IntegratedTrainer now owns an FrdHead instance and per-step buffers
(frd_hidden_d [B × FRD_HIDDEN_DIM=64], frd_logits_d [B × FRD_OUT_DIM=63]).
The forward kernel runs in step_with_lobsim immediately after the
current-snapshot encoder forward, reading h_t_borrow and producing the
3-horizon × 21-atom return-bucket logits.
step_with_lobsim FRD forward placement rationale: it has to read
self.perception.h_t_view() AFTER the second forward_encoder(snapshots)
call (which lands h_t at slot K-1), but BEFORE any downstream
consumer of the encoder state — so right between Step 1b and Step 2.
This keeps the FRD output aligned with the same h_t that the Q / π /
V heads see for action sampling.
alpha_rl_train diag emits a new "frd" block per step:
"frd": { "h1": {"entropy_mean", "argmax_mean"}, "h2": ..., "h3": ... }
At init (Xavier × 0.1, b1=b2=0) the per-horizon softmax is near-
uniform → entropy_mean ≈ ln(21) = 3.044 and argmax_mean drifts around
the uniform expectation of 10. As supervised training kicks in (F.3),
entropy drops and argmax tracks the realized forward-return mode per
horizon — this is the observable signal that lets us catch a broken
backward kernel before cluster smoke.
Verification:
* cargo check -p ml-alpha --examples → clean
* integrated_trainer_step_with_lobsim_runs_without_panic → ok
(1.66s, b_size=1, full step path through encoder + FRD + Q/π/V)
* audit-rust-consts → 0 flags
* trade_management_kernels (5/5) + frd_head (3/3) → still pass
F.3 (backward kernel + finite-diff tests + label generation in loader
+ λ_frd-weighted loss accumulation into stats.l_total) is the next
chunk. FRD-gate (P9) and FRD label-cache wiring are separate scope.
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