TgAuth_Web.cs

// controller

        [HttpGet("tgCheckWebAppAuth")]
        public async Task<IActionResult> CheckWebAppAuth([FromQuery] Dictionary<string, string> userData)
        {
            var user = telegramLoginUrl.CheckWebAppTelegramAuthorization(userData);

            if (await Invalid(user)) return Unauthorized();

            await SignIn(user, [new Claim("Source", "TelegramWebApp")]);

            return Ok(user);
        }
/// Test.razor (route baseURI to /CoolApp)
async Task Login()
{
            var auth_state = await authStateProv.GetAuthenticationStateAsync();
            if ((auth_state.User.Identity != null && auth_state.User.Identity.IsAuthenticated))
                return;
            var str = await JS.InvokeAsync<string>("eval", "window.Telegram.WebApp.initData");
            var user = await http_client.GetFromJsonAsync<TgUser>($"{nm.BaseUri}api/TgLoginUrl/tgCheckWebAppAuth?{str}");
            nm.NavigateTo(nm.BaseUri, true);
}
/// server class PersistingRevalidatingAuthenticationStateProvider : RevalidatingServerAuthenticationStateProvider
        private async Task OnPersistingAsync()
        {
            logger.LogWarning("OnPersistingAsync");
            if (authenticationStateTask is null)
            {
                throw new UnreachableException($"Authentication state not set in {nameof(OnPersistingAsync)}().");
            }

            var authenticationState = await authenticationStateTask;
            var principal = authenticationState.User;
            var id = principal.Identities.FirstOrDefault(x => x.IsAuthenticated);
            if (id == null)
            {
                logger.LogWarning("OnPersistingAsync principal.Identities.Count() = {x}", principal.Identities.Count());
                /// !!!! <= always here finish
                return;
            }
            var userId = id.FindFirst(options.ClaimsIdentity.UserIdClaimType)?.Value;
            var email = id.FindFirst(options.ClaimsIdentity.EmailClaimType)?.Value;
            var name = id.FindFirst(options.ClaimsIdentity.UserNameClaimType)?.Value;
            logger.LogWarning("OnPersistingAsync principal {principal} IsAuthenticated={IsAuthenticated}, {name}, {userId}, {email}", id, id.IsAuthenticated, name, userId, email);
            if (principal.Identity?.IsAuthenticated == true)
            {

                if (userId != null && email != null && name != null)
                {
                    state.PersistAsJson(nameof(UserInfo), new UserInfo
                    {
                        UserId = userId,
                        Email = email,
                        Name = name
                    });
                }
            }
        }