merge_message_runs

langchain_core.messages.utils.merge_message_runs(messages: Sequence[MessageLikeRepresentation] | None = None, **kwargs: Any) → List[BaseMessage] | Runnable[Sequence[MessageLikeRepresentation], List[BaseMessage]]

Merge consecutive Messages of the same type.

NOTE: ToolMessages are not merged, as each has a distinct tool call id that can’t be merged.

Parameters:

• messages (Optional[Sequence[MessageLikeRepresentation]]) – Sequence Message-like objects to merge.

• kwargs (Any)

Returns:

List of BaseMessages with consecutive runs of message types merged into single messages. If two messages being merged both have string contents, the merged content is a concatenation of the two strings with a new-line separator. If at least one of the messages has a list of content blocks, the merged content is a list of content blocks.

Return type:

Union[List[BaseMessage], Runnable[Sequence[MessageLikeRepresentation], List[BaseMessage]]]

Example

from langchain_core.messages import (
    merge_message_runs,
    AIMessage,
    HumanMessage,
    SystemMessage,
    ToolCall,
)

messages = [
    SystemMessage("you're a good assistant."),
    HumanMessage("what's your favorite color", id="foo",),
    HumanMessage("wait your favorite food", id="bar",),
    AIMessage(
        "my favorite colo",
        tool_calls=[ToolCall(name="blah_tool", args={"x": 2}, id="123", type="tool_call")],
        id="baz",
    ),
    AIMessage(
        [{"type": "text", "text": "my favorite dish is lasagna"}],
        tool_calls=[ToolCall(name="blah_tool", args={"x": -10}, id="456", type="tool_call")],
        id="blur",
    ),
]

merge_message_runs(messages)

[
    SystemMessage("you're a good assistant."),
    HumanMessage("what's your favorite color\nwait your favorite food", id="foo",),
    AIMessage(
        [
            "my favorite colo",
            {"type": "text", "text": "my favorite dish is lasagna"}
        ],
        tool_calls=[
            ToolCall({"name": "blah_tool", "args": {"x": 2}, "id": "123", "type": "tool_call"}),
            ToolCall({"name": "blah_tool", "args": {"x": -10}, "id": "456", "type": "tool_call"})
        ]
        id="baz"
    ),
]