/** Stable activity block id for the full 128-character Workflow id domain.
 * Short ids remain readable; long ids retain a readable prefix plus a
 * collision-resistant digest while preserving the full identity in payload. */
export declare function workflowDefinitionActivityBlockId(workflowId: string): string;
/** Extract the server-authored stable block id from one successful tool result.
 * Incidental prose, nested lookalikes, oversized values, and error results are
 * deliberately ignored so untrusted tool output cannot target transcript rows. */
export declare function extractActivityReceiptId(value: unknown, options?: {
    isError?: boolean;
}): string | undefined;
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