ConditionalRenewMiddleware.cs

public static void UseCactiCookieAuthentication(this IApplicationBuilder app, IHostingEnvironment environment)
{
    var cookieName = "AuthCookie";
    app.Use(next => context =>
    {
        context.Response.OnStarting(state =>
        {
            if(context.Items.ContainsKey("dontRenewAuthCookie"))
            {
                var response = (HttpResponse) state;
                // Omit Set-Cookie header with the offending cookie name
                var cookieHeader = response.Headers[HeaderNames.SetCookie].Where(s => !s.Contains(cookieName)).Aggregate(new StringValues(), (current, s) => StringValues.Concat(current, s));
                response.Headers[HeaderNames.SetCookie] = cookieHeader;
            }
            return Task.CompletedTask;
        }, context.Response);
        return next(context);
    });

    app.UseCookieAuthentication(new CookieAuthenticationOptions
    {
        AuthenticationScheme = CookieAuthenticationDefaults.AuthenticationScheme,
        CookiePath = "/",
        CookieName = cookieName,
        AutomaticAuthenticate = true,
        ExpireTimeSpan = TimeSpan.FromMinutes(20),
        AutomaticChallenge = true,
        SlidingExpiration = true,
        CookieSecure = CookieSecurePolicy.Always
        // Additional auth options...
    });
}