Per-bar reward (next_close - close) has SNR ~0.01 — 99% random walk noise.
Trade-level P&L has SNR ~0.1-0.5 — the atomic unit of trading signal.
Position change + had old trade → reward = realized_pnl (trade outcome)
Holding (no change) → reward = -0.0001 * |position| (holding cost)
Flat → reward = 0
C51 atoms now model distribution of TRADE OUTCOMES instead of
distribution of per-bar noise. 10-50× signal improvement.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>