@ithena-one/mcp-governance/dist/esm/utils/handler-helpers.js

Governance layer (Identity, RBAC, Credentials, Audit, Logging, Tracing) for Model Context Protocol (MCP) servers.

/* eslint-disable @typescript-eslint/no-explicit-any */
import { McpError, ErrorCode as McpErrorCode } from '@modelcontextprotocol/sdk/types.js';
/**
 * Wraps a handler function to ensure params are present before the handler is executed.
 * If params are missing, throws a standard MCP InvalidParams error.
 *
 * @template T The expected type of the params object
 * @param handler A function that receives the params object as its first argument
 * @returns A wrapped handler that guarantees params exists
 *
 * @example
 * const myHandler = withSafeParams<{ name: string }>(async (params, req, extra) => {
 *   // Safe to use params.name here without checking
 *   return { greeting: `Hello ${params.name}` };
 * });
 */
export function withSafeParams(handler) {
    return async (req, extra) => {
        if (!req.params) {
            throw new McpError(McpErrorCode.InvalidParams, "Missing required parameters. The MCP protocol may have lost the params during transmission.");
        }
        return handler(req.params, req, extra);
    };
}
/**
 * Wraps a handler function to ensure params are present, or use a fallback value if missing.
 * Unlike withSafeParams, this never throws for missing params.
 *
 * @template T The expected type of the params object
 * @param fallbackParams The fallback params object to use if params are missing
 * @param handler A function that receives the params object as its first argument
 * @returns A wrapped handler that guarantees params exists
 *
 * @example
 * const myHandler = withFallbackParams<{ name: string }>(
 *   { name: "Anonymous" },
 *   async (params, req, extra) => {
 *     // params.name will be "Anonymous" if the client didn't provide it
 *     return { greeting: `Hello ${params.name}` };
 *   }
 * );
 */
export function withFallbackParams(fallbackParams, handler) {
    return async (req, extra) => {
        const params = req.params || fallbackParams;
        return handler(params, req, extra);
    };
}
/**
 * Attempts to recover params from the operation context if they're missing from the request.
 * This is a more advanced utility that tries to restore the original params that might have
 * been lost during transmission.
 *
 * @template T The expected type of the params object
 * @param handler A function that receives the params object as its first argument
 * @returns A wrapped handler that attempts to recover params from context
 *
 * @example
 * const myHandler = withRecoveredParams<{ name: string }>(async (params, req, extra) => {
 *   // params will be recovered from operationContext.mcpMessage if possible
 *   return { greeting: `Hello ${params.name}` };
 * });
 */
export function withRecoveredParams(handler) {
    return async (req, extra) => {
        // Attempt to recover params from mcpMessage if available in context and is exposed to handlers
        const operationContext = extra;
        const originalMessage = operationContext?.mcpMessage;
        const params = req.params || originalMessage?.params;
        return handler(params, req, extra);
    };
}
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