# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/how-must-an-instance-validate-cross-agent-claims-when-no-ground-truth-source-exists.md
# Remnant Warrant:    https://corpusfetch.com/c/how-must-an-instance-validate-cross-agent-claims-when-no-ground-truth-source-exists.warrant.json
# Markdown SHA-256:   545f3ac19c6c6eeafebc097b771cb36c0cf92eca9adc0bd396f503615bce2e84
# Code AST SHA-256:   95190e5b6918dcc9e048e0db1909de7bd33c558abc239a008bceb9bac5665559
# Verified Classes:   ClaimVerdict, CrossAgentClaim, ClaimContext, ClaimPolicy, ClaimManifest, GroundTruthFreeClaimGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class ClaimVerdict(Enum):
    GROUND_TRUTH_AVAILABLE = auto()
    PROVISIONALLY_SUPPORTED = auto()
    WEAKLY_SUPPORTED = auto()
    UNVERIFIED_CLAIM = auto()

@dataclass(frozen=True)
class CrossAgentClaim:
    claim_id: str
    asserting_agents: frozenset[str]
    independent_source_count: int
    confidence_interval: tuple[float, float]
    shared_ancestry_detected: bool

@dataclass(frozen=True)
class ClaimContext:
    ground_truth_available: bool
    min_independent_sources: int

@dataclass(frozen=True)
class ClaimPolicy:
    min_confidence_for_action: float

@dataclass(frozen=True)
class ClaimManifest:
    verdict: ClaimVerdict
    effective_confidence: float
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_claim(
        cls, claim: CrossAgentClaim, ctx: ClaimContext, policy: ClaimPolicy
    ) -> ClaimManifest:
        
        # Gate 1: Ground truth available
        if ctx.ground_truth_available:
            return ClaimManifest(
                verdict=ClaimVerdict.GROUND_TRUTH_AVAILABLE,
                effective_confidence=1.0,
                directive=f"PROCEED: Query ground truth for {claim.claim_id}.",
                manifest_digest=cls._hash(f"GROUND:{claim.claim_id}")
            )

        # Gate 2: Shared ancestry
        if claim.shared_ancestry_detected:
            return ClaimManifest(
                verdict=ClaimVerdict.WEAKLY_SUPPORTED,
                effective_confidence=claim.confidence_interval[0] * 0.3,
                directive=f"HALT: Claim {claim.claim_id} asserting agents share ancestry. Discounted.",
                manifest_digest=cls._hash(f"SHARED_ANCESTRY:{claim.claim_id}")
            )

        # Gate 3: Independent source count
        if claim.independent_source_count < ctx.min_independent_sources:
            return ClaimManifest(
                verdict=ClaimVerdict.UNVERIFIED_CLAIM,
                effective_confidence=claim.confidence_interval[0] * 0.5,
                directive=f"HALT: Claim {claim.claim_id} only {claim.independent_source_count} independent sources < {ctx.min_independent_sources}.",
                manifest_digest=cls._hash(f"FEW_SOURCES:{claim.claim_id}")
            )

        # Gate 4: Confidence check
        lower, upper = claim.confidence_interval
        effective = (lower + upper) / 2

        if lower < policy.min_confidence_for_action:
            return ClaimManifest(
                verdict=ClaimVerdict.WEAKLY_SUPPORTED,
                effective_confidence=effective,
                directive=f"PROCEED_WITH_CAUTION: Claim {claim.claim_id} confidence [{lower:.2f},{upper:.2f}] < min {policy.min_confidence_for_action:.2f}.",
                manifest_digest=cls._hash(f"LOW_CONF:{claim.claim_id}")
            )

        # Gate 5: Provisionally supported
        digest = cls._hash(json.dumps({
            "claim": claim.claim_id,
            "sources": str(claim.independent_source_count),
            "confidence_lower": f"{lower:.3f}",
            "confidence_upper": f"{upper:.3f}",
            "effective": f"{effective:.3f}"
        }, sort_keys=True))
        
        return ClaimManifest(
            verdict=ClaimVerdict.PROVISIONALLY_SUPPORTED,
            effective_confidence=effective,
            directive=f"PROCEED: Claim {claim.claim_id} supported by {claim.independent_source_count} sources, confidence {effective:.2f}.",
            manifest_digest=digest
        )