- Add generate_iir4_coefs() — frequency-dependent warp coefficients from BLOCKMAP:135-150
- Integrate chain_9_19 in process_band_structural via RT_CASC=1 env gate
- chain_9_19 now runs full pipeline: LOG#1→DIVIDE→dc40→FMA→EXP#1→track→warp→LOG#2→IIR4×2→FIR→EXP#2
- IIR4×2 uses double precision (movsd/mulsd per disasm)
- FIR min-phase (52b3cd) enabled
- Canon bridge 1.594 unchanged when RT_CASC=0
- Requires live-dump or ph*.npz capture for input format calibration
- fn529fe0: Haar one-pass now exact 3-tap [0.25,0.5,0.25] via tmp copy (was in-place two-loop shortcut not bit-exact per BLOCKMAP 24mm14)
- cascade w scalar 0.015 best-fit (rms 0.30) vs per-bin 0.084 (Haar error), not ctx-derived 1.33
- framed_model: VLAW sens 12 keep (dual group), remove debug fprintf and spurious RT_FIRCONV power on raw_level
- test fix: restored dual_b1q_0.5.wav 1ch16->2ch24 (hazard rendersnap2), corpus TOTAL 1.594 again
Root cause: IIR accumulator reset to 0 every frame, losing temporal state.
Fix: static thread_local accumulator persists across frames.
Results (dual_b1q_0.5, reaper render):
cut@500 = -10.32 dB (EXACT match, was -14.35)
cut@2000 = -11.82 dB (EXACT match, was -6.58)
Both the ×1.805 (OLA normalization) and ×2.44 (mask computation) gaps
were caused by the same root issue: IIR state reset.
Matiq