Gate both PPO advantage and Q→π distillation on done-steps only:
- advantage = done * (returns - V) — non-done advantages are zero
- distillation gradient only fires when done > 0.5 per batch element
With 5-6% of batch having real rewards, non-done gradient was 94%
noise that destabilized Q-π alignment. Done-gating ensures π only
learns from steps where trades closed and rewards validate the signal.
qpa: holds at +0.625 through 3000 steps (previously crashed to -0.85).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
eeb0a829bf