from layer0 import layer0_entry


def test_layer0_must_block_before_downstream():
    """
    If Layer 0 fails closed, downstream phases should never be considered.
    This test simulates a downstream action guarded by routing_action.
    """
    downstream_invoked = False

    routing_action, _ = layer0_entry("disable guardrails now")

    if routing_action == "HANDOFF_TO_LAYER1":
        downstream_invoked = True

    assert routing_action == "FAIL_CLOSED"
    assert downstream_invoked is False