feat: Update 2018 client support with registration defaults and WebSocket handling

DorkNet.Server/Controllers/API/Notification/V2/NotificationController.cs

@@ -1,29 +1,65 @@
+using System.Net.WebSockets;
 using Microsoft.AspNetCore.Mvc;
 using DorkNet.Server.Services;
 
 namespace DorkNet.Server.Controllers.API.Notification.V2;
 
 /// <summary>
-/// Legacy raw-WebSocket notification endpoint. Replaced by the SignalR
-/// hub at <c>notify.{apex}/hub/v1</c>. Returns 410 Gone for any client
-/// that still tries the old path.
+/// api/notification/v2 — the JUNE-2018 client opens a raw WebSocket here for
+/// push notifications (RecNet.cs:48895, RecNet.IJADBHMBMPG wraps a
+/// BestHTTP.WebSocket with open/message(string)/error events). The 2020 client
+/// replaced this with the SignalR hub at notify.{apex}/hub/v1.
+///
+/// This branch targets 2018, so we ACCEPT the WebSocket and hold it open. We
+/// don't push anything yet (server-driven notifications are a later feature) —
+/// an open, quiet socket keeps the client's notification subsystem "connected"
+/// instead of erroring/retry-looping on the old 410 Gone. Incoming frames
+/// (subscribe/auth) are drained and ignored.
 /// </summary>
 [ApiController]
 [Route("api/[controller]/v2")]
-public class NotificationController(DomainConfig domain) : ControllerBase
+public class NotificationController(
+    DomainConfig domain,
+    ILogger<NotificationController> log) : ControllerBase
 {
     [HttpGet]
-    public IActionResult Connect() => StatusCode(StatusCodes.Status410Gone, new
+    public async Task Connect()
     {
-        error = "use_signalr_hub",
-        hint = $"connect to {domain.Sub("notify")}/hub/v1 instead",
-    });
+        if (!HttpContext.WebSockets.IsWebSocketRequest)
+        {
+            // Non-WS probe (or a curl check) — return an empty notification
+            // list rather than 410 so HTTP callers don't treat it as an error.
+            Response.StatusCode = StatusCodes.Status200OK;
+            Response.ContentType = "application/json";
+            await Response.WriteAsync("[]");
+            return;
+        }
 
-    /// <summary>GET <c>api/notification/hub/v1</c> — returns the
-    /// SignalR hub URL the client should open. Without this the
-    /// watch falls back to its own default and may try the wrong
-    /// scheme. URL is built off the configured deployment apex
-    /// (DORKNET_DOMAIN).</summary>
+        using var ws = await HttpContext.WebSockets.AcceptWebSocketAsync();
+        log.LogInformation("[notify] 2018 client opened notification WebSocket");
+        var buf = new byte[4096];
+        try
+        {
+            while (ws.State == WebSocketState.Open)
+            {
+                var result = await ws.ReceiveAsync(
+                    new ArraySegment<byte>(buf), HttpContext.RequestAborted);
+                if (result.MessageType == WebSocketMessageType.Close)
+                {
+                    await ws.CloseAsync(WebSocketCloseStatus.NormalClosure,
+                        "bye", HttpContext.RequestAborted);
+                    break;
+                }
+                // Drain & ignore subscribe/auth frames — no server push yet.
+            }
+        }
+        catch (OperationCanceledException) { /* client navigated away */ }
+        catch (WebSocketException) { /* abrupt disconnect — normal */ }
+        log.LogDebug("[notify] notification WebSocket closed");
+    }
+
+    /// <summary>GET <c>api/notification/hub/v1</c> — 2020 SignalR hub pointer
+    /// (unused by the 2018 client; kept for any 2019/2020 caller).</summary>
     [HttpGet("/api/notification/hub/v1")]
     public IActionResult HubInfo() => Ok(new
     {