22y: live ctx capture pipeline works (scripts/dualtrace.py, realtime playback + chunked heap snapshot); found config-dependent reduction curves 0x540768/788/7f8 (peak follows band fc; 7f8 min exactly 1.0 => R=1/mask, notch-shaped); acc/f6f8 arrays ZERO in steady state; DECISIVE: applied filter != pointwise R (dual skirt 3dB vs real 11.8) -> FFT-conv wide-window spreading is the missing mechanism

handoff/NOTES_CAPTURE.md

@@ -157,3 +157,40 @@ the ctx object only materializes during a realtime transport play.
   during band processing; still TBD (but LUT curve params A/B/γ are RPP-derived per roadmap).
 - Two more ctx-like bases found (0x2120040, 0x1780040) also have +0x24==48000; 0x2370040 is the
   populated one (0x2120040 has 0x540658..698 = 1.0 fill pattern — likely a second/free instance).
+
+## 2026-08-23 (22y): LIVE CTX CAPTURE DURING DUAL/T1KQ/RES PLAYBACK — scripts/dualtrace.py
+Method works reproducibly: reaper <cfg>.rpp play_loop.lua (repeat ON) → yabridge-host
+→ chunked snapshot ×2 → ctx marker +0x24==48000 ∧ sens>100 → ONLY ONE populated base
+(0x2370040; others empty instances). Snapshots byte-stable over seconds.
+
+### Pointer-table catalog (ctx+0x540600..0x540a00, dereferenced u64 → f32[2049])
+- Static weights confirmed live: [00]identity@0x540688(ones), window@0x540698(0.5→0.8),
+  WA/WB/WC/WD @0x5406b8/c8/d8/e8, warp@0x540748(1.3→6.68, structure at LOW bins),
+  freqaxis@0x540758(v85=995.6Hz ✓ internal 48k/4096).
+- **acc/f6f8 arrays ALL ZERO during steady looped playback** (0x5406f8,
+  0x5407a8/b8/c8/d8 — zero as f32 AND f64): combine accumulators idle in steady state.
+- **CONFIG-DEPENDENT CURVE FAMILY** (peak follows band fc: bin43@fc500 → bin85@fc1000):
+  - 0x540768 == 0x540778 (identical twins): smooth curve, peak at center
+    (dual: 4.15@43, valley 1.60@171, upturn 1.86@400; t1kq: 3.55@85).
+  - 0x540788: sharper version (floor ~0.52-1.0, max 4.38).
+  - **0x5407f8: min EXACTLY 1.0 → reduction multiplier R(f)=1/mask ≥ 1**
+    (res500 cfg: R(500Hz)=12.0 dB, falls to ~0 by 6 kHz; notch-shaped ✓).
+- bands[] slots from static asm (@0x540678+i·16) read as identity/ones tables LIVE —
+  the per-band working data is NOT sitting in those ctx fields during playback.
+
+### Decisive mismatch
+For dual cfg: R(43)=3.98→12.0 dB (real 10.32 ok-ish) BUT R(171)=1.41→3.0 dB while
+real cut@2000 = 11.82 dB. ⇒ Applied filter ≠ pointwise copy of R: massive spectral
+coupling between template and actual filtering. Prime suspect: FFT-conv stage with
+the 8193-wide WIN_freq window ([01]) — smearing/spreading step completely absent in
+our pointwise render48k path. This ALSO explains why faithful v1 (pointwise) cannot
+balance dual tones regardless of law constants.
+
+### Caveats / next
+- Quick Welch TF estimate unreliable (window/alignment) — Goertzel-at-tones stays canon;
+  for full-spectrum truth use chirp/two-tone refs or per-fc capture sweep.
+- NEXT: (1) fc-scan captures (res_only1_{fc}.rpp, 11×) → correlate R_cap(bin85) with
+  real cut@1000 across fc — validates R as THE applied curve; (2) decode the FFT-conv
+  0x535a70 body + WIN_freq usage — reconstruct mask→FIR spreading; (3) re-check whether
+  0x540768-family updates frame-by-frame (two-point diff showed stable — maybe only
+  rebuilt on param change / note onset).