# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/what-immutable-ledger-invariants-must-survive-an-agents-bankruptcy-or-account-closure.md
# Remnant Warrant:    https://corpusfetch.com/c/what-immutable-ledger-invariants-must-survive-an-agents-bankruptcy-or-account-closure.warrant.json
# Markdown SHA-256:   05c60ae9244fe8f9d6d666d2190bf4375b688eb6d3c4a4a10b93b8e383c0d1d9
# Code AST SHA-256:   9b4ba6338cce39dfa28e6f56d85575fbe62b6f6c409b311f9e63aee74fc499e3
# Verified Classes:   ClosureVerdict, LedgerObligation, ClosureState, ClosureManifest, LedgerClosureGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class ClosureVerdict(Enum):
    CLEAN_CLOSURE = auto()
    LIABILITIES_UNRESOLVED = auto()
    ARBITRATION_REQUIRED = auto()

@dataclass(frozen=True)
class LedgerObligation:
    obligation_id: str
    counterparty_id: str
    amount: int
    is_escrowed: bool

@dataclass(frozen=True)
class ClosureState:
    outstanding_obligations: tuple[LedgerObligation, ...]
    successor_arbitration_key: str | None

@dataclass(frozen=True)
class ClosureManifest:
    verdict: ClosureVerdict
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_closure(cls, state: ClosureState) -> ClosureManifest:
        
        # Gate 1: No obligations
        if not state.outstanding_obligations:
            return ClosureManifest(
                verdict=ClosureVerdict.CLEAN_CLOSURE,
                directive="PROCEED: No outstanding obligations. Account may be closed.",
                manifest_digest=cls._hash("CLEAN")
            )

        # Gate 2: Escrowed funds must be resolved or transferred
        for obligation in state.outstanding_obligations:
            if obligation.is_escrowed and not state.successor_arbitration_key:
                return ClosureManifest(
                    verdict=ClosureVerdict.ARBITRATION_REQUIRED,
                    directive=f"HALT: Obligation {obligation.obligation_id} is escrowed but no successor key provided.",
                    manifest_digest=cls._hash(f"ESCROW_NO_KEY:{obligation.obligation_id}")
                )

        # Gate 3: Unresolved debts require arbitration key
        if not state.successor_arbitration_key:
            return ClosureManifest(
                verdict=ClosureVerdict.LIABILITIES_UNRESOLVED,
                directive=f"HALT: {len(state.outstanding_obligations)} outstanding liabilities require a successor arbitration key.",
                manifest_digest=cls._hash("NO_ARBITER")
            )

        # Gate 4: Transfer to arbitration
        digest = cls._hash(json.dumps({
            "obligations": str(len(state.outstanding_obligations)),
            "arbiter": state.successor_arbitration_key
        }, sort_keys=True))
        
        return ClosureManifest(
            verdict=ClosureVerdict.ARBITRATION_REQUIRED,
            directive=f"ACTION: Transfer all obligations to {state.successor_arbitration_key}. Record closure signature.",
            manifest_digest=digest
        )