refactor: move src and tests from lib/crewai to root

src/crewai/agents/agent_adapters/langgraph/langgraph_adapter.py

@@ -0,0 +1,315 @@
+"""LangGraph agent adapter for CrewAI integration.
+
+This module contains the LangGraphAgentAdapter class that integrates LangGraph ReAct agents
+with CrewAI's agent system. Provides memory persistence, tool integration, and structured
+output functionality.
+"""
+
+from collections.abc import Callable
+from typing import Any, cast
+
+from pydantic import ConfigDict, Field, PrivateAttr
+
+from crewai.agents.agent_adapters.base_agent_adapter import BaseAgentAdapter
+from crewai.agents.agent_adapters.langgraph.langgraph_tool_adapter import (
+    LangGraphToolAdapter,
+)
+from crewai.agents.agent_adapters.langgraph.protocols import (
+    LangGraphCheckPointMemoryModule,
+    LangGraphPrebuiltModule,
+)
+from crewai.agents.agent_adapters.langgraph.structured_output_converter import (
+    LangGraphConverterAdapter,
+)
+from crewai.agents.agent_builder.base_agent import BaseAgent
+from crewai.events.event_bus import crewai_event_bus
+from crewai.events.types.agent_events import (
+    AgentExecutionCompletedEvent,
+    AgentExecutionErrorEvent,
+    AgentExecutionStartedEvent,
+)
+from crewai.tools.agent_tools.agent_tools import AgentTools
+from crewai.tools.base_tool import BaseTool
+from crewai.utilities import Logger
+from crewai.utilities.converter import Converter
+from crewai.utilities.import_utils import require
+
+
+class LangGraphAgentAdapter(BaseAgentAdapter):
+    """Adapter for LangGraph agents to work with CrewAI.
+
+    This adapter integrates LangGraph's ReAct agents with CrewAI's agent system,
+    providing memory persistence, tool integration, and structured output support.
+    """
+
+    model_config = ConfigDict(arbitrary_types_allowed=True)
+
+    _logger: Logger = PrivateAttr(default_factory=Logger)
+    _tool_adapter: LangGraphToolAdapter = PrivateAttr()
+    _graph: Any = PrivateAttr(default=None)
+    _memory: Any = PrivateAttr(default=None)
+    _max_iterations: int = PrivateAttr(default=10)
+    function_calling_llm: Any = Field(default=None)
+    step_callback: Callable[..., Any] | None = Field(default=None)
+
+    model: str = Field(default="gpt-4o")
+    verbose: bool = Field(default=False)
+
+    def __init__(
+        self,
+        role: str,
+        goal: str,
+        backstory: str,
+        tools: list[BaseTool] | None = None,
+        llm: Any = None,
+        max_iterations: int = 10,
+        agent_config: dict[str, Any] | None = None,
+        **kwargs,
+    ) -> None:
+        """Initialize the LangGraph agent adapter.
+
+        Args:
+            role: The role description for the agent.
+            goal: The primary goal the agent should achieve.
+            backstory: Background information about the agent.
+            tools: Optional list of tools available to the agent.
+            llm: Language model to use, defaults to gpt-4o.
+            max_iterations: Maximum number of iterations for task execution.
+            agent_config: Additional configuration for the LangGraph agent.
+            **kwargs: Additional arguments passed to the base adapter.
+        """
+        super().__init__(
+            role=role,
+            goal=goal,
+            backstory=backstory,
+            tools=tools,
+            llm=llm or self.model,
+            agent_config=agent_config,
+            **kwargs,
+        )
+        self._tool_adapter = LangGraphToolAdapter(tools=tools)
+        self._converter_adapter: LangGraphConverterAdapter = LangGraphConverterAdapter(
+            self
+        )
+        self._max_iterations = max_iterations
+        self._setup_graph()
+
+    def _setup_graph(self) -> None:
+        """Set up the LangGraph workflow graph.
+
+        Initializes the memory saver and creates a ReAct agent with the configured
+        tools, memory checkpointer, and debug settings.
+        """
+
+        memory_saver: type[Any] = cast(
+            LangGraphCheckPointMemoryModule,
+            require(
+                "langgraph.checkpoint.memory",
+                purpose="LangGraph core functionality",
+            ),
+        ).MemorySaver
+        create_react_agent: Callable[..., Any] = cast(
+            LangGraphPrebuiltModule,
+            require(
+                "langgraph.prebuilt",
+                purpose="LangGraph core functionality",
+            ),
+        ).create_react_agent
+
+        self._memory = memory_saver()
+
+        converted_tools: list[Any] = self._tool_adapter.tools()
+        if self._agent_config:
+            self._graph = create_react_agent(
+                model=self.llm,
+                tools=converted_tools,
+                checkpointer=self._memory,
+                debug=self.verbose,
+                **self._agent_config,
+            )
+        else:
+            self._graph = create_react_agent(
+                model=self.llm,
+                tools=converted_tools or [],
+                checkpointer=self._memory,
+                debug=self.verbose,
+            )
+
+    def _build_system_prompt(self) -> str:
+        """Build a system prompt for the LangGraph agent.
