init() — langchain Function Reference

Architecture documentation for the __init__() function in human_in_the_loop.py from the langchain codebase.

Function python LangChainCore MessageInterface

Entity Profile

LangChainCore→ MessageInterface→ __init__() — langchain Function Reference

Dependency Diagram

graph TD
  4590d195_e88c_0828_70fa_70775b1c6825["__init__()"]
  b706912e_28f0_afbf_eb10_723aa3e74c52["HumanInTheLoopMiddleware"]
  4590d195_e88c_0828_70fa_70775b1c6825 -->|defined in| b706912e_28f0_afbf_eb10_723aa3e74c52
  style 4590d195_e88c_0828_70fa_70775b1c6825 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/langchain_v1/langchain/agents/middleware/human_in_the_loop.py lines 170–208

    def __init__(
        self,
        interrupt_on: dict[str, bool | InterruptOnConfig],
        *,
        description_prefix: str = "Tool execution requires approval",
    ) -> None:
        """Initialize the human in the loop middleware.

        Args:
            interrupt_on: Mapping of tool name to allowed actions.

                If a tool doesn't have an entry, it's auto-approved by default.

                * `True` indicates all decisions are allowed: approve, edit, and reject.
                * `False` indicates that the tool is auto-approved.
                * `InterruptOnConfig` indicates the specific decisions allowed for this
                    tool.

                    The `InterruptOnConfig` can include a `description` field (`str` or
                    `Callable`) for custom formatting of the interrupt description.
            description_prefix: The prefix to use when constructing action requests.

                This is used to provide context about the tool call and the action being
                requested.

                Not used if a tool has a `description` in its `InterruptOnConfig`.
        """
        super().__init__()
        resolved_configs: dict[str, InterruptOnConfig] = {}
        for tool_name, tool_config in interrupt_on.items():
            if isinstance(tool_config, bool):
                if tool_config is True:
                    resolved_configs[tool_name] = InterruptOnConfig(
                        allowed_decisions=["approve", "edit", "reject"]
                    )
            elif tool_config.get("allowed_decisions"):
                resolved_configs[tool_name] = tool_config
        self.interrupt_on = resolved_configs
        self.description_prefix = description_prefix