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foxhunt/crates
jgrusewski 185add7dc8 feat(rl): adaptive RATIO + EWMA V_MIN/V_MAX + λ_distill bump
wwcsz analysis identified atom-resolution starvation + asymmetric
RATIO mismatch as the empirical ceiling on win rate (38.56% vs
break-even 45.3%). Three coupled fixes shipped in one pass per
"no deferrals":

(a) Adaptive RATIO from observed |loss|/|win| EMAs:
  - apply_reward_scale tracks max(-scaled, 0) per step (slot 489)
  - rl_reward_clamp_controller maintains neg_max_ema (slot 490,
    sparse-aware like pos_max_ema)
  - RATIO = clamp(MIN=1.0, neg_ema/pos_ema, MAX=3.0); writes to
    slot 481
  - Removes built-in 3:1 loss-aversion bias when reality is
    symmetric (wwcsz: actual avg|loss|/avg(win) = 0.83). Floor
    1.0 prevents inverted asymmetry; ceiling 3.0 preserves
    original loss-aversion as the worst case.

(b) C51 V_MAX/V_MIN: ratchet → slow EWMA (α=0.001, half-life ~700
    steps):
  - Static ratchet wasted atom resolution on rare tails — wwcsz
    had V_MIN=-60, V_MAX=20 but realized rewards mostly in [-5, +5]
    (Δz=4 vs typical reward magnitude 1-5)
  - Slow EWMA lets atom span shrink toward active reward range,
    gaining resolution where data lives. Floors at [-1, +1]
    preserve original C51 baseline as the worst case.
  - Slow α gives Q's atom mapping time to be valid across
    encoder/head co-adaptation (vs aggressive EWMA which would
    invalidate Q's learned distribution every step)

(c) Q→π distillation λ bumped 0.01 → 0.05:
  - wwcsz showed KL dropped 2.10 → 0.30 with λ=0.01 — Q signal
    landing but conservatively. Bump tests whether stronger Q
    pull translates to better policy → better R/done.

Diag exposes neg_scaled_max + neg_scaled_max_ema so the RATIO
adaptation chain is observable.

apply_reward_scale shared_mem doubled from 2× to 3× block × f32
to fit the three parallel reductions (abs, pos, neg).

Companion to investigation (e) — n_rollout_steps controller was
suspected of misalignment (256-8192 vs trade_duration ≈ 6 steps)
but turned out to be a K-loop param, not used in Bellman target.
1-step Bellman with γ-bootstrap is the actual mechanism; closed
without code change.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-24 14:20:05 +02:00
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