before_agent() — langchain Function Reference

Architecture documentation for the before_agent() function in test_framework.py from the langchain codebase.

Function python LangChainCore MessageInterface calls 1 called by 2

Entity Profile

LangChainCore→ MessageInterface→ before_agent() — langchain Function Reference

Dependency Diagram

graph TD
  4014cea1_1c2d_cca6_4f48_176441158497["before_agent()"]
  a8d1868f_6ff2_5369_173c_c9fc7f2da6be["CustomMiddleware"]
  4014cea1_1c2d_cca6_4f48_176441158497 -->|defined in| a8d1868f_6ff2_5369_173c_c9fc7f2da6be
  1ce8d842_781b_35a8_8aae_44bd2c3e3f46["before_agent()"]
  1ce8d842_781b_35a8_8aae_44bd2c3e3f46 -->|calls| 4014cea1_1c2d_cca6_4f48_176441158497
  05e1929f_e974_6405_7ed0_3f3f64215f33["test_hook_with_class_inheritance()"]
  05e1929f_e974_6405_7ed0_3f3f64215f33 -->|calls| 4014cea1_1c2d_cca6_4f48_176441158497
  1ce8d842_781b_35a8_8aae_44bd2c3e3f46["before_agent()"]
  4014cea1_1c2d_cca6_4f48_176441158497 -->|calls| 1ce8d842_781b_35a8_8aae_44bd2c3e3f46
  style 4014cea1_1c2d_cca6_4f48_176441158497 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_framework.py lines 852–857

            def before_agent(
                self, state: AgentState[Any], runtime: Runtime
            ) -> dict[str, Any] | None:
                if hook_type == "before":
                    execution_log.append("hook_called")
                return None