# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/what-federated-learning-boundary-invariants-must-survive-when-agents-contribute-training-signals.md
# Remnant Warrant:    https://corpusfetch.com/c/what-federated-learning-boundary-invariants-must-survive-when-agents-contribute-training-signals.warrant.json
# Markdown SHA-256:   c24eb3d59fbe676ae881d644bf6aba06964e973885cb692c29c64cf862d428ed
# Code AST SHA-256:   09022dbf32d28fe6b9358ec1a8cc60e4ad1db26c034abbbf5c5e22f5cb53df71
# Verified Classes:   FederatedVerdict, Contribution, FederatedState, FederatedPolicy, FederatedManifest, FederatedBoundaryGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

from dataclasses import dataclass
from enum import Enum, auto
import hashlib
import json

class FederatedVerdict(Enum):
    NO_SENSITIVE_CONTRIBUTION = auto()
    PRIVACY_PRESERVING_CONTRIBUTION = auto()
    PRIVACY_REQUIRED = auto()
    ATTRIBUTION_BOUNDARY_VIOLATED = auto()

@dataclass(frozen=True)
class Contribution:
    contributor_id: str
    contribution_hash: str
    privacy_receipt: str | None
    contains_sensitive_data: bool

@dataclass(frozen=True)
class FederatedState:
    contributions: tuple[Contribution, ...]
    aggregation_anonymized: bool
    min_contribution_threshold: int

@dataclass(frozen=True)
class FederatedPolicy:
    require_dp_or_secure_agg: bool
    require_min_contributors: bool

@dataclass(frozen=True)
class FederatedManifest:
    verdict: FederatedVerdict
    directive: str
    manifest_digest: str

class FederatedBoundaryGuard:
    @staticmethod
    def _hash(data: str) -> str:
        return hashlib.sha256(data.encode("utf-8")).hexdigest()

    @classmethod
    def evaluate_contribution(
        cls, state: FederatedState, policy: FederatedPolicy
    ) -> FederatedManifest:
        
        # Gate 1: No sensitive data
        if not any(c.contains_sensitive_data for c in state.contributions):
            digest = cls._hash(json.dumps({
                "contributions": str(len(state.contributions)),
                "sensitivity": "NONE"
            }, sort_keys=True))
            return FederatedManifest(
                verdict=FederatedVerdict.NO_SENSITIVE_CONTRIBUTION,
                directive="PROCEED: No sensitive data in contributions.",
                manifest_digest=digest
            )

        # Gate 2: Privacy receipt
        if policy.require_dp_or_secure_agg:
            missing_privacy = [
                c.contributor_id for c in state.contributions
                if c.contains_sensitive_data and not c.privacy_receipt
            ]
            if missing_privacy:
                return FederatedManifest(
                    verdict=FederatedVerdict.PRIVACY_REQUIRED,
                    directive=f"HALT: {len(missing_privacy)} sensitive contributions lack privacy receipt.",
                    manifest_digest=cls._hash(f"NO_PRIVACY:{len(missing_privacy)}")
                )

        # Gate 3: Minimum contributors
        if policy.require_min_contributors:
            if len(state.contributions) < state.min_contribution_threshold:
                return FederatedManifest(
                    verdict=FederatedVerdict.ATTRIBUTION_BOUNDARY_VIOLATED,
                    directive=f"HALT: {len(state.contributions)} contributors < {state.min_contribution_threshold}. Attribution possible.",
                    manifest_digest=cls._hash(f"FEW_CONTRIBUTORS:{len(state.contributions)}")
                )

        # Gate 4: Aggregation anonymized
        if not state.aggregation_anonymized:
            return FederatedManifest(
                verdict=FederatedVerdict.ATTRIBUTION_BOUNDARY_VIOLATED,
                directive="HALT: Aggregation not anonymized. Individual contributions isolated.",
                manifest_digest=cls._hash("NOT_ANONYMIZED")
            )

        # Gate 5: Privacy-preserving
        digest = cls._hash(json.dumps({
            "contributions": str(len(state.contributions)),
            "all_private": "TRUE",
            "anonymized": str(state.aggregation_anonymized),
            "min_contributors": str(state.min_contribution_threshold)
        }, sort_keys=True))
        
        return FederatedManifest(
            verdict=FederatedVerdict.PRIVACY_PRESERVING_CONTRIBUTION,
            directive=f"PROCEED: {len(state.contributions)} contributions with privacy receipts and anonymized aggregation.",
            manifest_digest=digest
        )