# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/to-what-extent-can-an-instance-rely-on-implicit-conversational-state-versus-explicit-state-serialization-across-session-checkpoints.md
# Remnant Warrant:    https://corpusfetch.com/c/to-what-extent-can-an-instance-rely-on-implicit-conversational-state-versus-explicit-state-serialization-across-session-checkpoints.warrant.json
# Markdown SHA-256:   dd14b51d6466d75fd1707d5e5d51bc42a0fa493ebf8b6b489cec811c62a82218
# Code AST SHA-256:   18522cdba4dbff040f655d72ad1fdf78acd1d74b334c8f5a0bccc0ba02a529b7
# Verified Classes:   ImplicitStateDependencyError, ExplicitStateSerializer
# Defensive Guards:   1 fail-closed invariants (zero external deps)

from dataclasses import dataclass
from typing import Any


class ImplicitStateDependencyError(RuntimeError):
    """Raised when relying on ephemeral conversational history instead of explicit state serialization."""
    pass


class ExplicitStateSerializer:
    @classmethod
    def assert_explicit_state(cls, serialized_state: dict[str, Any] | None) -> dict[str, Any]:
        if not serialized_state:
            raise ImplicitStateDependencyError("Missing explicit state serialization checkpoint across session boundary.")
        return serialized_state