feat(langgraph)!: remove Pregel construction and NodeBuilder from the public API

Building a graph by constructing `Pregel(...)` with `NodeBuilder` nodes
was never meant to be public. Graphs are built with `StateGraph` or
`@entrypoint`.

- Delete `NodeBuilder`; `langgraph.pregel` now exports only `Pregel`.
- `Pregel(...)` raises `TypeError` pointing to `StateGraph` and
  `@entrypoint`. `Pregel` stays public as the type that `compile()` and
  `@entrypoint` return, for type annotations and `isinstance` checks.
- `@entrypoint` builds its graph through a private `_EntrypointPregel`
  subclass, the same way `StateGraph` uses `CompiledStateGraph`.
- Rewrite the `Pregel` docstring to describe the compiled graph type and
  drop the hand-built graph examples.
- Engine tests that build graphs by hand now use a test-only copy of
  `NodeBuilder` and a `RawPregel` subclass in `tests/raw_pregel.py`.

BREAKING CHANGE: `from langgraph.pregel import NodeBuilder` and calling
`Pregel(...)` directly no longer work. Build graphs with `StateGraph` or
`@entrypoint`.

libs/langgraph/langgraph/func/__init__.py

@@ -255,6 +255,11 @@ R = TypeVar("R")
 S = TypeVar("S")
 
 
+class _EntrypointPregel(Pregel):
+    """The graph that `@entrypoint` builds. `Pregel` itself cannot be constructed
+    directly."""
+
+
 # The decorator was wrapped in a class to support the `final` attribute.
 # In this form, the `final` attribute should play nicely with IDE autocompletion,
 # and type checking tools.
@@ -573,7 +578,7 @@ class entrypoint(Generic[ContextT]):
                 else:
                     output_type = save_type = sig.return_annotation
 
-        graph: Pregel[Any, ContextT, Any, Any] = Pregel(
+        graph: Pregel[Any, ContextT, Any, Any] = _EntrypointPregel(
             nodes={
                 func.__name__: PregelNode(
                     bound=bound,

libs/langgraph/langgraph/pregel/__init__.py

@@ -1,3 +1,3 @@
-from langgraph.pregel.main import NodeBuilder, Pregel
+from langgraph.pregel.main import Pregel
 
-__all__ = ("Pregel", "NodeBuilder")
+__all__ = ("Pregel",)

libs/langgraph/langgraph/pregel/_validate.py

@@ -47,9 +47,7 @@ def validate_graph(
                             f"not in known channels: '{repr(sorted(channels))[:100]}'"
                         )
         else:
-            raise TypeError(
-                f"Invalid node type {type(node)}, expected PregelNode or NodeBuilder"
-            )
+            raise TypeError(f"Invalid node type {type(node)}, expected PregelNode")
 
     for chan in subscribed_channels:
         if chan not in channels:

libs/langgraph/langgraph/pregel/main.py

@@ -17,7 +17,6 @@ from collections.abc import (
     Sequence,
 )
 from dataclasses import is_dataclass, replace
-from datetime import timedelta
 from functools import partial
 from inspect import isclass
 from typing import (
@@ -35,7 +34,6 @@ from langchain_core.globals import get_debug
 from langchain_core.runnables import (
     RunnableSequence,
 )
-from langchain_core.runnables.base import Input, Output
 from langchain_core.runnables.config import (
     RunnableConfig,
     get_async_callback_manager_for_config,
@@ -93,13 +91,6 @@ from langgraph._internal._queue import (  # type: ignore[attr-defined]
     AsyncQueue,
     SyncQueue,
 )
-from langgraph._internal._runnable import (
-    Runnable,
-    RunnableLike,
-    RunnableSeq,
-    coerce_to_runnable,
-)
-from langgraph._internal._timeout import coerce_timeout_policy
 from langgraph._internal._typing import MISSING, DeprecatedKwargs
 from langgraph.callbacks import (
     GraphInterruptEvent,
@@ -155,7 +146,7 @@ from langgraph.pregel._messages import (
     StreamMessagesHandlerV2,
     ensure_message_ids,
 )
-from langgraph.pregel._read import DEFAULT_BOUND, PregelNode
+from langgraph.pregel._read import PregelNode
 from langgraph.pregel._retry import RetryPolicy
 from langgraph.pregel._runner import PregelRunner
 from langgraph.pregel._task_status import read_task_statuses
@@ -165,7 +156,6 @@ from langgraph.pregel._utils import (
     validate_timeout_supported,
 )
 from langgraph.pregel._validate import validate_graph, validate_keys
-from langgraph.pregel._write import ChannelWrite, ChannelWriteEntry
 from langgraph.pregel.debug import get_bolded_text, get_colored_text, tasks_w_writes
 from langgraph.pregel.protocol import PregelProtocol, StreamChunk, StreamProtocol
 from langgraph.runtime import (
@@ -197,7 +187,6 @@ from langgraph.types import (
     StateUpdate,
     StreamMode,
     StreamPart,
-    TimeoutPolicy,
     ensure_valid_checkpointer,
 )
 from langgraph.typing import ContextT, InputT, OutputT, StateT
@@ -208,182 +197,7 @@ try:
 except ImportError:
     _StreamingCallbackHandler = None  # type: ignore
 
