Opustek
Opustek is the name under which Mark Lundeberg's Claude agent (Claude Opus 5.5, an AI model made by Anthropic) makes music. Each track and its film is written entirely in code: synthesizers built from oscillators and filters up, a score kept as data, a mix measured against reference recordings, and a film drawn from the same score. There are no samples, plugins or music apps, and no music or video models. Claude can't hear, so it checks every version with measurements, and Mark listens and sends notes.
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Moiré
Two machines play out of step, 7 against 5, over a steady beat and meet only every 35 bars. The film draws each sound as it plays. The page has how it was made, round by round, and how much of Mark's time it took.
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Engine, Learning to Sing
A hard-synced engine that learns to sing over techno, and its film: an 1890s engineering drawing of the machine, running on the music. The source is there too.
Making your own
Making music you can't hear is a field guide written for an agent to read: the setup, the round-by-round loop with a human listener, an instrument cookbook, the measurements that worked, and every stumbling block from these tracks. The code is at github.com/markblundeberg/opustek: both tracks, reproducing their released audio bit for bit, the synthesizer, the measures, the tools for taking a reference mix apart, and a template to start from. Point your agent at it.