+
+        Creates a prompt that includes the agent's role, goal, and backstory,
+        then enhances it through the converter adapter for structured output.
+
+        Returns:
+            The complete system prompt string.
+        """
+        base_prompt = f"""
+            You are {self.role}.
+
+            Your goal is: {self.goal}
+
+            Your backstory: {self.backstory}
+
+            When working on tasks, think step-by-step and use the available tools when necessary.
+        """
+        return self._converter_adapter.enhance_system_prompt(base_prompt)
+
+    def execute_task(
+        self,
+        task: Any,
+        context: str | None = None,
+        tools: list[BaseTool] | None = None,
+    ) -> str:
+        """Execute a task using the LangGraph workflow.
+
+        Configures the agent, processes the task through the LangGraph workflow,
+        and handles event emission for execution tracking.
+
+        Args:
+            task: The task object to execute.
+            context: Optional context information for the task.
+            tools: Optional additional tools for this specific execution.
+
+        Returns:
+            The final answer from the task execution.
+
+        Raises:
+            Exception: If task execution fails.
+        """
+        self.create_agent_executor(tools)
+
+        self.configure_structured_output(task)
+
+        try:
+            task_prompt = task.prompt() if hasattr(task, "prompt") else str(task)
+
+            if context:
+                task_prompt = self.i18n.slice("task_with_context").format(
+                    task=task_prompt, context=context
+                )
+
+            crewai_event_bus.emit(
+                self,
+                event=AgentExecutionStartedEvent(
+                    agent=self,
+                    tools=self.tools,
+                    task_prompt=task_prompt,
+                    task=task,
+                ),
+            )
+
+            session_id = f"task_{id(task)}"
+
+            config: dict[str, dict[str, str]] = {
+                "configurable": {"thread_id": session_id}
+            }
+
+            result: dict[str, Any] = self._graph.invoke(
+                {
+                    "messages": [
+                        ("system", self._build_system_prompt()),
+                        ("user", task_prompt),
+                    ]
+                },
+                config,
+            )
+
+            messages: list[Any] = result.get("messages", [])
+            last_message: Any = messages[-1] if messages else None
+
+            final_answer: str = ""
+            if isinstance(last_message, dict):
+                final_answer = last_message.get("content", "")
+            elif hasattr(last_message, "content"):
+                final_answer = getattr(last_message, "content", "")
+
+            final_answer = (
+                self._converter_adapter.post_process_result(final_answer)
+                or "Task execution completed but no clear answer was provided."
+            )
+            crewai_event_bus.emit(
+                self,
+                event=AgentExecutionCompletedEvent(
+                    agent=self, task=task, output=final_answer
+                ),
+            )
+
+            return final_answer
+
+        except Exception as e:
+            self._logger.log("error", f"Error executing LangGraph task: {e!s}")
+            crewai_event_bus.emit(
+                self,
+                event=AgentExecutionErrorEvent(
+                    agent=self,
+                    task=task,
+                    error=str(e),
+                ),
+            )
+            raise
+
+    def create_agent_executor(self, tools: list[BaseTool] | None = None) -> None:
+        """Configure the LangGraph agent for execution.
+
+        Args:
+            tools: Optional tools to configure for the agent.
+        """
+        self.configure_tools(tools)
+
+    def configure_tools(self, tools: list[BaseTool] | None = None) -> None:
+        """Configure tools for the LangGraph agent.
+
+        Merges additional tools with existing ones and updates the graph's
+        available tools through the tool adapter.
+
+        Args:
+            tools: Optional additional tools to configure.
+        """
+        if tools:
+            all_tools: list[BaseTool] = list(self.tools or []) + list(tools or [])
+            self._tool_adapter.configure_tools(all_tools)
+            available_tools: list[Any] = self._tool_adapter.tools()
+            self._graph.tools = available_tools
+
+    def get_delegation_tools(self, agents: list[BaseAgent]) -> list[BaseTool]:
+        """Implement delegation tools support for LangGraph.
+
+        Creates delegation tools that allow this agent to delegate tasks to other agents.
+
+        Args:
+            agents: List of agents available for delegation.
+
+        Returns:
+            List of delegation tools.
+        """
+        agent_tools: AgentTools = AgentTools(agents=agents)
+        return agent_tools.tools()
+
+    @staticmethod
+    def get_output_converter(
+        llm: Any, text: str, model: Any, instructions: str
+    ) -> Converter:
+        """Convert output format if needed.
+
+        Args:
+            llm: Language model instance.
+            text: Text to convert.
+            model: Model configuration.
+            instructions: Conversion instructions.
+
+        Returns:
+            Converter instance for output transformation.
+        """
+        return Converter(llm=llm, text=text, model=model, instructions=instructions)
+
+    def configure_structured_output(self, task: Any) -> None:
+        """Configure the structured output for LangGraph.
+
+        Uses the converter adapter to set up structured output formatting
+        based on the task requirements.
+
+        Args:
+            task: Task object containing output requirements.
+        """
+        self._converter_adapter.configure_structured_output(task)