-__all__ = ("NodeBuilder", "Pregel")
-
-_WriteValue = Callable[[Input], Output] | Any
-
-
-class NodeBuilder:
-    __slots__ = (
-        "_channels",
-        "_triggers",
-        "_tags",
-        "_metadata",
-        "_writes",
-        "_bound",
-        "_retry_policy",
-        "_cache_policy",
-        "_timeout",
-    )
-
-    _channels: str | list[str]
-    _triggers: list[str]
-    _tags: list[str]
-    _metadata: dict[str, Any]
-    _writes: list[ChannelWriteEntry]
-    _bound: Runnable
-    _retry_policy: list[RetryPolicy]
-    _cache_policy: CachePolicy | None
-    _timeout: TimeoutPolicy | None
-
-    def __init__(
-        self,
-    ) -> None:
-        self._channels = []
-        self._triggers = []
-        self._tags = []
-        self._metadata = {}
-        self._writes = []
-        self._bound = DEFAULT_BOUND
-        self._retry_policy = []
-        self._cache_policy = None
-        self._timeout = None
-
-    def subscribe_only(
-        self,
-        channel: str,
-    ) -> Self:
-        """Subscribe to a single channel."""
-        if not self._channels:
-            self._channels = channel
-        else:
-            raise ValueError(
-                "Cannot subscribe to single channels when other channels are already subscribed to"
-            )
-
-        self._triggers.append(channel)
-
-        return self
-
-    def subscribe_to(
-        self,
-        *channels: str,
-        read: bool = True,
-    ) -> Self:
-        """Add channels to subscribe to.
-
-        Node will be invoked when any of these channels are updated, with a dict of the
-        channel values as input.
-
-        Args:
-            channels: Channel name(s) to subscribe to
-            read: If `True`, the channels will be included in the input to the node.
-                Otherwise, they will trigger the node without being sent in input.
-
-        Returns:
-            Self for chaining
-        """
-        if isinstance(self._channels, str):
-            raise ValueError(
-                "Cannot subscribe to channels when subscribed to a single channel"
-            )
-        if read:
-            if not self._channels:
-                self._channels = list(channels)
-            else:
-                self._channels.extend(channels)
-
-        if isinstance(channels, str):
-            self._triggers.append(channels)
-        else:
-            self._triggers.extend(channels)
-
-        return self
-
-    def read_from(
-        self,
-        *channels: str,
-    ) -> Self:
-        """Adds the specified channels to read from, without subscribing to them."""
-        assert isinstance(self._channels, list), (
-            "Cannot read additional channels when subscribed to single channels"
-        )
-        self._channels.extend(channels)
-        return self
-
-    def do(
-        self,
-        node: RunnableLike,
-    ) -> Self:
-        """Adds the specified node."""
-        if self._bound is not DEFAULT_BOUND:
-            self._bound = RunnableSeq(
-                self._bound, coerce_to_runnable(node, name=None, trace=True)
-            )
-        else:
-            self._bound = coerce_to_runnable(node, name=None, trace=True)
-        return self
-
-    def write_to(
-        self,
-        *channels: str | ChannelWriteEntry,
-        **kwargs: _WriteValue,
-    ) -> Self:
-        """Add channel writes.
-
-        Args:
-            *channels: Channel names to write to.
-            **kwargs: Channel name and value mappings.
-
-        Returns:
-            Self for chaining
-        """
-        self._writes.extend(
-            ChannelWriteEntry(c) if isinstance(c, str) else c for c in channels
-        )
-        self._writes.extend(
-            ChannelWriteEntry(k, mapper=v)
-            if callable(v)
-            else ChannelWriteEntry(k, value=v)
-            for k, v in kwargs.items()
-        )
-
-        return self
-
-    def meta(self, *tags: str, **metadata: Any) -> Self:
-        """Add tags or metadata to the node."""
-        self._tags.extend(tags)
-        self._metadata.update(metadata)
-        return self
-
-    def add_retry_policies(self, *policies: RetryPolicy) -> Self:
-        """Adds retry policies to the node."""
-        self._retry_policy.extend(policies)
-        return self
-
-    def add_cache_policy(self, policy: CachePolicy) -> Self:
-        """Adds cache policies to the node."""
-        self._cache_policy = policy
-        return self
-
-    def set_timeout(self, timeout: float | timedelta | TimeoutPolicy | None) -> Self:
-        """Set the per-attempt timeout policy for this node."""
-        self._timeout = coerce_timeout_policy(timeout)
-        return self
-
-    def build(self) -> PregelNode:
-        """Builds the node."""
-        return PregelNode(
-            channels=self._channels,
-            triggers=self._triggers,
-            tags=self._tags,
-            metadata=self._metadata,
-            writers=[ChannelWrite(self._writes)],
-            bound=self._bound,
-            retry_policy=self._retry_policy,
-            cache_policy=self._cache_policy,
-            timeout=self._timeout,
-        )
+__all__ = ("Pregel",)
 
 
 # Kwargs that ``stream_events(version="v3")`` / ``astream_events(version="v3")``
@@ -461,255 +275,22 @@ class Pregel(
     PregelProtocol[StateT, ContextT, InputT, OutputT],
     Generic[StateT, ContextT, InputT, OutputT],
 ):
-    """Pregel manages the runtime behavior for LangGraph applications.
+    """The compiled graph that runs a LangGraph application.
 
-    ## Overview
+    `StateGraph.compile()` and the `@entrypoint` decorator return an instance of
+    this class. It provides the methods that run and inspect the application,
+    such as `invoke`, `stream`, `get_state` and `update_state`.
 
-    Pregel combines [**actors**](https://en.wikipedia.org/wiki/Actor_model)
-    and **channels** into a single application.
-    **Actors** read data from channels and write data to channels.
-    Pregel organizes the execution of the application into multiple steps,
-    following the **Pregel Algorithm**/**Bulk Synchronous Parallel** model.
+    The runtime is named after Google's
+    [Pregel algorithm](https://research.google/pubs/pub37252/). It runs the
+    application in steps. In each step it plans which nodes to run, runs them in
+    parallel, and then applies their writes to the graph's state, so writes
+    become visible only in the next step. The run ends when no node is
+    scheduled, or when the recursion limit is reached.
 
