ESM / CommonJS module resolution collision in MCP server dynamically loaded tool plugins

[LorrdRazzy]

Environment

• OS: Linux x64 / macOS / Windows
• Runtime / Node: Node.js v20.x, npm / pnpm
• TypeScript Version: ^5.x
• atomic-agent version: v0.4.x (main branch)

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Summary

When attempting to dynamically import external Model Context Protocol (MCP) server modules or user-defined tool plugins configured via atomic.config.ts, the module loader fails with an ERR_REQUIRE_ESM or ERR_UNKNOWN_FILE_EXTENSION error.

This happens because the dynamic import pipeline in src/mcp/loader.ts assumes all plugin dependencies follow ES Modules ("type": "module"), failing when encountering legacy CommonJS packages or TypeScript files compiled to standard CJS formats.

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Steps to Reproduce

1. Define a custom local tool or install a third-party CJS-formatted MCP tool package.
2. Register the tool in your configuration file:

   // atomic.config.ts
   export default {
     tools: [
       {
         name: 'custom-tool',
         path: './plugins/my-cjs-tool.js'
       }
     ]
   };