Adds the DQN component of the integrated RL trainer per the plan at
docs/superpowers/plans/2026-05-22-integrated-rl-trainer.md.
What this commit lands:
- DqnHead: linear projection h_t [B, HIDDEN_DIM] -> atom logits
[B, N_ACTIONS=9, Q_N_ATOMS=21] with parallel target-network weights.
Xavier x 0.01 init (initial softmax-over-atoms approx uniform),
scoped_init_seed-guarded per pearl_scoped_init_seed_for_reproducibility.
- dqn_distributional_q.cu: forward (one block per (batch, action), one
thread per atom) + Bellman categorical-CE backward against a pre-projected
target distribution. Atom-softmax fused into backward.
- ReplayBuffer (rl/replay.rs): capacity-bounded PER with priority^alpha
sampling, random replacement, and TD-error priority update. O(N)
cumulative-sum sampling; Phase E may upgrade to a GPU sum-tree once
capacity profiling demands it.
- rl_gamma_controller.cu: ISV[RL_GAMMA_INDEX=400] producer; gamma
adapts toward 0.5^(1/mean_trade_duration) via Wiener-alpha blend
(floor 0.4 per pearl_wiener_alpha_floor_for_nonstationary), clamped
to [0.90, 0.999]. Bootstrap gamma = 0.99 on sentinel.
- rl_target_tau_controller.cu: ISV[RL_TARGET_TAU_INDEX=401] producer;
tau adapts multiplicatively from Q-divergence ratio vs anchor 0.01,
Wiener-alpha blend with floor 0.4, clamped to [0.001, 0.05].
Bootstrap tau = 0.005 on sentinel.
- Action enum + try_from_u32 in rl/common.rs (matches existing ml DQN
action grid for cross-system policy comparability).
- C51 atom support constants Q_V_MIN / Q_V_MAX in rl/common.rs (kept
for Phase E's projection kernel; backward in this commit operates in
categorical domain on a pre-projected target).
What this commit DEFERS to Phase E:
- soft_update_target kernel (struct fields w_target_d / b_target_d are
wired and read by the Bellman backward in this commit; the writer
lives in Phase E alongside the training-loop tau driver).
- Categorical projection kernel that reads gamma from ISV[400] and
produces the target_dist input to the backward kernel.
- Toy bandit test activation (tests/dqn_toy.rs is #[ignore]-gated; the
type contract is locked here, the training loop wires in Phase E).
- atomicAdd in the per-batch CE accumulator (Phase E replaces with the
warp-shuffle + shared reduce pattern from aux_loss.cu when batches
reach production sizes; B <= 32 toy contention is negligible).
Per pearl_controller_anchors_isv_driven and feedback_isv_for_adaptive_bounds:
gamma and tau are NOT hardcoded constants. They live in ISV[400] /
ISV[401], emitted by the controller kernels above, and Phase E consumers
read via __ldg(isv + INDEX). Bootstrap values (0.99, 0.005) appear only
in the controller kernel as first-observation defaults, NOT baked into
the loss kernel.
Validation:
- SQLX_OFFLINE=true cargo check -p ml-alpha --lib -> clean (1m 03s)
- SQLX_OFFLINE=true cargo check --workspace --lib -> clean (42s)
- SQLX_OFFLINE=true cargo test -p ml-alpha --lib rl::replay -> 3 pass
- Cubins built for all 3 new kernels (sm_80 default).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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