The standalone app

Valis builds as a plug-in (VST3, LV2 and optionally CLAP) and as a standalone application. Both run the same engine and show the same window, with the same Controls, Graph and Code views. The standalone needs no DAW: it opens an audio device and a MIDI input of its own, so it is the quickest way to try a circuit, and the one to use when an agent is driving Valis over MCP.

Starting it

Build it as described in Building, then run the launcher from the repository:

./valis

./valis starts the Release build if there is one and the Debug build otherwise, and passes any arguments through. Without a build it says so and stops. The program itself is build-release/valis_plugin_artefacts/Release/Standalone/Valis (or build/.../Debug/...).

Environment variables are read at start-up:

variable	meaning
`VALIS_MCP_PORT`	the first port the MCP server tries, 7676 by default
`VALIS_MCP_TOKEN`	if set, MCP requests need `Authorization: Bearer <token>`

Audio and MIDI

The window is a JUCE standalone wrapper, so audio and MIDI are set from its Options button: choose the output device (and an input, if the circuit processes audio), the sample rate and buffer size, and the MIDI input that plays instruments. The choice is saved between runs in ~/.config/Valis.settings.

An instrument circuit is played from a MIDI keyboard, or from the on-screen keyboard: the MIDI Kbd button in the editor shows it. An effect circuit processes the audio input, so give it an input device, or load a circuit that makes its own sound.

Working in it

Load Circuit and Save Circuit in the File menu read and write a Turtle file. Everything in circuits/ loads this way.
The Code view is the circuit's source. Edit it and the circuit is rebuilt when the text compiles; if it does not, the last working circuit keeps playing and the error is shown with its line.
The Controls view shows the knobs a circuit exposes. The Graph view shows its signal flow and lets you edit it.
The Console view takes commands and talks to a language model. See Console.

The standalone keeps its own state between runs (the circuit, the sound files chosen with val:SampleLoad, window position), as a plug-in saves it in a DAW project.

Driving it from an agent

The MCP server is off by default. Turn it on in Settings, MCP Server; the menu then reads "MCP Server (port 7676)". Check it with:

curl -s localhost:7676/health

An agent such as Claude Code connects to http://localhost:7676/mcp. See The MCP surface for the tools and Guide for agents for how to build circuits through them.

Run a second copy of the standalone, or load Valis in a host while the standalone is open, and it takes the next free port (7677, then 7678, and so on). Each copy's /health reply names its port, and the menu shows it. Several copies in one host work the same way, each with a server of its own; see Several instances.

The standalone and the plug-in differ only in who supplies audio, MIDI and the transport. In a DAW the host's timeline and tempo reach the circuit. The standalone has no timeline of its own to report, so tempo-synced elements (val:LFO with sync, val:StepSequencer, val:Transport) run free at 120 BPM, the tempo Valis assumes when a host gives none.

Without a window

valis-render runs a circuit with no GUI, no audio device and no host, which suits batch work, tests and rendering a part from a MIDI file:

valis_render circuits/halloween-bass.ttl --midi bass.mid --tempo 140 --rolling \
    --seconds 186 -o bass.wav

It gives the circuit a playing transport at the tempo you choose, so tempo-synced elements stay in time. The valis-render page lists every option. See also the Halloween notes for a worked example that makes a whole song this way.