@ithena-one/mcp-governance
Version:
Governance layer (Identity, RBAC, Credentials, Audit, Logging, Tracing) for Model Context Protocol (MCP) servers.
78 lines • 3.3 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.withSafeParams = withSafeParams;
exports.withFallbackParams = withFallbackParams;
exports.withRecoveredParams = withRecoveredParams;
/* eslint-disable @typescript-eslint/no-explicit-any */
const types_js_1 = require("@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}` };
* });
*/
function withSafeParams(handler) {
return async (req, extra) => {
if (!req.params) {
throw new types_js_1.McpError(types_js_1.ErrorCode.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}` };
* }
* );
*/
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}` };
* });
*/
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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