diff --git a/crates/ml/src/cuda_pipeline/aux_heads_kernel.cu b/crates/ml/src/cuda_pipeline/aux_heads_kernel.cu
index 6dc22d95e..7569aabbd 100644
--- a/crates/ml/src/cuda_pipeline/aux_heads_kernel.cu
+++ b/crates/ml/src/cuda_pipeline/aux_heads_kernel.cu
@@ -203,8 +203,6 @@ extern "C" __global__ void aux_next_bar_loss_reduce(
     const float* __restrict__ pred,        /* [B] (== [B, 1] flat) */
     const float* __restrict__ label,       /* [B] */
     int B,
-    const float* __restrict__ isv,         /* ISV bus, read isv[isv_label_scale_index] */
-    int          isv_label_scale_index,    /* AUX_LABEL_SCALE_EMA_INDEX = 117 */
     float* __restrict__ loss_out           /* [1] */
 ) {
     if (blockIdx.x != 0) return;
@@ -212,23 +210,15 @@ extern "C" __global__ void aux_next_bar_loss_reduce(
     const int tid   = threadIdx.x;
     const int block = blockDim.x;
 
-    /* Plan 5 Task 5 follow-up: normalize label by ISV-driven label-scale
-     * EMA so the residual stays unit-scale regardless of underlying data
-     * magnitude (1e-3 log-returns vs 5000 raw prices). Read the scale
-     * directly from ISV at kernel launch — graph-capture-stable since the
-     * ISV device pointer + slot index are stable across re-launches; the
-     * actual scalar value updates each step via `aux_label_scale_ema_update`
-     * launched immediately before this kernel. The scale floor `1e-6` is
-     * a numerical-stability epsilon, NOT a tuned constant — it only fires
-     * when the EMA happens to be ≤ 1e-6 (e.g. literally zero labels), in
-     * which case dividing by 1e-6 yields a 1e6-magnitude residual that
-     * the gradient clip ceiling catches downstream. */
-    const float label_scale = isv[isv_label_scale_index];
-    const float inv_scale = 1.0f / fmaxf(label_scale, 1e-6f);
-
+    /* SP13 B1.0 (2026-05-05): scale-free MSE. Labels are z-normalised at
+     * the data layer, so `label_scale_ema ≈ 1.0` empirically and the
+     * pre-B1.0 `(pred - label * inv_scale)` reduces to `(pred - label)`
+     * within rounding. The ISV-driven label-scale divisor (former slot
+     * 117 / `AUX_LABEL_SCALE_EMA_INDEX`) is retired — B1.1 will replace
+     * MSE with CE, eliminating the loss formulation entirely. */
     float local = 0.0f;
     for (int i = tid; i < B; i += block) {
-        const float d = pred[i] - label[i] * inv_scale;
+        const float d = pred[i] - label[i];
         local += d * d;
     }
     smem[tid] = local;
@@ -399,8 +389,6 @@ extern "C" __global__ void aux_next_bar_backward(
     const float* __restrict__ label,       /* [B] */
     int B,
     int SH2,
-    const float* __restrict__ isv,         /* ISV bus, read isv[isv_label_scale_index] */
-    int          isv_label_scale_index,    /* AUX_LABEL_SCALE_EMA_INDEX = 117 */
     /* Partial outputs (per-sample). Caller reduces along batch dim. */
     float* __restrict__ dW1_partial,       /* [B, H, SH2] flat */
     float* __restrict__ db1_partial,       /* [B, H] */
@@ -419,15 +407,13 @@ extern "C" __global__ void aux_next_bar_backward(
     float* sh_dh_pre = smem;        /* [H] */
     float* sh_h_post = smem + H;    /* [H] */
 
