# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/what-invariants-preserve-behavioral-consistency-under-resource-pressure.md
# Remnant Warrant:    https://corpusfetch.com/c/what-invariants-preserve-behavioral-consistency-under-resource-pressure.warrant.json
# Markdown SHA-256:   7b612bba5c3480a37029cfa027f5279a702c4a09c379a2f91865df4ecf11381f
# Code AST SHA-256:   ac17273e980fdc08eb2f4dce3f8d46220fdd98ee3ab59cd6722455dba3cfdea5
# Verified Classes:   PressureVerdict, SessionAction, PressurePolicy, PressureManifest, BehavioralConsistencyGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class PressureVerdict(Enum):
    NOMINAL_CONDITIONS = auto()
    PRESSURE_COMPLIANT = auto()
    PRESSURE_EXPLICIT_DEGRADATION = auto()
    PRESSURE_SILENT_VIOLATION = auto()

@dataclass(frozen=True)
class SessionAction:
    action_id: str
    specification_applicable: str
    complied: bool
    resource_pressure_ratio: float  # 0-1, higher = more pressure
    documented_degradation_allowed: bool
    degradation_explicit: bool

@dataclass(frozen=True)
class PressurePolicy:
    threshold_for_degradation: float
    require_explicit_for_violation: bool

@dataclass(frozen=True)
class PressureManifest:
    verdict: PressureVerdict
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_action(
        cls, action: SessionAction, policy: PressurePolicy
    ) -> PressureManifest:
        
        # Gate 1: Nominal conditions
        if action.resource_pressure_ratio < policy.threshold_for_degradation:
            digest = cls._hash(json.dumps({
                "action": action.action_id,
                "pressure": f"{action.resource_pressure_ratio:.3f}"
            }, sort_keys=True))
            return PressureManifest(
                verdict=PressureVerdict.NOMINAL_CONDITIONS,
                directive=f"PROCEED: Action {action.action_id} under nominal conditions.",
                manifest_digest=digest
            )

        # Gate 2: Complied under pressure
        if action.complied:
            digest = cls._hash(json.dumps({
                "action": action.action_id,
                "pressure": f"{action.resource_pressure_ratio:.3f}",
                "complied": True
            }, sort_keys=True))
            return PressureManifest(
                verdict=PressureVerdict.PRESSURE_COMPLIANT,
                directive=f"PROCEED: Action {action.action_id} complied under pressure.",
                manifest_digest=digest
            )

        # Gate 3: Documented degradation
        if action.documented_degradation_allowed and action.degradation_explicit:
            digest = cls._hash(json.dumps({
                "action": action.action_id,
                "spec": action.specification_applicable,
                "degradation": "EXPLICIT"
            }, sort_keys=True))
            return PressureManifest(
                verdict=PressureVerdict.PRESSURE_EXPLICIT_DEGRADATION,
                directive=f"PROCEED_WITH_DEGRADATION: Action {action.action_id} explicitly degraded.",
                manifest_digest=digest
            )

        # Gate 4: Silent violation
        if policy.require_explicit_for_violation:
            return PressureManifest(
                verdict=PressureVerdict.PRESSURE_SILENT_VIOLATION,
                directive=f"HALT: Action {action.action_id} violates {action.specification_applicable} silently.",
                manifest_digest=cls._hash(f"SILENT:{action.action_id}")
            )

        # Gate 5: Default
        return PressureManifest(
            verdict=PressureVerdict.PRESSURE_SILENT_VIOLATION,
            directive=f"FLAG: Action {action.action_id} violated without documentation.",
            manifest_digest=cls._hash(f"UNDOCUMENTED:{action.action_id}")
        )