docs: two-point 180s capture confirms registry stability; twin per-note state = {A[3],B[3]} not 342-dbl; Step C closed

handoff/NOTES_CAPTURE.md

@@ -63,3 +63,16 @@
 - Next: render_long + capture at t=10-20s into sustain, then locate the per-bin
   attack/release smoothing coefficients (0x540888/88c set, converted via ln(10)/20)
   inside the arena near registry.
+
+## 2026-08-19b (two-point snapshots t1=8s, t2=40s of render_long 180s)
+- rtsnap2.py: TWO snapshots of the SAME 180s render at t1/t2; each 318MB/547regs ~0.2s.
+- Registry tables byte-identical between t1/t2 (stable per-band coeffs; confirmed authoritative).
+- Diff of arbitrary 342-double windows = pure audio-buffer noise (21981 phantom matches; twin
+  per-band state is NOT a 342-dbl array a level away). Real twin kernel state per NOTES_TWIN:64
+  is {double A[3], double B[3]} per band (6 doubles), seeded in build_twin_coeff FUN_180533ec0.
+- Conclusion: live per-note-band twin state not usefully separable via full-heap diff; the
+  attack/release input coeffs live in the DSP ctx scalars: 0x540888/0x54088c = expf(p*0.11513)
+  (static-derived), registry holds the per-bin WEIGHT tables (already captured). Twin kernels
+  themselves validated statically (twin_check max|err|=1.27e-5). => Step C goal (window + axes +
+  weights + kernel parity) is effectively CLOSED; only scalar A/R params remain, derived from RPP
+  params, no live capture needed.

rtsnap2.py

@@ -0,0 +1,43 @@
+import subprocess, os, glob, time, struct
+def mem_open(pid): return os.open(f'/proc/{pid}/mem', os.O_RDONLY)
+def find_hosts():
+    hosts=[]
+    for p in glob.glob('/proc/[0-9]*'):
+        pid=int(os.path.basename(p))
+        try:
+            cmd=open(f'/proc/{pid}/cmdline','rb').read().replace(b'\0',b' ').decode('utf8','replace')
+            maps=open(f'/proc/{pid}/maps').read()
+        except Exception: continue
+        if 'soothe2' in maps and 'reaper' not in cmd:
+            hosts.append(pid)
+    return hosts
+os.system("pkill -9 -x reaper 2>/dev/null; pkill -9 -f '[y]abridge' 2>/dev/null; sleep 1")
+proc=subprocess.Popen(['/usr/bin/reaper','-nosplash','-ignoreerrors','-renderproject','/home/m/soothe-bt/render_long.rpp'],
+                      stdout=open('/dev/null','w'),stderr=subprocess.STDOUT)
+t0=time.time(); host=None
+while time.time()-t0<60 and not host:
+    hs=find_hosts(); host=hs[0] if hs else None; time.sleep(0.2)
+print('host',host, flush=True)
+fd=mem_open(host)
+def snap(tag):
+    out=open('/tmp/snap_%s.bin'%tag,'wb'); idx=open('/tmp/snap_%s.idx'%tag,'wb')
+    t0=time.time(); nreg=0; nb=0
+    for line in open(f'/proc/{host}/maps').read().splitlines():
+        p=line.split(); lo,hi=(int(x,16) for x in p[0].split('-'))
+        if 'r' not in p[1]: continue
+        a=lo
+        while a<hi:
+            n=min(hi-a,8*1024*1024)
+            try: d=os.pread(fd,n,a)
+            except Exception: a+=n; continue
+            if not d: a+=n; continue
+            out.write(struct.pack('<QQ',a,len(d))); out.write(d)
+            idx.write(struct.pack('<QQ',a,len(d)))
+            nreg+=1; nb+=len(d); a+=n
+    out.close(); idx.close()
+    print('snap %s: %d MB %d regs in %.1fs'%(tag,nb/1e6,nreg,time.time()-t0), flush=True)
+time.sleep(8);  snap('t1')
+time.sleep(32); snap('t2')
+time.sleep(200)
+if proc.poll() is None: proc.kill()
+print('done')