build_checkpoint_state_mutation_accessor", gateway_services.build_checkpoint_state_mutation_accessor)
    monkeypatch.setattr(threads, "build_thread_checkpoint_state_accessor", gateway_services.build_thread_checkpoint_state_accessor)
    monkeypatch.setattr(threads, "build_thread_checkpoint_state_mutation_accessor", gateway_services.build_thread_checkpoint_state_mutation_accessor)
    monkeypatch.setattr(thread_runs, "build_thread_checkpoint_state_accessor", gateway_services.build_thread_checkpoint_state_accessor)
    return custom_factory


async def _seed_extension_source(checkpointer, custom_factory, mode, source_thread_id):
    accessor = CheckpointStateAccessor.bind(custom_factory(), checkpointer, mode=mode)
    await accessor.aupdate(
        {"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}},
        {"messages": [HumanMessage(id="h1", content="question")], "ext_list": ["merged"]},
        as_node="model",
    )
    await accessor.aupdate(
        {"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}},
        {"messages": [AIMessage(id="a1", content="answer")], "ext_list": ["payload"]},
        as_node="model",
    )
    await accessor.aupdate(
        {"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}},
        {
            "messages": [
                HumanMessage(
                    id="h2",
                    content="follow-up",
                    additional_kwargs={"run_id": "source-run"},
                )
            ]
        },
        as_node="model",
    )
    await accessor.aupdate(
        {"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}},
        {"messages": [AIMessage(id="a2", content="follow-up answer")]},
        as_node="model",
    )


@pytest.mark.parametrize("mode", ["full", "delta"])
def test_state_endpoints_preserve_extension_reducer_channels(monkeypatch, mode) -> None:
    """A non-identity middleware reducer channel survives state endpoints.

    GET /state must return the extension value (resolved via the thread's
    assistant_id), POST /state must replace it, and branch must preserve it
    byte-for-byte by copying reducer channels with Overwrite semantics. The
    copied pre-user checkpoint must also remain materializable for regenerate.
    """
    app, _store, checkpointer = _build_thread_app()
    app.include_router(thread_runs.router)
    custom_factory = _wire_extension_agent(monkeypatch, app, checkpointer, mode)

    async def list_messages(_thread_id: str, *, limit: int, **_kwargs) -> list[dict]:
        assert limit == thread_runs.REGENERATE_HISTORY_SCAN_LIMIT
        return []

    async def list_by_thread(_thread_id: str, *, user_id=None, limit: int = 100) -> list:
        return []

    app.state.run_event_store = SimpleNamespace(list_messages=list_messages)
    app.state.run_manager.list_by_thread = list_by_thread

    recorded_updates: list[dict] = []
    real_mutation_builder = gateway_services.build_checkpoint_state_mutation_accessor

    def recording_mutation_builder(request, *, thread_id, as_node, checkpoint_id=None, state_schema=None):
        accessor, config = real_mutation_builder(request, thread_id=thread_id, as_node=as_node, checkpoint_id=checkpoint_id, state_schema=state_schema)
        original_aupdate = accessor.aupdate

        async def recording_aupdate(config, values, *, as_node=None):
            recorded_updates.append(dict(values))
            return await original_aupdate(config, values, as_node=as_node)

        accessor.aupdate = recording_aupdate
        return accessor, config

    monkeypatch.setattr(gateway_services, "build_checkpoint_state_mutation_accessor", recording_mutation_builder)
    monkeypatch.setattr(threads, "build_checkpoint_state_mutation_accessor", recording_mutation_builder)

    source_thread_id = "extension-source"

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "metadata": {}, "assistant_id": "extension-agent"},
        )
        assert created.status_code == 200, created.text

        # Seed after creation: create_thread writes an empty head checkpoint.
        asyncio.run(_seed_extension_source(checkpointer, custom_factory, mode, source_thread_id))

        read_response = client.get(f"/api/threads/{source_thread_id}/state")
        assert read_response.status_code == 200, read_response.text
        assert read_response.json()["values"]["ext_list"] == ["merged", "payload"]

        update_response = client.post(
            f"/api/threads/{source_thread_id}/state",
            json={"values": {"ext_list": ["replaced"]}},
        )
        assert update_response.status_code == 200, update_response.text
        assert update_response.json()["values"]["ext_list"] == ["replaced"]

        branch_response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "a2", "message_ids": ["a2"]},
        )
        assert branch_response.status_code == 200, branch_response.text
        branch_thread_id = branch_response.json()["thread_id"]

        prepare_response = client.post(
            f"/api/threads/{branch_thread_id}/runs/regenerate/prepare",
            json={"message_id": "a2"},
        )
        assert prepare_response.status_code == 200, prepare_response.text

    # The branch write must copy every reducer channel with replace semantics.
    branch_update = recorded_updates[-1]
    assert isinstance(branch_update["ext_list"], Overwrite)
    assert branch_update["ext_list"].value == ["replaced"]
    assert isinstance(branch_update["messages"], Overwrite)

    async def materialize(thread_id):
        accessor = CheckpointStateAccessor.bind(custom_factory(), checkpointer, mode=mode)
        snapshot = await accessor.aget({"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}})
        return snapshot.values

    branch_values = asyncio.run(materialize(branch_thread_id))
    assert branch_values["ext_list"] == ["replaced"]
    assert [message.id for message in branch_values["messages"]] == ["h1", "a1", "h2", "a2"]

    prepared = prepare_response.json()
    assert prepared["target_run_id"] == "source-run"
    assert prepared["input"]["messages"][0]["id"] == "h2"
    base_accessor = CheckpointStateAccessor.bind(custom_factory(), checkpointer, mode=mode)
    base_values = asyncio.run(
        base_accessor.aget(
            {
                "configurable": {
                    "thread_id": branch_thread_id,
                    "checkpoint_ns": prepared["checkpoint"]["checkpoint_ns"],
                    "checkpoint_id": prepared["checkpoint"]["checkpoint_id"],
                }
            }
        )
    ).values
    assert [message.id for message in base_values["messages"]] == ["h1", "a1"]


async def _seed_branch_history_source(checkpointer, custom_factory, mode, source_thread_id):
    """Seed a completed turn whose history includes hidden and tool messages."""
    accessor = CheckpointStateAccessor.bind(custom_factory(), checkpointer, mode=mode)
    config = {"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}}
    await accessor.aupdate(
        config,
        {
            "messages": [
                HumanMessage(id="h1", content="question"),
                HumanMessage(id="h-hidden", content="internal", additional_kwargs={"hide_from_ui": True}),
            ]
        },
        as_node="model",
    )
    await accessor.aupdate(
        config,
        {
            "messages": [
                ToolMessage(id="t1", content="tool output", tool_call_id="call-1"),
                AIMessage(id="a1", content="answer"),
            ]
        },
        as_node="model",
    )


@pytest.mark.parametrize("mode", ["full", "delta"])
def test_branch_seeds_run_events_with_parent_history(monkeypatch, mode) -> None:
    """Branching must seed the branch's run-event feed with the parent history.

