ValBridgeServer

A Valheim BepInEx mod that enables AI agents to control and inspect Valheim through the GABP (Game Agent Bridge Protocol). Built using forked verions of @pardeike's GABS and Lib.GAB frameworks that are adapted to work with Valheim.

Note: Tested with Claude Code. Not compatible with Cursor as it doesn't dynamically reload MCP tools.

🏗️ Architecture

AI Agent (Claude Code)
  ↕ MCP Protocol
GABS (orchestration server)
  ↕ GABP Protocol
ValBridgeServer (this mod - GABP server)
  ↓ Uses
Valheim Game APIs

Important: ValBridgeServer acts as a GABP server (listens for connections), while GABS acts as a GABP client (connects to your mod).

🔗 Required Components

This mod requires two other components to function:

1. Lib.GAB - .NET library implementing the GABP protocol
2. GABS - Game Agent Bridge Server that connects AI agents to games

✨ Available Tools

Player Tools

• player_get_health - Get player's current health statistics (health, max health, percentage)
• player_get_position - Get player's world position coordinates (x, y, z)

Terminal Tools

• run_command - Execute Valheim console commands (e.g., spawn Boar 1 1, god, heal, tod 0)

ZNetScene Tools (Prefab Registry)

• znetscene_search_prefabs - Search for prefabs by name (partial match, case-insensitive)
• znetscene_get_prefab - Get detailed prefab information by exact name
• znetscene_list_prefab_names - List all available prefab names with optional prefix filter

Unity Explorer Tools (Scene Inspection)

• unity_search_objects - Search for Unity objects (GameObjects, Components) by name/type with filters
• unity_search_singletons - Find singleton instances by type name
• unity_get_loaded_scenes - Get list of all currently loaded scenes (including DontDestroyOnLoad)
• unity_get_scene_roots - Get root GameObjects in a scene by handle
• unity_inspect_object - Get detailed information about any Unity object by instance ID
• unity_read_component - Read component data from a GameObject by type name
• unity_get_children - Get child GameObjects of a parent by instance ID

Event Channels

• player/death - Player death notifications
• player/health_changed - Health change events

📦 Installation

Prerequisites

• Valheim via Steam
• BepInEx 5.4.2200+ - For macOS, follow this guide to set up modded Valheim with run_bepinex.sh
• .NET SDK for building
• GABS installed
• Lib.GAB - Clone and build, reference the DLL

Steps

1. Build and Install Dependencies

   # Clone and build Lib.GAB
   git clone https://github.com/jneb802/Lib.GAB.git
   cd Lib.GAB/Lib.GAB
   dotnet build
   cd ../..
   
   # Clone and build ValBridgeServer
   git clone https://github.com/jneb802/ValBridgeServer.git
   cd ValBridgeServer
   dotnet build
   
   # Copy all required DLLs to BepInEx plugins
   cp bin/Debug/ValBridgeServer.dll "<Valheim>/BepInEx/plugins/"
   cp ../Lib.GAB/Lib.GAB/bin/Debug/netstandard2.0/Lib.GAB.dll "<Valheim>/BepInEx/plugins/"
   cp bin/Debug/Newtonsoft.Json.dll "<Valheim>/BepInEx/plugins/"
   

2. Configure GABS for Valheim (Configuration Guide)

   For vanilla Valheim:

   gabs games add valheim --steam-app-id 892970
   

   For modded Valheim (macOS with BepInEx):

   gabs games add valheim
   # When prompted, select "DirectPath" mode
   # Target: /path/to/Valheim/run_bepinex.sh
   # Working Directory: /path/to/Valheim
   # Stop Process Name: Valheim
   

   Example config:

   Launch Mode: DirectPath
   Target: ~/Library/Application Support/Steam/steamapps/common/Valheim/run_bepinex.sh
   Stop Process Name: Valheim
   

3. Add GABS MCP Server

   Add to your MCP settings (e.g., Claude Desktop config.json):

   {
     "mcpServers": {
       "gabs": {
         "command": "gabs",
         "args": ["server"]
       }
     }
   }
   

4. Launch and Connect

   In Claude Code:

   Tell Claude to launch Valheim using GABS
   Wait for Valheim to start, launch into world. 
   Tell Claude to use game connect tool.
   Tools should sync. 
   Now you can access any of the available tools.
   

💡 Example Usage

AI: "What's the player's current health?"
> Uses player_get_health
> Returns: { "success": true, "health": 25.0, "maxHealth": 25.0, "healthPercentage": 100.0 }

AI: "Where is the player?"
> Uses player_get_position  
> Returns: { "success": true, "position": { "x": 123.45, "y": 50.0, "z": -67.89 } }

AI: "Spawn 5 boars near me"
> Uses run_command with "spawn Boar 5"
> Returns: { "success": true, "command": "spawn Boar 5", "queued": true }

AI: "Search for all wolf prefabs"
> Uses znetscene_search_prefabs with nameFilter: "wolf"
> Returns: List of matching prefabs (Wolf, Fenring, etc.)

AI: "Find the Player singleton"
> Uses unity_search_singletons with typeFilter: "Player"
> Returns: Player singleton instance with ID for further inspection

📄 License

MIT License - see LICENSE file for details.

🔗 Related Projects

• GABS - Game Agent Bridge Server (orchestrator)
• Lib.GAB - GABP protocol library for .NET
• GABP Specification - Protocol documentation