I’d start with an autocorrelation‑based pitch detector that runs on a 64‑sample window, then feed that into a fast phase‑locked loop that corrects only when the deviation exceeds, say, 10 cents. Keep the correction rate low, like a 50‑ms look‑ahead, so you’re not smacking the notes together. Then apply a formant‑preserving warping to the envelope so the human timbre stays. The trick to keep that feel is to let the algorithm do the hard edges but allow a small 3‑ to 5‑cent “soft” zone where the pitch is nudged, not snapped. That preserves micro‑vibrato and natural timing. Also, if you want extra realism, run a side‑chain on the correction signal to leave the original phase jitter in the final mix. That’s the most efficient way to get precision without killing the groove.