/**
 * The one place a prompt variable becomes the string the prompt compiler
 * substitutes. Both a code-supplied `variables` map and the arguments a parent
 * model passes to a typed delegation tool go through it, so a variable a
 * subagent receives from the model compiles exactly like one written in code.
 */
export declare function stringifyPromptVariables(variables: Record<string, unknown>): Record<string, string>;