A 440 + 660 Hz chord's |STFT(1024, 256)| goes through
griffinlim(32) with deterministic zero-phase init. Before the
repair this returned one sample (istft arg-shift put
center=true into length). Badges mirror
examples/node/xa-advanced.mjs: audio-length output, strictly
decreasing spectral convergence over iterations 1–8, <10% relative L2
magnitude error after 32 iterations, and an FFT-peak pitch within 1% of
440 Hz. A/B the audio yourself — phase is invented, pitch must survive.