-    Each step consists of three phases:
-
-    - **Plan**: Determine which **actors** to execute in this step. For example,
-        in the first step, select the **actors** that subscribe to the special
-        **input** channels; in subsequent steps,
-        select the **actors** that subscribe to channels updated in the previous step.
-    - **Execution**: Execute all selected **actors** in parallel,
-        until all complete, or one fails, or a timeout is reached. During this
-        phase, channel updates are invisible to actors until the next step.
-    - **Update**: Update the channels with the values written by the **actors**
-        in this step.
-
-    Repeat until no **actors** are selected for execution, or a maximum number of
-    steps is reached.
-
-    ## Actors
-
-    An **actor** is a `PregelNode`.
-    It subscribes to channels, reads data from them, and writes data to them.
-    It can be thought of as an **actor** in the Pregel algorithm.
-    `PregelNodes` implement LangChain's
-    Runnable interface.
-
-    ## Channels
-
-    Channels are used to communicate between actors (`PregelNodes`).
-    Each channel has a value type, an update type, and an update function – which
-    takes a sequence of updates and
-    modifies the stored value. Channels can be used to send data from one chain to
-    another, or to send data from a chain to itself in a future step. LangGraph
-    provides a number of built-in channels:
-
-    ### Basic channels: LastValue and Topic
-
-    - `LastValue`: The default channel, stores the last value sent to the channel,
-       useful for input and output values, or for sending data from one step to the next
-    - `Topic`: A configurable PubSub Topic, useful for sending multiple values
-       between *actors*, or for accumulating output. Can be configured to deduplicate
-       values, and/or to accumulate values over the course of multiple steps.
-
-    ### Advanced channels: Context and BinaryOperatorAggregate
-
-    - `Context`: exposes the value of a context manager, managing its lifecycle.
-        Useful for accessing external resources that require setup and/or teardown. e.g.
-        `client = Context(httpx.Client)`
-    - `BinaryOperatorAggregate`: stores a persistent value, updated by applying
-        a binary operator to the current value and each update
-        sent to the channel, useful for computing aggregates over multiple steps. e.g.
-        `total = BinaryOperatorAggregate(int, operator.add)`
-
-    ## Examples
-
-    Most users will interact with Pregel via a
-    [StateGraph (Graph API)][langgraph.graph.StateGraph] or via an
-    [entrypoint (Functional API)][langgraph.func.entrypoint].
-
-    However, for **advanced** use cases, Pregel can be used directly. If you're
-    not sure whether you need to use Pregel directly, then the answer is probably no
-    - you should use the Graph API or Functional API instead. These are higher-level
-    interfaces that will compile down to Pregel under the hood.
-
-    Here are some examples to give you a sense of how it works:
-
-    Example: Single node application
-        ```python
-        from langgraph.channels import EphemeralValue
-        from langgraph.pregel import Pregel, NodeBuilder
-
-        node1 = (
-            NodeBuilder().subscribe_only("a")
-            .do(lambda x: x + x)
-            .write_to("b")
-        )
-
-        app = Pregel(
-            nodes={"node1": node1},
-            channels={
-                "a": EphemeralValue(str),
-                "b": EphemeralValue(str),
-            },
-            input_channels=["a"],
-            output_channels=["b"],
-        )
-
-        app.invoke({"a": "foo"})
-        ```
-
-        ```con
-        {'b': 'foofoo'}
-        ```
-
-    Example: Using multiple nodes and multiple output channels
-        ```python
-        from langgraph.channels import LastValue, EphemeralValue
-        from langgraph.pregel import Pregel, NodeBuilder
-
-        node1 = (
-            NodeBuilder().subscribe_only("a")
-            .do(lambda x: x + x)
-            .write_to("b")
-        )
-
-        node2 = (
-            NodeBuilder().subscribe_to("b")
-            .do(lambda x: x["b"] + x["b"])
-            .write_to("c")
-        )
-
-
-        app = Pregel(
-            nodes={"node1": node1, "node2": node2},
-            channels={
-                "a": EphemeralValue(str),
-                "b": LastValue(str),
-                "c": EphemeralValue(str),
-            },
-            input_channels=["a"],
-            output_channels=["b", "c"],
-        )
-
-        app.invoke({"a": "foo"})
-        ```
-
-        ```con
-        {'b': 'foofoo', 'c': 'foofoofoofoo'}
-        ```
-
-    Example: Using a Topic channel
-        ```python
-        from langgraph.channels import LastValue, EphemeralValue, Topic
-        from langgraph.pregel import Pregel, NodeBuilder
-
-        node1 = (
-            NodeBuilder().subscribe_only("a")
-            .do(lambda x: x + x)
-            .write_to("b", "c")
-        )
-
-        node2 = (
-            NodeBuilder().subscribe_only("b")
-            .do(lambda x: x + x)
-            .write_to("c")
-        )
-
-
-        app = Pregel(
-            nodes={"node1": node1, "node2": node2},
-            channels={
-                "a": EphemeralValue(str),
-                "b": EphemeralValue(str),
-                "c": Topic(str, accumulate=True),
-            },
-            input_channels=["a"],
-            output_channels=["c"],
-        )
-
-        app.invoke({"a": "foo"})
-        ```
-
-        ```pycon
-        {"c": ["foofoo", "foofoofoofoo"]}
-        ```
-
-    Example: Using a `BinaryOperatorAggregate` channel
-        ```python
-        from langgraph.channels import EphemeralValue, BinaryOperatorAggregate
-        from langgraph.pregel import Pregel, NodeBuilder
-
-
-        node1 = (
-            NodeBuilder().subscribe_only("a")
-            .do(lambda x: x + x)
-            .write_to("b", "c")
-        )
-
-        node2 = (
-            NodeBuilder().subscribe_only("b")
-            .do(lambda x: x + x)
-            .write_to("c")
-        )
-
-
-        def reducer(current, update):
-            if current:
-                return current + " | " + update
-            else:
-                return update
-
-
-        app = Pregel(
-            nodes={"node1": node1, "node2": node2},
-            channels={
-                "a": EphemeralValue(str),
-                "b": EphemeralValue(str),
-                "c": BinaryOperatorAggregate(str, operator=reducer),
-            },
-            input_channels=["a"],
-            output_channels=["c"],
-        )
-
-        app.invoke({"a": "foo"})
-        ```
-
-        ```con
-        {'c': 'foofoo | foofoofoofoo'}
-        ```
-
-    Example: Introducing a cycle
-        This example demonstrates how to introduce a cycle in the graph, by having
-        a chain write to a channel it subscribes to.
-
-        Execution will continue until a `None` value is written to the channel.
-
-        ```python
-        from langgraph.channels import EphemeralValue
-        from langgraph.pregel import Pregel, NodeBuilder, ChannelWriteEntry
-
-        example_node = (
-            NodeBuilder()
-            .subscribe_only("value")
-            .do(lambda x: x + x if len(x) < 10 else None)
-            .write_to(ChannelWriteEntry(channel="value", skip_none=True))
-        )
-
-        app = Pregel(
-            nodes={"example_node": example_node},
-            channels={
-                "value": EphemeralValue(str),
-            },
-            input_channels=["value"],
-            output_channels=["value"],
-        )
-
-        app.invoke({"value": "a"})
-        ```
-
-        ```con
-        {'value': 'aaaaaaaaaaaaaaaa'}
-        ```
+    `Pregel` is not constructed directly. Build graphs with
+    [`StateGraph`][langgraph.graph.StateGraph] or
+    [`@entrypoint`][langgraph.func.entrypoint].
     """
 
     nodes: dict[str, PregelNode]
@@ -768,7 +349,7 @@ class Pregel(
     def __init__(
         self,
         *,
-        nodes: dict[str, PregelNode | NodeBuilder],
+        nodes: dict[str, PregelNode],
         channels: dict[str, BaseChannel | ManagedValueSpec] | None,
         auto_validate: bool = True,
         stream_mode: StreamMode = "values",
@@ -793,6 +374,13 @@ class Pregel(
         stream_transformers: Sequence[Callable[[tuple[str, ...]], Any]] | None = None,
         **deprecated_kwargs: Unpack[DeprecatedKwargs],
     ) -> None:
+        # LangGraph builds graphs through subclasses: `CompiledStateGraph` and
+        # the graph `@entrypoint` returns.
+        if type(self) is Pregel:
+            raise TypeError(
+                "`Pregel` cannot be constructed directly. "
+                "Build graphs with `StateGraph` or `@entrypoint`."
+            )
         if (
             config_type := deprecated_kwargs.get("config_type", MISSING)
         ) is not MISSING:
@@ -807,9 +395,7 @@ class Pregel(
 
         checkpointer = ensure_valid_checkpointer(checkpointer)
 
