A hybrid AI-controlled game mod that bridges Stardew Valley with AI assistants via the Model Context Protocol (MCP). Enables autonomous AI agents to control and play Stardew Valley through real-time game state synchronization.

┌─────────────────────────────────────────────────────────┐
│ STARDEW VALLEY (Game)                                   │
│   SMAPI Mod (C# .NET 6)                                 │
│     ModEntry → GameStateSerializer                      │
│              → CommandExecutor (w/ Pathfinder)          │
│              → WebSocketServer                          │
└─────────────────────────────────────────────────────────┘
              ↕ ws://localhost:8765/game
┌─────────────────────────────────────────────────────────┐
│ MCP Server (Go)                                         │
│   GameClient: WebSocket connection, state tracking      │
│   StardewAgent: 12 tools, autonomous loop, LLM calls    │
└─────────────────────────────────────────────────────────┘
              ↕ Copilot SDK
┌─────────────────────────────────────────────────────────┐
│ Claude Sonnet (via GitHub Copilot SDK)                  │
└─────────────────────────────────────────────────────────┘

• Stardew Valley (game)
• SMAPI (Stardew Modding API) v4.0.0+
• .NET 6.0 SDK

• Go 1.23+
• GitHub Copilot access (for Claude Sonnet via Copilot SDK)

cd mod/StardewMCP
dotnet build

This compiles StardewMCP.dll and places it in bin/Debug/net6.0/.

cd mcp-server
go build -o stardew-mcp

This produces the stardew-mcp executable.

1. Build the mod (see above)
2. Copy the entire mod/StardewMCP/bin/Debug/net6.0/ folder to your Stardew Valley mods directory:
   • Windows: %AppData%\StardewValley\Mods\StardewMCP\
   • macOS: ~/.config/StardewValley/Mods/StardewMCP/
   • Linux: ~/.config/StardewValley/Mods/StardewMCP/
3. Copy manifest.json to the same folder

Or use SMAPI's mod folder structure:

Mods/
└── StardewMCP/
    ├── manifest.json
    ├── StardewMCP.dll
    └── (other build outputs)

Launch the game through SMAPI. The mod will automatically start a WebSocket server on ws://localhost:8765/game.

The mod activates once you load into a game save.

cd mcp-server
./stardew-mcp

The server connects to the game via WebSocket and begins the autonomous AI agent loop.

The AI agent has access to 12 tools for controlling the game:

The mod and server communicate via JSON over WebSocket.

Request format:

{
  "id": "uuid",
  "type": "command",
  "action": "move_to",
  "params": {"x": 10, "y": 20}
}

Response format:

{
  "id": "uuid",
  "type": "response",
  "success": true,
  "message": "Moved to position",
  "data": {}
}

• WebSocket Port: Default 8765 (configured in WebSocketServer.cs)
• Tool Cooldown: 30 game ticks between tool swings (~0.5s at 60fps)
• State Broadcast: Game state sent every 1 second
• Pathfinding: A* with 50,000 iteration limit, 30-tile scan radius

Mod not loading: Ensure SMAPI 4.0.0+ is installed and the mod files are in the correct Mods folder structure.

WebSocket connection failed: Check that the game is running and a save is loaded. The server retries connection every 5 seconds.

Pathfinding failures: The A* algorithm attempts up to 5 path recalculations. Some areas may be unreachable due to obstacles.