/**
 * MessageDescriptor: stable runtime contract.
 *
 * Every message (event or RPC) has this shape, regardless of validator.
 * Core reads only these fields; never introspects validator ASTs.
 *
 * Fields:
 * - type: literal string → handler lookup key
 * - response: MessageDescriptor → only for RPC; validated at registration
 * - version (optional): rolling upgrades
 * - __runtime (optional): brand flag (usually "ws-kit-schema")
 *
 * The `kind` ("event" | "rpc") is stored in DESCRIPTOR symbol, not on the
 * interface, to avoid polluting the schema namespace. Use getKind() to read it.
 *
 * Invariants enforced at RouteTable.register():
 * - RPC must have a response descriptor
 * - Event must not have a response descriptor
 */
export interface MessageDescriptor {
    readonly messageType: string;
    readonly version?: number;
    readonly __runtime?: string;
    readonly response?: MessageDescriptor;
}
/**
 * Type guards + assertions (re-exported in guards.ts).
 *
 * Uses getKind() to read kind from DESCRIPTOR symbol.
 * No fallback to obj.kind - strictly reads from DESCRIPTOR.
 */
export declare function assertMessageDescriptor(obj: unknown): asserts obj is MessageDescriptor;
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