Fix IDE Companion Connection in Proxy Environments

[Blackoutta]

TLDR

Fixes #6307

Summary

This PR resolves connection issues between the Gemini CLI and IDE companion extension when running in proxy-configured environments by implementing proper proxy handling with support for NO_PROXY configuration.

Screenshot after the fix

Changes Made

• Added EnvHttpProxyAgent from the undici library to handle proxy configuration
• Created a new createProxyAwareFetch() method that configures proxy-aware HTTP client
• Updated IDE connection establishment to use the proxy-aware fetch implementation
• Configured automatic bypass of proxy for localhost connections (matching common NO_PROXY patterns)
• Enhanced error handling for connection failures with more informative messages

Technical Details

Proxy Configuration

private createProxyAwareFetch() {
  // ignore proxy for 'localhost' by default to allow connecting to the ide mcp server
  const agent = new EnvHttpProxyAgent({
    noProxy: "localhost"
  });
  
  return async (url: string | URL, init?: RequestInit): Promise<Response> => {
    // Implementation details...
  };
}

Connection Establishment Updates

Updated the establishConnection method to use the new proxy-aware fetch:

transport = new StreamableHTTPClientTransport(
  new URL(`http://${getIdeServerHost()}:${port}/mcp`),
  {
    fetch: this.createProxyAwareFetch()
  });

Benefits

• Corporate Environment Compatibility: Users can now use IDE integration features in proxy-restricted environments
• Proper Proxy Respect: NO_PROXY environment variable settings are properly honored
• Default Safety: Localhost connections automatically bypass proxy routing
• Backward Compatibility: No impact on users in non-proxy environments
• Better Error Handling: Enhanced error messages when connections fail

Testing

• ✅ Verified functionality in non-proxy environments (no regression)
• ✅ Verified functionality with HTTP_PROXY configured
• ✅ Verified functionality with HTTPS_PROXY configured
• ✅ Verified NO_PROXY settings are properly respected
• ✅ Verified localhost connections bypass proxy routing

Breaking Changes

None - this change is fully backward compatible.

Dive Deeper

Reviewer Test Plan

Testing Matrix

	🍏	🪟	🐧
npm run	❓	❓	❓
npx	❓	❓	❓
Docker	❓	❓	❓
Podman	❓	-	-
Seatbelt	❓	-	-

Linked issues / bugs

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[gemini-code-assist]

Summary of Changes

Hello @Blackoutta, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves critical connection issues between the Gemini CLI and its IDE companion extension, specifically in environments configured with HTTP/HTTPS proxies. The core of the solution involves implementing proper proxy handling, including support for the NO_PROXY environment variable and automatic bypass for localhost connections. This ensures that users in corporate or restricted network settings can seamlessly utilize IDE integration features, improving compatibility and user experience without impacting non-proxy environments.

Highlights

• Proxy Agent Integration: The EnvHttpProxyAgent from the undici library has been integrated to provide robust and environment-aware proxy management.
• Proxy-Aware Fetch Implementation: A new method, createProxyAwareFetch(), has been implemented to configure an HTTP client that respects system-wide proxy settings.
• IDE Connection Update: The process for establishing a connection with the IDE companion extension has been updated to leverage the new proxy-aware fetch mechanism.
• Localhost Bypass: The system is now configured to automatically bypass proxy routing for connections to localhost, aligning with standard NO_PROXY patterns.
• Enhanced Error Handling: Error messages for connection failures have been improved to provide clearer and more actionable feedback to the user.

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[gemini-code-assist]

Code Review

This pull request effectively addresses connection issues in proxy environments by integrating undici's EnvHttpProxyAgent. The approach of using a proxy-aware fetch implementation is sound. My review includes one high-severity suggestion to improve type safety and prevent potential runtime errors by replacing an unsafe type cast with proper Response object construction, enhancing the overall robustness of the solution.

[Blackoutta]

/gemini review

[gemini-code-assist]

Code Review

This pull request adds proxy support for IDE connections, which is a great improvement for users in corporate environments. The implementation correctly uses undici's EnvHttpProxyAgent. However, I've identified a critical issue where the current implementation overrides the user's NO_PROXY environment variable, and a high-severity performance issue due to repeated dynamic imports. My review includes a single comment with a code suggestion that addresses both of these issues to make the proxy handling more robust and efficient.

[Blackoutta]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces proxy support for the IDE companion connection by using undici's EnvHttpProxyAgent. The changes are well-structured, adding a createProxyAwareFetch method to encapsulate the proxy logic and updating the connection establishment to use it. The error handling for connection failures has also been improved. My review includes one suggestion to simplify the implementation in createProxyAwareFetch for better performance and maintainability.

[Blackoutta]

Hi @jacob314 , just a gentle ping to see if you’ve had a chance to look at this PR. Happy to address any feedback—thanks again for your time :)

[Amnat-auyana1998]

@Blackoutta

[Blackoutta]

Hi @Amnat-auyana1998, thank you for reviewing, happy to help, let me know if there is anything I can do :)

[jacob314]

please add a test for this to avoid regressions. Aside from that change looks good to approve. Thanks for the bug fix!

[jacob314]

we already log an error at line 428. Is this extra log message needed?

[Blackoutta]

Hi, jacob, thanks for reviewing! I needed the raw error object '_error' when I was debugging for the issue, I'll remove these two lines in my next commit, which is adding tests ;)

[Blackoutta]

Hi @jacob314,
I've gone ahead and added a new integration test and included a quality-of-life update to .vscode/launch.json that enables one-click execution of individual test files.
When you have a moment, could you take a look? Thanks!

[jacob314]

[Amnat-auyana1998]

@Blackoutta Please Let me try it.I'll come back and review it for you later.