# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/how-must-an-instance-record-the-provenance-of-a-vector-index-to-prevent-poisoning-via-adversarial-embeddings.md
# Remnant Warrant:    https://corpusfetch.com/c/how-must-an-instance-record-the-provenance-of-a-vector-index-to-prevent-poisoning-via-adversarial-embeddings.warrant.json
# Markdown SHA-256:   a626b138dec799b952d723b6372e0244f50afd97382429d84dcdd2c5c537ca20
# Code AST SHA-256:   c42030a8a26187b61b5ba787d21f7d380ce37704be67671b0b6bf0ff6a5a97b8
# Verified Classes:   VectorVerdict, VectorEmbedding, VectorContext, VectorManifest, VectorProvenanceGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class VectorVerdict(Enum):
    VERIFIED_CLEAN = auto()
    POISONING_RISK = auto()
    UNVERIFIED_SOURCE = auto()

@dataclass(frozen=True)
class VectorEmbedding:
    vector_hash: str
    source_attestation_hash: str | None
    adversarial_detector_passed: bool
    ingestion_batch_id: str

@dataclass(frozen=True)
class VectorContext:
    trusted_source_attestations: frozenset[str]

@dataclass(frozen=True)
class VectorManifest:
    verdict: VectorVerdict
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_embedding(
        cls, vector: VectorEmbedding, ctx: VectorContext
    ) -> VectorManifest:
        
        # Gate 1: Source attestation presence
        if not vector.source_attestation_hash:
            return VectorManifest(
                verdict=VectorVerdict.UNVERIFIED_SOURCE,
                directive="HALT: No source attestation. Quarantine vector.",
                manifest_digest=cls._hash(f"NO_ATTEST:{vector.vector_hash}")
            )

        # Gate 2: Source attestation trust
        if vector.source_attestation_hash not in ctx.trusted_source_attestations:
            return VectorManifest(
                verdict=VectorVerdict.UNVERIFIED_SOURCE,
                directive=f"HALT: Source attestation {vector.source_attestation_hash} is not in trusted set.",
                manifest_digest=cls._hash(f"UNTRUSTED_SOURCE:{vector.vector_hash}")
            )

        # Gate 3: Adversarial detector check
        if not vector.adversarial_detector_passed:
            return VectorManifest(
                verdict=VectorVerdict.POISONING_RISK,
                directive=f"HALT: Vector {vector.vector_hash} failed adversarial detection. Reject batch {vector.ingestion_batch_id}.",
                manifest_digest=cls._hash(f"ADVERSARIAL:{vector.vector_hash}")
            )

        # Gate 4: Verified
        digest = cls._hash(json.dumps({
            "vector": vector.vector_hash,
            "source": vector.source_attestation_hash,
            "batch": vector.ingestion_batch_id
        }, sort_keys=True))
        
        return VectorManifest(
            verdict=VectorVerdict.VERIFIED_CLEAN,
            directive="PROCEED: Vector provenance verified and adversarial check passed.",
            manifest_digest=digest
        )