POC only: Bifrost

engine/src/main/java/org/terasology/engine/core/TerasologyEngine.java

@@ -111,7 +111,8 @@ public class TerasologyEngine implements GameEngine {
      * You don't want to add to this! If you need a module, make a module!
      */
     private static final Set<String> LEGACY_ENGINE_MODULE_POLLUTERS = Set.of(
-            "org.terasology.subsystem.discordrpc.DiscordRPCSubSystem"
+            "org.terasology.subsystem.discordrpc.DiscordRPCSubSystem",
+            "org.terasology.subsystem.nakama.NakamaSubSystem"
     );
 
     private final List<Class<?>> classesOnClasspathsToAddToEngine = new ArrayList<>();

facades/PC/build.gradle.kts

@@ -19,6 +19,13 @@ plugins {
     id("facade")
 }
 
+repositories {
+    maven {
+        name = "JitPack"
+        url = uri("https://jitpack.io")
+    }
+}
+
 // Grab all the common stuff like plugins to use, artifact repositories, code analysis config
 apply(from = "$rootDir/config/gradle/publish.gradle")
 
@@ -64,6 +71,7 @@ dependencies {
 
     implementation(project(":engine"))
     implementation(project(":subsystems:DiscordRPC"))
+    implementation(project(":subsystems:Nakama"))
     implementation("io.projectreactor:reactor-core:3.4.7")
 
     // TODO: Consider whether we can move the CR dependency back here from the engine, where it is referenced from the main menu

facades/PC/src/main/java/org/terasology/engine/Terasology.java

@@ -314,6 +314,7 @@ private void populateSubsystems(TerasologyEngineBuilder builder) {
                     .add(new LwjglInput())
                     .add(new BindsSubsystem());
             builder.add(new DiscordRPCSubSystem());
+            builder.add(new org.terasology.subsystem.nakama.NakamaSubSystem());
         }
         builder.add(new HibernationSubsystem());
     }

settings.gradle.kts

@@ -26,7 +26,7 @@ dependencyResolutionManagement {
             library("mockito-inline", "org.mockito:mockito-inline:3.12.4")
             library("mockito-junit", "org.mockito", "mockito-junit-jupiter").versionRef(mockito)
             // protobuf does not work as the others, see https://github.com/google/protobuf-gradle-plugin/issues/563
-            val protobuf = version("protobuf", "3.22.5")
+            val protobuf = version("protobuf", "4.28.2")
             val slf4j = version("slf4j", "2.0.11")
             library("slf4j-api", "org.slf4j", "slf4j-api").versionRef(slf4j)
             library("slf4j-jul", "org.slf4j", "jul-to-slf4j").versionRef(slf4j)

subsystems/Nakama/build.gradle.kts

@@ -0,0 +1,45 @@
+// Nakama subsystem - optional Bifrost integration
+// Bridges Gestalt chat events to/from a Nakama chat channel
+
+plugins {
+    java
+    `java-library`
+    id("terasology-common")
+}
+
+apply(from = "$rootDir/config/gradle/common.gradle")
+
+configure<SourceSetContainer> {
+    main { java.destinationDirectory.set(layout.buildDirectory.dir("classes")) }
+    test { java.destinationDirectory.set(layout.buildDirectory.dir("testClasses")) }
+}
+
+repositories {
+    maven {
+        name = "JitPack"
+        url = uri("https://jitpack.io")
+    }
+}
+
+dependencies {
+    implementation(project(":engine"))
+
+    annotationProcessor(libs.gestalt.injectjava)
+
+    api("com.github.heroiclabs.nakama-java:nakama-java:2.5.3")
+}
+
+tasks.named<Test>("test") {
+    // Exclude integration tests by default — they need a running Nakama server
+    useJUnitPlatform {
+        if (!project.hasProperty("includeTags")) {
+            excludeTags("integration")
+        } else {
+            includeTags(project.property("includeTags") as String)
+        }
+    }
+    // Pass nakama.test.* system properties through to the test JVM
+    System.getProperties().entries
+        .filter { (it.key as String).startsWith("nakama.test.") }
+        .forEach { systemProperty(it.key as String, it.value) }
+}

subsystems/Nakama/src/main/java/org/terasology/subsystem/nakama/NakamaAutoConfig.java

