Redirect users to login page after session timeout using OpenIdConnectAuthentication - asp.net

Question

I'm using Azure B2C in an ASP.NET application with OpenIdConnectAuthentication. My sign-in policy has an absolute session length of 90 minutes.
After the session expires, I'd like the user to be automatically redirected to the login page, so they know they've been logged out. This doesn't seem to happen automatically. I was hoping this could be done automatically, perhaps using OWIN.
For now, as a workaround, I set a Refresh header in all HTTP responses that uses the remaining session life (calculated based on the iat claim and current time). But I was hoping this could just be handled automatically from the server. Is there any way to make the redirect occur automatically from the server-side once the session expires?
Below is my Startup class in Startup.Auth.cs:
public void ConfigureAuth(IAppBuilder app)
{
// ... other code ... //
app.UseOpenIdConnectAuthentication(CreateOptionsFromPolicy(SignInPolicyId));
}
private OpenIdConnectAuthenticationOptions CreateOptionsFromPolicy(string policy) {
var options = new OpenIdConnectAuthenticationOptions {
// For each policy, give OWIN the policy-specific metadata address, and
// set the authentication type to the id of the policy
MetadataAddress = String.Format(aadInstance, tenant, policy),
AuthenticationType = policy,
UseTokenLifetime = true,
// These are standard OpenID Connect parameters, with values pulled from
// Web.config
ClientId = clientId,
RedirectUri = redirectUri,
PostLogoutRedirectUri = logoutUri,
Notifications =
new OpenIdConnectAuthenticationNotifications {
AuthenticationFailed = AuthenticationFailed,
RedirectToIdentityProvider =
(context) => {
var value = context.OwinContext.Request.Path.Value;
if (value != "/default.aspx") {
context.OwinContext.Response.Redirect("/");
context.HandleResponse();
}
return Task.FromResult(0);
}
},
Scope = "openid",
ResponseType = "id_token",
TokenValidationParameters =
new TokenValidationParameters {
NameClaimType = "name",
},
};
return options;
}