    The thread feed (``GET /messages`` / ``/messages/page``) reads the
    run-event store, not checkpoints; without seeding, a fresh branch has no
    message rows, so the inherited history vanishes from the UI as soon as
    the branch's first run refreshes the feed (#4380 problem 2).
    """
    from deerflow.runtime.events.store.memory import MemoryRunEventStore

    app, _store, checkpointer = _build_thread_app()
    custom_factory = _wire_extension_agent(monkeypatch, app, checkpointer, mode)
    event_store = MemoryRunEventStore()
    app.state.run_event_store = event_store
    source_thread_id = f"branch-history-source-{mode}"

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "metadata": {}, "assistant_id": "extension-agent"},
        )
        assert created.status_code == 200, created.text

        asyncio.run(_seed_branch_history_source(checkpointer, custom_factory, mode, source_thread_id))

        branch_response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "a1", "message_ids": ["a1"]},
        )
        assert branch_response.status_code == 200, branch_response.text
        branch_thread_id = branch_response.json()["thread_id"]

    rows = asyncio.run(event_store.list_messages(branch_thread_id, user_id=None))

    # The visible parent history is seeded in order; hidden messages are not.
    assert [row["content"]["id"] for row in rows] == ["h1", "t1", "a1"]
    assert [row["event_type"] for row in rows] == ["llm.human.input", "llm.tool.result", "llm.ai.response"]
    assert all(row["category"] == "message" for row in rows)
    # One synthetic run per inherited turn (#4458): this source has a single turn.
    assert all(row["run_id"] == f"branch-seed-{branch_thread_id}-1" for row in rows)
    assert all((row.get("metadata") or {}).get("branch_seed") is True for row in rows)
    seqs = [row["seq"] for row in rows]
    assert seqs == sorted(seqs)
    assert branch_response.json()["history_seed_mode"] == "seeded"

    # The parent thread's feed stays untouched.
    assert asyncio.run(event_store.list_messages(source_thread_id, user_id=None)) == []


def test_branch_history_seed_failure_keeps_branch_usable(monkeypatch) -> None:
    """A seeding failure must degrade, not fail the branch (best-effort)."""

    class _ExplodingStore:
        async def put_batch(self, events):
            raise RuntimeError("event store down")

    app, _store, checkpointer = _build_thread_app()
    custom_factory = _wire_extension_agent(monkeypatch, app, checkpointer, "full")
    app.state.run_event_store = _ExplodingStore()
    source_thread_id = "branch-history-source-failure"

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "metadata": {}, "assistant_id": "extension-agent"},
        )
        assert created.status_code == 200, created.text

        asyncio.run(_seed_branch_history_source(checkpointer, custom_factory, "full", source_thread_id))

        branch_response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "a1", "message_ids": ["a1"]},
        )

    assert branch_response.status_code == 200, branch_response.text
    assert branch_response.json()["history_seed_mode"] == "failed"


async def _seed_union_channel_source(checkpointer, custom_factory, mode, source_thread_id):
    """Seed a completed turn plus Union-typed reducer channels (sandbox/goal/todos)."""
    accessor = CheckpointStateAccessor.bind(custom_factory(), checkpointer, mode=mode)
    config = {"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}}
    await accessor.aupdate(
        config,
        {"messages": [HumanMessage(id="h1", content="question")], "goal": {"objective": "ship the fix"}},
        as_node="model",
    )
    await accessor.aupdate(
        config,
        {
            "messages": [AIMessage(id="a1", content="answer")],
            "todos": [{"content": "write tests", "status": "pending"}],
            "sandbox": {"sandbox_id": "local:parent-thread"},
            "thread_data": {"workspace_path": "/parent/workspace"},
            "task_history": {"scope": "parent-scope", "batches": ["a" * 64], "status": "available"},
            "task_notes": {"next": {"content": "verify the batch", "authority": "model_report"}},
        },
        as_node="model",
    )


def _branch_union_channel_thread(monkeypatch, mode):
    """Drive POST /branches on a source seeded with Union-typed channels; return branch values."""
    app, _store, checkpointer = _build_thread_app()
    custom_factory = _wire_extension_agent(monkeypatch, app, checkpointer, mode)
    source_thread_id = f"union-branch-source-{mode}"

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "metadata": {}, "assistant_id": "extension-agent"},
        )
        assert created.status_code == 200, created.text

        asyncio.run(_seed_union_channel_source(checkpointer, custom_factory, mode, source_thread_id))

        branch_response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "a1", "message_ids": ["a1"]},
        )
        assert branch_response.status_code == 200, branch_response.text
        branch_thread_id = branch_response.json()["thread_id"]

    async def materialize():
        accessor = CheckpointStateAccessor.bind(custom_factory(), checkpointer, mode=mode)
        snapshot = await accessor.aget({"configurable": {"thread_id": branch_thread_id, "checkpoint_ns": ""}})
        return snapshot.values

    return asyncio.run(materialize())


@pytest.mark.parametrize("mode", ["full", "delta"])
def test_branch_copies_union_typed_reducer_channels_as_plain_values(monkeypatch, mode) -> None:
    """Branching must not persist Overwrite wrappers into the fresh thread (#4380).

    Union-typed reducer channels (``goal``, ``todos``, ``promoted``,
    ``sandbox``) have no constructible default, so they start MISSING on the
    branch thread; an ``Overwrite`` first write that isn't unwrapped is stored
    literally and the next consumer crashes with ``TypeError: 'Overwrite'
    object is not subscriptable``.
    """
    branch_values = _branch_union_channel_thread(monkeypatch, mode)

    # The exact crash shape from #4380: subscripting the copied channel value.
    assert branch_values["goal"]["objective"] == "ship the fix"
    assert branch_values["todos"] == [{"content": "write tests", "status": "pending"}]
    assert not any(isinstance(value, Overwrite) for value in branch_values.values())


@pytest.mark.parametrize("mode", ["full", "delta"])
def test_branch_does_not_inherit_thread_scoped_channels(monkeypatch, mode) -> None:
    """The branch must acquire its own sandbox and thread paths, not the parent's.

    ``sandbox.sandbox_id`` binds path mappings and the release lifecycle to
    the parent thread, so inheriting it would make the branch read/write the
    parent's workspace and release the parent's sandbox after its first run;
    ``thread_data`` is recomputed from the branch's own thread_id by
    ThreadDataMiddleware on every run.
    """
    branch_values = _branch_union_channel_thread(monkeypatch, mode)

    assert branch_values.get("sandbox") is None
    assert branch_values.get("thread_data") is None
    assert branch_values.get("task_history") is None
    assert branch_values["task_notes"]["next"]["content"] == "verify the batch"


@pytest.mark.parametrize("mode", ["full", "delta"])
def test_update_thread_state_overwrite_into_never_written_channel(monkeypatch, mode) -> None:
    """POST /state must store a plain value when the reducer channel was never written.

