agent ──MCP(stdio)──▶ game-bridge-mcp ──HTTP──▶ 127.0.0.1:7820  ← it launched this one
                                      ├───────▶ 127.0.0.1:7801  ← your IDE started this one
                                      └───────▶ 127.0.0.1:7802  ← a colleague's session

npx @wildware/game-bridge-mcp --help

claude mcp add game-bridge -- npx -y @wildware/game-bridge-mcp

launch_instance {}                                 // start a game; the bridge picks the port
list_instances  {}                                 // ...or find one already running
list_toolsets   { "port": 7820 }                   // what can this instance do?
describe_toolset { "port": 7820, "name": "play" }  // exact schemas
call_tool { "port": 7820, "name": "drop", "arguments": { "x": 1.2 } }
stop_instance { "port": 7820 }                     // clean shutdown, not a kill

GET /health

{ "ok": true, "frame": 91422 }

{
  "frame": 91422,
  "simFrame": 48110,
  "completedCommandId": 17,
  "paused": false,
  "ui": {
    "screen": "GameScreen",
    "elements": [ { "label": "Restart", "visible": true } ]
  },
  "events": [ { "m": "merge:cherry" }, { "m": "click:Restart" } ],
  "game": { "score": 1280, "state": "RUNNING" }
}

GET /command?cmd=spawn&type=cherry&x=-1.5

{ "accepted": true, "commandId": 18, "frame": 91430 }

// game thread, once per frame
while (true) {
    val cmd = queue.poll() ?: break
    apply(cmd)
    completedCommandId = cmd.id   // published in the next /state snapshot
}

{
  "game": { "name": "Orbital Freight", "version": "0.9.2", "protocol": 1 },
  "toolsets": [
    {
      "name": "play",
      "description": "Drive the game the way a player does.",
      "tools": [
        {
          "name": "drop",
          "description": "Release the held crate, aiming first if x is given.",
          "args": [
            { "name": "x", "type": "number", "description": "World x, -2..2", "required": true, "default": null },
            { "name": "settle", "type": "boolean", "description": "Wait for the stack to settle", "default": "true" }
          ]
        }
      ]
    }
  ],
  "passthrough": {
    "description": "Any command the debug bridge accepts, passed straight through.",
    "examples": ["set_seed { seed }", "set_gravity { x, y }"]
  }
}

~/.game-bridge/instances/<pid>.json

{
  "name": "Orbital Freight",
  "version": "0.9.2",
  "protocol": 1,
  "port": 7820,
  "pid": 12345,
  "host": "127.0.0.1",
  "started": "2026-08-20T22:27:19.774Z",
  "cwd": "/home/dev/checkouts/main"
}

{
  "name": "Orbital Freight",
  "launch": {
    "command": "./gradlew lwjgl3:run -PdebugPort={port} --console=plain",
    "cwd": ".",
    "portRange": "7820-7839",
    "readyTimeoutMs": 180000,
    "env": { "ORBITAL_DEV": "1" }
  }
}

// 1. What is already running?
list_instances {}

{
  "registryDir": "/home/dev/.game-bridge/instances",
  "live": [
    { "port": 7801, "discovery": "scan", "status": "live-no-manifest",
      "frame": 2453, "manifest": "fallback", "screen": "GameScreen" },
    { "port": 7820, "discovery": "both", "status": "live", "game": "Orbital Freight",
      "version": "0.9.2", "protocol": 1, "manifest": "game", "pid": 87488,
      "cwd": "/home/dev/checkouts/main", "screen": "MenuScreen",
      "toolsets": ["play", "build", "flow", "bridge"], "launchedByThisBridge": true }
  ],
  "stale": [],
  "notAGame": [],
  "free": [7777, 7802, 7803]
}

