mgba-live-mcp 0.3.0

MCP server for persistent live mGBA control with script bridge, screenshots, memory and input tooling

mgba-live-mcp

MCP server for persistent, live mGBA control. It is designed for agent workflows that need to keep one emulator process running across multiple tool calls (input, Lua, memory reads, OAM/entity dumps, screenshots).

If you need one-shot/headless runs instead of persistent sessions, see struktured-labs/mgba-mcp.

What You Get (MCP Context)

• Long-lived session lifecycle: mgba_live_start, mgba_live_attach, mgba_live_status, mgba_live_stop
• Live control: mgba_live_input_tap, mgba_live_input_set, mgba_live_input_clear, mgba_live_run_lua
• Inspection: mgba_live_read_memory, mgba_live_read_range, mgba_live_dump_pointers, mgba_live_dump_oam, mgba_live_dump_entities
• Snapshot output: mgba_live_export_screenshot plus image snapshots returned by status/attach/start_with_lua/most live commands

MCP reference: docs/mcp-reference.md

Quick Start (uvx)

1. Run directly from PyPI with uvx:

uvx mgba-live-mcp

2. If you want to run from git (for unreleased changes), use:

uvx --from git+https://github.com/penandlim/mgba-live-mcp mgba-live-mcp

3. Register in an MCP client (Codex example):

[mcp_servers.mgba]
command = "uvx"
args = ["mgba-live-mcp"]

Git fallback (if package is not yet published):

[mcp_servers.mgba]
command = "uvx"
args = ["--from", "git+https://github.com/penandlim/mgba-live-mcp", "mgba-live-mcp"]

Local Development

1. Install dependencies for this repo:

uv sync

2. Run the MCP server:

uv run mgba-live-mcp

3. Register it in your MCP client (Codex example):

[mcp_servers.mgba]
command = "uv"
args = [
  "run",
  "--directory",
  "/absolute/path/to/mgba-live-mcp",
  "mgba-live-mcp",
]

4. Install and run pre-commit hooks (lint/checks via uv run):

make precommit-install
make precommit-run

Requirements And Setup Links

• mGBA: Build/install a Qt + Lua-capable binary (mgba-qt/mGBA) with these required CMake flags: -DBUILD_QT=ON -DENABLE_SCRIPTING=ON -DUSE_LUA=ON
• uv: Python package/runtime manager used by this repo (uv sync, uv run ...)
• Model Context Protocol: Protocol used by the server; configure this process as an MCP server in your client

Important runtime notes:

• A ROM path is required to start (.gba, .gb, .gbc).
• Binary auto-discovery order: mgba-qt, mgba, mGBA.
• If auto-discovery fails, pass mgba_path in mgba_live_start or mgba_live_start_with_lua.
• Runtime state is stored at ~/.mgba-live-mcp/runtime (sessions, logs, command/response files).
• This is a hard cutover from repo-local .runtime; no hybrid fallback is used.
• If you have old repo-local sessions, migrate manually by copying .runtime/* to ~/.mgba-live-mcp/runtime/.
• mgba_live_status with all=true lists sessions from this shared user-level runtime root.
• scripts/mgba_live_bridge.lua is transitional for local workflows; packaged src/mgba_live_mcp/resources/mgba_live_bridge.lua is the runtime source of truth.

Common MCP Flows

1) Start a session

{
  "rom": "/absolute/path/to/game.gba",
  "fast": true
}

Notes:

• fast: true maps to fps_target=600
• default when omitted is fps_target=120

2) Start + run Lua immediately

Use mgba_live_start_with_lua when you need first-frame setup and a post-Lua snapshot in one call.

{
  "rom": "/absolute/path/to/game.gba",
  "code": "return emu:currentFrame()"
}

3) Tap input and capture after settle

{
  "session": "20260220-120000",
  "key": "A",
  "frames": 2,
  "wait_frames": 6
}

wait_frames is applied after release before the screenshot is captured.

4) Read memory

{
  "session": "20260220-120000",
  "start": 49664,
  "length": 64
}

5) Save screenshot to a known path

{
  "session": "20260220-120000",
  "out": "/tmp/mgba-shot.png"
}

Important Behavior

• mgba_live_start is bootstrap-only (no Lua arg, no screenshot return).
• mgba_live_start_with_lua requires exactly one of file or code.
• mgba_live_run_lua supports callback-style macros by returning { macro_key = "..." } and setting _G[macro_key].active = false when done; the tool waits for completion before returning its snapshot.
• mgba_live_input_set and mgba_live_input_clear update held keys but do not include a snapshot; call mgba_live_status to verify visually.
• Automatic snapshots in tool responses include only frame metadata and image content. Files are persisted only via mgba_live_export_screenshot.

Local CLI (Dev/Debug)

The MCP server wraps scripts/mgba_live.py. This script is a compatibility shim that delegates to the packaged module CLI.

uv run python scripts/mgba_live.py --help
uv run python scripts/mgba_live.py start --help
uv run pytest

Quality commands:

make lint
make typecheck
make test
make check

Release Checklist

1. Update version in pyproject.toml and src/mgba_live_mcp/__init__.py.
2. Add release notes in CHANGELOG.md.
3. Run local checks: uv sync --group dev && make check && uv build
4. Trigger TestPyPI publish workflow (publish-testpypi) and verify install from TestPyPI.
5. Push tag vX.Y.Z to trigger the PyPI release workflow.
6. Smoke test: uvx mgba-live-mcp and uvx --from git+https://github.com/penandlim/mgba-live-mcp mgba-live-mcp.