support for CREDENTIALPROVIDERS for nuget in LinqPad

LINQPad doesn't support VSTS authentication right now. Have you tried creating a personal access token?

https://www.visualstudio.com/en-us/docs/setup-admin/team-services/use-personal-access-tokens-to-authenticate

LINQPad feeds your proxy credentials to the NuGet library using the following code:

static void SetupProxy ()
{
	if (_proxySetupDone) return;
	_proxySetupDone = true;

	// Set up proxy handling for v3 sources.
	// We need to sync the v2 proxy cache and v3 proxy cache so that the user will not
	// get prompted twice for the same authenticated proxy.
	var v2ProxyCache = global::NuGet.ProxyCache.Instance as IProxyCache;

	global::NuGet.Protocol.Core.v3.HttpHandlerResourceV3.PromptForProxyCredentials = (uri, proxy, cancellationToken) =>
	{
		var v2Credentials = v2ProxyCache?.GetProxy (uri)?.Credentials;
		if (v2Credentials != null && proxy.Credentials != v2Credentials)
		{
			// if cached v2 credentials have not been used, try using it first.
			return Task.FromResult (v2Credentials);
		}

		return Task.FromResult (GetProxyCredentials());
	};

	global::NuGet.Protocol.Core.v3.HttpHandlerResourceV3.ProxyPassed = proxy =>
	{
		// add the proxy to v2 proxy cache.
		v2ProxyCache?.Add (proxy);
	};
}

In addition, it populates the http_proxy environment variable before calling NuGet.Core library features such as search (crazy, I know, but that's the only way I know to get it to use a web proxy.)

Joe, is there any chance you may give this issue a lift?

I feel like I'm in a constant crazy loop that forces me to download new internal packages from VSTS into a folder in order to be able to use my lovely tool LinqPad.

Is there any chance you can give us a way to make this work?

Thanks in advance

While using this advice allowed me to see the content of my VSTS feed in LINQPad's package manager, it gave an error when I'm trying to add a package to the query. Also, when I try to access the feed again after re-opening the package manager window, it won't show again with "TF400813: Resource not available for anonymous access. Client authentication required." message.
Looks like LINQPad only uses the provided credentials once and then stops passing them.

+1 This is really frustrating