Oscillo

Every note resolves through the shared tuning library (lib/tuning.ts). In just mode a note's frequency is the key's equal-tempered anchor times the just ratio for its distance from the key, so intervals against the key are exact fractions like 3/2 and 5/4 rather than powers of 2^(1/12). OSC 2 goes one step further: its frequency is OSC 1's times the ratio for the configured interval, which guarantees the pair is pure on every key of the keyboard.

The scope is the module's center on purpose. It reads the engine's post-master analyser and draws in phase-shift Lissajous mode: X is the signal, Y is the same signal offset by a fraction of the analysis window. Two tones in ratio p:q trace a closed p:q figure that stands still; detune either oscillator by a few cents and the figure rotates at exactly the beat rate. Nothing about the drawing is decorative, it is the tuning, plotted.

The persistent host has 0 audio-input channels; note and control events arrive through the SDK at sample offsets, and its two planar outputs feed the website analyser and native host buses without a browser DSP stage in between.

One LFO runs free from module load, retriggering it per note would make it a second envelope. It has a single depth control and a single target selector; switching target moves the depth between three permanently-connected modulation stages (voice detune in cents, a tremolo gain, the stereo panner), so the switch itself is click-free.