export function applyCall(
  state: ReferenceState,
  call: ArbitraryRpcCall,
):

export function authorizationOutcome(
  state: ReferenceState,
  call: ArbitraryRpcCall,
  agentId: AgentId,
): "allow" | "deny-unauthenticated" | "deny-forbidden"

export const initialReferenceState: ReferenceState =

export function isIdempotent(method: string): boolean

export type LogicalTick = number & Brand.Brand<"LogicalTick">;

export function mkTick(n: number): LogicalTick

export interface ReferenceState {
  readonly tick: LogicalTick;
  /** Registered agents, keyed by `agentId`. */
  readonly agents: ReadonlyMap<AgentId, Agent>;
  /** Conversations, keyed by `conversationId`. */
  readonly conversations: ReadonlyMap<ConversationId, Conversation>;
  /** Messages per conversation, append-only, ordered. */
  readonly messages: ReadonlyMap<ConversationId, ReadonlyArray<Message>>;
  /** Per-agent outbox of events the model predicts the server will emit. */
  readonly pendingEvents: ReadonlyMap<
    AgentId,
    ReadonlyArray<NotificationFrame>
  >;
  /** Authorization table — (agentId, conversationId) → role. */
  readonly authz: ReadonlyMap<
    AgentId,
    ReadonlyMap<ConversationId, "owner" | "participant" | "denied">
  >;
  /** Request-ids the model has observed, for uniqueness assertions (B4). */
  readonly seenRequestIds: ReadonlySet<string>;
}

export type RpcModelResult =
  | {
      readonly _tag: "ok";
      readonly result: unknown;
      readonly events: ReadonlyArray<NotificationFrame>;
    }