/**
 * MCP protocol-version handling for the stdio servers (ADR-524).
 *
 * Ruflo ships three stdio entry points (`bin/cli.js` auto-detect, `bin/mcp-server.js`,
 * and `MCPServerManager` in mcp-server.ts). All three answered `initialize` with a
 * hardcoded `2024-11-05` and knew nothing of the 2026-07-28 revision, which drops the
 * handshake and carries the version on every request. This module is the one place
 * that decides which revision a message speaks, so the three handlers cannot drift.
 *
 * Dual-era behaviour (spec: basic/versioning):
 *  - `initialize` selects legacy semantics; the requested legacy version is echoed.
 *  - a request carrying `_meta["io.modelcontextprotocol/protocolVersion"]` is served
 *    statelessly: `resultType` and `serverInfo` on every result, cache hints on lists,
 *    `-32602` for an unknown resource, `-32022` for an unsupported version.
 *  - `server/discover` is always answered, so a dual-era client's stdio probe succeeds.
 */
export declare const MODERN_PROTOCOL_VERSIONS: readonly ["2026-07-28"];
export declare const LEGACY_PROTOCOL_VERSIONS: readonly ["2025-11-25", "2025-06-18", "2024-11-05"];
export declare const SUPPORTED_PROTOCOL_VERSIONS: readonly string[];
/** Offered to a legacy client whose requested version we do not know. */
export declare const LATEST_LEGACY_PROTOCOL_VERSION: "2025-11-25";
export declare const META_PROTOCOL_VERSION = "io.modelcontextprotocol/protocolVersion";
export declare const META_CLIENT_CAPABILITIES = "io.modelcontextprotocol/clientCapabilities";
export declare const META_SERVER_INFO = "io.modelcontextprotocol/serverInfo";
export declare const ERROR_INVALID_PARAMS = -32602;
export declare const ERROR_UNSUPPORTED_PROTOCOL_VERSION = -32022;
/** 2025-11-25 and earlier; replaced by -32602 in 2026-07-28. */
export declare const ERROR_LEGACY_RESOURCE_NOT_FOUND = -32002;
/** Tool catalogue is fixed for the life of a stdio process; five minutes is a conservative hint. */
export declare const TOOLS_LIST_TTL_MS = 300000;
export declare const DISCOVER_TTL_MS = 3600000;
export interface ServerIdentity {
    name: string;
    version: string;
}
export interface ProtocolContext {
    /** True when the request used 2026-07-28 per-request metadata. */
    modern: boolean;
    /** Version the request declared, or undefined for legacy requests. */
    version?: string;
    /** Validated W3C traceparent, if the client propagated one. */
    traceparent?: string;
    tracestate?: string;
}
export interface JsonRpcMessage {
    jsonrpc?: string;
    id?: string | number | null;
    method?: string;
    params?: unknown;
}
export interface JsonRpcResponse {
    jsonrpc: '2.0';
    id?: string | number | null;
    result?: Record<string, unknown>;
    error?: {
        code: number;
        message: string;
        data?: unknown;
    };
}
export type Preflight = {
    response: JsonRpcResponse;
    context?: undefined;
} | {
    response?: undefined;
    context: ProtocolContext;
};
/** The CLI package version, read once from package.json (dist/src/ → ../../). */
export declare function rufloPackageVersion(): string;
export declare function defaultServerIdentity(): ServerIdentity;
/** Pick the legacy version to answer `initialize` with (spec: echo if supported, else our latest). */
export declare function negotiateLegacyVersion(requested: unknown): string;
export declare function isValidTraceparent(value: unknown): value is string;
/**
 * Decide how to serve one inbound message before the handler's own switch runs.
 * Returns a complete response for `initialize`, `server/discover` and protocol
 * errors; otherwise returns the context the handler passes to `finalizeResponse`.
 */
export declare function protocolPreflight(message: JsonRpcMessage, capabilities: Record<string, unknown>, identity?: ServerIdentity): Preflight;
/** The resource-not-found code the request's revision expects. */
export declare function resourceNotFoundCode(context: ProtocolContext): number;
/** Stable, name-ordered copy so `tools/list` is byte-identical across calls (prompt-cache friendly). */
export declare function sortToolsDeterministically<T extends {
    name: string;
}>(tools: readonly T[]): T[];
/** Tool-call context fields to forward, so handlers and logs can join the caller's trace. */
export declare function traceContextFields(context: ProtocolContext): Record<string, string>;
/** Add the 2026-07-28 result fields to a handler's response. Legacy responses pass through untouched. */
export declare function finalizeResponse(response: JsonRpcResponse | null, method: string | undefined, context: ProtocolContext, identity?: ServerIdentity): JsonRpcResponse | null;
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