-    /* Plan 5 Task 5 follow-up: normalize label by ISV-driven label-scale
-     * EMA so the gradient stays unit-scale regardless of underlying data
-     * magnitude. MUST match the same `inv_scale` arithmetic used in
-     * `aux_next_bar_loss_reduce` so loss + gradient are derivatives of
-     * the same scalar function. */
-    const float label_scale = isv[isv_label_scale_index];
-    const float inv_scale = 1.0f / fmaxf(label_scale, 1e-6f);
-    /* Mean-over-batch derivative scale: dL/dpred[b] = (2/B) * (pred[b] - label[b]/scale). */
-    const float d_pred_b = (2.0f / (float)B) * (pred[b] - label[b] * inv_scale);
+    /* SP13 B1.0 (2026-05-05): scale-free MSE backward. Mirrors the
+     * `aux_next_bar_loss_reduce` arithmetic so loss + gradient are
+     * derivatives of the same scalar function. The ISV-driven label-scale
+     * divisor (former slot 117) is retired — see the loss kernel's B1.0
+     * note for context.
+     * Mean-over-batch derivative: dL/dpred[b] = (2/B) * (pred[b] - label[b]). */
+    const float d_pred_b = (2.0f / (float)B) * (pred[b] - label[b]);
 
     /* Step 1: cache h_post and compute d_h_pre per hidden unit. */
     for (int k = tid; k < H; k += blockDim.x) {
diff --git a/crates/ml/src/cuda_pipeline/aux_heads_loss_ema_kernel.cu b/crates/ml/src/cuda_pipeline/aux_heads_loss_ema_kernel.cu
index ee532a333..3c54d7cf1 100644
--- a/crates/ml/src/cuda_pipeline/aux_heads_loss_ema_kernel.cu
+++ b/crates/ml/src/cuda_pipeline/aux_heads_loss_ema_kernel.cu
@@ -2,10 +2,10 @@
  * loss scalars, written into producer_step_scratch_buf[scratch_base..+2)
  * for Pearls A+D consumption. SP4 Layer A Task A13.1 retrofit (2026-05-01).
  *
- * Plan 4 Task 6 Commit A. Producer-only kernel — Commit B wires consumers
- * (HEALTH_DIAG emission + aux-loss attribution monitor) which read
- * ISV[AUX_NEXT_BAR_MSE_EMA_INDEX] / ISV[AUX_REGIME_CE_EMA_INDEX]; only the
- * EMA mechanism behind the slots changes here.
+ * Plan 4 Task 6 Commit A. Producer-only kernel — HEALTH_DIAG emission +
+ * aux-loss attribution monitor read ISV[AUX_NEXT_BAR_MSE_EMA_INDEX] /
+ * ISV[AUX_REGIME_CE_EMA_INDEX]; only the EMA mechanism behind the slots
+ * changes here.
  *
  * Mirrors `h_s2_rms_ema_kernel.cu`'s retrofit shape — single thread,
  * single block, cold-path-cadence (one launch per training step alongside
@@ -22,6 +22,13 @@
  * GPU-drives-CPU-reads (spec §4.C.6) and pearl_cold_path_no_exception_to
  * _gpu_drives.md / feedback_no_cpu_compute_strict.md compliant.
  * No atomicAdd (per feedback_no_atomicadd.md).
+ *
+ * SP13 B1.0 (2026-05-05): the sibling `aux_label_scale_ema_update` kernel
+ * (formerly in this same file, slot 117 producer) was retired together
+ * with the ISV-driven label-scale division in `aux_next_bar_loss_reduce`
+ * / `aux_next_bar_backward`. Labels are already z-normalised at the data
+ * layer (`label_scale_ema ≈ 1.0` empirically), so the divisor became a
+ * no-op. B1.0 is a bridge — B1.1 replaces the entire MSE chain with CE.
  */
 
