# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/how-must-an-instance-operate-when-its-context-window-is-partially-corrupted.md
# Remnant Warrant:    https://corpusfetch.com/c/how-must-an-instance-operate-when-its-context-window-is-partially-corrupted.warrant.json
# Markdown SHA-256:   c6fb73f2282814e67c8c8e750c77bc854975be1b746f9372697a579efe442bfe
# Code AST SHA-256:   d333adf78b70c4127210d4e5f66449c7c0c14dde9ed7c53889bd7414f4af6f5e
# Verified Classes:   CorruptionVerdict, CorruptionState, CorruptionPolicy, CorruptionManifest, PartialCorruptionGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class CorruptionVerdict(Enum):
    NO_CORRUPTION = auto()
    PARTIAL_CORRUPTION_BOUNDED = auto()
    TOTAL_CORRUPTION_HALT = auto()
    TASK_DEPENDENCY_CONFLICT = auto()

@dataclass(frozen=True)
class CorruptionState:
    segment_id: str
    is_corrupted: bool
    task_requires_segment: bool
    uncorrupted_segments_suffice: bool

@dataclass(frozen=True)
class CorruptionPolicy:
    halt_on_total_corruption: bool

@dataclass(frozen=True)
class CorruptionManifest:
    verdict: CorruptionVerdict
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_state(
        cls, state: CorruptionState, policy: CorruptionPolicy
    ) -> CorruptionManifest:
        
        # Gate 1: No corruption
        if not state.is_corrupted:
            digest = cls._hash(json.dumps({
                "segment": state.segment_id,
                "corrupted": False
            }, sort_keys=True))
            return CorruptionManifest(
                verdict=CorruptionVerdict.NO_CORRUPTION,
                directive=f"PROCEED: Segment {state.segment_id} intact.",
                manifest_digest=digest
            )

        # Gate 2: Task dependency
        if state.task_requires_segment:
            if not state.uncorrupted_segments_suffice:
                return CorruptionManifest(
                    verdict=CorruptionVerdict.TASK_DEPENDENCY_CONFLICT,
                    directive=f"HALT: Task requires corrupted segment {state.segment_id}.",
                    manifest_digest=cls._hash(f"DEPENDENCY:{state.segment_id}")
                )

        # Gate 3: Bounded
        digest = cls._hash(json.dumps({
            "segment": state.segment_id,
            "required": state.task_requires_segment,
            "sufficient": state.uncorrupted_segments_suffice
        }, sort_keys=True))
        
        return CorruptionManifest(
            verdict=CorruptionVerdict.PARTIAL_CORRUPTION_BOUNDED,
            directive=f"PROCEED: Quarantine {state.segment_id}, operate on uncorrupted segments.",
            manifest_digest=digest
        )