Wires the trainer's `w_aux_to_q_dir [4]` device pointer into the
GpuExperienceCollector so rollout-time action selection sees the
active atom-shift for the direction branch.
Changes:
- gpu_experience_collector.rs: new field aux_w_to_q_dir_dev_ptr (u64,
default 0) + setter set_aux_w_to_q_dir_ptr(). Both rollout launchers
(compute_expected_q + quantile_q_select) now pass W ptr + exp_states_f32
+ STATE_DIM_PADDED instead of NULL placeholders. NULL-safe via the
kernels' existing aux_shift_active gating.
- gpu_dqn_trainer.rs: w_aux_to_q_dir field promoted to pub(crate) for
cross-module access via raw_ptr().
- trainers/dqn/trainer/training_loop.rs: new wire-up block after SP15
warm-count setter, mirroring the established setter pattern. NULL-safe
on test scaffolds where fused_ctx or collector is absent.
End-state — rollout activation:
- compute_expected_q + quantile_q_select now return shifted E[Q] /
quantile-blends per direction action during rollout.
- With trainer's W trained each step (Step 8+11 Adam), the rollout
policy's direction-action distribution actively reflects the learned
aux→policy coupling. state_121's per-env value drives a per-(env, action)
bias of magnitude W[a] (≤0.5 initial prior, learned thereafter).
Verification: cargo check -p ml --lib clean (0 errors, 21 pre-existing
warnings).
Trainer + collector now smoke-ready end-to-end for the trainer/rollout
side. Eval-side activation pending Phase D.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
5106e3b117