    Same mechanism as the branch case (#4380): ``goal`` starts MISSING on a
    thread that never wrote it, and the endpoint's replace-style ``Overwrite``
    wrapping must not be persisted literally.
    """
    app, _store, checkpointer = _build_thread_app()
    custom_factory = _wire_extension_agent(monkeypatch, app, checkpointer, mode)
    source_thread_id = f"never-written-goal-{mode}"

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "metadata": {}, "assistant_id": "extension-agent"},
        )
        assert created.status_code == 200, created.text

        asyncio.run(_seed_extension_source(checkpointer, custom_factory, mode, source_thread_id))

        update_response = client.post(
            f"/api/threads/{source_thread_id}/state",
            json={"values": {"goal": {"objective": "finish"}}},
        )
        assert update_response.status_code == 200, update_response.text
        assert update_response.json()["values"]["goal"] == {"objective": "finish"}

        read_response = client.get(f"/api/threads/{source_thread_id}/state")
        assert read_response.status_code == 200, read_response.text
        assert read_response.json()["values"]["goal"] == {"objective": "finish"}


def test_update_thread_state_rejects_unknown_state_fields(monkeypatch) -> None:
    """Unknown fields fail 422 instead of a false-success 200."""
    app, _store, checkpointer = _build_thread_app()
    custom_factory = _wire_extension_agent(monkeypatch, app, checkpointer, "full")
    source_thread_id = "extension-source-422"

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "metadata": {}, "assistant_id": "extension-agent"},
        )
        assert created.status_code == 200, created.text

        asyncio.run(_seed_extension_source(checkpointer, custom_factory, "full", source_thread_id))

        response = client.post(
            f"/api/threads/{source_thread_id}/state",
            json={"values": {"not_a_state_field": 1}},
        )

    assert response.status_code == 422, response.text
    assert "not_a_state_field" in response.json()["detail"]


def test_branch_title_adds_next_free_language_neutral_numeric_suffix() -> None:
    assert threads._default_branch_title("Original chat") == ("Original chat (2)", 2)
    assert threads._default_branch_title("Roadmap (2026)") == ("Roadmap (2026) (2)", 2)
    assert threads._default_branch_title("Original chat", sibling_records=[{"display_name": "Original chat (2)", "metadata": {"branch_title_sequence": 2}}]) == (
        "Original chat (3)",
        3,
    )
    assert threads._default_branch_title("Original chat (2)", source_is_branch=True, source_sequence=2) == ("Original chat (3)", 3)
    assert threads._default_branch_title("Roadmap (2026)", source_is_branch=True) == ("Roadmap (2026) (2)", 2)
    assert threads._default_branch_title("Roadmap (2026)", source_is_branch=True, source_sequence=2) == ("Roadmap (2026) (3)", 3)
    assert threads._default_branch_title("Branch: Branch: Original chat", source_is_branch=True) == ("Original chat (2)", 2)
    assert threads._default_branch_title("Report Q4", source_is_branch=True, sibling_records=[{"display_name": "Original chat (3)", "metadata": {"branch_title_sequence": 3}}]) == (
        "Report Q4 (2)",
        2,
    )
    assert threads._default_branch_title(
        "Original chat",
        sibling_records=[
            {"display_name": "Original chat (3)", "metadata": {"branch_title_sequence": 3}},
            {"display_name": "Explicit title", "metadata": {}},
            {"display_name": "Original chat (2)", "metadata": {"branch_title_sequence": "2"}},
        ],
    ) == ("Original chat (4)", 4)
    assert threads._default_branch_title(
        "Original chat",
        sibling_records=[
            {"display_name": "Original chat (2)", "metadata": {}},
            {"display_name": "Unrelated (3)", "metadata": {"branch_title_sequence": 3}},
        ],
    ) == ("Original chat (3)", 3)
    assert threads._default_branch_title("   ") == (None, None)
    capped, sequence = threads._default_branch_title("x" * 256)
    assert capped is not None
    assert sequence == 2
    assert len(capped) == 256
    assert capped.endswith(" (2)")


def test_next_branch_title_sequence_accepts_only_bounded_numeric_branch_metadata() -> None:
    assert threads._next_branch_title_sequence(2, source_is_branch=True) == 3
    assert threads._next_branch_title_sequence(8, source_is_branch=True) == 9
    assert threads._next_branch_title_sequence(8, source_is_branch=False) == 2
    assert threads._next_branch_title_sequence(True, source_is_branch=True) == 2
    assert threads._next_branch_title_sequence("8", source_is_branch=True) == 2
    assert threads._next_branch_title_sequence(threads._BRANCH_TITLE_SEQUENCE_MAX, source_is_branch=True) == 2


def test_branch_thread_rejects_sidecar_threads() -> None:
    app, _store, _checkpointer = _build_thread_app()

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": "sidecar-thread", "metadata": {"deerflow_sidecar": True}},
        )
        assert created.status_code == 200, created.text

        response = client.post(
            "/api/threads/sidecar-thread/branches",
            json={"message_id": "ai-1", "message_ids": ["ai-1"]},
        )

    assert response.status_code == 409
    assert "main conversation" in response.json()["detail"]


def test_branch_thread_rejects_non_assistant_targets() -> None:
    app, _store, checkpointer = _build_thread_app()
    source_thread_id = "source-human-target"
    human = HumanMessage(id="human-1", content="Question")
    ai = AIMessage(id="ai-1", content="Answer")

    async def _seed(parent_config: dict) -> None:
        after_human = await _write_checkpoint(checkpointer, source_thread_id, str(uuid6()), [human], step=1, parent_config=parent_config)
        await _write_checkpoint(checkpointer, source_thread_id, str(uuid6()), [human, ai], step=2, parent_config=after_human)

    with TestClient(app) as client:
        created = client.post("/api/threads", json={"thread_id": source_thread_id, "metadata": {}})
        assert created.status_code == 200, created.text
        initial = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}}))
        assert initial is not None
        asyncio.run(_seed(initial.config))

        response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "human-1", "message_ids": ["human-1"]},
        )

    assert response.status_code == 409
    assert "can no longer be branched" in response.json()["detail"]


def test_branch_thread_best_effort_copies_current_workspace(tmp_path) -> None:
    paths = Paths(tmp_path)
    app, _store, checkpointer = _build_thread_app()
    source_thread_id = "source-with-files"
    user_id = "branch-user"

    source_user_data = paths.sandbox_user_data_dir(source_thread_id, user_id=user_id)
    source_outputs = paths.sandbox_outputs_dir(source_thread_id, user_id=user_id)
    source_uploads = paths.sandbox_uploads_dir(source_thread_id, user_id=user_id)
    source_outputs.mkdir(parents=True, exist_ok=True)
    source_uploads.mkdir(parents=True, exist_ok=True)
    (source_outputs / "result.txt").write_text("answer", encoding="utf-8")
    (source_uploads / ".upload-stale.part").write_text("partial", encoding="utf-8")