@@ -0,0 +1,59 @@
+// Copyright 2026 The Terasology Foundation
+// SPDX-License-Identifier: Apache-2.0
+
+package org.terasology.subsystem.nakama;
+
+import org.terasology.engine.config.flexible.AutoConfig;
+import org.terasology.engine.config.flexible.Setting;
+
+import static org.terasology.engine.config.flexible.SettingArgument.defaultValue;
+import static org.terasology.engine.config.flexible.SettingArgument.name;
+import static org.terasology.engine.config.flexible.SettingArgument.type;
+
+/**
+ * Persistent configuration for the Nakama subsystem.
+ * Auto-discovered by the engine and saved to ~/.terasology/configs/nakama/NakamaAutoConfig.cfg
+ */
+public class NakamaAutoConfig extends AutoConfig {
+
+    public final Setting<Boolean> enabled = setting(
+            type(Boolean.class),
+            defaultValue(false),
+            name("Enable Nakama")
+    );
+
+    public final Setting<String> host = setting(
+            type(String.class),
+            defaultValue("localhost"),
+            name("Nakama Server Host")
+    );
+
+    public final Setting<Integer> grpcPort = setting(
+            type(Integer.class),
+            defaultValue(7349),
+            name("gRPC Port")
+    );
+
+    public final Setting<Integer> wsPort = setting(
+            type(Integer.class),
+            defaultValue(7350),
+            name("WebSocket Port")
+    );
+
+    public final Setting<String> channel = setting(
+            type(String.class),
+            defaultValue("bifrost.lobby"),
+            name("Chat Channel")
+    );
+
+    public final Setting<String> playerName = setting(
+            type(String.class),
+            defaultValue(""),
+            name("Player Name")
+    );
+
+    @Override
+    public String getName() {
+        return "Nakama Settings";
+    }
+}

subsystems/Nakama/src/main/java/org/terasology/subsystem/nakama/NakamaConfig.java

@@ -0,0 +1,59 @@
+// Copyright 2026 The Terasology Foundation
+// SPDX-License-Identifier: Apache-2.0
+
+package org.terasology.subsystem.nakama;
+
+/**
+ * Configuration for the Nakama subsystem.
+ * Read from system properties for the POC.
+ */
+public class NakamaConfig {
+    private boolean enabled = false;
+    private String host = "localhost";
+    private int grpcPort = 7349;
+    private int wsPort = 7350;
+    private String channel = "bifrost.lobby";
+    private String playerName = "";
+
+    public boolean isEnabled() { return enabled; }
+    public void setEnabled(boolean enabled) { this.enabled = enabled; }
+
+    public String getHost() { return host; }
+    public void setHost(String host) { this.host = host; }
+
+    /** gRPC port for API calls (auth, account). Default: 7349. */
+    public int getGrpcPort() { return grpcPort; }
+    public void setGrpcPort(int grpcPort) { this.grpcPort = grpcPort; }
+
+    /** @deprecated Use {@link #getGrpcPort()}. Kept for backwards compatibility. */
+    @Deprecated
+    public int getPort() { return grpcPort; }
+    /** @deprecated Use {@link #setGrpcPort(int)}. */
+    @Deprecated
+    public void setPort(int port) { this.grpcPort = port; }
+
+    /** WebSocket port for realtime (chat, presence). Default: 7350. */
+    public int getWsPort() { return wsPort; }
+    public void setWsPort(int wsPort) { this.wsPort = wsPort; }
+
+    public String getChannel() { return channel; }
+    public void setChannel(String channel) { this.channel = channel; }
+
+    public String getPlayerName() { return playerName; }
+    public void setPlayerName(String playerName) { this.playerName = playerName; }
+
+    /**
+     * Load config from system properties (nakama.enabled, nakama.host, etc.)
+     * Falls back to defaults if not set.
+     */
+    public static NakamaConfig fromSystemProperties() {
+        NakamaConfig config = new NakamaConfig();
+        config.setEnabled(Boolean.parseBoolean(System.getProperty("nakama.enabled", "false")));
+        config.setHost(System.getProperty("nakama.host", "localhost"));
+        config.setGrpcPort(Integer.parseInt(System.getProperty("nakama.grpcPort", "7349")));
+        config.setWsPort(Integer.parseInt(System.getProperty("nakama.wsPort", "7350")));
+        config.setChannel(System.getProperty("nakama.channel", "bifrost.lobby"));
+        config.setPlayerName(System.getProperty("nakama.playerName", ""));
+        return config;
+    }
+}