Terminology
Composition
A video you can render, with an id, a size, a frame rate and a length.
A composition is one video in a project. It has an id, a size, an fps and a length. It also has the code that draws each frame.
<Composition id="Intro" component={Intro} durationInFrames={90} fps={30} width={1920} height={1080} />The HyperFrames length is in seconds, at 30 fps. Three seconds is the same 90 frames.
One project can hold many compositions. Pick one with --comp <id>. Without it, the first one is used. List them with npx kinetograph compositions <entry>. A <Composition> draws nothing itself. It only declares the video.