WPAD Discovers a Route Without Opening a Webpage
Distinguish proxy auto-discovery from a mechanism that navigates every local device to a landing page.
WPAD discovers the location of a proxy auto-configuration script. A participating client downloads that script and asks FindProxyForURL which proxy, or direct route, to use for a requested destination.
The returned value describes routing. It is not a webpage URL for the browser to open, and PAC execution does not provide an ordinary webpage’s navigation interface.
A proxy reached through that policy can return HTTP responses, but that is a later exchange. It does not make WPAD a universal landing-page mechanism, especially for devices or applications that ignore automatic proxy discovery.
Keep discovery and request handling as separate requirements. Publishing a PAC file only supplies policy to clients that actually obtain and use it.