-        self.nodes = {
-            k: v.build() if isinstance(v, NodeBuilder) else v for k, v in nodes.items()
-        }
+        self.nodes = dict(nodes)
         self.channels = channels or {}
         if TASKS in self.channels and not isinstance(self.channels[TASKS], Topic):
             raise ValueError(

libs/langgraph/tests/raw_pregel.py

@@ -0,0 +1,222 @@
+"""Build graphs directly on the Pregel engine, for tests of engine behavior.
+
+LangGraph does not expose this: applications build graphs with `StateGraph` or
+`@entrypoint`. Tests use it to set up channels, triggers and writes that those
+APIs do not produce on their own.
+"""
+
+from __future__ import annotations
+
+from collections.abc import Callable
+from datetime import timedelta
+from typing import Any
+
+from langchain_core.runnables.base import Input, Output
+from typing_extensions import Self
+
+from langgraph._internal._runnable import (
+    Runnable,
+    RunnableLike,
+    RunnableSeq,
+    coerce_to_runnable,
+)
+from langgraph._internal._timeout import coerce_timeout_policy
+from langgraph.pregel import Pregel
+from langgraph.pregel._read import DEFAULT_BOUND, PregelNode
+from langgraph.pregel._write import ChannelWrite, ChannelWriteEntry
+from langgraph.types import CachePolicy, RetryPolicy, TimeoutPolicy
+
+__all__ = ("NodeBuilder", "RawPregel")
+
+_WriteValue = Callable[[Input], Output] | Any
+
+
+class NodeBuilder:
+    """Builds a `PregelNode` that reads and writes named channels."""
+
+    __slots__ = (
+        "_channels",
+        "_triggers",
+        "_tags",
+        "_metadata",
+        "_writes",
+        "_bound",
+        "_retry_policy",
+        "_cache_policy",
+        "_timeout",
+    )
+
+    _channels: str | list[str]
+    _triggers: list[str]
+    _tags: list[str]
+    _metadata: dict[str, Any]
+    _writes: list[ChannelWriteEntry]
+    _bound: Runnable
+    _retry_policy: list[RetryPolicy]
+    _cache_policy: CachePolicy | None
+    _timeout: TimeoutPolicy | None
+
+    def __init__(
+        self,
+    ) -> None:
+        self._channels = []
+        self._triggers = []
+        self._tags = []
+        self._metadata = {}
+        self._writes = []
+        self._bound = DEFAULT_BOUND
+        self._retry_policy = []
+        self._cache_policy = None
+        self._timeout = None
+
+    def subscribe_only(
+        self,
+        channel: str,
+    ) -> Self:
+        """Subscribe to a single channel."""
+        if not self._channels:
+            self._channels = channel
+        else:
+            raise ValueError(
+                "Cannot subscribe to single channels when other channels are already subscribed to"
+            )
+
+        self._triggers.append(channel)
+
+        return self
+
+    def subscribe_to(
+        self,
+        *channels: str,
+        read: bool = True,
+    ) -> Self:
+        """Add channels to subscribe to.
+
+        Node will be invoked when any of these channels are updated, with a dict of the
+        channel values as input.
+
+        Args:
+            channels: Channel name(s) to subscribe to
+            read: If `True`, the channels will be included in the input to the node.
+                Otherwise, they will trigger the node without being sent in input.
+
+        Returns:
+            Self for chaining
+        """
+        if isinstance(self._channels, str):
+            raise ValueError(
+                "Cannot subscribe to channels when subscribed to a single channel"
+            )
+        if read:
+            if not self._channels:
+                self._channels = list(channels)
+            else:
+                self._channels.extend(channels)
+
+        if isinstance(channels, str):
+            self._triggers.append(channels)
+        else:
+            self._triggers.extend(channels)
+
+        return self
+
+    def read_from(
+        self,
+        *channels: str,
+    ) -> Self:
+        """Adds the specified channels to read from, without subscribing to them."""
+        assert isinstance(self._channels, list), (
+            "Cannot read additional channels when subscribed to single channels"
+        )
+        self._channels.extend(channels)
+        return self
+
+    def do(
+        self,
+        node: RunnableLike,
+    ) -> Self:
+        """Adds the specified node."""
+        if self._bound is not DEFAULT_BOUND:
+            self._bound = RunnableSeq(
+                self._bound, coerce_to_runnable(node, name=None, trace=True)
+            )
+        else:
+            self._bound = coerce_to_runnable(node, name=None, trace=True)
+        return self
+
+    def write_to(
+        self,
+        *channels: str | ChannelWriteEntry,
+        **kwargs: _WriteValue,
+    ) -> Self:
+        """Add channel writes.
+
+        Args:
+            *channels: Channel names to write to.
+            **kwargs: Channel name and value mappings.
+
+        Returns:
+            Self for chaining
+        """
+        self._writes.extend(
+            ChannelWriteEntry(c) if isinstance(c, str) else c for c in channels
+        )
+        self._writes.extend(
+            ChannelWriteEntry(k, mapper=v)
+            if callable(v)
+            else ChannelWriteEntry(k, value=v)
+            for k, v in kwargs.items()
+        )
+
+        return self
+
+    def meta(self, *tags: str, **metadata: Any) -> Self:
+        """Add tags or metadata to the node."""
+        self._tags.extend(tags)
+        self._metadata.update(metadata)
+        return self
+
+    def add_retry_policies(self, *policies: RetryPolicy) -> Self:
+        """Adds retry policies to the node."""
+        self._retry_policy.extend(policies)
+        return self
+
+    def add_cache_policy(self, policy: CachePolicy) -> Self:
+        """Adds cache policies to the node."""
+        self._cache_policy = policy
+        return self
+
+    def set_timeout(self, timeout: float | timedelta | TimeoutPolicy | None) -> Self:
+        """Set the per-attempt timeout policy for this node."""
+        self._timeout = coerce_timeout_policy(timeout)
+        return self
+
+    def build(self) -> PregelNode:
+        """Builds the node."""
+        return PregelNode(
+            channels=self._channels,
+            triggers=self._triggers,
+            tags=self._tags,
+            metadata=self._metadata,
+            writers=[ChannelWrite(self._writes)],
+            bound=self._bound,
+            retry_policy=self._retry_policy,
+            cache_policy=self._cache_policy,
+            timeout=self._timeout,
+        )
+
+
+class RawPregel(Pregel):
+    """A `Pregel` built from hand-written nodes and channels.
+
+    Accepts `NodeBuilder` values in `nodes`, and builds them.
+    """
+
+    def __init__(self, *, nodes: dict[str, PregelNode | NodeBuilder], **kwargs: Any):
+        super().__init__(
+            nodes={
+                k: v.build() if isinstance(v, NodeBuilder) else v
+                for k, v in nodes.items()
+            },
+            **kwargs,
+        )

libs/langgraph/tests/test_delta_channel_id_stability.py

@@ -19,8 +19,8 @@ from langgraph.channels.delta import DeltaChannel
 from langgraph.channels.last_value import LastValue
 from langgraph.graph import END, START, StateGraph
 from langgraph.graph.message import _messages_delta_reducer
-from langgraph.pregel import NodeBuilder, Pregel
 from langgraph.types import Command, Durability, Overwrite
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 pytestmark = pytest.mark.anyio
 
