Q1 design decision (b): add explicit hold_reward_ema to center the per-bar
Hold reward, so Q(Hold) and Q(trade) targets are scale-comparable. The
marginal Q(trade) > Q(Hold) preference now comes from data variance in
each state (high-aux states pull Q(Hold) more negative), not from
structural scale asymmetry that depends on cost_scale magnitude.
Q2 decision: keep 4-quadrant fixed (no ramping partials). Already in spec.
Changes:
- §4.2 Hold opp-cost: dual emission documented — R_per_bar_centered
(= R_per_bar - hold_reward_ema) for Q-target/replay tuple,
R_per_bar uncentered for hold_baseline_buffer (Component 1 baseline)
- §4.5 Kernel 1: hold_reward_ema added (per-step on Hold-state bars only)
- §5 data flow: per-bar reward path shows the centered/uncentered split
- ISV slots: 9 → 10 (HOLD_REWARD_EMA_INDEX added)
- §8 footprint: Component 2 LoC 70 → 90 (+20 for dual emission)
- Total LoC estimate: 1620
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