/**
 * Differential harness — three-way parity gate.
 *
 *                      IR fixture
 *                          |
 *             +------------+------------+
 *             |            |            |
 *       ReferenceRunner  TS emitter  Python emitter
 *             |            |            |
 *          Trace_R      Trace_TS     Trace_PY
 *             |            |            |
 *             +------------+------------+
 *                          |
 *                   verdict: R == TS == PY ?
 *
 * Phase 1 (PR-1) ships the harness skeleton with two stub legs — `runTsEmitter`
 * and `runPythonEmitter` throw until PR-3 wires them. The reference leg works
 * but has no contracts to dispatch to until PR-2.
 */
import { type NodeFixture, type SemanticEnv } from './index.js';
import { type Trace } from './trace.js';
export type Verdict = 'pass' | 'reference-mismatch' | 'ts-divergence' | 'python-divergence' | 'three-way-divergence' | 'leg-error';
export interface DifferentialResult {
    fixture: NodeFixture;
    verdict: Verdict;
    reference?: Trace;
    ts?: Trace;
    python?: Trace;
    /** Populated when verdict is `leg-error` — which leg threw and why. */
    legError?: {
        leg: 'reference' | 'ts' | 'python';
        message: string;
    };
}
export interface DifferentialOptions {
    /**
     * Skip the Python leg. Useful during PR-3a when the Python leg isn't
     * provided. PR-3b ships the leg via the `pythonLeg` callback below.
     */
    skipPython?: boolean;
    /**
     * Skip the TS leg. Symmetric with skipPython; rarely used.
     */
    skipTs?: boolean;
    /**
     * PR-3b — Python leg runner injected from `@kernlang/python` (the core
     * package can't depend on fastapi without a circular import, so the
     * Python leg lives in fastapi and is passed in here). When omitted AND
     * `skipPython !== true`, the harness falls back to throwing "not wired",
     * which the harness records as `leg-error`.
     */
    pythonLeg?: (fixture: NodeFixture, env: SemanticEnv) => Promise<Trace>;
}
/**
 * Run one fixture through up to three legs and compare against `fixture.expected`.
 *
 * Decision order:
 *   1. If reference != expected → `reference-mismatch` (contract or fixture bug).
 *   2. If TS != reference and Python != reference → `three-way-divergence`.
 *   3. If only TS diverges → `ts-divergence`. Only Python → `python-divergence`.
 *   4. Any leg throws → `leg-error` with the offending leg recorded.
 */
export declare function runDifferential(fixture: NodeFixture, opts?: DifferentialOptions): Promise<DifferentialResult>;
/** Run every fixture from every registered contract. */
export declare function runAllContracts(opts?: DifferentialOptions): Promise<DifferentialResult[]>;