pocketsmith-mcp/dist/mcp-client/transports/stdioClientTransport.js

MCP server for managing budgets via PocketSmith API

/**
 * @fileoverview Provides functions for creating and configuring MCP StdioClientTransport.
 * This module is responsible for instantiating and setting up the StdioClientTransport
 * from the @modelcontextprotocol/sdk, which is used to communicate with local MCP
 * server processes via their standard input/output streams.
 * @module src/mcp-client/transports/stdioClientTransport
 */
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";
import { BaseErrorCode, McpError } from "../../types-global/errors.js";
import { logger, requestContextService, } from "../../utils/index.js"; // Centralized internal imports
/**
 * Creates and configures a `StdioClientTransport` instance (from the `@modelcontextprotocol/sdk`)
 * for launching and communicating with an MCP server process via its standard input and output streams.
 *
 * @param transportConfig - Configuration containing the command, arguments,
 *                                                 and environment variables for the server process.
 * @param parentContext - Optional parent request context for logging and tracing.
 * @returns A configured `StdioClientTransport` instance, ready to be connected.
 * @throws {McpError} If the provided `transportConfig` is invalid (e.g., missing command)
 *                    or if the transport fails to initialize for other reasons.
 */
export function createStdioClientTransport(transportConfig, parentContext) {
    const baseContext = parentContext ? { ...parentContext } : {};
    const context = requestContextService.createRequestContext({
        ...baseContext,
        operation: "createStdioClientTransport",
        transportType: "stdio",
        command: transportConfig.command,
    });
    logger.debug("Creating StdioClientTransport", context);
    if (!transportConfig.command || typeof transportConfig.command !== "string") {
        logger.error("Invalid command provided for StdioClientTransport", context);
        throw new McpError(BaseErrorCode.CONFIGURATION_ERROR, "Invalid command for StdioClientTransport: command must be a non-empty string.", context);
    }
    // Args validation (Array.isArray) is handled by TypeScript and Zod schema at config load time.
    // If individual arg string validation (e.g., non-empty) is needed,
    // it should be part of the Zod schema in configLoader.ts.
    try {
        // Only pass through environment variables explicitly defined in the server's configuration.
        // Inheriting all of process.env is a security risk.
        // If specific variables from process.env are needed, they should be explicitly
        // listed in the mcp-config.json for that server or handled by an allowlist mechanism.
        const serverSpecificEnv = {
            ...(transportConfig.env || {}), // Only use explicitly defined env vars from config
        };
        logger.debug("Creating StdioClientTransport with merged environment", {
            ...context,
            envKeysCount: Object.keys(serverSpecificEnv).length,
            envVarNames: Object.keys(serverSpecificEnv).join(", ") || "None",
        });
        const transport = new StdioClientTransport({
            command: transportConfig.command,
            args: transportConfig.args, // Assumed to be string[] by this point
            env: serverSpecificEnv,
        });
        logger.info("StdioClientTransport created successfully", context);
        return transport;
    }
    catch (error) {
        logger.error("Failed to create StdioClientTransport", {
            ...context,
            error: error instanceof Error ? error.message : String(error),
            stack: error instanceof Error ? error.stack : undefined,
        });
        throw new McpError(BaseErrorCode.INTERNAL_ERROR, `Failed to create StdioClientTransport: ${error instanceof Error ? error.message : String(error)}`, { originalError: error, ...context });
    }
}