refactor(langgraph,prebuilt): merge EventLog into StreamChannel with optional name (#7637)

libs/prebuilt/langgraph/prebuilt/_tool_call_stream.py

@@ -11,7 +11,7 @@ from __future__ import annotations
 from collections.abc import AsyncIterator, Iterator
 from typing import Any
 
-from langgraph.stream._event_log import EventLog
+from langgraph.stream.stream_channel import StreamChannel
 
 
 class ToolCallStream:
@@ -21,7 +21,7 @@ class ToolCallStream:
     are populated as events arrive:
 
     - `tool_call_id`, `tool_name`, `input`: stable from the start event.
-    - `output_deltas`: an `EventLog` of delta chunks. Iterate (sync or
+    - `output_deltas`: a `StreamChannel` of delta chunks. Iterate (sync or
       async) to consume partial output in arrival order.
     - `output`: terminal payload from `tool-finished`, or `None` if the
       call failed or is still in flight.
@@ -51,14 +51,14 @@ class ToolCallStream:
         self.tool_call_id = tool_call_id
         self.tool_name = tool_name
         self.input = input
-        self._output_deltas: EventLog[Any] = EventLog()
+        self._output_deltas: StreamChannel[Any] = StreamChannel()
         self.output: Any = None
         self.error: str | None = None
         self.completed = False
 
     @property
-    def output_deltas(self) -> EventLog[Any]:
-        """The EventLog of streamed `tool-output-delta` payloads.
+    def output_deltas(self) -> StreamChannel[Any]:
+        """The channel of streamed `tool-output-delta` payloads.
 
         Iterate (sync or async depending on how the run was started)
         to consume partial output in arrival order. The log closes when

libs/prebuilt/langgraph/prebuilt/_tool_call_transformer.py

@@ -5,8 +5,8 @@ from __future__ import annotations
 from collections.abc import Awaitable, Callable
 from typing import Any
 
-from langgraph.stream._event_log import EventLog
 from langgraph.stream._types import ProtocolEvent, StreamTransformer
+from langgraph.stream.stream_channel import StreamChannel
 
 from langgraph.prebuilt._tool_call_stream import ToolCallStream
 
@@ -21,11 +21,12 @@ class ToolCallTransformer(StreamTransformer):
     Native transformer — the `tool_calls` projection is exposed as a
     direct attribute on the run stream.
 
-    `EventLog[ToolCallStream]` is used (not `StreamChannel`) because the
-    live handles are not serializable and should not be auto-forwarded
-    onto the main event log. Wire consumers subscribe to the `tools`
-    channel instead, where the raw protocol events flow through
-    untouched by this transformer (`process` returns `True`).
+    A nameless `StreamChannel[ToolCallStream]` is used (no protocol
+    auto-forwarding) because the live handles are not serializable and
+    should not be injected into the main event log. Wire consumers
+    subscribe to the `tools` channel instead, where the raw protocol
+    events flow through untouched by this transformer (`process`
+    returns `True`).
 
     Registered explicitly by users at compile time via
     `builder.compile(transformers=[ToolCallTransformer])` — not a
@@ -37,7 +38,7 @@ class ToolCallTransformer(StreamTransformer):
 
     def __init__(self, scope: tuple[str, ...] = ()) -> None:
         super().__init__(scope)
-        self._log: EventLog[ToolCallStream] = EventLog()
+        self._log: StreamChannel[ToolCallStream] = StreamChannel()
         self._active: dict[str, ToolCallStream] = {}
         self._is_async = False
         self._pump_fn: Callable[[], bool] | None = None

libs/prebuilt/tests/test_tool_call_transformer.py

@@ -11,9 +11,9 @@ from langchain_core.tools import tool
 from langgraph.constants import END, START
 from langgraph.graph import StateGraph
 from langgraph.graph.message import add_messages
-from langgraph.stream._event_log import EventLog
 from langgraph.stream._mux import StreamMux
 from langgraph.stream._types import ProtocolEvent
+from langgraph.stream.stream_channel import StreamChannel
 from langgraph.stream.transformers import (
     MessagesTransformer,
     ValuesTransformer,
@@ -63,7 +63,7 @@ def _tool_event(
     }
 
 
-def _subscribe(log: EventLog) -> None:
+def _subscribe(log: StreamChannel) -> None:
     log._subscribed = True