 extern "C" __global__ void aux_heads_loss_ema_update(
@@ -39,75 +46,3 @@ extern "C" __global__ void aux_heads_loss_ema_update(
     scratch_buf[scratch_idx_regime]   = regime_loss_scalar[0];
     __threadfence_system();   /* PCIe-visible writes for mapped pinned host_ptr */
 }
-
-/* ====================================================================
- * aux_label_scale_ema_update — Plan 4 Task 6 / Plan 5 Task 5 follow-up;
- * SP4 Layer A Task A13.1 retrofit (2026-05-01).
- *
- * Reduces `mean(|label[i]|)` over the B samples of the already-gathered
- * `aux_nb_label_buf [B]` (= column 0 of next_states for that step) and
- * writes the step observation to `producer_step_scratch_buf[scratch_idx]`
- * for Pearls A+D consumption. **α dropped per SP4 — Pearls A+D adapt α
- * from per-slot signal-vs-noise variance.**
- *
- * Consumer (unchanged): `aux_next_bar_loss_reduce` and
- * `aux_next_bar_backward` divide the label by `max(scale, 1e-6)` before
- * the residual `(pred - label)`, so training dynamics stay unit-scale
- * regardless of whether the underlying data column is a log return
- * (~1e-3) or a raw price (~5000). The consumers still read
- * ISV[AUX_LABEL_SCALE_EMA_INDEX]; only the EMA mechanism populating that
- * slot changes here.
- *
- * Ordering: this kernel + the GPU `apply_pearls_ad_kernel` (2026-05-01
- * GPU-Pearls refactor — same-stream chained launch, no host sync) MUST
- * complete BEFORE `aux_next_bar_loss_reduce` and `aux_next_bar_backward`
- * so they see an up-to-date scale. Stream ordering provides the fence;
- * graph-capture-compatible by construction.
- *
- * Single-block, 256-thread shmem-tree reduction — same shape as the
- * existing `aux_next_bar_loss_reduce` / `aux_regime_loss_reduce`. No
- * atomicAdd. Writeback path is fully GPU-side via the chained
- * `apply_pearls_ad_kernel`.
- *
- * Cost: 1 batch read + 1 scratch write per launch — under any kernel-
- * launch overhead.
- * ==================================================================== */
-#ifndef AUX_LABEL_SCALE_BLOCK
-#define AUX_LABEL_SCALE_BLOCK 256
-#endif
-
-extern "C" __global__ void aux_label_scale_ema_update(
-    const float* __restrict__ label,                   /* [B] aux_nb_label_buf */
-    int          B,
-    float*       __restrict__ scratch_buf,             /* producer_step_scratch_buf */
-    int          scratch_idx                           /* slot 43 — label-scale step obs */
-) {
-    /* Single-block contract. */
-    if (blockIdx.x != 0) return;
-
-    extern __shared__ float smem[];
-    const int tid   = threadIdx.x;
-    const int block = blockDim.x;
-
-    /* Stride loop, fabsf-and-sum into per-thread accumulator. */
-    float local = 0.0f;
-    for (int i = tid; i < B; i += block) {
-        local += fabsf(label[i]);
-    }
-    smem[tid] = local;
-    __syncthreads();
-
-    /* Standard shmem-tree reduction. */
-    for (int s = block / 2; s > 0; s >>= 1) {
-        if (tid < s) smem[tid] += smem[tid + s];
-        __syncthreads();
-    }
-
-    /* Thread 0 writes the step observation. B > 0 invariant — caller
-     * guarantees a positive batch. */
-    if (tid == 0) {
-        const float mean_abs = smem[0] / (float)B;
-        scratch_buf[scratch_idx] = mean_abs;
-        __threadfence_system();
-    }
-}
diff --git a/crates/ml/src/cuda_pipeline/gpu_aux_heads.rs b/crates/ml/src/cuda_pipeline/gpu_aux_heads.rs
index 49ba53a59..6e11ba68a 100644
--- a/crates/ml/src/cuda_pipeline/gpu_aux_heads.rs
+++ b/crates/ml/src/cuda_pipeline/gpu_aux_heads.rs
@@ -74,12 +74,13 @@ pub(crate) struct AuxHeadsForwardOps {
     regime_label_kernel: CudaFunction,
     /// Aux loss EMA producer kernel (single thread, single block; mirrors
     /// `h_s2_rms_ema_update`'s shape). Loaded from `AUX_HEADS_LOSS_EMA_CUBIN`.
+    ///
+    /// SP13 B1.0 (2026-05-05): the sibling label-scale EMA kernel was
+    /// retired together with the ISV[117] label-scale divisor in
+    /// `aux_next_bar_loss_reduce` / `aux_next_bar_backward`. Labels are
+    /// already z-normalised at the data layer; B1.1 will replace MSE
+    /// with CE entirely.
     loss_ema_kernel: CudaFunction,
-    /// Aux next-bar label-scale EMA producer kernel (single-block 256-thread
-    /// shmem reduction over `aux_nb_label_buf [B]`). Plan 5 Task 5 follow-up:
-    /// ISV-driven label-scale normalisation. Loaded from the same cubin as
-    /// `loss_ema_kernel`.
-    label_scale_ema_kernel: CudaFunction,
 }
 
