Adds the scaffolding for Narrow-Band Vital Information ranking: an
exponentially-weighted moving variance per subcarrier (alpha = 0.02
→ tau ≈ 10 s at 5 pps), refreshed every 25 frames into a stable_bin
mask = bins whose EMA variance is below the across-band median.
The intended payoff is to drive per-node CV in STILL down by averaging
broad_mean_amp_history over quiet bins only (instead of all 128), so
ADR-101's STILL/EMPTY classifier separates them at a smaller body block.
Activated path is REVERTED in this commit on purpose. Quiet bins by
construction barely move, so windowed variance of their mean collapses
to ~0 and motion_energy goes constant. Empirical verification 2026-05-17:
motion_score pinned at 0.013/0.021 with std=0 across 125 frames after
turning quiet-only averaging on; reverted to full-band push_val for
motion_energy with a comment explaining why.
The right shape is a second channel in rv_feature_state_t carrying
"baseline_quiet" alongside motion_score so the server can use one for
classification and the other for motion gating — that's an additive
protocol bump and a separate change. EMA state lands now so we don't
have to wire it back from scratch when we do it.
Also kept from the earlier session: the n_subcarriers > 128 truncate
fix (root cause of motion_energy = 0 — process_frame used to early-
return on 384-byte CSI frames from this silicon) and the broadband-mean
amplitude history that feeds Step 8.
Co-Authored-By: claude-flow <ruv@ruv.net>
03b123bfc3