I completed the entire sur.cpp module that now takes care of everything from chroma extraction to tonic and scale detection based on western pitch classes as well as hindustani swaras. I included lookup tables for note names, swaras, mapping of western scales to hindustani scales, and Krumhansl-Kessler probe tone profile for correlation based on major/minor scales. In the update loop, we now have peak-picking, parabolic interpolation, MIDI/cents conversion, pitch-class accumulation with weights that go into fast/slow chroma filters for stability. Estimation involves rotating chroma against probe-tone templates, sustain-biasing, choosing the most prominent tonic, evaluating the coverage of the scale, and using a locking/challenging mechanism to eliminate any jitter and handle actual key changes. All put together, this makes sur.cpp an accurate pitch-scale detection module producing stable tonics, confidence values, and best-fit scales.

Overall a significant amount of progress was made.