/**
 * Variable resolver for pipeline steps.
 *
 * Resolves:
 * - $step_id.output  → output path from a previous step
 * - $step_id.data.X  → arbitrary data from a previous step result
 * - ${ENV_VAR}       → environment variable
 */
import type { StepResult } from "./types.js";
/**
 * Resolve all variable references in a step's parameters.
 * Returns a new object with all $refs replaced by actual values.
 */
export declare function resolveStepParams(params: Record<string, unknown>, completedSteps: Map<string, StepResult>): Record<string, unknown>;
/**
 * Validate that all $refs in a step can be resolved.
 * Returns list of unresolvable references.
 */
export declare function findUnresolvedRefs(params: Record<string, unknown>, availableStepIds: Set<string>): string[];
