NDSP QC MCP

An unofficial, modular control platform for Neural DSP Quad Cortex devices. The project provides hardware-faithful Windows and Android controllers plus a standalone MCP server, while keeping future iOS, web, and other clients from duplicating device-control logic.

Repository shape

apps/                       End-user clients
  windows/                  Tauri + web UI desktop client
  android/                  Capacitor Android client with native USB, AI, and voice adapters
  ios/                      Future iOS composition root
services/                   Independently runnable processes
  device-broker/            Native single-owner USB/protobuf broker
  device-gateway/           Legacy Python parity gateway for development
  mcp-server/               Standalone MCP server
packages/
  rust/
    qc-protocol/             Shared QC framing, protobuf schema, and native state engine
    qc-android/              Narrow JNI binding for the shared native state engine
  python/
    qc-core/                Pure device model, use cases, ports, safety rules
    qc-pyquadcortex/        Development-only pyquadcortex parity adapter
    qc-gateway-client/      Client for a running device gateway
  typescript/
    qc-core/                Shared client behavior, commands, reducers, transport port
    qc-client/              Generated contracts and gateway transport types
    qc-ui/                  Platform-neutral web UI primitives
    qc-form-factors/        QC geometry, skins, and control manifests
contracts/                  Versioned wire schemas; the cross-language source of truth
docs/                       Product, architecture, and decision records
tests/                      Cross-module contract and real-hardware tests

Every directory initially contains a boundary document. Code is added only to the module that owns the responsibility.

Related MCP server: reaper-daw-mcp-server

Architectural rules

• qc-core contains no HID, MCP, HTTP, UI, Tauri, or operating-system imports.

• Production device behavior lives in the shared Rust crates; qc-pyquadcortex isolates the optional Python parity oracle.

• Exactly one process owns the QC USB-HID session at a time.

• Clients communicate in typed domain commands and events, never protobuf packets or raw grid coordinates.

• contracts/ is the source of truth for cross-process and cross-language messages.

• The MCP server is independently installable and never imports a desktop or mobile app.

• Form-factor geometry, skins, and behavior are separate; adding a client or skin must not change device logic.

• AI is an optional adapter. Manual device control continues to work without an AI provider.

See Architecture, the Windows implementation plan, and the pyquadcortex coverage and deferred OpenCortex research.

Status

The Windows client now has a Tauri/WebView2 shell, reusable hardware surface, form-factor/skin packages, keyboard/mouse interaction, connection diagnostics, menus, chat composer, and microphone capture lifecycle. A native Rust broker owns QC HID, exposes the complete application gateway API, keeps the session warm, and publishes realtime state from the same Rust decoder compiled into Android. The optional Python gateway is a development-only differential oracle. One Rust session machine now owns reconnect, handshake, keepalive, and link-loss policy for both native hosts, and shared payload schemas generate the TypeScript, Rust, and Python boundary types. Scene selection, block bypass, tuner, and Gig View controls are enabled, along with mode-aware A–H footswitch emulation through the QC's Windows MIDI endpoint and verified tempo/encoder/tap control, live setlist browsing, installed model discovery, guarded block placement/removal/movement, STOMP assignment and signal-routing editing, guarded preset recall, bank navigation, metadata-driven block parameter editing, and explicit dirty-state recovery. The Grid rails and split/rejoin markers are derived from the live preset's four-row routing topology rather than demo labels, including parallel-lane blocks and split/rejoin points. Visible device state synchronizes in the background so touchscreen changes appear without a manual refresh. Explicit disconnect/reconnect, a privacy-safe connection log, current-device details, and an allowlisted redacted diagnostics export are available from the application menus. State-changing commands use expected-state guards, value readback, and dirty-state verification. Local .qcw workspace snapshots can be saved and reopened without touching the hardware. Persistent preset, library, and global-setting writes require explicit review and confirmation. The chat dock now supports a configurable OpenAI Responses-compatible conversational model, supplies current QC context as untrusted data, and exposes an allowlisted set of typed device tools. Read tools can be followed by a natural answer; performance actions retain expected-state guards; bypass and parameter edits still require review before temporary application. The deterministic offline command parser remains available when no model is configured. Windows installer builds embed only the native Rust device broker; Python and pyquadcortex remain source-level parity tools and are not installed. The installer also embeds the optional YouTube reference-audio resolver: after explicit rights confirmation, chat can fetch a bounded excerpt as Opus/WebM or AAC/M4A, losslessly remux it, attach it to the next model round, and remove the temporary file. An installed app does not require Python, Node, Rust, the source tree, or a repository .venv at runtime. Push-to-talk voice transcription is runtime-detected and opt-in: the app discloses that stable Microsoft Edge speech recognition may send microphone audio to Microsoft Azure before starting it, then routes the visible transcript through the same guarded typed-command path.

The public MCP and remote-control services are implemented in Rust, with the legacy Python server retained only as a compatibility oracle. Neither deployed path exposes raw HID, protobuf, or arbitrary JSON-RPC; global-setting mutations remain typed, allowlisted, and confirmation-gated. See Chat and MCP setup.

The Android client is available as a branded Firebase App Distribution build. It presents the QC display, compact performance controls, and chat in a phone-first layout. Android owns a direct USB-host HID session with the Quad Cortex (USB permission is requested on first attachment), uses Firebase AI Logic with Gemini 3.7 Flash without embedding a personal Gemini key, and sends Android speech-recognition transcripts through the same chat/action path. The mobile shell composes the same preset, Grid, routing, scene, parameter, footswitch, history, save, and performance workflows as Windows, including the same guarded assistant action executor, generated hardware-safe action allowlist, and offline intent resolver. That shared allowlist covers the contracted read, performance, edit, library, and confirmed system surface. Live USB messages populate the preset grid, routes, scene metadata, setlist position, dirty state, tempo, mode/footswitch state, and master volume through the shared Rust state engine. The Firebase project registers the stable distribution certificate used by the tester APK. App Check is not yet activated in the project. Before enabling Play Integrity enforcement for Firebase AI Logic, review the off-Play policy in the hardware-conformance release checklist so Firebase App Distribution builds are not rejected as unrecognized Play installs.

Run npm run app-parity:check for the executable capability inventory. It distinguishes required Windows/Android parity from justified platform-only features and validates the shared/native evidence for every listed capability.

The native transport and legacy parity adapter have been validated locally against a connected Quad Cortex. See Native QC device broker.

Licensing

No project license has been selected yet. Until one is added, the source is not offered under an open-source license. Third-party dependencies retain their own licenses; release builds will include generated third-party notices.