The metrics CUDA kernel already iterated over actions_history for trade
counting but never counted buy/sell/hold distribution. evaluate_gpu()
hardcoded all three to 0.0, making calculate_hft_activity_score_wave10()
return a constant -5.0 for every trial — PSO searched blind for 25% of
the objective space.
Kernel: 3 new shared-memory reduction arrays (s_buys/s_sells/s_holds),
action counting in existing per-step loop (0,1→sell, 2→hold, 3,4→buy),
output expanded from 10→13 floats/window. Zero extra kernel launches,
zero extra GPU→CPU transfers (piggybacks on existing memcpy_dtoh).
Shared memory: 25 KB (was 22 KB) — well within H100 228 KB/SM limit.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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