graph.py

"""
LangGraph graph definition for ReasonGraph.
Wires all nodes and edges into a single compiled graph.
"""

from langgraph.graph import END, START, StateGraph

from app.graph.state import GraphState
from app.nodes.generator import generator_node
from app.nodes.loop_controller import increment_search_node, loop_controller
from app.nodes.query_optimizer import query_optimizer_node
from app.nodes.retriever import retriever_node
from app.nodes.verifier import verifier_node


builder = StateGraph(GraphState)

# Nodes
builder.add_node("query_optimizer", query_optimizer_node)
builder.add_node("retriever", retriever_node)
builder.add_node("generator", generator_node)
builder.add_node("verifier", verifier_node)
builder.add_node("increment_search", increment_search_node)
builder.add_node(
    "graceful_failure",
    lambda state: {
        "draft_answer": "Available evidence does not sufficiently support a reliable answer.",
        "verifier_passed": False,
    },
)

# Edges
builder.add_edge(START, "query_optimizer")
builder.add_edge("query_optimizer", "retriever")
builder.add_edge("retriever", "generator")
builder.add_edge("generator", "verifier")
builder.add_conditional_edges(
    "verifier",
    loop_controller,
    {
        "end": END,
        "increment_search": "increment_search",
        "graceful_failure": "graceful_failure",
    },
)
builder.add_edge("increment_search", "query_optimizer")
builder.add_edge("graceful_failure", END)

graph = builder.compile()