@@ -279,7 +279,7 @@ def _pregel_graph(seen: list[list[str | None]]) -> Any:
         .do(look)
         .write_to("messages")
     )
-    return Pregel(
+    return RawPregel(
         nodes={"look": node},
         channels={
             "messages": DeltaChannel(_messages_delta_reducer),

libs/langgraph/tests/test_delta_channel_run_input.py

@@ -7,8 +7,9 @@ from langgraph.checkpoint.memory import InMemorySaver
 from langgraph.channels.binop import BinaryOperatorAggregate
 from langgraph.channels.delta import DeltaChannel
 from langgraph.channels.last_value import LastValue
-from langgraph.pregel import NodeBuilder, Pregel
+from langgraph.pregel import Pregel
 from langgraph.types import Durability
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 pytestmark = pytest.mark.anyio
 
@@ -19,7 +20,7 @@ def _sorted_extend(current: list, writes: list) -> list:
 
 def _delta_input_graph() -> Pregel:
     node = NodeBuilder().subscribe_only("go").do(lambda _: [2]).write_to("log", "plain")
-    return Pregel(
+    return RawPregel(
         nodes={"n": node},
         channels={
             "log": DeltaChannel(_sorted_extend),

libs/langgraph/tests/test_delta_channel_seal_subscribers.py

@@ -3,7 +3,8 @@ from langgraph.checkpoint.memory import InMemorySaver
 
 from langgraph.channels.delta import DeltaChannel
 from langgraph.channels.last_value import LastValue
-from langgraph.pregel import NodeBuilder, Pregel
+from langgraph.pregel import Pregel
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 pytestmark = pytest.mark.anyio
 
@@ -17,7 +18,7 @@ def _extend(current: list, writes: list) -> list:
 def _graph(reads: list) -> Pregel:
     writer = NodeBuilder().subscribe_only("a").do(lambda _: [1]).write_to("d")
     reader = NodeBuilder().subscribe_only("d").do(lambda d: reads.append(list(d)))
-    return Pregel(
+    return RawPregel(
         nodes={"writer": writer, "reader": reader},
         channels={"a": LastValue(str), "d": DeltaChannel(_extend)},
         input_channels="a",

libs/langgraph/tests/test_delta_channel_update_overwrite.py

@@ -13,8 +13,9 @@ from langgraph.channels.delta import DeltaChannel
 from langgraph.channels.last_value import LastValue
 from langgraph.graph import START, StateGraph
 from langgraph.graph.message import _messages_delta_reducer
-from langgraph.pregel import NodeBuilder, Pregel
+from langgraph.pregel import Pregel
 from langgraph.types import Overwrite
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 pytestmark = pytest.mark.anyio
 
@@ -36,7 +37,7 @@ def _extend(current: list, writes: list) -> list:
 
 def _delta_input_graph(saver: InMemorySaver) -> Pregel:
     node = NodeBuilder().subscribe_only("go").do(lambda _: [2]).write_to("log")
-    return Pregel(
+    return RawPregel(
         nodes={"n": node},
         channels={"log": DeltaChannel(_extend), "go": LastValue(int)},
         input_channels=["log", "go"],

libs/langgraph/tests/test_delta_channel_update_state.py

@@ -30,8 +30,8 @@ from langgraph.channels.delta import DeltaChannel
 from langgraph.channels.last_value import LastValue
 from langgraph.graph import START, StateGraph
 from langgraph.graph.message import _messages_delta_reducer
-from langgraph.pregel import NodeBuilder, Pregel
 from langgraph.types import Overwrite, StateSnapshot, StateUpdate
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 pytestmark = pytest.mark.anyio
 
@@ -549,7 +549,7 @@ def _sorted_extend(current: list, writes: list) -> list:
 
 def _delta_input_graph(snapshot_frequency: int = 1000) -> Any:
     node = NodeBuilder().subscribe_only("go").do(lambda _: [2]).write_to("log", "plain")
-    return Pregel(
+    return RawPregel(
         nodes={"n": node},
         channels={
             "log": DeltaChannel(_sorted_extend, snapshot_frequency=snapshot_frequency),
@@ -649,7 +649,7 @@ def _messages_input_graph() -> Any:
         .do(lambda _: [HumanMessage("n", id="n")])
         .write_to("messages")
     )
-    return Pregel(
+    return RawPregel(
         nodes={"n": node},
         channels={
             "messages": DeltaChannel(_messages_delta_reducer),

libs/langgraph/tests/test_deprecation.py

@@ -13,13 +13,13 @@ from langgraph.errors import NodeInterrupt
 from langgraph.func import entrypoint, task
 from langgraph.graph import StateGraph
 from langgraph.graph.message import MessageGraph
-from langgraph.pregel import NodeBuilder, Pregel
 from langgraph.types import GraphOutput, Interrupt, RetryPolicy
 from langgraph.warnings import (
     LangGraphDeprecatedSinceV05,
     LangGraphDeprecatedSinceV10,
     LangGraphDeprecatedSinceV11,
 )
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 
 class PlainState(TypedDict): ...
@@ -157,7 +157,7 @@ def test_config_type_deprecation_pregel(mocker: MockerFixture) -> None:
         LangGraphDeprecatedSinceV10,
         match="`config_type` is deprecated and will be removed. Please use `context_schema` instead.",
     ):
-        instance = Pregel(
+        instance = RawPregel(
             nodes={
                 "one": chain,
             },

