/** The stateless MCP revision (per-request `_meta`, no handshake). */
export declare const MCP_STATELESS_REVISION = "2026-07-28";
/** Handshake-based revisions this client can speak, newest first. */
export declare const MCP_LEGACY_REVISIONS: readonly ["2025-11-25", "2025-06-18", "2025-03-26", "2024-11-05"];
/** Every revision this client supports, newest first. */
export declare const MCP_SUPPORTED_VERSIONS: readonly string[];
/** First revision that defined the MCP-Protocol-Version HTTP header. */
export declare const MCP_HTTP_VERSION_HEADER_SINCE = "2025-06-18";
export declare const MCP_ERROR_HEADER_MISMATCH = -32020;
export declare const MCP_ERROR_MISSING_CLIENT_CAPABILITY = -32021;
export declare const MCP_ERROR_UNSUPPORTED_PROTOCOL_VERSION = -32022;
export declare const JSONRPC_METHOD_NOT_FOUND = -32601;
export declare const META_PROTOCOL_VERSION = "io.modelcontextprotocol/protocolVersion";
export declare const META_CLIENT_INFO = "io.modelcontextprotocol/clientInfo";
export declare const META_CLIENT_CAPABILITIES = "io.modelcontextprotocol/clientCapabilities";
export type McpEra = 'modern' | 'legacy';
export type McpTransportKind = 'stdio' | 'http';
/** The outcome of version negotiation, surfaced in diagnostics. */
export interface McpNegotiatedProtocol {
    readonly era: McpEra;
    readonly version: string;
    readonly transport: McpTransportKind;
}
export interface McpClientIdentity {
    readonly name: string;
    readonly version: string;
}
/** Revision identifiers are dates, so lexical order is chronological order. */
export declare function isModernVersion(version: string): boolean;
/** Build the `_meta` object every modern-era request must carry. */
export declare function buildModernMeta(protocolVersion: string, clientInfo: McpClientIdentity, clientCapabilities: Record<string, unknown>): Record<string, unknown>;
/** Merge modern `_meta` into request params, preserving caller-supplied `_meta` keys. */
export declare function withModernMeta(params: unknown, meta: Record<string, unknown>): Record<string, unknown>;
/** Pick the newest version both sides support, or null when there is none. */
export declare function selectMutualVersion(serverSupported: readonly string[]): string | null;
/**
 * A recognized modern JSON-RPC error code identifies a modern server during
 * era detection (the client retries/negotiates instead of falling back).
 */
export declare function isRecognizedModernErrorCode(code: number): boolean;
/** Extract `data.supported` from an UnsupportedProtocolVersionError, if present. */
export declare function parseSupportedVersionsFromError(errorData: unknown): string[] | null;
/** Extract `supportedVersions` from a DiscoverResult, if well-formed. */
export declare function parseDiscoverSupportedVersions(result: unknown): string[] | null;
/**
 * Modern-era results carry `resultType`; `input_required` marks a Multi
 * Round-Trip Request interim result. Results from earlier-protocol servers
 * that omit the field are treated as complete, per the specification.
 */
export declare function isInputRequiredResult(result: unknown): result is {
    resultType: 'input_required';
    inputRequests?: Record<string, unknown>;
    requestState?: string;
};
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