"""
Field propagation — the generation heartbeat.

Each step: F <- versor_apply(V, F)

V is the rotor for the current node's outgoing edge in the vocab manifold.
No correction. No normalization. No conditional branching. The loop is tight.
"""

from algebra.versor import versor_apply
from field.state import FieldState


def propagate_step(state: FieldState, V) -> FieldState:
    """
    Apply one versor transition.
    V is the edge rotor from the current node.
    Returns a new FieldState one step forward on the manifold.
    """
    new_F = versor_apply(V, state.F)
    return FieldState(F=new_F, node=state.node, step=state.step + 1)