MG101 Studio

A native desktop editor for the NUX MG-101 guitar multi-effects processor. Edit patches safely on your computer: browse a library, tweak amp/cab/effect models and parameters, sync with the device over MIDI, and — optionally — drive edits with an AI agent. The editor, the writer, and the MCP server all share one device profile and one command bus, so every path applies the same validation.

Status: active implementation is the Rust workspace under rust/. The original Swift 1.x app is archived under archive/swift-v1/ for reference and is no longer developed. The .mg101patch file format is fully supported — the codec is lossless byte-for-byte.

Not affiliated with or endorsed by NUX / Cherub Technology. "NUX" and "MG-101" are trademarks of their respective owners; used here only to describe compatibility.

Highlights

• Patch library — persistent SQLite store with revisions, undo, tags, ratings, notes, and collections. On first launch it seeds a few generic starter presets (see Seed data below).
• Model-aware editor — name, BPM, send/return, bypasses, models, and parameters, validated against the device's effect catalog; inactive parameters are zeroed on model change.
• Lossless codec — unknown bytes are preserved exactly; export always writes a new file and never overwrites in place.
• Binary view — logical (grouped fields) and raw (offset + hex + ASCII) layouts with changed ranges highlighted; hex/decimal toggle.
• Device sync (MIDI/SysEx) — read the device state, follow its notifications (patch change, tempo, expression), and send controlled writes.
• DRUM control — pick a rhythm pattern via a two-level group→pattern menu, start/stop, set volume and tempo live.
• AI agent — in-app assistant that edits patches through the same typed commands. Three backends (see AI backends).
• MCP server — expose the same tools to external agents over stdio, either editing files or bridging to the live running app.

Architecture

The core is device-agnostic: mg101-core knows nothing about the MG-101 specifically — a Device Pack (mg101-pack-nux-mg101) supplies the device profile and effect catalog as data (JSON), so new devices are packs, not forks. All state changes flow through a single command bus (Studio::execute(&Command)), shared by the UI (Slint), the AI agent, and the MCP server. See docs/adr/ and docs/architecture/.

The workspace is ~11 crates: core, device-pack-api, device-link, pack-nux-mg101, commands, library, transfer-engine, studio, agent-core, mcp, desktop. The core builds to wasm32.

Build and run

cd rust
cargo build --workspace
cargo run -p mg101-desktop        # desktop app (Slint)
cargo run -p mg101-mcp            # MCP server over stdio (rmcp)

Quality gates (same as CI, on macOS + Windows):

cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings
cargo fmt --all -- --check

AI backends

Configure in Settings. All three go through the same command bus; the API key (when needed) lives only in the OS keychain, never in a config file.

• Anthropic — native Messages API. Requires an API key.
• OpenAI-compatible — any Chat Completions endpoint, including local servers (Ollama, LM Studio). Requires the endpoint + model.
• Claude Code (subscription) — drives a locally installed claude -p; your Claude subscription pays, no API key needed. Tools reach the app through the MCP bridge (below). Permissions are scoped to mcp__mg101 — no shell, no file access.

MCP

The MCP server runs over stdio and has two modes:

• --file — edits .mg101patch files (input → output); the running app does not see these changes.
• --bridge — tools act on the live library of the running app, so edits appear in the UI immediately. Listens only on 127.0.0.1, behind a token in ~/.mg101_bridge_token (mode 0600). Enable the bridge in Settings.
• no flag (--auto, default) — bridge if the app is running, else files.

Register it with a client, e.g.:

claude mcp add mg101 -- /path/to/mg101-mcp --bridge

Tools include the full library variant in bridge mode: list_patches, get_patch, get_selection, set_model, set_parameter, set_bpm, set_name, set_bypass, set_ir/clear_ir, metadata/collection tools, and DRUM controls. In file mode, inspect_patch reads a record to JSON, and every mutating tool requires a separate input and output path (never overwrites).

Seed data and factory patches

MG101 Studio does not ship the manufacturer's factory patches — those are NUX's property, and you pull them from your own device. On first launch the library is seeded with a handful of generic, synthetic presets generated from the device profile (structurally valid 8402-byte records, no proprietary data). Edit or delete them freely.

Device profile

A pack is two JSON files: device-profile.json (record size, blocks, selectors, parameter windows, BPM, named fields) and effects-catalog.json (models, active parameters, offsets, allowed ranges). The bundled MG-101 pack lives in rust/crates/pack-nux-mg101/resources/.

Testing the codec against real hardware

The default suite proves the codec's lossless round-trip on synthetic data, so it needs no proprietary files. Fidelity tests against a real NUX factory dump (36/36 byte-exact, the wire decoder, golden decoded values) are gated behind an off-by-default feature. If you own the device and want to run them, drop your local dumps into rust/crates/pack-nux-mg101/oracle/ (git-ignored) and:

cargo test -p mg101-pack-nux-mg101 --features hardware-oracle

Contributing

See CONTRIBUTING.md. Please don't commit factory patch dumps or other manufacturer-owned data.

License

MIT © 2026 Maciek Ostaszewski.