/**
 * Matrix (cross-product) expansion for experiment configs.
 *
 * A `matrix:` block declares one or more named axes, each of which overrides
 * a single whole-field config path with a list of values. Expansion produces
 * the full cartesian product as the standard `variants` map, plus a derived
 * `baseline` (string) and `vary` (array), so the resolver and every layer
 * downstream never has to know matrix existed.
 *
 * Surface:
 *
 * ```yaml
 * matrix:
 *   model:
 *     path: /defaults/model
 *     values: [gpt-5, claude-sonnet-4.6]
 *   skills:
 *     path: /environment/skills
 *     values:
 *       - none: []
 *       - matched: ["plugins/${eval.parent}/skills/*"]
 * baseline: { model: gpt-5, skills: none }
 * ```
 */
import type { VariantOverride } from "./types.js";
/** Result of expanding a `matrix:` block. */
export interface ExpandedMatrix {
    variants: Record<string, VariantOverride>;
    baseline: string;
    vary: string[];
}
/**
 * The subset of a parsed experiment spec that {@link expandMatrix} reads. Both
 * fields hold the raw `parseYaml` output and are validated at runtime — the
 * types document which keys are consulted, not a guarantee of their shape.
 */
export interface MatrixSpec {
    /** The raw `matrix:` block: a map of axis name → `{ path, values }`. */
    matrix?: unknown;
    /** The raw `baseline:` block: a map of axis name → value label. */
    baseline?: unknown;
}
/**
 * Expand the `matrix` block of a parsed experiment spec into variants,
 * baseline, and vary. Reads `spec.matrix` and `spec.baseline`.
 *
 * This performs matrix-specific validation only; the generated `variants` /
 * `baseline` / `vary` are re-validated by {@link loadExperimentConfig}, which
 * is the supported entry point. Throws {@link ExperimentValidationError} on
 * any invalid input.
 */
export declare function expandMatrix(spec: MatrixSpec): ExpandedMatrix;
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