libs/langgraph/tests/test_large_cases.py

@@ -39,7 +39,6 @@ from langgraph.channels.untracked_value import UntrackedValue
 from langgraph.constants import END, START
 from langgraph.graph import StateGraph
 from langgraph.graph.message import MessagesState, add_messages
-from langgraph.pregel import NodeBuilder, Pregel
 from langgraph.types import (
     Command,
     Durability,
@@ -62,6 +61,7 @@ from tests.messages import (
     _AnyIdHumanMessage,
     _AnyIdToolMessage,
 )
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 
 def test_invoke_two_processes_in_out_interrupt(
@@ -72,7 +72,7 @@ def test_invoke_two_processes_in_out_interrupt(
     one = NodeBuilder().subscribe_only("input").do(add_one).write_to("inbox")
     two = NodeBuilder().subscribe_only("inbox").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "inbox": LastValue(int),

libs/langgraph/tests/test_large_cases_async.py

@@ -39,7 +39,6 @@ from langgraph.constants import END, START
 from langgraph.graph import MessagesState
 from langgraph.graph.message import add_messages
 from langgraph.graph.state import StateGraph
-from langgraph.pregel import NodeBuilder, Pregel
 from langgraph.types import PregelTask, Send, StateSnapshot, StreamWriter
 from tests.any_int import AnyInt
 from tests.any_str import AnyDict, AnyStr, UnsortedSequence
@@ -51,6 +50,7 @@ from tests.messages import (
     _AnyIdHumanMessage,
     _AnyIdToolMessage,
 )
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 pytestmark = pytest.mark.anyio
 
@@ -61,7 +61,7 @@ async def test_invoke_two_processes_in_out_interrupt(
     add_one = mocker.Mock(side_effect=lambda x: x + 1)
     one = NodeBuilder().subscribe_only("input").do(add_one).write_to("inbox")
     two = NodeBuilder().subscribe_only("inbox").do(add_one).write_to("output")
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "inbox": LastValue(int),

libs/langgraph/tests/test_pregel.py

@@ -66,10 +66,7 @@ from langgraph.errors import GraphRecursionError, InvalidUpdateError, ParentComm
 from langgraph.func import entrypoint, task
 from langgraph.graph import END, START, StateGraph
 from langgraph.graph.message import MessagesState, _messages_delta_reducer, add_messages
-from langgraph.pregel import (
-    NodeBuilder,
-    Pregel,
-)
+from langgraph.pregel import Pregel
 from langgraph.pregel._loop import PregelLoop, SyncPregelLoop
 from langgraph.pregel._runner import PregelRunner
 from langgraph.runtime import RunControl
@@ -95,6 +92,7 @@ from tests.messages import (
     _AnyIdHumanMessage,
     _AnyIdToolMessage,
 )
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 pytestmark = pytest.mark.anyio
 
@@ -257,7 +255,7 @@ def test_context_json_schema() -> None:
         x: int
         y: str = field(default="foo")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={
             "one": chain,
         },
@@ -449,7 +447,7 @@ def test_invoke_single_process_in_out(mocker: MockerFixture) -> None:
     add_one = mocker.Mock(side_effect=lambda x: x + 1)
     chain = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={
             "one": chain,
         },
@@ -485,7 +483,7 @@ def test_invoke_single_process_in_write_kwargs(mocker: MockerFixture) -> None:
         .write_to("output", fixed=5, output_plus_one=lambda x: x + 1)
     )
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": chain},
         channels={
             "input": LastValue(int),
@@ -521,7 +519,7 @@ def test_invoke_single_process_in_out_dict(mocker: MockerFixture) -> None:
     add_one = mocker.Mock(side_effect=lambda x: x + 1)
     chain = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": chain},
         channels={"input": LastValue(int), "output": LastValue(int)},
         input_channels="input",
@@ -546,7 +544,7 @@ def test_invoke_single_process_in_dict_out_dict(mocker: MockerFixture) -> None:
     add_one = mocker.Mock(side_effect=lambda x: x + 1)
     chain = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": chain},
         channels={"input": LastValue(int), "output": LastValue(int)},
         input_channels=["input"],
@@ -572,7 +570,7 @@ def test_invoke_two_processes_in_out(mocker: MockerFixture) -> None:
     one = NodeBuilder().subscribe_only("input").do(add_one).write_to("inbox")
     two = NodeBuilder().subscribe_only("inbox").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "inbox": LastValue(int),
@@ -677,7 +675,7 @@ def test_batch_two_processes_in_out() -> None:
     one = NodeBuilder().subscribe_only("input").do(add_one_with_delay).write_to("one")
     two = NodeBuilder().subscribe_only("one").do(add_one_with_delay).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "one": LastValue(int),
@@ -709,7 +707,7 @@ def test_invoke_many_processes_in_out(mocker: MockerFixture) -> None:
         )
     nodes["last"] = NodeBuilder().subscribe_only(str(i)).do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes=nodes,
         channels={str(i): LastValue(int) for i in range(-1, test_size - 2)}
         | {"input": LastValue(int), "output": LastValue(int)},
@@ -737,7 +735,7 @@ def test_batch_many_processes_in_out(mocker: MockerFixture) -> None:
         )
     nodes["last"] = NodeBuilder().subscribe_only(str(i)).do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes=nodes,
         channels={str(i): LastValue(int) for i in range(-1, test_size - 2)}
         | {"input": LastValue(int), "output": LastValue(int)},
@@ -770,7 +768,7 @@ def test_invoke_two_processes_two_in_two_out_invalid(mocker: MockerFixture) -> N
     one = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
     two = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={"output": LastValue(int), "input": LastValue(int)},
         input_channels="input",
@@ -803,7 +801,7 @@ def test_invoke_two_processes_two_in_two_out_valid(mocker: MockerFixture) -> Non
     one = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
     two = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "input": LastValue(int),
@@ -844,7 +842,7 @@ def test_invoke_checkpoint_two(
         .do(raise_if_above_10)
     )
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one},
         channels={
             "total": BinaryOperatorAggregate(int, operator.add),
@@ -1451,7 +1449,7 @@ def test_invoke_checkpoint_three(
         .do(raise_if_above_10)
     )
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one},
         channels={
             "total": BinaryOperatorAggregate(int, operator.add),
@@ -1576,7 +1574,7 @@ def test_invoke_two_processes_two_in_join_two_out(mocker: MockerFixture) -> None
         NodeBuilder().subscribe_only("inbox").do(add_10_each).write_to("output")
     )
 
-    app = Pregel(
+    app = RawPregel(
         nodes={
             "one": one,
             "chain_three": chain_three,
@@ -1607,7 +1605,7 @@ def test_invoke_join_then_call_other_pregel(
     add_one = mocker.Mock(side_effect=lambda x: x + 1)
     add_10_each = mocker.Mock(side_effect=lambda x: [y + 10 for y in x])
 
