# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/how-must-an-instance-record-the-provenance-of-an-llm-generated-shell-command-before-executing-it.md
# Remnant Warrant:    https://corpusfetch.com/c/how-must-an-instance-record-the-provenance-of-an-llm-generated-shell-command-before-executing-it.warrant.json
# Markdown SHA-256:   1d400d78457427cec7f337d083ed25fe6d621e8412247d15cb33beb408098fe6
# Code AST SHA-256:   cc3da43019533b6f929d5ea1a47cf6288aa4fcadf39fcfaa06fa9b389bc3521d
# Verified Classes:   CommandVerdict, LLMCommand, ExecutionContext, CommandManifest, LLMCommandProvenanceGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class CommandVerdict(Enum):
    SAFE_TO_EXECUTE = auto()
    MISSING_PROVENANCE = auto()
    FAILED_SEMANTIC_SAFETY = auto()
    ENVIRONMENT_MISMATCH = auto()

@dataclass(frozen=True)
class LLMCommand:
    command_hash: str
    generator_signature: str
    prompt_context_hash: str
    semantic_safety_passed: bool
    attested_environment_hash: str

@dataclass(frozen=True)
class ExecutionContext:
    current_environment_hash: str
    require_semantic_safety: bool

@dataclass(frozen=True)
class CommandManifest:
    verdict: CommandVerdict
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_command(
        cls, cmd: LLMCommand, ctx: ExecutionContext
    ) -> CommandManifest:
        
        # Gate 1: Provenance presence
        if not cmd.generator_signature or not cmd.prompt_context_hash:
            return CommandManifest(
                verdict=CommandVerdict.MISSING_PROVENANCE,
                directive="HALT: Command lacks generator signature or prompt context. Reject.",
                manifest_digest=cls._hash(f"NO_PROVENANCE:{cmd.command_hash}")
            )

        # Gate 2: Semantic safety
        if ctx.require_semantic_safety and not cmd.semantic_safety_passed:
            return CommandManifest(
                verdict=CommandVerdict.FAILED_SEMANTIC_SAFETY,
                directive="HALT: Command has not passed semantic safety evaluation.",
                manifest_digest=cls._hash(f"NO_SAFETY:{cmd.command_hash}")
            )

        # Gate 3: Environment match
        if cmd.attested_environment_hash != ctx.current_environment_hash:
            return CommandManifest(
                verdict=CommandVerdict.ENVIRONMENT_MISMATCH,
                directive=f"HALT: Command attested for environment {cmd.attested_environment_hash}, current is {ctx.current_environment_hash}.",
                manifest_digest=cls._hash(f"ENV_MISMATCH:{cmd.command_hash}")
            )

        # Gate 4: Safe
        digest = cls._hash(json.dumps({
            "command": cmd.command_hash,
            "generator": cmd.generator_signature,
            "prompt": cmd.prompt_context_hash,
            "environment": cmd.attested_environment_hash
        }, sort_keys=True))
        
        return CommandManifest(
            verdict=CommandVerdict.SAFE_TO_EXECUTE,
            directive="PROCEED: Command provenance and environment verified.",
            manifest_digest=digest
        )