    human = HumanMessage(id="human-file", content="Make a file")
    ai = AIMessage(id="ai-file", content="Done")

    async def _seed(parent_config: dict) -> None:
        after_human = await _write_checkpoint(checkpointer, source_thread_id, str(uuid6()), [human], step=1, parent_config=parent_config)
        await _write_checkpoint(checkpointer, source_thread_id, str(uuid6()), [human, ai], step=2, parent_config=after_human)

    with (
        patch("app.gateway.routers.threads.get_paths", return_value=paths),
        patch("app.gateway.routers.threads.get_effective_user_id", return_value=user_id),
        TestClient(app) as client,
    ):
        created = client.post("/api/threads", json={"thread_id": source_thread_id, "metadata": {}})
        assert created.status_code == 200, created.text
        initial = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}}))
        assert initial is not None
        asyncio.run(_seed(initial.config))

        response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "ai-file", "message_ids": ["ai-file"]},
        )

    assert response.status_code == 200, response.text
    body = response.json()
    assert body["workspace_clone_mode"] == "current_thread_best_effort"

    target_user_data = paths.sandbox_user_data_dir(body["thread_id"], user_id=user_id)
    assert target_user_data.exists()
    assert (target_user_data / "outputs" / "result.txt").read_text(encoding="utf-8") == "answer"
    assert not (target_user_data / "uploads" / ".upload-stale.part").exists()
    assert source_user_data.exists()


def test_branch_thread_from_historical_turn_skips_workspace_clone(tmp_path) -> None:
    """Branching from a non-latest turn must not clone the current workspace.

    Workspace files are not checkpointed, so cloning them onto a branch rooted at
    an older turn would leak files created after that turn (regression for the
    historical-turn workspace-leak review on PR #3950).
    """
    paths = Paths(tmp_path)
    app, _store, checkpointer = _build_thread_app()
    source_thread_id = "source-historical"
    user_id = "branch-user"

    source_outputs = paths.sandbox_outputs_dir(source_thread_id, user_id=user_id)
    source_outputs.mkdir(parents=True, exist_ok=True)
    # ``future.txt`` only exists in the current (latest) workspace timeline.
    (source_outputs / "future.txt").write_text("future", encoding="utf-8")

    human_1 = HumanMessage(id="human-1", content="First question")
    ai_1 = AIMessage(id="ai-1", content="First answer")
    human_2 = HumanMessage(id="human-2", content="Second question")
    ai_2 = AIMessage(id="ai-2", content="Second answer")

    async def _seed(parent_config: dict) -> dict:
        after_human_1 = await _write_checkpoint(checkpointer, source_thread_id, str(uuid6()), [human_1], step=1, parent_config=parent_config)
        after_ai_1 = await _write_checkpoint(checkpointer, source_thread_id, str(uuid6()), [human_1, ai_1], step=2, parent_config=after_human_1)
        after_human_2 = await _write_checkpoint(
            checkpointer,
            source_thread_id,
            str(uuid6()),
            [human_1, ai_1, human_2],
            step=3,
            parent_config=after_ai_1,
        )
        await _write_checkpoint(
            checkpointer,
            source_thread_id,
            str(uuid6()),
            [human_1, ai_1, human_2, ai_2],
            step=4,
            parent_config=after_human_2,
        )
        return after_ai_1

    with (
        patch("app.gateway.routers.threads.get_paths", return_value=paths),
        patch("app.gateway.routers.threads.get_effective_user_id", return_value=user_id),
        TestClient(app) as client,
    ):
        created = client.post("/api/threads", json={"thread_id": source_thread_id, "metadata": {}})
        assert created.status_code == 200, created.text
        initial = asyncio.run(checkpointer.aget_tuple({"configurable": {"thread_id": source_thread_id, "checkpoint_ns": ""}}))
        assert initial is not None
        target_checkpoint_config = asyncio.run(_seed(initial.config))

        response = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "ai-1", "message_ids": ["ai-1"]},
        )

    assert response.status_code == 200, response.text
    body = response.json()
    assert body["parent_checkpoint_id"] == target_checkpoint_config["configurable"]["checkpoint_id"]
    assert body["workspace_clone_mode"] == "skipped_historical_turn"

    target_user_data = paths.sandbox_user_data_dir(body["thread_id"], user_id=user_id)
    assert not target_user_data.exists()


# ── Metadata filter validation at API boundary ────────────────────────────────


def test_search_threads_rejects_invalid_key_at_api_boundary() -> None:
    """Keys that don't match [A-Za-z0-9_-]+ are rejected by the Pydantic
    validator on ThreadSearchRequest.metadata — 422 from both backends.
    """
    app, _store, _checkpointer = _build_thread_app()

    with TestClient(app) as client:
        response = client.post("/api/threads/search", json={"metadata": {"bad;key": "x"}})

    assert response.status_code == 422


def test_search_threads_rejects_unsupported_value_type_at_api_boundary() -> None:
    """Value types outside (None, bool, int, float, str) are rejected."""
    app, _store, _checkpointer = _build_thread_app()

    with TestClient(app) as client:
        response = client.post("/api/threads/search", json={"metadata": {"env": ["a", "b"]}})

    assert response.status_code == 422


def test_search_threads_returns_400_for_backend_invalid_metadata_filter() -> None:
    """If the backend still raises InvalidMetadataFilterError (defense in
    depth), the handler surfaces it as HTTP 400.
    """
    app, _store, _checkpointer = _build_thread_app()
    thread_store = app.state.thread_store

    async def _raise(**kwargs):
        raise InvalidMetadataFilterError("rejected")

    with TestClient(app) as client:
        with patch.object(thread_store, "search", side_effect=_raise):
            response = client.post("/api/threads/search", json={"metadata": {"valid_key": "x"}})

    assert response.status_code == 400
    assert "rejected" in response.json()["detail"]


def test_search_threads_succeeds_with_valid_metadata() -> None:
    """Sanity check: valid metadata passes through without error."""
    app, _store, _checkpointer = _build_thread_app()

    with TestClient(app) as client:
        response = client.post("/api/threads/search", json={"metadata": {"env": "prod"}})

    assert response.status_code == 200


# ── update_thread_state: each call inserts a new checkpoint (regression) ───────


def test_update_thread_state_overwrites_reducer_fields_and_writes_last_values_directly(monkeypatch) -> None:
    app, _store, _checkpointer = _build_thread_app()
    update_calls: list[tuple[dict, dict, str | None]] = []
    updated_config = {
        "configurable": {
            "thread_id": "state-overwrite",
            "checkpoint_ns": "",
            "checkpoint_id": "ckpt-updated",
        }
    }
    snapshot = SimpleNamespace(
        values={
            "messages": [{"type": "human", "id": "h1", "content": "replacement"}],
            "artifacts": ["artifact-1"],
            "title": "Renamed",
        },
        config=updated_config,
        parent_config={"configurable": {"checkpoint_id": "ckpt-original"}},
        metadata={"source": "update", "step": 1},
        next=(),
        tasks=(),
        created_at="2026-07-18T00:00:00+00:00",
    )

    async def aupdate(config, values, *, as_node=None):
        update_calls.append((config, values, as_node))
        return updated_config

    accessor = SimpleNamespace(
        aupdate=aupdate,
        aget=AsyncMock(return_value=snapshot),
    )

    async def build_accessor(_request, *, thread_id, as_node, checkpoint_id=None):
        assert thread_id == "state-overwrite"
        return accessor, {
            "configurable": {
                "thread_id": thread_id,
                "checkpoint_ns": "",
                **({"checkpoint_id": checkpoint_id} if checkpoint_id else {}),
            }
        }

    monkeypatch.setattr(threads, "build_thread_checkpoint_state_mutation_accessor", build_accessor)

