A rainbowgram demo (the NSynth visualization): hue = demodulated phase differential diff(unwrap(∠D − 2πft)), alpha = amplitude_to_db(|D|)/80 + 1 on black. Signal: a linear chirp 32 → 1024 Hz plus a steady 440 Hz partial, at sr 16384 / n_fft 2048 so 440 Hz is EXACTLY bin 55 — a bin-centered partial has zero demodulated drift, so its band renders one constant hue while the chirp sweeps the full color wheel. Quantitative badges (node-verified against dist first): mean |demodulated Δφ| at the 440 Hz bin < 0.05 rad over ALL frames (measured 0.0139 — the only contribution is the chirp crossing the band; away from the crossing it measures 0.0002), and a deliberately detuned 452 Hz partial measured at bin 56 (448 Hz) drifts at exactly 2π·Δf·hop/sr = π/4 rad/frame ±10% (measured ratio 1.000, per-frame deviation ≈ 0) — the rainbow's hue gradient is the frequency offset, verified.
computing…