In resetChatAndPhase() (the rewound() handler), also clear all spectators from both PlayerManager and PlayerListWidget before the replay rebuilds from event 0. The forward replay then re-adds exactly the spectators whose join events fall within the new time range via eventGameStateChanged/eventJoin.

cockatrice/src/game/player/player_manager.cpp

@@ -75,6 +75,14 @@ PlayerLogic *PlayerManager::getPlayer(int playerId) const
     return player;
 }
 
+void PlayerManager::clearSpectators()
+{
+    const QList<int> spectatorIds = spectators.keys();
+    for (int spectatorId : spectatorIds) {
+        removeSpectator(spectatorId);
+    }
+}
+
 void PlayerManager::onPlayerConceded(int playerId, bool conceded)
 {
     // Everything else cares about this

cockatrice/src/game/player/player_manager.h

@@ -100,6 +100,9 @@ public:
         emit spectatorRemoved(spectatorId, spectatorInfo);
     }
 
+    /** @brief Remove all spectators, emitting the removal signal for each. */
+    void clearSpectators();
+
     [[nodiscard]] AbstractGame *getGame() const
     {
         return game;

cockatrice/src/game_graphics/player/player_list_widget.cpp

@@ -181,6 +181,17 @@ void PlayerListWidget::removePlayer(int playerId)
     delete takeTopLevelItem(indexOfTopLevelItem(player));
 }
 
+void PlayerListWidget::clearSpectators()
+{
+    const QList<int> playerIds = players.keys();
+    for (int playerId : playerIds) {
+        QTreeWidgetItem *player = players.value(playerId, 0);
+        if (player && !player->data(1, Qt::UserRole).toBool()) {
+            removePlayer(playerId);
+        }
+    }
+}
+
 void PlayerListWidget::setActivePlayer(int playerId)
 {
     QMapIterator<int, QTreeWidgetItem *> i(players);

cockatrice/src/game_graphics/player/player_list_widget.h

@@ -66,6 +66,7 @@ public slots:
     void addPlayer(const ServerInfo_PlayerProperties &player);
     void removePlayer(int playerId);
     void updatePlayerProperties(const ServerInfo_PlayerProperties &prop, int playerId = -1);
+    void clearSpectators();
 };
 
 #endif

cockatrice/src/interface/widgets/tabs/tab_game.cpp

@@ -266,6 +266,10 @@ void TabGame::resetChatAndPhase()
 
     // reset phase markers
     game->getGameState()->setCurrentPhase(-1);
+
+    // reset spectator state so the replay can rebuild it from the start
+    game->getPlayerManager()->clearSpectators();
+    playerListWidget->clearSpectators();
 }
 
 void TabGame::emitUserEvent()