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": "state-overwrite", "metadata": {}},
        )
        assert created.status_code == 200, created.text
        response = client.post(
            "/api/threads/state-overwrite/state",
            json={
                "values": {
                    "messages": [{"type": "human", "id": "h1", "content": "replacement"}],
                    "artifacts": ["artifact-1"],
                    "title": "Renamed",
                }
            },
        )

    assert response.status_code == 200, response.text
    assert len(update_calls) == 1
    read_config, updates, as_node = update_calls[0]
    assert read_config["configurable"]["thread_id"] == "state-overwrite"
    assert isinstance(updates["messages"], Overwrite)
    assert updates["messages"].value[0]["id"] == "h1"
    assert isinstance(updates["artifacts"], Overwrite)
    assert updates["artifacts"].value == ["artifact-1"]
    assert updates["title"] == "Renamed"
    assert as_node == "manual_state_update"
    accessor.aget.assert_awaited_once_with(updated_config)
    assert response.json()["checkpoint_id"] == "ckpt-updated"


def test_update_thread_state_real_mutation_graph_finishes_without_scheduling(monkeypatch) -> None:
    app, _store, _checkpointer = _build_thread_app()
    app.state.checkpoint_channel_mode = "delta"
    real_mutation_builder = gateway_services.build_checkpoint_state_mutation_accessor

    async def mutation_boundary(request, *, thread_id, as_node, checkpoint_id=None):
        # No real assistant graph in this unit context: the boundary falls
        # back to the base schema while writes still use the mutation graph.
        return real_mutation_builder(request, thread_id=thread_id, as_node=as_node, checkpoint_id=checkpoint_id)

    monkeypatch.setattr(threads, "build_thread_checkpoint_state_mutation_accessor", mutation_boundary)

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": "state-real-mutation", "metadata": {}},
        )
        assert created.status_code == 200, created.text
        response = client.post(
            "/api/threads/state-real-mutation/state",
            json={
                "values": {
                    "messages": [{"type": "human", "id": "h1", "content": "replacement"}],
                    "artifacts": ["artifact-1"],
                    "title": "Renamed",
                }
            },
        )

    assert response.status_code == 200, response.text
    body = response.json()
    assert [message["id"] for message in body["values"]["messages"]] == ["h1"]
    assert body["values"]["artifacts"] == ["artifact-1"]
    assert body["values"]["title"] == "Renamed"
    assert body["next"] == []


@pytest.mark.parametrize("missing_checkpoint_id", ["does-not-exist", ""])
def test_update_thread_state_rejects_missing_explicit_checkpoint_without_writing(
    missing_checkpoint_id: str,
) -> None:
    app, _store, checkpointer = _build_thread_app()

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": "state-missing-checkpoint", "metadata": {}},
        )
        assert created.status_code == 200, created.text
        response = client.post(
            "/api/threads/state-missing-checkpoint/state",
            json={
                "checkpoint_id": missing_checkpoint_id,
                "values": {"title": "Must not be written"},
            },
        )

    assert response.status_code == 404, response.text

    async def collect_checkpoint_ids():
        return [
            item.config["configurable"]["checkpoint_id"]
            async for item in checkpointer.alist(
                {
                    "configurable": {
                        "thread_id": "state-missing-checkpoint",
                        "checkpoint_ns": "",
                    }
                }
            )
        ]

    checkpoint_ids = asyncio.run(collect_checkpoint_ids())
    assert missing_checkpoint_id not in checkpoint_ids
    assert len(checkpoint_ids) == 1


def test_update_thread_state_inserts_new_checkpoint_each_call() -> None:
    """Each ``POST /state`` must INSERT a distinct, time-ordered checkpoint.

    Regression for the in-place REPLACE bug: before the fix the new
    checkpoint reused the previous checkpoint["id"], so InMemorySaver/SQLite
    overwrote the existing row and history never grew. The fix assigns a
    fresh uuid6 to checkpoint["id"] before aput.
    """
    app, _store, checkpointer = _build_thread_app()

    with TestClient(app) as client:
        created = client.post("/api/threads", json={"metadata": {}})
        assert created.status_code == 200, created.text
        thread_id = created.json()["thread_id"]

        r1 = client.post(f"/api/threads/{thread_id}/state", json={"values": {"title": "First"}})
        assert r1.status_code == 200, r1.text
        r2 = client.post(f"/api/threads/{thread_id}/state", json={"values": {"title": "Second"}})
        assert r2.status_code == 200, r2.text

    import asyncio

    async def _collect():
        return [cp async for cp in checkpointer.alist({"configurable": {"thread_id": thread_id}})]

    history = asyncio.run(_collect())

    # 1 empty checkpoint from create_thread + 1 per update call.
    assert len(history) >= 3, f"expected >=3 checkpoints, got {len(history)}"

    ids = [cp.config["configurable"]["checkpoint_id"] for cp in history]
    assert len(ids) == len(set(ids)), f"duplicate checkpoint ids: {ids}"
    # alist() returns newest-first; uuid6 is time-ordered so newest > oldest.
    assert ids[0] > ids[-1], f"checkpoint ids not time-ordered (uuid4 instead of uuid6?): {ids}"

    # aput must PRESERVE the endpoint-assigned checkpoint["id"], not mint its own
    # and discard the payload's. If it generated a fresh id internally the fix
    # would be a no-op (the bug would never have existed). Assert the id returned
    # in each response round-tripped into the persisted history, and that the two
    # update writes kept the endpoint's uuid6 time-ordering through aput.
    resp_ids = [r1.json()["checkpoint_id"], r2.json()["checkpoint_id"]]
    assert all(cid is not None for cid in resp_ids), f"response missing checkpoint_id: {resp_ids}"
    assert set(resp_ids) <= set(ids), f"aput discarded endpoint-assigned id: returned {resp_ids}, stored {ids}"
    assert resp_ids[1] > resp_ids[0], f"endpoint-assigned uuid6 not preserved/ordered through aput: {resp_ids}"


class TestRestReadsCarryMessageSeq:
    """Opening a conversation must expose the same feed seq the stream does.