// 2. Start a second one. You do not choose the port.
launch_instance {}

{ "port": 7821, "pid": 90114, "name": "Orbital Freight", "version": "0.9.3-rc1",
  "cwd": "/home/dev/checkouts/rc", "readyInMs": 4080,
  "logFile": "/tmp/game-bridge-logs/instance-7821-1787264835950.log" }

// 3. Same seed, same move, both runs.
call_tool { "port": 7820, "name": "set_seed", "arguments": { "seed": 12345 } }
call_tool { "port": 7821, "name": "set_seed", "arguments": { "seed": 12345 } }

call_tool { "port": 7820, "name": "drop", "arguments": { "x": 1.2 } }
call_tool { "port": 7821, "name": "drop", "arguments": { "x": 1.2 } }

{
  "port": 7821, "tool": "drop", "via": "manifest", "command": "drop",
  "applied": true, "commandId": 18, "confirmation": "completedCommandId",
  "frame": 948, "screen": "GameScreen",
  "game": { "score": 1280, "state": "RUNNING" },
  "events": ["merge:cherry", "score:+40"]
}

// 4. Wait for something the command could not report.
call_tool { "port": 7821, "name": "wait_for",
            "arguments": { "path": "game.pendingMerges", "equals": 0, "timeoutMs": 5000 } }

// 5. Clean up what you started. 7801 is not yours - leave it alone.
stop_instance { "port": 7821 }

{ "port": 7821, "stopped": true, "how": "closed cleanly" }

GameOffline: No game is answering on http://127.0.0.1:7809.
Start one with:
  ./gradlew lwjgl3:run -PdebugPort=7809

NotAGameSurface: Something is listening on http://127.0.0.1:7802, but it is not a
debuggable game: GET /health returned HTTP 404.
A drivable game must answer GET /health with {"ok":true,"frame":N}. Check whether
another process has taken this port.

CommandTimeout: Command 'restart' was queued on port 7801 but was not applied
within 5000ms. The game accepted it, so it is probably blocked, frozen, or on a
screen that ignores this command.

npx @wildware/game-bridge-mcp [options]

  -p, --port <n>           Default port for tools that do not name one (default 7777)
      --scan-range <spec>  Ports list_instances sweeps (default 7777,7800-7810)
      --no-scan            Discover only via the instance registry
      --no-registry        Discover only by scanning ports
      --registry-dir <dir> Where instance entries live (default ~/.game-bridge/instances)
      --config <file>      Project launch declaration (default: nearest gamebridge.json)
      --launch-hint <cmd>  Command shown when a port is dead; {port} is substituted
      --manifest <file>    Tool manifest for games that do not serve GET /tools
      --eager              Advertise every tool flatly, for clients that cannot discover
      --timeout <ms>       HTTP and command timeout (default 5000)
  -h, --help
  -v, --version

#!/usr/bin/env node
import { parseCli, applyProjectConfig, startStdioServer } from "@wildware/game-bridge-mcp";

const { config } = parseCli(process.argv.slice(2), process.env);
await applyProjectConfig(config);

await startStdioServer(config, {
  composites: [
    {
      name: "drop_and_settle",
      description: "Drop at world x and wait until nothing is moving. The main way to play.",
      only: "Orbital Freight",            // never offered to a game that has no crates
      args: [{ name: "x", type: "number", required: true, description: "World x" }],
      async run(ctx) {
        const before = await ctx.state();
        await ctx.commandAndSync("drop", { x: ctx.args.x });
        const settled = await ctx.call("wait_for", { path: "game.moving", equals: 0, timeoutMs: 10000 });
        const after = await ctx.state();
        return { settled: settled.matched, scoreDelta: after.game.score - before.game.score };
      },
    },
  ],
});

npm install
npm run build     # TypeScript -> dist/
npm test          # builds, then runs node --test

npm version minor          # keep SERVER_VERSION in src/server.ts in step
npm test                   # prepublishOnly runs build + test again
npm pack --dry-run         # confirm dist/, README.md and LICENSE are the payload
npm publish                # publishConfig.access is already "public"