The studio

claudius studio

opens the studio in its own window. claudius serve runs the same studio in your browser at http://127.0.0.1:7878. Both are views of one session: you can have the window, a browser tab and an assistant working on the same song at once, and each sees the others’ changes as they happen.

Every change is rendered and judged in the background. The arrangement shows when the render you hear is older than the song, and the score badge in the toolbar updates when the new verdict arrives, a few seconds later.

The first time

The first time it opens, a short tour points at the parts of the studio in five cards: making a song, listening, the verdict, the editors, and connecting an assistant, with the Connect buttons right in the last card. The app then asks once whether to send anonymous usage statistics, which stay off unless you say yes (what they are). The tour never blocks the studio. Skip the tour or Esc ends it for good, and ? in the bottom right corner, Take the tour, starts it again.

The first time it starts, claudius downloads its listening models (about 0.8 GB) in the background; the verdict judges with meters and music theory until they are ready, and the log says when they are. If the default sample packs are not installed, the studio says so and offers Download the packs (a 2.2 GB download): until then, the sampled instruments are synthesized. The Sounds tab lists every pack, with a button for each one that is not installed.

Starting a song

New song asks for a genre and, if you like, a seed, tempo and key. The same genre and seed always give the same song, so a seed is a way to come back to one you liked. Open loads a song folder you saved or a .rhai script.

The panels

• Arrangement. The sections of the song from left to right (intro, build, drop and so on), and below them one row per track. Click a cell, or drag across cells, to switch a track on or off in those sections. Drag a section to move it; right-click it to duplicate, insert or remove one. The waveform of the latest render is underneath; click it to jump.
• Section. The selected section’s length, energy, drum variant, which chord progression it plays, and the switches for a build, a gap before the next section, an impact, drum fills, and a filter that opens over the section.
• Steps. A step sequencer for every drum track. Click a step to toggle it, drag to paint, shift-drag to set how hard a hit is.
• Parts. The bass, chords, pad, lead and arpeggio parts: their writing style, their sound (a synth or a sampled instrument), their range and how busy they are. Reseed rewrites a part.
• Mixer. Level, pan, reverb, delay and how much each track ducks under the kick; mute and solo; meters from the last render; the master’s loudness and true peak.
• Harmony. The chord progressions, as chords in the song’s key and as numerals, and which sections play which.
• Script. The whole song as a script. Edit it and press Cmd+Enter (Ctrl+Enter on Windows and Linux) to run it. The sound browser lists every drum, synth and instrument name.
• Verdict. The score and its parts, the issues with what to change, and what earshot hears.
• Log. What happened, and the song’s history.

Mutate tries a few variations and keeps the best one if it beats the current song; Evolve runs several generations of that. Both run in the background and can be stopped. Save writes the song folder.

Help and assistants

? in the bottom right corner opens the help menu: Take the tour, Connect an assistant, Check for updates and Update automatically and the switch for anonymous usage statistics (in the app), the documentation, and a form to report a problem. When a new release has been downloaded, a bar under the toolbar offers Restart to update (Updates). Connect an assistant lists Claude Desktop, Claude Code, Cursor and Codex, says which are connected, and connects one with a click, the way claudius connect does (Working with an assistant). The assistant then makes and edits the song open here, and you hear every change.

Keys

When something does not work

claudius doctor checks the installation. If the studio window opens but stays empty, the engine may not have started: claudius serve prints why. Troubleshooting has more.