npmplus-mcp-server/src/utils/path-resolver.ts

Production-ready MCP server for intelligent JavaScript package management. Works with Claude, Windsurf, Cursor, VS Code, and any MCP-compatible AI editor.

import { resolve, isAbsolute } from 'path';
import { existsSync, statSync } from 'fs';

/**
 * Resolves a directory path, handling relative paths like "." properly
 * 
 * @param cwd - The directory path that might be relative
 * @returns Absolute path to the directory
 * @throws Error if the path doesn't exist or isn't a directory
 */
export function resolveCwd(cwd: string): string {
  let resolvedPath: string;
  
  // Handle special case of "." which should be current working directory
  if (cwd === '.') {
    // CRITICAL FIX: When MCP server runs from root, don't resolve "." to "/"
    // Instead, let npm/yarn handle the current directory resolution
    if (process.cwd() === '/') {
      // For MCP servers running from root, return "." to let the package manager
      // resolve it from the actual user's directory
      return '.';
    }
    resolvedPath = process.cwd();
  } else if (isAbsolute(cwd)) {
    resolvedPath = cwd;
  } else {
    // Resolve relative paths against current working directory
    resolvedPath = resolve(process.cwd(), cwd);
  }
  
  // Skip validation for "." when running from root
  if (cwd === '.' && process.cwd() === '/') {
    return '.';
  }
  
  // Validate that the path exists and is a directory
  if (!existsSync(resolvedPath)) {
    throw new Error(`Invalid project directory: ${resolvedPath} (does not exist)`);
  }
  
  const stat = statSync(resolvedPath);
  if (!stat.isDirectory()) {
    throw new Error(`Invalid project directory: ${resolvedPath} (not a directory)`);
  }
  
  return resolvedPath;
}

/**
 * Validates that a directory contains a package.json file
 * 
 * @param cwd - The directory path to check
 * @returns True if package.json exists
 */
export function isNodeProject(cwd: string): boolean {
  // Special handling for "." when MCP runs from root
  if (cwd === '.' && process.cwd() === '/') {
    // Can't validate, just trust that npm/yarn will handle it
    return true;
  }
  
  const resolvedPath = resolveCwd(cwd);
  return existsSync(resolve(resolvedPath, 'package.json'));
}

/**
 * Resolves and validates a Node.js project directory
 * 
 * @param cwd - The directory path that should contain a Node.js project
 * @returns Absolute path to the project directory
 * @throws Error if not a valid Node.js project directory
 */
export function resolveProjectCwd(cwd: string): string {
  // Special handling for "." when MCP runs from root
  if (cwd === '.' && process.cwd() === '/') {
    // Return "." to let npm/yarn resolve from their execution context
    return '.';
  }
  
  const resolvedPath = resolveCwd(cwd);
  
  if (!isNodeProject(resolvedPath)) {
    throw new Error(`Invalid project directory: ${resolvedPath} (no package.json found)`);
  }
  
  return resolvedPath;
}