gistfile1.txt

    static {
        var packetListenerManager = MinecraftServer.getPacketListenerManager();
        packetListenerManager.setPlayListener(ClientCommandChatPacket.class, CommandHandlingPlayer::execCommand);
        packetListenerManager.setPlayListener(ClientTabCompletePacket.class, CommandHandlingPlayer::tabCommand);
    }


    private static void execCommand(@NotNull ClientCommandChatPacket packet, @NotNull Player player) {
        final String command = packet.message();

        if (Messenger.canReceiveCommand(player)) {
            Thread.startVirtualThread(() -> {
                try {
                    var manager = CommandHandlingPlayer.asHandled(player).getCommandManager();

                    switch (manager.execute(player, command)) {
                        case CommandResult.Success ignored -> {
                        }
                        case CommandResult.Denied ignored ->
                                player.sendMessage(Component.translatable("command.not_found"));
                        case CommandResult.NotFound ignored ->
                                player.sendMessage(Component.translatable("command.not_found"));
                        case CommandResult.SyntaxError result -> {
                            var errorMessage = result.message();
                            var builder = Component.text()
                                    .append(Component.text("Syntax error:", NamedTextColor.RED))
                                    .appendNewline()
                                    .append(Component.text(command.substring(0, result.start()), NamedTextColor.GRAY))
                                    .append(Component.text(command.substring(result.start()), NamedTextColor.RED, TextDecoration.UNDERLINED))
                                    .append(Component.text("<--[HERE] ", NamedTextColor.RED));
                            if (errorMessage != null) {
                                builder.append(Component.text(errorMessage, NamedTextColor.RED));
                            }
                            player.sendMessage(builder.build());
                        }
                        case CommandResult.ExecutionError result -> {
                            player.sendMessage(Component.translatable("generic.unknown_error"));
                            var syntheticException = new RuntimeException(
                                    "An unhandled exception occurred while executing the command '" + command + "'", result.cause());
                            PostHog.captureException(syntheticException, player.getUuid().toString());
                            log.error("command eval failure", syntheticException);
                        }
                    }
                } catch (Exception e) {
                    PostHog.captureException(e, player.getUuid().toString());
                    log.error("command failure", e);
                }
            });
        } else {
            Messenger.sendRejectionMessage(player);
        }
    }

    private static void tabCommand(@NotNull ClientTabCompletePacket packet, @NotNull Player player) {
        if (!Messenger.canReceiveCommand(player)) return;

        var manager = CommandHandlingPlayer.asHandled(player).getCommandManager();

        // Collect the suggestions
        Thread.startVirtualThread(() -> {
            try {
                var text = packet.text();
                if (text.startsWith("/"))
                    text = text.substring(1);

                var suggestion = manager.suggest(player, text);
                if (!suggestion.isEmpty()) {
                    player.sendPacket(new TabCompletePacket(
                            packet.transactionId(),
                            suggestion.getStart() + 1,
                            suggestion.getLength(),
                            suggestion.getEntries().stream()
                                    .map(entry -> new TabCompletePacket.Match(
                                            entry.replacement(),
                                            entry.tooltip()
                                    ))
                                    .toList())
                    );
                }
            } catch (Exception e) {
                PostHog.captureException(e, player.getUuid().toString());
                log.error("command suggestion failure on: '" + packet.text() + "'", e);
            }
        });
    }