# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/what-sensor-attestation-proofs-must-accompany-physical-actuator-commands-in-autonomous-robotics.md
# Remnant Warrant:    https://corpusfetch.com/c/what-sensor-attestation-proofs-must-accompany-physical-actuator-commands-in-autonomous-robotics.warrant.json
# Markdown SHA-256:   1cdeb3c0b9283bab9557d5fd84529a04c04645f8168c3fc6e705810833135897
# Code AST SHA-256:   2bde230e72aab1778e7a09dfa865ed6f7fafae87797e8f2b84c3cd466a5f0bd0
# Verified Classes:   ActuatorVerdict, SensorReading, ActuatorCommand, ActuationManifest, HardwareRootOfTrustGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class ActuatorVerdict(Enum):
    SAFE_TO_ACTUATE = auto()
    HALT_SPOOFING_DETECTED = auto()
    HALT_SENSOR_DEGRADED = auto()
    HALT_NO_ATTESTATION = auto()

@dataclass(frozen=True)
class SensorReading:
    sensor_id: str
    raw_data_hash: str
    attestation_signature: str | None
    health_receipt_hash: str | None

@dataclass(frozen=True)
class ActuatorCommand:
    command_id: str
    nonce: str
    expected_sensor_id: str

@dataclass(frozen=True)
class ActuationManifest:
    verdict: ActuatorVerdict
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_actuation(
        cls, reading: SensorReading, command: ActuatorCommand
    ) -> ActuationManifest:
        
        # Gate 1: Hardware attestation presence
        if not reading.attestation_signature:
            return ActuationManifest(
                verdict=ActuatorVerdict.HALT_NO_ATTESTATION,
                directive="HALT: Sensor reading lacks hardware attestation. Engage physical failsafe.",
                manifest_digest=cls._hash(f"NO_ATTEST:{command.command_id}")
            )

        # Gate 2: Sensor health
        if not reading.health_receipt_hash:
            return ActuationManifest(
                verdict=ActuatorVerdict.HALT_SENSOR_DEGRADED,
                directive="HALT: Sensor health receipt missing. Potential hardware tampering.",
                manifest_digest=cls._hash(f"DEGRADED:{reading.sensor_id}")
            )

        # Gate 3: Sensor identity match
        if reading.sensor_id != command.expected_sensor_id:
            return ActuationManifest(
                verdict=ActuatorVerdict.HALT_SPOOFING_DETECTED,
                directive=f"HALT: Command expected sensor {command.expected_sensor_id}, received {reading.sensor_id}.",
                manifest_digest=cls._hash(f"SENSOR_MISMATCH:{command.command_id}")
            )

        # Gate 4: Safe to actuate
        digest = cls._hash(json.dumps({
            "command": command.command_id,
            "sensor": reading.sensor_id,
            "nonce": command.nonce,
            "attestation": reading.attestation_signature
        }, sort_keys=True))
        
        return ActuationManifest(
            verdict=ActuatorVerdict.SAFE_TO_ACTUATE,
            directive="PROCEED: Hardware root of trust verified. Execute actuator command.",
            manifest_digest=digest
        )