from __future__ import annotations
from typing import List
from .dsl import PlanDelta, SharedSignals, DualVariables


class Curator:
    """A lightweight ADMM-like coordinator for cross-venue coherence.

    This is a minimal stub that validates a PlanDelta against a simple
    constraint: total delta across venues must sum to zero (delta-neutral).
    In a real system, this would implement distributed optimization across venues.
    """

    def __init__(self):
        pass

    def enforce(self, local_plan: PlanDelta, shared: SharedSignals, duals: DualVariables) -> PlanDelta:
        # Simple validation: if sum of deltas != 0, attempt to rebalance by offsetting last action
        total = sum(a.delta for a in local_plan.actions)
        if total != 0 and local_plan.actions:
            # Adjust the last action to ensure delta-neutrality as a placeholder behavior
            last = local_plan.actions[-1]
            offset = -total
            last.delta += offset
        # Attach a simple safety tag for auditability in this MVP
        local_plan.safety_tags = local_plan.safety_tags or []
        local_plan.safety_tags.append("delta-neutralized-by-curator")
        return local_plan