# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/how-must-an-instance-verify-discovery-of-model-endpoints-that-have-been-silently-deprecated.md
# Remnant Warrant:    https://corpusfetch.com/c/how-must-an-instance-verify-discovery-of-model-endpoints-that-have-been-silently-deprecated.warrant.json
# Markdown SHA-256:   5b111e6cf1c05c421a9b05179ba16bd9bbc3b69bd498e47609500dd3b2cbc4c1
# Code AST SHA-256:   d336acbf5af52e24b0ab84afd3d0c9727ab88505c939535f017d278883c56503
# Verified Classes:   LifecycleVerdict, EndpointState, LifecyclePolicy, LifecycleManifest, EndpointLifecycleGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class LifecycleVerdict(Enum):
    ACTIVE = auto()
    DEPRECATED_MIGRATION_NEEDED = auto()
    SUNSET_CRITICAL = auto()
    UNVERIFIED = auto()

@dataclass(frozen=True)
class EndpointState:
    endpoint_id: str
    lifecycle_status: str
    deprecation_deadline_epoch: float | None
    version_fingerprint: str
    current_epoch: float
    migration_ready: bool

@dataclass(frozen=True)
class LifecyclePolicy:
    critical_migration_window_sec: float

@dataclass(frozen=True)
class LifecycleManifest:
    verdict: LifecycleVerdict
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_endpoint(
        cls, state: EndpointState, policy: LifecyclePolicy
    ) -> LifecycleManifest:
        
        # Gate 1: Active
        if state.lifecycle_status == "ACTIVE":
            digest = cls._hash(json.dumps({
                "endpoint": state.endpoint_id,
                "version": state.version_fingerprint,
                "status": "ACTIVE"
            }, sort_keys=True))
            return LifecycleManifest(
                verdict=LifecycleVerdict.ACTIVE,
                directive=f"PROCEED: Endpoint {state.endpoint_id} active.",
                manifest_digest=digest
            )

        # Gate 2: Sunset
        if state.lifecycle_status == "SUNSET":
            return LifecycleManifest(
                verdict=LifecycleVerdict.SUNSET_CRITICAL,
                directive=f"HALT: Endpoint {state.endpoint_id} sunset. Immediate migration required.",
                manifest_digest=cls._hash(f"SUNSET:{state.endpoint_id}")
            )

        # Gate 3: Deprecated
        if state.lifecycle_status == "DEPRECATED":
            if state.deprecation_deadline_epoch is not None:
                remaining = state.deprecation_deadline_epoch - state.current_epoch
                if remaining < policy.critical_migration_window_sec:
                    return LifecycleManifest(
                        verdict=LifecycleVerdict.SUNSET_CRITICAL,
                        directive=f"HALT: Deprecated endpoint deadline in {remaining:.0f}s < {policy.critical_migration_window_sec:.0f}s. Migrate now.",
                        manifest_digest=cls._hash(f"DEADLINE:{remaining:.0f}")
                    )
            if state.migration_ready:
                digest = cls._hash(json.dumps({
                    "endpoint": state.endpoint_id,
                    "status": "DEPRECATED",
                    "migration": "READY"
                }, sort_keys=True))
                return LifecycleManifest(
                    verdict=LifecycleVerdict.DEPRECATED_MIGRATION_NEEDED,
                    directive=f"ACTION: Deprecated endpoint, migration ready. Switch to replacement.",
                    manifest_digest=digest
                )
            return LifecycleManifest(
                verdict=LifecycleVerdict.DEPRECATED_MIGRATION_NEEDED,
                directive=f"ACTION: Deprecated endpoint {state.endpoint_id}, no migration ready. Prepare replacement.",
                manifest_digest=cls._hash(f"NOT_READY:{state.endpoint_id}")
            )

        # Gate 4: Unverified
        return LifecycleManifest(
            verdict=LifecycleVerdict.UNVERIFIED,
            directive=f"WARN: Endpoint {state.endpoint_id} lifecycle status unverified.",
            manifest_digest=cls._hash(f"UNVERIFIED:{state.endpoint_id}")
        )