diff --git a/handoff/NOTES_LEVEL.md b/handoff/NOTES_LEVEL.md
index 899cbcd..3b59474 100644
--- a/handoff/NOTES_LEVEL.md
+++ b/handoff/NOTES_LEVEL.md
@@ -1016,3 +1016,23 @@ vs Python bandres (GAIN=4.132=10^(24.65/40), render_parity): match within ~1.5%
 300..2000 (fc300: 1.1798 vs 1.1887; fc1000: 0.11746 vs 0.11714; fc2000: 0.7057 vs 0.6963).
 => res shape is NOT the source of the res_only1 fc=300 residual (-1.71 over-cut); that
    residual is level-LUT related (input resonant.wav level differs from fit levels).
+
+## ============ UPDATE 2026-08-20u: F0 GATE — DETERMINISM VERIFIED (bit-exact REACHABLE) ============
+Re-rendered test RPPs twice each (reaper -nosplash -renderproject on /tmp copies with
+RENDER_FILE -> /tmp), then byte-compared data chunks:
+
+1. res_only1_500.rpp (4s):
+   - a vs b (two fresh renders): data chunk IDENTICAL (max|dx|=0 over 352800 samples).
+   - a vs committed res_only1_500.wav: data chunk IDENTICAL.
+2. t1kq_only1_1000.rpp (6s, 1587600 data bytes):
+   - a vs b: IDENTICAL.  a vs committed t1kq_only1_1000.wav: IDENTICAL.
+
+Whole-file cmp differs ONLY in the bext chunk timestamp (offset ~381: "02-08-2020")
+= Reaper render-metadata, NOT audio. Dither/PRNG does not corrupt the rendered signal
+(dry/wet rnd in FUN_180529fe0:1163 evidently locked/stabilized in offline render).
+
+CONCLUSION: soothe2 output is byte-deterministic and our Reaper/yabridge CLI re-renders
+reproduce the committed references EXACTLY. => Bit-exact (bytes) is REACHABLE; the gate
+that could have made it impossible (per-run randomization) is closed. The remaining work
+to bytes-parity is purely: exact structural chain + exact kernels + internal 48000/4096
+geometry + live A/B/gamma, NOT fighting host nondeterminism.