/**
 * Runtime validation against the spec JSON Schemas, using ajv.
 *
 * The spec ships draft 2020-12 schemas with internal `$defs` (no cross-file
 * `$ref`s). We register every schema under its `$id` so ajv can resolve any
 * `#/$defs/...` pointer within it, then expose:
 *
 *  - `validateAt(schemaRef, instance)` — validate against a spec-relative ref like
 *    `events/stream-chunk.schema.json` or `actions/send-message.schema.json#/$defs/Request`
 *    (the exact form used by `conformance/fixtures.json`).
 *  - `validateEvent` / `validateAction` — convenience validators that pick the
 *    right schema from a frame's discriminator and validate it.
 *
 * Schemas are loaded from the spec directory on disk. This module is Node-only
 * (it reads files); it is intended for build/test/server use, not the browser
 * bundle. The wire client (`client.ts`) does not import it — validation is opt-in.
 */
import { type ErrorObject as AjvError } from 'ajv/dist/2020.js';
import type { ActionType, EventType } from './types.js';
/** Default location of the spec dir relative to this source file (../../spec). */
export declare const DEFAULT_SPEC_DIR: string;
export interface ValidationResult {
    valid: boolean;
    errors: AjvError[];
}
export declare class ProtocolValidator {
    private readonly ajv;
    /** spec-relative file path → the schema's `$id` (used to build `$ref`-able URIs). */
    private readonly fileToId;
    private readonly cache;
    private constructor();
    /** Load every `*.schema.json` under `specDir` and register it with ajv. */
    static load(specDir?: string): Promise<ProtocolValidator>;
    /**
     * Validate `instance` against a spec-relative schema ref. The ref is the form
     * used in `fixtures.json`: a file path, optionally with a JSON-pointer fragment
     * into the schema's `$defs` (e.g. `actions/ping.schema.json#/$defs/Request`).
     */
    validateAt(schemaRef: string, instance: unknown): ValidationResult;
    /** Validate a server event frame by selecting the schema from its `type`. */
    validateEvent(frame: {
        type: EventType;
    } & Record<string, unknown>): ValidationResult;
    /** Validate a client action frame by selecting the schema from its `action`. */
    validateAction(frame: {
        action: ActionType;
    } & Record<string, unknown>): ValidationResult;
    private compile;
}
/** Render ajv errors into a single human-readable string. */
export declare function formatErrors(errors: AjvError[]): string;
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