Networking and Proxies

This page explains how Dline makes network requests in VS Code, to help you troubleshoot connections behind a corporate proxy or on a restricted network.

Which path requests take

Most of Dline’s network requests, including API requests to most model providers, go through a shared network layer. In VS Code this layer uses the fetch provided by the VS Code extension host, and relies on VS Code itself for proxy and system-certificate handling.

So when troubleshooting a proxy, first confirm that the editor itself can reach the network through the proxy, following VS Code’s network configuration guide.

Note

Dline does not read VS Code’s http.proxy or http.proxyStrictSSL settings, or the NODE_EXTRA_CA_CERTS environment variable, by itself. Whether those settings apply to Dline’s requests depends on how VS Code handles network requests in the extension host.

Exceptions

These parts do not go through the shared network layer and need to be checked separately:

Part	Network path
Amazon Bedrock	Uses the AWS SDK’s own request handling; Dline injects no proxy configuration
Browser tool, local web search and fetch	Visit pages through a browser (Puppeteer). In the browser settings you can pass browser arguments with Custom Browser Arguments (Optional) or turn on Use remote browser connection
MCP: Streamable HTTP	Uses the shared network layer
MCP: SSE	Only OAuth-related connections use the shared network layer; the rest is handled by the MCP SDK
MCP: stdio	Launches a separate process whose network behavior is its own; set proxy environment variables for it in the MCP configuration’s env

For MCP configuration, see MCP overview.

Troubleshooting steps

1. Confirm the editor’s network works: on the same machine, check whether other online features of VS Code (such as the Extensions Marketplace) work.
2. Confirm the provider address: for providers with a custom address, such as OpenAI-compatible ones, check that the Base URL is reachable from your machine; see OpenAI custom base URL.
3. Isolate the failing feature: if only web tools or MCP fail while model requests work, check the matching exception path in the table above.
4. Check the logs: Dline logs to the VS Code Output panel, with sensitive information redacted before writing.

Caution

Error messages vary by provider and by where the failure happens; Dline has no single “proxy error” message. For example, a failed web fetch shows Web fetch failed: … followed by the underlying error.