Fiddler itself isn't really designed for service use; most folks that want to do Fiddler-like things will build an application atop FiddlerCore. For end-user bug reporting, http://fiddlercap.com
is typically a good choice.
When you start Fiddler as a service, it changes the proxy settings only for that (service) user-account, not for the user account of a foreground user. You'd need to manually configure the foreground user's proxy settings to point at 127.0.0.1:8888 (or set the ProxySettingsPerUser=0 group policy and run Fiddler as Admin) to get traffic from foreground user accounts.
You haven't mentioned how you're triggering a save of the traffic? One approach would be to save the traffic anytime you see a request for a given "magic URL" (e.g. http://localhost.fiddler:8888/savetrafficnow
) and you'd just manually "invoke" a save operation that way...
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