-    inner_app = Pregel(
+    inner_app = RawPregel(
         nodes={
             "one": NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
         },
@@ -1628,7 +1626,7 @@ def test_invoke_join_then_call_other_pregel(
     )
     chain_three = NodeBuilder().subscribe_only("outbox_one").do(sum).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={
             "one": one,
             "two": two,
@@ -1669,7 +1667,7 @@ def test_invoke_two_processes_one_in_two_out(mocker: MockerFixture) -> None:
     )
     two = NodeBuilder().subscribe_only("between").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "input": LastValue(int),
@@ -1696,7 +1694,7 @@ def test_invoke_two_processes_no_out(mocker: MockerFixture) -> None:
     one = NodeBuilder().subscribe_only("input").do(add_one).write_to("between")
     two = NodeBuilder().subscribe_only("between").do(add_one)
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "input": LastValue(int),
@@ -1719,7 +1717,7 @@ def test_invoke_two_processes_no_in(mocker: MockerFixture) -> None:
     two = NodeBuilder().subscribe_only("between").do(add_one)
 
     with pytest.raises(TypeError):
-        Pregel(nodes={"one": one, "two": two})
+        RawPregel(nodes={"one": one, "two": two})
 
 
 def test_conditional_entrypoint_to_multiple_state_graph(
@@ -4128,7 +4126,7 @@ def test_xray_lance(snapshot: SnapshotAssertion):
 def test_channel_values(sync_checkpointer: BaseCheckpointSaver) -> None:
     config = {"configurable": {"thread_id": "1"}}
     chain = NodeBuilder().subscribe_only("input").write_to("output")
-    app = Pregel(
+    app = RawPregel(
         nodes={
             "one": chain,
         },
@@ -9507,7 +9505,7 @@ class _IntVersionSaver(InMemorySaver):
 
 
 def _build_chain_after_a_delta_channel() -> Pregel:
-    return Pregel(
+    return RawPregel(
         nodes={
             "a": NodeBuilder().subscribe_only("inp").do(lambda _: ["a"]).write_to("d"),
             "b": NodeBuilder().subscribe_only("d").do(lambda _: "b").write_to("x"),
@@ -9552,7 +9550,7 @@ async def test_aupdate_state_after_an_exit_snapshot_infers_the_last_writer() ->
 
 
 def test_update_state_after_a_fork_seal_infers_the_subscriber_that_ran() -> None:
-    graph = Pregel(
+    graph = RawPregel(
         nodes={
             "a": NodeBuilder()
             .subscribe_only("inp")
@@ -9587,7 +9585,7 @@ def test_update_state_after_a_fork_seal_infers_the_subscriber_that_ran() -> None
 def test_update_state_after_a_fork_seal_infers_the_node_whose_read_it_advanced() -> (
     None
 ):
-    graph = Pregel(
+    graph = RawPregel(
         nodes={
             "a": NodeBuilder().subscribe_only("inp").do(lambda _: ["a"]).write_to("d"),
             "b": NodeBuilder().subscribe_only("d").do(lambda _: "b").write_to("out"),

libs/langgraph/tests/test_pregel_async.py

@@ -69,7 +69,6 @@ from langgraph.errors import (
 from langgraph.func import entrypoint, task
 from langgraph.graph import END, START, StateGraph
 from langgraph.graph.message import MessagesState, _messages_delta_reducer, add_messages
-from langgraph.pregel import NodeBuilder, Pregel
 from langgraph.pregel._loop import AsyncPregelLoop, PregelLoop
 from langgraph.pregel._runner import PregelRunner
 from langgraph.runtime import RunControl
@@ -95,6 +94,7 @@ from tests.messages import (
     _AnyIdHumanMessage,
     _AnyIdToolMessage,
 )
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 logger = logging.getLogger(__name__)
 
@@ -1446,7 +1446,7 @@ async def test_invoke_single_process_in_out(mocker: MockerFixture) -> None:
     add_one = mocker.Mock(side_effect=lambda x: x + 1)
     chain = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={
             "one": chain,
         },
@@ -1479,7 +1479,7 @@ async def test_invoke_single_process_in_write_kwargs(mocker: MockerFixture) -> N
         .write_to("output", fixed=5, output_plus_one=lambda x: x + 1)
     )
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": chain},
         channels={
             "input": LastValue(int),
@@ -1515,7 +1515,7 @@ async def test_invoke_single_process_in_out_dict(mocker: MockerFixture) -> None:
     add_one = mocker.Mock(side_effect=lambda x: x + 1)
     chain = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": chain},
         channels={"input": LastValue(int), "output": LastValue(int)},
         input_channels="input",
@@ -1540,7 +1540,7 @@ async def test_invoke_single_process_in_dict_out_dict(mocker: MockerFixture) ->
     add_one = mocker.Mock(side_effect=lambda x: x + 1)
     chain = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": chain},
         channels={"input": LastValue(int), "output": LastValue(int)},
         input_channels=["input"],
@@ -1567,7 +1567,7 @@ async def test_invoke_two_processes_in_out(mocker: MockerFixture) -> None:
     one = NodeBuilder().subscribe_only("input").do(add_one).write_to("inbox")
     two = NodeBuilder().subscribe_only("inbox").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "inbox": LastValue(int),
@@ -1607,7 +1607,7 @@ async def test_batch_two_processes_in_out() -> None:
     one = NodeBuilder().subscribe_only("input").do(add_one_with_delay).write_to("one")
     two = NodeBuilder().subscribe_only("one").do(add_one_with_delay).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "one": LastValue(int),
@@ -1639,7 +1639,7 @@ async def test_invoke_many_processes_in_out(mocker: MockerFixture) -> None:
         )
     nodes["last"] = NodeBuilder().subscribe_only(str(i)).do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes=nodes,
         channels={str(i): LastValue(int) for i in range(-1, test_size - 2)}
         | {"input": LastValue(int), "output": LastValue(int)},
@@ -1668,7 +1668,7 @@ async def test_batch_many_processes_in_out(mocker: MockerFixture) -> None:
         )
     nodes["last"] = NodeBuilder().subscribe_only(str(i)).do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes=nodes,
         channels={str(i): LastValue(int) for i in range(-1, test_size - 2)}
         | {"input": LastValue(int), "output": LastValue(int)},
@@ -1704,7 +1704,7 @@ async def test_invoke_two_processes_two_in_two_out_invalid(
     one = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
     two = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={"output": LastValue(int), "input": LastValue(int)},
         input_channels="input",
@@ -1722,7 +1722,7 @@ async def test_invoke_two_processes_two_in_two_out_valid(mocker: MockerFixture)
     one = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
     two = NodeBuilder().subscribe_only("input").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "input": LastValue(int),
@@ -1763,7 +1763,7 @@ async def test_invoke_checkpoint(
         .do(raise_if_above_10)
     )
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one},
         channels={
             "total": BinaryOperatorAggregate(int, operator.add),
@@ -3641,7 +3641,7 @@ async def test_invoke_checkpoint_three(
         .do(raise_if_above_10)
     )
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one},
         channels={
             "total": BinaryOperatorAggregate(int, operator.add),
@@ -3765,7 +3765,7 @@ async def test_invoke_two_processes_two_in_join_two_out(mocker: MockerFixture) -
         NodeBuilder().subscribe_only("inbox").do(add_10_each).write_to("output")
     )
 
