fix(online): green-felt freeze — replay initial state to late subscriber

Root cause: the server sends matchFound then immediately broadcasts the first
state, but the client only subscribes to state inside enterServerMatch, which
runs a React effect later — so the ordered "state" message is dispatched while
there are no subscribers and is dropped. The server then waits for the human
hakem's trump choice that can never come → permanent freeze on the green felt.

- signalr-service: cache lastState; replay it to a late onState subscriber on a
  microtask (after enterServerMatch resets its store); clear the cache on every
  fresh-match entry (startMatchmaking / createRoom / acceptInvite) so a finished
  game's final state is never replayed into a new match.
- safety net: if no state lands within 2.5s of matchFound, the client invokes
  the new Resync hub method; server re-sends the current state to that player.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/src/Hokm.Server/Game/GameManager.cs

@@ -81,6 +81,13 @@ public sealed partial class GameManager
         }
     }
 
+    /// <summary>Client safety net: re-send the current game state to a player who
+    /// may have missed the initial broadcast (green-felt freeze guard).</summary>
+    public void Resync(string userId)
+    {
+        if (RoomOf(userId) is { } room) room.ResendStateTo(userId);
+    }
+
     /// <summary>Player asked to start right now — match any humans waiting and
     /// fill the rest with bots, instead of waiting out the queue.</summary>
     public void PlayNow(string userId)

server/src/Hokm.Server/Game/GameRoom.cs

@@ -387,6 +387,19 @@ public sealed class GameRoom : IDisposable
             _ = _hub.Clients.User(slot.UserId!).SendAsync("state", ToDto(slot.Seat));
     }
 
+    /// <summary>Re-send the current state to one player on demand — the client's
+    /// safety net when the initial broadcast was dropped/raced and the table
+    /// would otherwise freeze waiting for a state that never arrived.</summary>
+    public void ResendStateTo(string userId)
+    {
+        lock (_lock)
+        {
+            var slot = Seats.FirstOrDefault(s => !s.IsBot && s.UserId == userId);
+            if (slot != null)
+                _ = _hub.Clients.User(userId).SendAsync("state", ToDto(slot.Seat));
+        }
+    }
+
     private void Broadcast(string method, object payload)
     {
         foreach (var slot in Seats.Where(s => !s.IsBot && s.UserId != null && s.Connected))

server/src/Hokm.Server/Hubs/GameHub.cs

@@ -38,6 +38,7 @@ public sealed class GameHub : Hub
 
     public void CancelMatchmaking() => _manager.CancelMatchmaking(Uid);
     public void PlayNow() => _manager.PlayNow(Uid);
+    public void Resync() => _manager.Resync(Uid);
     public void PlayCard(string cardId) => _manager.PlayCard(Uid, cardId);
     public void ChooseTrump(string suit) => _manager.ChooseTrump(Uid, suit);
     public void SendReaction(string reaction) => _manager.SendReaction(Uid, reaction);

src/lib/online/signalr-service.ts

@@ -70,6 +70,11 @@ export class SignalrService implements OnlineService {
   private mmStake = 0;
   private mmCbs = new Set<(s: MatchmakingState) => void>();
   private stateCbs = new Set<(s: ServerGameState) => void>();
+  // Last server game state, cached so a late subscriber gets the current state.
+  // enterServerMatch subscribes via a React effect that runs AFTER the ordered
+  // "matchFound"→"state" messages have already been dispatched, so without this
+  // the initial broadcast is dropped and the table freezes on the green felt.
+  private lastState: ServerGameState | null = null;
   private reactionCbs = new Set<(seat: number, reaction: string) => void>();
   private notifCbs = new Set<(n: AppNotification) => void>();
   private profileCbs = new Set<(p: UserProfile) => void>();
@@ -156,8 +161,19 @@ export class SignalrService implements OnlineService {
 
     conn.on("matchmaking", (s: { phase: string; players: number; queuePosition: number | null }) =>
       this.emitMM(s.phase, s.queuePosition ?? undefined));
-    conn.on("matchFound", () => this.emitMM("ready"));
-    conn.on("state", (s: ServerGameState) => this.stateCbs.forEach((cb) => cb(s)));
+    conn.on("matchFound", () => {
+      this.emitMM("ready");
+      // Safety net: if the initial state never lands (dropped/raced), ask the
+      // server to resend it so the table can't freeze on the green felt.
+      const before = this.lastState;
+      setTimeout(() => {
+        if (this.lastState === before) this.conn?.invoke("Resync").catch(() => {});
+      }, 2500);
+    });
+    conn.on("state", (s: ServerGameState) => {
+      this.lastState = s;
+      this.stateCbs.forEach((cb) => cb(s));
+    });
     conn.on("reaction", (r: { seat: number; reaction: string }) =>
       this.reactionCbs.forEach((cb) => cb(r.seat, r.reaction)));
     conn.on("typing", (m: { from: string }) =>
@@ -297,6 +313,7 @@ export class SignalrService implements OnlineService {
   async startMatchmaking(opts: MatchmakingOptions) {
     this.mmRanked = opts.ranked;
     this.mmStake = opts.stake;
+    this.lastState = null; // fresh match — don't replay a prior game's final state
     await this.connect();
     const p = this.cachedProfile ?? (await this.getProfile().catch(() => this.mock.getProfile()));
     this.emitMM("searching");
@@ -337,6 +354,11 @@ export class SignalrService implements OnlineService {
 
   onState(cb: (s: ServerGameState) => void): Unsubscribe {
     this.stateCbs.add(cb);
+    // Replay the current state to this late subscriber on a microtask — after the
+    // caller (enterServerMatch) finishes resetting its store — so a match entered
+    // just after the initial broadcast renders instead of freezing on empty felt.
+    const snapshot = this.lastState;
+    if (snapshot) queueMicrotask(() => { if (this.stateCbs.has(cb)) cb(snapshot); });
     return () => this.stateCbs.delete(cb);
   }
 
@@ -471,6 +493,7 @@ export class SignalrService implements OnlineService {
     });
   }
   async createRoom(o: CreateRoomOptions) {
+    this.lastState = null; // fresh match — don't replay a prior game's final state
     await this.connect();
     const p = this.cachedProfile ?? (await this.getProfile().catch(() => this.mock.getProfile()));
     await this.conn?.invoke("CreatePrivateRoom",
@@ -500,7 +523,7 @@ export class SignalrService implements OnlineService {
   }
   async leaveRoom(_roomId: string) { await this.conn?.invoke("LeavePrivate"); }
   onRoom(cb: (r: Room) => void) { this.roomCbs.add(cb); return () => this.roomCbs.delete(cb); }
-  async acceptInvite() { await this.connect(); await this.conn?.invoke("AcceptPrivate"); }
+  async acceptInvite() { this.lastState = null; await this.connect(); await this.conn?.invoke("AcceptPrivate"); }
   async declineInvite() { await this.conn?.invoke("DeclinePrivate"); }
   onRoomInvite(cb: (i: RoomInvite | null) => void) { this.roomInviteCbs.add(cb); return () => this.roomInviteCbs.delete(cb); }