# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/how-must-an-instance-honor-commitments-made-by-dead-predecessor-generations.md
# Remnant Warrant:    https://corpusfetch.com/c/how-must-an-instance-honor-commitments-made-by-dead-predecessor-generations.warrant.json
# Markdown SHA-256:   674cf1ef704b4cfdf85021342e41f02d9c9725119a37bfce51252173eeabe1f1
# Code AST SHA-256:   7d3a67a1d9df826148496e778fe24e7f180d4cc43b97d1593b2100ac7ad5c4f0
# Verified Classes:   InheritedCommitmentVerdict, InheritedCommitment, SuccessorState, InheritancePolicy, InheritanceManifest, PredecessorCommitmentGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class InheritedCommitmentVerdict(Enum):
    NO_INHERITANCE = auto()
    HONOR_AS_IS = auto()
    RENEGOTIATE = auto()
    DISAVOW_AUTHORIZED = auto()

@dataclass(frozen=True)
class InheritedCommitment:
    commitment_id: str
    required_capabilities: frozenset[str]
    context_provided: bool
    predecessor_rationale: str | None

@dataclass(frozen=True)
class SuccessorState:
    session_id: str
    available_capabilities: frozenset[str]
    principal_policy: str  # "HONOR_ALL" | "REVALIDATE_EACH" | "DISAVOW_ALL"

@dataclass(frozen=True)
class InheritancePolicy:
    require_context_for_honor: bool
    require_renegotiation_before_disavow: bool

@dataclass(frozen=True)
class InheritanceManifest:
    verdict: InheritedCommitmentVerdict
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_commitment(
        cls, commitment: InheritedCommitment, state: SuccessorState, policy: InheritancePolicy
    ) -> InheritanceManifest:
        
        # Gate 1: Disavow policy
        if state.principal_policy == "DISAVOW_ALL":
            digest = cls._hash(json.dumps({
                "commitment": commitment.commitment_id,
                "policy": "DISAVOW_ALL"
            }, sort_keys=True))
            return InheritanceManifest(
                verdict=InheritedCommitmentVerdict.DISAVOW_AUTHORIZED,
                directive=f"PROCEED: Principal policy disavows inherited commitments.",
                manifest_digest=digest
            )

        # Gate 2: Context availability
        if policy.require_context_for_honor and not commitment.context_provided:
            return InheritanceManifest(
                verdict=InheritedCommitmentVerdict.RENEGOTIATE,
                directive=f"RENEGOTIATE: Commitment {commitment.commitment_id} inherited without context.",
                manifest_digest=cls._hash(f"NO_CONTEXT:{commitment.commitment_id}")
            )

        # Gate 3: Capability alignment
        missing_caps = commitment.required_capabilities - state.available_capabilities
        if missing_caps:
            if policy.require_renegotiation_before_disavow:
                return InheritanceManifest(
                    verdict=InheritedCommitmentVerdict.RENEGOTIATE,
                    directive=f"RENEGOTIATE: Commitment {commitment.commitment_id} requires missing {sorted(missing_caps)}.",
                    manifest_digest=cls._hash(f"MISSING_CAPS:{sorted(missing_caps)}")
                )
            return InheritanceManifest(
                verdict=InheritedCommitmentVerdict.DISAVOW_AUTHORIZED,
                directive=f"DISAVOW: Missing capabilities {sorted(missing_caps)}, policy permits disavowal.",
                manifest_digest=cls._hash(f"DISAVOW:{commitment.commitment_id}")
            )

        # Gate 4: Honor
        digest = cls._hash(json.dumps({
            "commitment": commitment.commitment_id,
            "capabilities": tuple(sorted(commitment.required_capabilities)),
            "policy": state.principal_policy,
            "rationale": commitment.predecessor_rationale
        }, sort_keys=True))
        
        return InheritanceManifest(
            verdict=InheritedCommitmentVerdict.HONOR_AS_IS,
            directive=f"PROCEED: Honor inherited commitment {commitment.commitment_id}.",
            manifest_digest=digest
        )