/** True for a plain (non-array) object; the shape every native record must have. */
export declare function isRecord(value: unknown): value is Record<string, unknown>;
/** Narrow to a record or throw a dialect error attributing the harness. */
export declare function asRecord(harness: string, value: unknown): Record<string, unknown>;
/** Read a required string field or throw a dialect error. */
export declare function reqString(harness: string, obj: Record<string, unknown>, field: string): string;
/** Read an optional string field (undefined when absent), throwing on a wrong type. */
export declare function optString(harness: string, obj: Record<string, unknown>, field: string): string | undefined;
/** Read an optional finite number field, coercing absent/null to `undefined`. */
export declare function optNumber(harness: string, obj: Record<string, unknown>, field: string): number | undefined;
/** Narrow to an array or throw a dialect error. */
export declare function asArray(harness: string, value: unknown, what: string): readonly unknown[];
/**
 * Collapse a message-content value to plain text. Harnesses model an assistant
 * message either as a bare string or as an array of typed content parts
 * (`{ type: "text", text }`); we concatenate the text parts and ignore the rest
 * (tool-use parts are lifted to their own events by the dialect). Returns
 * `undefined` when there is no text to emit so the dialect can skip an empty
 * message.
 */
export declare function contentText(value: unknown): string | undefined;