- Wire GpuReplayBuffer into DQN constructor with OOM fallback to CPU PER
- Fix P0: GPU PER priorities never updated in single-batch train_step()
(result.indices was empty CPU Vec; GPU tensors td_errors_gpu/indices_gpu
were silently dropped)
- Fix IS-weight ordering: apply weights AFTER Huber loss, not before
(weighting before nonlinear Huber shifts quadratic/linear regime boundary)
- Fix IQN CVaR: add .contiguous() before sort_last_dim (341/341 tests pass)
- Defer loss scalar readback to after backward pass (piggyback on grad flush)
- Add next_states to ExperienceBatch with episode-aware shift computation
- Add insert_batch_tensors() for direct GPU tensor insertion into replay buffer
- Make Q-value estimation periodic (every 50 steps) to reduce forward passes
- Fix CPU fallback path types (u8 action, i32 fixed-point reward, timestamp)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
e35ead5f3e