QWED A2A protocol

from qwed_a2a.interceptor import A2AVerificationInterceptor
from qwed_a2a.protocol.schema import AgentMessage, PayloadType

interceptor = A2AVerificationInterceptor()

message = AgentMessage(
    sender_agent_id="procurement-agent",
    receiver_agent_id="treasury-agent",
    payload_type=PayloadType.FINANCIAL_TRANSACTION,
    payload={
        "data": {
            "claimed_total": 150.00,
            "line_items": [
                {"description": "Widget A", "amount": 50.00, "quantity": 2},
                {"description": "Widget B", "amount": 25.00, "quantity": 2},
            ]
        }
    }
)

verdict = await interceptor.intercept(message, trace_id="a2a_demo_001")

print(verdict.status)           # "forwarded" ✅
print(verdict.engine_used)      # "finance_guard"
print(verdict.attestation_jwt)  # "eyJhbGciOiJFUzI1NiIs..."