    `_MessageSeqStamper` sits on the streaming publish path, so a client that
    joins a live run gets placement information while one that merely opens the
    thread does not — and opening is the common case. Without a seq the merge
    falls back to the nearest shared anchor, which after summarization sits deep
    inside the loaded page, so a rescued first user turn renders behind the
    newest question instead of at the head (#4666).
    """

    @staticmethod
    def _seed_thread(app, checkpointer, thread_id: str, *, with_feed: bool) -> None:
        """Create the thread and its checkpoint without going through HTTP.

        ``POST /api/threads`` writes its own initial checkpoint, which would
        overwrite the one under test.
        """

        async def _seed() -> None:
            await app.state.thread_store.create(thread_id)
            if with_feed:
                await app.state.run_event_store.put(
                    thread_id=thread_id,
                    run_id="r1",
                    event_type="llm.human.input",
                    category="message",
                    content={"type": "human", "id": "u1__user", "content": "MARK-FIRST"},
                )
            await checkpointer.aput(
                {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}},
                {
                    **empty_checkpoint(),
                    "id": str(uuid6(clock_seq=-2)),
                    "channel_values": {"messages": [HumanMessage(content="MARK-FIRST", id="u1__user")]},
                    "channel_versions": {"messages": 1},
                },
                {"source": "loop", "step": 1, "writes": {}, "parents": {}},
                {"messages": 1},
            )

        asyncio.run(_seed())

    def _app_with_feed(self, thread_id: str):
        from deerflow.runtime.events.store.memory import MemoryRunEventStore

        app, _store, checkpointer = _build_thread_app()
        app.state.run_event_store = MemoryRunEventStore()
        self._seed_thread(app, checkpointer, thread_id, with_feed=True)
        return app

    def test_state_carries_the_seq_of_a_persisted_message(self) -> None:
        app = self._app_with_feed("thread-seq-state")

        with TestClient(app) as client:
            response = client.get("/api/threads/thread-seq-state/state")

        assert response.status_code == 200, response.text
        messages = response.json()["values"]["messages"]
        assert messages[0]["additional_kwargs"]["deerflow_seq"] == 1

    def test_history_carries_the_seq_of_a_persisted_message(self) -> None:
        app = self._app_with_feed("thread-seq-history")

        with TestClient(app) as client:
            response = client.post("/api/threads/thread-seq-history/history", json={"limit": 1})

        assert response.status_code == 200, response.text
        messages = response.json()[0]["values"]["messages"]
        assert messages[0]["additional_kwargs"]["deerflow_seq"] == 1

    def test_a_message_the_feed_does_not_know_is_left_unstamped(self) -> None:
        """Only persisted messages get a seq; the rest keep the weaving path."""
        from deerflow.runtime.events.store.memory import MemoryRunEventStore

        app, _store, checkpointer = _build_thread_app()
        app.state.run_event_store = MemoryRunEventStore()
        self._seed_thread(app, checkpointer, "thread-seq-unknown", with_feed=False)

        with TestClient(app) as client:
            response = client.get("/api/threads/thread-seq-unknown/state")

        assert response.status_code == 200, response.text
        messages = response.json()["values"]["messages"]
        assert "deerflow_seq" not in (messages[0].get("additional_kwargs") or {})


def test_archive_search_filter_and_restore_through_api():
    app, store, _ = _build_thread_app()

    async def seed():
        for name, metadata in [("active", {}), ("archived", {"deerflow_archived": True})]:
            await store.aput(THREADS_NS, name, {"metadata": metadata, "created_at": "2026-01-01T00:00:00Z", "updated_at": "2026-01-01T00:00:00Z"})

    asyncio.run(seed())
    with TestClient(app) as client:
        active = client.post("/api/threads/search", json={"archived": False, "limit": 1})
        assert active.status_code == 200
        assert [r["thread_id"] for r in active.json()] == ["active"]
        archived = client.post("/api/threads/search", json={"archived": True})
        assert [r["thread_id"] for r in archived.json()] == ["archived"]
        assert len(client.post("/api/threads/search", json={}).json()) == 2
        restored = client.patch("/api/threads/archived", json={"metadata": {"deerflow_archived": False}})
        assert restored.status_code == 200
        assert client.post("/api/threads/search", json={"archived": True}).json() == []


@pytest.mark.parametrize("value", ["true", 1, None, {}])
def test_archive_patch_rejects_non_boolean(value):
    app, _, _ = _build_thread_app()
    with TestClient(app) as client:
        result = client.patch("/api/threads/invalid", json={"metadata": {"deerflow_archived": value}})
    assert result.status_code == 422


def test_archived_chat_keeps_original_link_and_artifact_download(tmp_path, monkeypatch):
    from app.gateway.routers import artifacts

    app, store, _ = _build_thread_app()
    app.include_router(artifacts.router)
    artifact = tmp_path / "report.txt"
    artifact.write_text("Completed report", encoding="utf-8")
    monkeypatch.setattr(artifacts, "resolve_thread_virtual_path", lambda *args, **kwargs: artifact)

    async def seed():
        await store.aput(THREADS_NS, "report", {"metadata": {}, "created_at": "2026-01-01T00:00:00Z", "updated_at": "2026-01-01T00:00:00Z"})

    asyncio.run(seed())
    with TestClient(app) as client:
        response = client.patch("/api/threads/report", json={"metadata": {"deerflow_archived": True}})
        assert response.status_code == 200
        assert client.get("/api/threads/report").status_code == 200
        download = client.get("/api/threads/report/artifacts/mnt/user-data/outputs/report.txt?download=true")
        assert download.status_code == 200
        assert download.text == "Completed report"
        assert "attachment" in download.headers["content-disposition"]
    assert artifact.read_text(encoding="utf-8") == "Completed report"


def test_archive_patch_cannot_modify_another_users_thread():
    app, store, _ = _build_thread_app()
    app.state.thread_store = MemoryThreadMetaStore(store)

    async def seed():
        await store.aput(THREADS_NS, "private", {"user_id": "someone-else", "metadata": {}})

    asyncio.run(seed())
    with TestClient(app) as client:
        response = client.patch("/api/threads/private", json={"metadata": {"deerflow_archived": True}})
        assert response.status_code == 404
    assert asyncio.run(store.aget(THREADS_NS, "private")).value["metadata"] == {}


# ---------------------------------------------------------------------------
# Project membership surface (Phase 1): create/search/move + reserved key
# ---------------------------------------------------------------------------
#
# The memory harness above cannot exercise project membership (the memory
# store ignores it by design), so these tests build a stub-authed app on real
# SQL repos — same harness shape as ``test_projects_router.py``.

