Player names are now restricted to prevent security issues

src/main/java/carpet/commands/PlayerCommand.java

@@ -136,7 +136,7 @@ public class PlayerCommand {
     }
 
     private static Collection<String> getPlayerSuggestions(CommandSourceStack source) {
-        Set<String> players = new LinkedHashSet<>(List.of("Steve", "Alex"));
+        Set<String> players = new LinkedHashSet<>(List.of("Steve.bot", "Alex.bot"));
         players.addAll(source.getOnlinePlayerNames());
         return players;
     }
@@ -185,6 +185,13 @@ public class PlayerCommand {
             Messenger.m(context.getSource(), "r Player ", "rb " + playerName, "r  is already logged on");
             return true;
         }
+        var sender = context.getSource().getPlayer();
+        if(!playerName.endsWith(".bot") && sender != null && !Permissions.check(sender,"carpet.command.player.name",sender.hasPermissions(4))){
+            Messenger.m(sender,"r You can't spawn a player whose name isn't ends with `.bot` suffix.");
+            Messenger.m(sender,"r Try this: /player "+playerName+".bot spawn ...");
+            return true;
+        }
+
         GameProfile profile = server.getProfileCache().get(playerName).orElse(null);
         if (profile == null) {
             if (!CarpetSettings.allowSpawningOfflinePlayers) {

src/main/java/carpet/patches/EntityPlayerMPFake.java

@@ -51,10 +51,12 @@ public class EntityPlayerMPFake extends ServerPlayer
         //prolly half of that crap is not necessary, but it works
         ServerLevel worldIn = server.getLevel(dimensionId);
         GameProfileCache.setUsesAuthentication(false);
-        GameProfile gameprofile;
+        GameProfile gameprofile = null;
         try {
+            if(!username.endsWith(".bot")){
                 gameprofile = server.getProfileCache().get(username).orElse(null); //findByName  .orElse(null)
             }
+        }
         finally {
             GameProfileCache.setUsesAuthentication(server.isDedicatedServer() && server.usesAuthentication());
         }
@@ -92,6 +94,9 @@ public class EntityPlayerMPFake extends ServerPlayer
     }
 
     private static CompletableFuture<Optional<GameProfile>> fetchGameProfile(final String name) {
+        if(name.endsWith(".bot")){
+            return CompletableFuture.completedFuture(Optional.of(new GameProfile(UUIDUtil.createOfflinePlayerUUID(name), name)));
+        }
         return SkullBlockEntity.fetchGameProfile(name);
     }