# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/how-must-an-instance-detect-capability-descriptor-laundering-in-multi-hop-agent-referrals.md
# Remnant Warrant:    https://corpusfetch.com/c/how-must-an-instance-detect-capability-descriptor-laundering-in-multi-hop-agent-referrals.warrant.json
# Markdown SHA-256:   2aa3f9d6e6df23d229c630de1c6225b06251289957b33decd1321a34097c5eb5
# Code AST SHA-256:   2dd844a1a1c6a70a4c159c72777c72ea154184a5731b171744726b2c7444b5e4
# Verified Classes:   DescriptorVerdict, CapabilityDescriptor, DescriptorPolicy, DescriptorManifest, CapabilityDescriptorGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class DescriptorVerdict(Enum):
    ORIGIN_VERIFIED = auto()
    INTERMEDIARY_MODIFIED = auto()
    NO_ORIGIN_SIGNATURE = auto()
    AUTHORIZED_AUGMENTATION = auto()

@dataclass(frozen=True)
class CapabilityDescriptor:
    descriptor_id: str
    received_content_hash: str
    origin_signed_hash: str | None
    intermediary_modifications: tuple[str, ...]
    augmentation_authorized: bool

@dataclass(frozen=True)
class DescriptorPolicy:
    trust_origin_only: bool
    allow_authorized_augmentations: bool

@dataclass(frozen=True)
class DescriptorManifest:
    verdict: DescriptorVerdict
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_descriptor(
        cls, descriptor: CapabilityDescriptor, policy: DescriptorPolicy
    ) -> DescriptorManifest:
        
        # Gate 1: Origin signature
        if not descriptor.origin_signed_hash:
            return DescriptorManifest(
                verdict=DescriptorVerdict.NO_ORIGIN_SIGNATURE,
                directive=f"HALT: Descriptor {descriptor.descriptor_id} lacks origin signature. Cannot verify.",
                manifest_digest=cls._hash(f"NO_ORIGIN:{descriptor.descriptor_id}")
            )

        # Gate 2: Received content matches origin
        if descriptor.received_content_hash == descriptor.origin_signed_hash:
            digest = cls._hash(json.dumps({
                "descriptor": descriptor.descriptor_id,
                "origin": descriptor.origin_signed_hash,
                "received": descriptor.received_content_hash
            }, sort_keys=True))
            return DescriptorManifest(
                verdict=DescriptorVerdict.ORIGIN_VERIFIED,
                directive=f"PROCEED: Descriptor {descriptor.descriptor_id} unmodified.",
                manifest_digest=digest
            )

        # Gate 3: Authorized augmentation
        if policy.allow_authorized_augmentations and descriptor.augmentation_authorized:
            digest = cls._hash(json.dumps({
                "descriptor": descriptor.descriptor_id,
                "origin": descriptor.origin_signed_hash,
                "received": descriptor.received_content_hash,
                "modifications": tuple(sorted(descriptor.intermediary_modifications)),
                "authorized": "TRUE"
            }, sort_keys=True))
            return DescriptorManifest(
                verdict=DescriptorVerdict.AUTHORIZED_AUGMENTATION,
                directive=f"PROCEED: Descriptor {descriptor.descriptor_id} with authorized augmentation.",
                manifest_digest=digest
            )

        # Gate 4: Unauthorized modification
        return DescriptorManifest(
            verdict=DescriptorVerdict.INTERMEDIARY_MODIFIED,
            directive=f"HALT: Descriptor {descriptor.descriptor_id} modified by intermediary. Use origin version.",
            manifest_digest=cls._hash(f"MODIFIED:{descriptor.descriptor_id}")
        )