fix: add corporate proxy support using https-proxy-agent (fixes #18)

[zouyi100]

Summary

The MCP server originally does not work behind a corporate proxy because Node.js native fetch() does not respect HTTP_PROXY/HTTPS_PROXY environment variables. This PR adds proxy support using https-proxy-agent and node-fetch, enabling the server to function correctly in proxied environments.

Commits

• bf73e5e - Initial proxy support: Added getProxyAgent() that reads proxy configuration from HTTPS_PROXY, https_proxy, HTTP_PROXY, http_proxy environment variables.
• 20f6bca - Replaced undici with node-fetch + https-proxy-agent for robust proxy support. Added proxyFetch() wrapper, comprehensive unit tests with nock, and proper env var priority handling.

Key Changes

• Added node-fetch and https-proxy-agent as runtime dependencies; removed undici
• Added nock as dev dependency for clean HTTP mocking in tests
• getProxyAgent() returns an HttpsProxyAgent based on proxy env vars
• New proxyFetch() wrapper routes all outbound requests through proxy when configured
• Environment variable priority: HTTPS_PROXY > https_proxy > HTTP_PROXY > http_proxy
• Updated manifest_processor to use proxyFetch instead of raw fetch
• Rewrote manifest_processor tests to use nock instead of mocking global.fetch
• Added getProxyAgent unit tests with proper env var isolation

Fixes #18

[cla-assistant]

All committers have signed the CLA.

[dobrinyonkov]

Thanks for this, and for the tests. The proxy bug is real, I reproduced it locally.

Since we're on Node 20+, native fetch is backed by undici (already in Node). Its EnvHttpProxyAgent makes native fetch proxy-aware with no call-site changes:

import { EnvHttpProxyAgent, setGlobalDispatcher } from 'undici';
setGlobalDispatcher(new EnvHttpProxyAgent());

I tested it against a local proxy and it works. That lets us drop node-fetch and https-proxy-agent and remove proxyFetch/getProxyAgent.

Your first commit used undici's ProxyAgent, then you switched away. What went wrong with undici? That decides whether we go this route or keep yours.

Let's keep the nock migration either way. One fix if we keep your approach: getProxyAgent logs the full proxy URL, which leaks credentials when someone sets user:pass@proxy. Log host and port only:

const { hostname, port } = new URL(proxyUrl);
logger.debug(`Using proxy: ${hostname}:${port}`);

[dobrinyonkov]

Hi @zouyi100, any thoughts on the above?