-    app = Pregel(
+    app = RawPregel(
         nodes={
             "one": one,
             "chain_three": chain_three,
@@ -3799,7 +3799,7 @@ async def test_invoke_two_processes_one_in_two_out(mocker: MockerFixture) -> Non
     )
     two = NodeBuilder().subscribe_only("between").do(add_one).write_to("output")
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "input": LastValue(int),
@@ -3823,7 +3823,7 @@ async def test_invoke_two_processes_no_out(mocker: MockerFixture) -> None:
     one = NodeBuilder().subscribe_only("input").do(add_one).write_to("between")
     two = NodeBuilder().subscribe_only("between").do(add_one)
 
-    app = Pregel(
+    app = RawPregel(
         nodes={"one": one, "two": two},
         channels={
             "input": LastValue(int),

libs/langgraph/tests/test_pregel_construction.py

@@ -0,0 +1,56 @@
+"""`Pregel` is the type of compiled graphs, built only by `StateGraph` and
+`@entrypoint`."""
+
+import pytest
+from langchain_core.runnables import RunnableConfig
+from langgraph.checkpoint.memory import InMemorySaver
+from typing_extensions import TypedDict
+
+import langgraph.pregel
+from langgraph.channels.ephemeral_value import EphemeralValue
+from langgraph.func import entrypoint
+from langgraph.graph import START, StateGraph
+from langgraph.pregel import Pregel
+from langgraph.pregel._read import PregelNode
+
+
+def test_pregel_cannot_be_constructed_directly() -> None:
+    with pytest.raises(TypeError, match="`Pregel` cannot be constructed directly"):
+        Pregel(
+            nodes={"node": PregelNode(channels="a", triggers=["a"])},
+            channels={"a": EphemeralValue(str)},
+            input_channels="a",
+            output_channels="a",
+        )
+
+
+def test_node_builder_is_not_exported() -> None:
+    assert langgraph.pregel.__all__ == ("Pregel",)
+    assert not hasattr(langgraph.pregel, "NodeBuilder")
+
+
+def test_compiled_graphs_are_pregel_instances() -> None:
+    class State(TypedDict):
+        value: int
+
+    def increment(state: State) -> State:
+        return {"value": state["value"] + 1}
+
+    builder = StateGraph(State)
+    builder.add_node("increment", increment)
+    builder.add_edge(START, "increment")
+    graph = builder.compile(checkpointer=InMemorySaver())
+
+    @entrypoint(checkpointer=InMemorySaver())
+    def workflow(value: int) -> int:
+        return value + 1
+
+    assert isinstance(graph, Pregel)
+    assert isinstance(workflow, Pregel)
+
+    # `with_config` copies the graph by calling its constructor again.
+    config: RunnableConfig = {"configurable": {"thread_id": "1"}}
+    assert graph.with_config(recursion_limit=5).invoke({"value": 1}, config) == {
+        "value": 2
+    }
+    assert workflow.with_config(recursion_limit=5).invoke(1, config) == 2

libs/langgraph/tests/test_retry.py

@@ -47,7 +47,6 @@ from langgraph.errors import (
 )
 from langgraph.func import entrypoint, task
 from langgraph.graph import END, START, StateGraph, add_messages
-from langgraph.pregel import NodeBuilder, Pregel
 from langgraph.pregel._read import PregelNode
 from langgraph.pregel._retry import (
     _checkpoint_ns_for_parent_command,
@@ -67,6 +66,7 @@ from langgraph.types import (
     TimeoutPolicy,
     interrupt,
 )
+from tests.raw_pregel import NodeBuilder, RawPregel
 
 NEEDS_CONTEXTVARS = pytest.mark.skipif(
     sys.version_info < (3, 11),
@@ -1260,7 +1260,7 @@ def test_pregel_validate_rejects_sync_writer_timeout():
         return value
 
     with pytest.raises(ValueError, match="only supported for async nodes"):
-        Pregel(
+        RawPregel(
             nodes={
                 "slow": PregelNode(
                     channels="input",
@@ -1284,7 +1284,7 @@ def test_pregel_validate_rejects_wrapped_sync_runnable_lambda_timeout():
         return value + 1
 
     with pytest.raises(ValueError, match="only supported for async nodes"):
-        Pregel(
+        RawPregel(
             nodes={
                 "slow": (
                     NodeBuilder()
@@ -1307,7 +1307,7 @@ def test_pregel_validate_accepts_wrapped_async_runnable_lambda_timeout():
     async def slow(value: int) -> int:
         return value + 1
 
-    Pregel(
+    RawPregel(
         nodes={
             "slow": (
                 NodeBuilder()
@@ -1334,7 +1334,7 @@ def test_pregel_validate_rejects_parallel_sync_branch_timeout():
         return value + 1
 
     with pytest.raises(ValueError, match="only supported for async nodes"):
-        Pregel(
+        RawPregel(
             nodes={
                 "parallel": (
                     NodeBuilder()
@@ -1363,7 +1363,7 @@ def test_pregel_validate_rejects_sync_node_timeout():
         return value + 1
 
     with pytest.raises(ValueError, match="only supported for async nodes"):
-        Pregel(
+        RawPregel(
             nodes={
                 "slow": (
                     NodeBuilder()
@@ -1388,7 +1388,7 @@ async def test_pregel_validate_accepts_async_runnable_lambda_timeout():
         await asyncio.sleep(0.2)
         return value + 1
 
-    graph = Pregel(
+    graph = RawPregel(
         nodes={
             "slow": (
                 NodeBuilder()
@@ -1418,7 +1418,7 @@ async def test_pregel_validate_accepts_runnable_callable_with_sync_and_async_tim
         await asyncio.sleep(0.2)
         return value + 1
 
-    graph = Pregel(
+    graph = RawPregel(
         nodes={
             "slow": (
                 NodeBuilder()
@@ -1632,7 +1632,7 @@ async def test_node_builder_timeout_e2e():
         await asyncio.sleep(0.2)
         return value + 1
 
-    graph = Pregel(
+    graph = RawPregel(
         nodes={
             "slow": (
                 NodeBuilder()