Create Blazor Server Login Page to fetch Jwt - asp.net-core

Question

We have a Blazor server app which is packaged as an electron desktop app.
Identity cannot reside alongside the app it must be remote so I decided to use Jwt. I have created a Jwt server & have JwtBearer middleware enabled in the Blazor server app startup.cs (see code).
At present we can attach a Jwt to context.Token manually in 'JwtBearerEvents --> OnMessageReceived' and middleware picks this up so we can use [Authorize] & also include Policies [Authorize(Policy="account_write")] this works great.
The Jwt is created manually in Postman (calling our Jwt server and the pasting in the result - see code) as I cannot figure out how to have a login page that uses the Un/Pw to fetch a Jwt from the server.
I appreciate HTTP is only availabe for a few requests before SignalR kicks in, and that is the crux of the problem but im hoping there is a way around this.
I thought I could use a combination of Blazor and razor pages, ie login page is cshtml and saves token to LocalStorage or Cookie then we start blazor (Javascript autostart off for the blazor.server.js) & read the cookie - I have not been able to get this to work as I cannot get razor and cshtml working together.
Any ideas how can I create a login page to fetch the Jwt & attach it to the context?
services.AddAuthentication(options =>
{
options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
})
.AddJwtBearer(options =>
{
options.TokenValidationParameters = new TokenValidationParameters
{
ValidateIssuer = false,
ValidateAudience = false,
ValidateLifetime = true,
RequireExpirationTime = true,
ValidateIssuerSigningKey = true,
IssuerSigningKey = new SymmetricSecurityKey(key),
};
options.Events = new JwtBearerEvents
{
OnMessageReceived = context =>
{
// Is token in Querystring?
var accessToken = context.Request.Query["access_token"];
Debug.WriteLine($"JwtBearer - OnMessageReceived - access_token in QS: {ShorterJWT(accessToken)}");
//
// Attach the token manually
//
// Jwt fetched manually using Postman - 10 year
accessToken = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjNjMzIxMjI2LTFhNGYtNGQ3NS1iZjM1LTIwYjQ1NmVlYmYzOSIsImJvb2tlciI6InRydWUiLCJuYW1lIjoiQm9iIENyYXRjaGV0IiwibmJmIjoxNjI5NzM3MTk4LCJleHAiOjE5NDUyNjk5OTgsImlhdCI6MTYyOTczNzE5OH0.N9HUFM3zIl9BkoPJlPj_WQIUhhQ2Rk53ymEEm42LTD4";
context.Token = accessToken;
return Task.CompletedTask;
}
};
});````