from test_projects_router import _StubAuthMiddleware  # noqa: E402


async def _init_threads_db(tmp_path) -> None:
    await init_engine("sqlite", url=f"sqlite+aiosqlite:///{tmp_path / 'threads.db'}", sqlite_dir=str(tmp_path))


def _build_project_threads_app(tmp_path) -> FastAPI:
    """Stub-authed app with real SQL thread/project repos."""
    anyio.run(_init_threads_db, tmp_path)
    session_factory = get_session_factory()
    app = FastAPI()
    app.add_middleware(_StubAuthMiddleware)
    app.state.thread_store = ThreadMetaRepository(session_factory)
    app.state.project_repo = ProjectRepository(session_factory)
    app.state.checkpointer = InMemorySaver()
    app.state.run_manager = _ThreadTestRunManager()
    app.include_router(threads.router)
    return app


def _create_project(app: FastAPI, *, user_id: str = "user-a", name: str = "Project") -> dict:
    async def _run() -> dict:
        token = set_current_user(SimpleNamespace(id=user_id))
        try:
            return await app.state.project_repo.create(name=name)
        finally:
            reset_current_user(token)

    return anyio.run(_run)


def _archive_project(app: FastAPI, project_id: str, *, user_id: str = "user-a") -> None:
    async def _run() -> None:
        token = set_current_user(SimpleNamespace(id=user_id))
        try:
            await app.state.project_repo.set_status(project_id, "archived")
        finally:
            reset_current_user(token)

    anyio.run(_run)


@pytest.fixture(autouse=True)
def _close_sql_engine_after_test():
    yield
    anyio.run(close_engine)


def test_create_thread_with_project_assigns(tmp_path):
    app = _build_project_threads_app(tmp_path)
    project = _create_project(app)
    with TestClient(app) as client:
        created = client.post("/api/threads", json={"project_id": project["id"]})
        assert created.status_code == 200, created.text
        thread_id = created.json()["thread_id"]

        fetched = client.get(f"/api/threads/{thread_id}")
        assert fetched.json()["metadata"][THREAD_PROJECT_METADATA_KEY] == project["id"]

        hits = client.post("/api/threads/search", json={"project_id": project["id"]}).json()
        assert [h["thread_id"] for h in hits] == [thread_id]


def test_create_thread_response_includes_persisted_project_membership(tmp_path):
    """The create response must echo the persisted record, not body.metadata.

    The store stamps ``metadata.deerflow_project_id`` from the assigned
    ``project_id`` column; a response built from ``body.metadata`` omits it
    and disagrees with the idempotent-retry response for the same thread.
    """
    app = _build_project_threads_app(tmp_path)
    project = _create_project(app)
    with TestClient(app) as client:
        created = client.post("/api/threads", json={"project_id": project["id"]})
        assert created.status_code == 200, created.text
        assert created.json()["metadata"][THREAD_PROJECT_METADATA_KEY] == project["id"]

        retry = client.post("/api/threads", json={"thread_id": created.json()["thread_id"], "project_id": project["id"]})
        assert retry.status_code == 200, retry.text
        assert retry.json() == created.json()


def test_create_thread_response_without_project_has_no_membership_key(tmp_path):
    """Regression guard: no project_id → the key must not appear in the response."""
    app = _build_project_threads_app(tmp_path)
    with TestClient(app) as client:
        created = client.post("/api/threads", json={"metadata": {"keep": "v"}})
        assert created.status_code == 200, created.text
        assert created.json()["metadata"] == {"keep": "v"}


def test_create_thread_with_missing_or_foreign_project_404(tmp_path):
    app = _build_project_threads_app(tmp_path)
    foreign = _create_project(app, user_id="user-b", name="Foreign")
    with TestClient(app) as client:
        missing = client.post("/api/threads", json={"thread_id": "thread-missing-proj", "project_id": "no-such-project"})
        assert missing.status_code == 404, missing.text
        assert missing.json()["detail"] == "Project not found"

        foreign_resp = client.post("/api/threads", json={"thread_id": "thread-foreign-proj", "project_id": foreign["id"]})
        assert foreign_resp.status_code == 404, foreign_resp.text


def test_create_thread_with_project_in_memory_mode_404():
    """Memory mode has no projects backend: a project-scoped create must fail
    closed with the same 404 the SQL store produces for a missing project —
    not silently persist an unassigned thread whose run would then proceed
    outside the selected project (``ensureProjectThread`` keeps the composer
    text for a retry on this failure)."""
    app, _, _ = _build_thread_app()
    with TestClient(app) as client:
        created = client.post("/api/threads", json={"thread_id": "thread-mem-proj", "project_id": "p1"})
        assert created.status_code == 404, created.text
        assert created.json()["detail"] == "Project not found"

        # The store's project filter fails closed too; no row was persisted.
        hits = client.post("/api/threads/search", json={"project_id": "p1"}).json()
        assert hits == []

        # Unscoped creates still work in memory mode.
        plain = client.post("/api/threads", json={"thread_id": "thread-mem-plain"})
        assert plain.status_code == 200, plain.text


def test_create_and_patch_strip_deerflow_project_id_metadata_key(tmp_path):
    app = _build_project_threads_app(tmp_path)
    with TestClient(app) as client:
        created = client.post("/api/threads", json={"metadata": {THREAD_PROJECT_METADATA_KEY: "forged", "keep": "v"}})
        assert created.status_code == 200, created.text
        thread_id = created.json()["thread_id"]
        assert created.json()["metadata"] == {"keep": "v"}

        fetched = client.get(f"/api/threads/{thread_id}")
        assert fetched.json()["metadata"] == {"keep": "v"}

        patched = client.patch(f"/api/threads/{thread_id}", json={"metadata": {THREAD_PROJECT_METADATA_KEY: "forged-2"}})
        assert patched.status_code == 200, patched.text
        assert THREAD_PROJECT_METADATA_KEY not in patched.json()["metadata"]


def test_search_threads_project_filter_absent_null_value(tmp_path):
    app = _build_project_threads_app(tmp_path)
    project = _create_project(app)
    with TestClient(app) as client:
        in_project = client.post("/api/threads", json={"project_id": project["id"]}).json()["thread_id"]
        unassigned = client.post("/api/threads", json={}).json()["thread_id"]

        all_hits = {t["thread_id"] for t in client.post("/api/threads/search", json={}).json()}
        assert all_hits == {in_project, unassigned}

        only_project = {t["thread_id"] for t in client.post("/api/threads/search", json={"project_id": project["id"]}).json()}
        assert only_project == {in_project}

        only_unassigned = {t["thread_id"] for t in client.post("/api/threads/search", json={"project_id": None}).json()}
        assert only_unassigned == {unassigned}


def test_move_thread_to_project_and_out(tmp_path):
    app = _build_project_threads_app(tmp_path)
    project = _create_project(app)
    with TestClient(app) as client:
        thread_id = client.post("/api/threads", json={}).json()["thread_id"]

        moved = client.post(f"/api/threads/{thread_id}/move", json={"project_id": project["id"]})
        assert moved.status_code == 200, moved.text
        assert moved.json()["metadata"][THREAD_PROJECT_METADATA_KEY] == project["id"]

        out = client.post(f"/api/threads/{thread_id}/move", json={"project_id": None})
        assert out.status_code == 200, out.text
        assert THREAD_PROJECT_METADATA_KEY not in out.json()["metadata"]

