Emacs Can Open a Browser and Still Need Its Own Proxy

Two commands that both “open a URL” can take different routes in Emacs.

One can hand the URL to an external browser. The browser then uses its own proxy configuration. Another can retrieve the resource through Emacs's URL library. The browser's successful request says little about that second path.

The URL library documents proxy environment variables and the Lisp option url-proxy-services. A basic explicit configuration has this form:

(setq url-proxy-services
      '(("http" . "proxy.example:8080")
        ("https" . "proxy.example:8080")))

The scheme names select the destination protocol. The proxy values are the endpoint format expected by this option, not a PAC script URL. For permitted public HTTP routes, take the host and port from a candidate in the HTTP proxy list.

This setting concerns clients using that library. A package invoking an external Git executable, for example, has another network path. Identify the operation before assuming all Emacs networking shares one configuration.

For Windows, avoid treating a registry-reading snippet from an old third-party package as a general solution to PAC evaluation, credentials, and changing network policy. First establish whether a fixed endpoint or the library's documented environment configuration meets the actual requirement.