The desktop app

The desktop app is a canvas window and a settings window that opens beside it (close it any time; bring it back with ⌘ , on macOS or Ctrl , elsewhere). It is Marble mode with MIDI in — there is no Play mode on desktop.

The canvas is an ordinary window with its title bar on every platform: drag it, snap it, resize it, and use Fullscreen (Settings › Window, or ⌃⌘F on macOS and F11 elsewhere) for the display.

The settings window

Section	What it holds
Canvas	paper dip (fresh sheet), the print folder, save the last print as PNG
Layout & look	the thirteen layouts with Partials on an arc under the brass and Tuning under the strings, viscosity, ink feed, tempo and roll speed for the piano rolls, full-resolution simulation
Prints	the ledger: every dip of the session, export size, Anod over alpha, export PNG
Presets	the session as a file: load, delete, save as, export, import — presets
Replay	record, stop, the recordings, play, play file, stop replay — replay
Substrate	the paper’s tint, roughness and fibre scale; the glass’s darkness, grain, bloom and reach
Palette	the active palette, the library, the custom slot’s editor — palettes
Medium	Sumi or Anod, the glow scale, the grid lines, the strike charge — the medium
Expression routing	the input dialect · Per-note bend → Glide / Ripple / Torsion wavelength / Spark frequency / Chladni stir · Channel pressure → Ink feed / Swirl / Torsion · Slide (CC 74) → Hue / Pinch / Spark frequency · the medium default for each · Pinch style · Vortex profile → Exponential / Rankine / Torsion · Stylus wake and its spread · Torsion sweep on note-on
Ripple, Chladni, Burst, Spark, Chirikov	each operator’s knobs; the sliders that ride a CC (102/103, 106–109) go through the real control path
CC map	the routing table — any CC, any channel or “any”, to any global dimension, the sound’s bus effects included; defaults for the mod wheel, breath aliases and the Airwave; add, edit, restore
MIDI inputs	every connected port with its rescan status — hotplug is automatic — and the Panic button
Sound	the sound engine: internal sound, volume, source, the sampler’s instrument or WAV, every knob of the current Suzu voice
Suzu trace	the orbit trace’s routes, scale, segments, stroke, and the scope on the canvas
Window	fullscreen (⌃⌘F on macOS, F11 elsewhere)
Lab bench (—dev)	smoothing, the MIDI log, the debug keys
About	version (from the release tag), commit, engine version

The iPad and Android sheets carry the same rows where the concept exists (see the settings reference).

Settings persist in the platform’s config directory (~/Library/Application Support/midi-sink, %APPDATA%\midi-sink, ~/.config/midi-sink).

Mouse

Left click = drop (the spark under Anod) · left drag = tine · right drag = vortex (profile from the settings) · Shift + left drag = pinch (distance = strength delta, angle = fold axis) · middle drag = stylus wake (scroll wheel sets the tip radius) · Shift + right drag = pressure.

MIDI

All inputs open automatically: CoreMIDI on macOS, WinMM on Windows, ALSA on Linux. For a virtual source on Windows, create a loopMIDI port; on Linux the harness’s 1 Hz rescan picks up any snd_seq port as it appears.

Command line

--window <w>x<h> opens the canvas at an exact size in screen points, for reproducing a report at a given resolution (the default is 1280×720; the window stays resizable):

# macOS (the installed bundle)
/Applications/midi-sink.app/Contents/MacOS/midi-sink --window 1920x1080
# Windows
"C:\Program Files\midi-sink\midi-sink.exe" --window 1366x768
# Linux
midi-sink --window 2560x1440

On a HiDPI display the framebuffer is that size times the scale factor; the settings window’s Session line and the --dev bench report the pixel size.

--fullscreen starts with the canvas filling the display it opens on. It sets the Window › Fullscreen setting, so it persists like the checkbox; ⌃⌘F (macOS) or F11 toggles fullscreen from the canvas at any time.

The lab bench (--dev)

Without the flag the app accepts --window, --fullscreen, --help and --version, and the keyboard does nothing but the settings chord and the fullscreen toggle. With --dev you get the debug keys (viscosity, feed, roughness, palette, layout, dip, BPM, profile, ripple live/bake, pinch variant, pressure and bend routing, ripple angle and amplitude/frequency, the crossed-tine prototype stamp and the swirl test voice), the scripted operator tests, and --field-dump <file>, which writes the cross-backend field dump that the release gates compare across Metal, D3D11, OpenGL and WebGPU. The bench also holds the conservation soak of every operator (--soak <op>), the layout shots (--layout-shot), the sound profiles (--voxo-profile), the Voxo storm (--voxo-storm), and the replay gate’s recorder and player (--record-demo, --replay, --replay-wav); tools/README.md in the tree lists them all.