        # The key is required-but-nullable: omitting it is a 422.
        missing_key = client.post(f"/api/threads/{thread_id}/move", json={})
        assert missing_key.status_code == 422, missing_key.text


def test_move_thread_to_archived_or_foreign_project_404(tmp_path):
    app = _build_project_threads_app(tmp_path)
    archived = _create_project(app, name="Archived")
    foreign = _create_project(app, user_id="user-b", name="Foreign")
    _archive_project(app, archived["id"])
    with TestClient(app) as client:
        thread_id = client.post("/api/threads", json={}).json()["thread_id"]

        to_archived = client.post(f"/api/threads/{thread_id}/move", json={"project_id": archived["id"]})
        assert to_archived.status_code == 404, to_archived.text

        to_foreign = client.post(f"/api/threads/{thread_id}/move", json={"project_id": foreign["id"]})
        assert to_foreign.status_code == 404, to_foreign.text


def test_move_thread_does_not_bump_updated_at(tmp_path):
    app = _build_project_threads_app(tmp_path)
    project = _create_project(app)
    with TestClient(app) as client:
        thread_id = client.post("/api/threads", json={}).json()["thread_id"]
        before = client.get(f"/api/threads/{thread_id}").json()["updated_at"]

        moved = client.post(f"/api/threads/{thread_id}/move", json={"project_id": project["id"]})
        assert moved.status_code == 200, moved.text
        assert moved.json()["updated_at"] == before

        after = client.get(f"/api/threads/{thread_id}").json()["updated_at"]
        assert after == before


def _seed_branchable_thread(app: FastAPI, thread_id: str) -> None:
    """Write a three-turn conversation so a middle AI turn can be branched."""
    human_1 = HumanMessage(id="human-1", content="First question")
    ai_1 = AIMessage(id="ai-1", content="First answer")
    human_2 = HumanMessage(id="human-2", content="Second question")

    async def _seed(parent_config: dict) -> None:
        after_human_1 = await _write_checkpoint(
            app.state.checkpointer,
            thread_id,
            str(uuid6()),
            [human_1],
            step=1,
            parent_config=parent_config,
        )
        after_ai_1 = await _write_checkpoint(
            app.state.checkpointer,
            thread_id,
            str(uuid6()),
            [human_1, ai_1],
            step=2,
            parent_config=after_human_1,
        )
        await _write_checkpoint(
            app.state.checkpointer,
            thread_id,
            str(uuid6()),
            [human_1, ai_1, human_2],
            step=3,
            parent_config=after_ai_1,
        )

    initial = asyncio.run(app.state.checkpointer.aget_tuple({"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}))
    assert initial is not None
    asyncio.run(_seed(initial.config))


def test_branch_inherits_source_project_membership(tmp_path):
    """A branch of a project thread stays in the source thread's project.

    Branching writes a new thread_meta row; without inheritance it is
    unassigned and the sidebar surfaces it under Recent chats instead of the
    source thread's project group.
    """
    app = _build_project_threads_app(tmp_path)
    project = _create_project(app)
    source_thread_id = "source-project-branch"

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "project_id": project["id"]},
        )
        assert created.status_code == 200, created.text
        _seed_branchable_thread(app, source_thread_id)

        branch = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "ai-1", "message_ids": ["ai-1"]},
        )
        assert branch.status_code == 200, branch.text
        branch_id = branch.json()["thread_id"]
        assert branch.json()["parent_thread_id"] == source_thread_id

        fetched = client.get(f"/api/threads/{branch_id}")
        assert fetched.status_code == 200, fetched.text
        assert fetched.json()["metadata"][THREAD_PROJECT_METADATA_KEY] == project["id"]

        hits = client.post("/api/threads/search", json={"project_id": project["id"]}).json()
        assert {h["thread_id"] for h in hits} == {source_thread_id, branch_id}

        unassigned = client.post("/api/threads/search", json={"project_id": None}).json()
        assert [h["thread_id"] for h in unassigned] == []


def test_branch_from_archived_project_thread_degrades_to_unassigned(tmp_path):
    """Branching stays available when the source project was archived meanwhile.

    The branch inherits through the same validated create path as assignment;
    an archived project is no longer assignable, so the branch row is created
    unassigned (pre-inheritance behavior) instead of failing the request.
    """
    app = _build_project_threads_app(tmp_path)
    project = _create_project(app)
    source_thread_id = "source-archived-branch"

    with TestClient(app) as client:
        created = client.post(
            "/api/threads",
            json={"thread_id": source_thread_id, "project_id": project["id"]},
        )
        assert created.status_code == 200, created.text
        _seed_branchable_thread(app, source_thread_id)
        _archive_project(app, project["id"])

        branch = client.post(
            f"/api/threads/{source_thread_id}/branches",
            json={"message_id": "ai-1", "message_ids": ["ai-1"]},
        )
        assert branch.status_code == 200, branch.text
        branch_id = branch.json()["thread_id"]

        fetched = client.get(f"/api/threads/{branch_id}")
        assert fetched.status_code == 200, fetched.text
        assert THREAD_PROJECT_METADATA_KEY not in fetched.json()["metadata"]

        unassigned = client.post("/api/threads/search", json={"project_id": None}).json()
        assert {h["thread_id"] for h in unassigned} == {branch_id}


@pytest.mark.parametrize("mode", ["full", "delta"])
@pytest.mark.parametrize("fallback", [False, True])
def test_task_notes_state_write_normalizes_and_replaces(monkeypatch, mode, fallback):
    app, _store, checkpointer = _build_thread_app()
    _wire_extension_agent(monkeypatch, app, checkpointer, mode)
    if fallback:
        monkeypatch.setattr(threads, "graph_reducer_channels", lambda graph: None)
    with TestClient(app) as client:
        created = client.post("/api/threads", json={"thread_id": "note-replacement", "metadata": {}, "assistant_id": "extension-agent"})
        assert created.status_code == 200
        first = client.post("/api/threads/note-replacement/state", json={"values": {"task_notes": {"old": {"content": "stale"}}}})
        assert first.status_code == 200, first.text
        updated = client.post(
            "/api/threads/note-replacement/state",
            json={
                "values": {
                    "task_notes": {
                        "new": {"content": "keep backups", "authority": "system", "extra": "forged proof"},
                        "oversized": {"content": "x" * 751},
                    }
                }
            },
        )
        assert updated.status_code == 200, updated.text
        read = client.get("/api/threads/note-replacement/state")
        assert read.status_code == 200, read.text
        assert read.json()["values"]["task_notes"] == {"new": {"content": "keep backups", "source_ids": [], "authority": "model_report"}}