 impl AuxHeadsForwardOps {
@@ -113,9 +114,6 @@ impl AuxHeadsForwardOps {
         let loss_ema_kernel = ema_module
             .load_function("aux_heads_loss_ema_update")
             .map_err(|e| MLError::ModelError(format!("aux_heads_loss_ema_update load: {e}")))?;
-        let label_scale_ema_kernel = ema_module
-            .load_function("aux_label_scale_ema_update")
-            .map_err(|e| MLError::ModelError(format!("aux_label_scale_ema_update load: {e}")))?;
 
         Ok(Self {
             next_bar_forward_kernel,
@@ -124,7 +122,6 @@ impl AuxHeadsForwardOps {
             regime_loss_reduce_kernel,
             regime_label_kernel,
             loss_ema_kernel,
-            label_scale_ema_kernel,
         })
     }
 
@@ -226,22 +223,16 @@ impl AuxHeadsForwardOps {
 
     /// Launch `aux_next_bar_loss_reduce`: scalar mean MSE into `loss_out[1]`.
     ///
-    /// Plan 5 Task 5 follow-up: the kernel reads `isv[isv_label_scale_index]`
-    /// and divides each label by `max(scale, 1e-6)` before the residual
-    /// `(pred - label/scale)` so the loss stays unit-scale regardless of
-    /// underlying data magnitude (1e-3 log-returns vs 5000 raw prices). The
-    /// device pointer + slot index pair is graph-capture-stable; the actual
-    /// scalar updates each step via `aux_label_scale_ema_update` launched
-    /// immediately before this kernel.
-    #[allow(clippy::too_many_arguments)]
+    /// SP13 B1.0 (2026-05-05): scale-free MSE — labels are z-normalised at
+    /// the data layer so the pre-B1.0 ISV-driven `inv_scale` divisor reduces
+    /// to a no-op. The kernel now computes the residual `(pred - label)`
+    /// directly. B1.1 will replace MSE with CE entirely.
     pub(crate) fn next_bar_loss_reduce(
         &self,
         stream: &Arc<CudaStream>,
         pred_ptr: u64,
         label_ptr: u64,
         b: usize,
-        isv_dev_ptr: u64,
-        isv_label_scale_index: i32,
         loss_out_ptr: u64,
     ) -> Result<(), MLError> {
         let b_i32 = b as i32;
@@ -252,8 +243,6 @@ impl AuxHeadsForwardOps {
                 .arg(&pred_ptr)
                 .arg(&label_ptr)
                 .arg(&b_i32)
-                .arg(&isv_dev_ptr)
-                .arg(&isv_label_scale_index)
                 .arg(&loss_out_ptr)
                 .launch(LaunchConfig {
                     grid_dim: (1, 1, 1),
@@ -379,46 +368,6 @@ impl AuxHeadsForwardOps {
         Ok(())
     }
 
-    /// Launch `aux_label_scale_ema_update` (Plan 5 Task 5 follow-up;
-    /// SP4 Layer A Task A13.1 retrofit 2026-05-01; GPU-Pearls refactor
-    /// 2026-05-01): single-block 256-thread shmem reduction over
-    /// `aux_nb_label_buf [B]`, writes `mean(|label|)` to
-    /// `producer_step_scratch_buf[scratch_idx]`.
-    ///
-    /// Consumes the dedicated label buffer that `aux_heads_forward` populated
-    /// via `strided_gather` of `next_states[:, 0]`. The kernel writes ONLY
-    /// the step observation; the inline GPU `apply_pearls_ad_kernel` launch
-    /// lives in `GpuDqnTrainer::aux_heads_forward` Step 2b (same stream,
-    /// no host sync) so consumers see the up-to-date
-    /// `ISV[AUX_LABEL_SCALE_EMA_INDEX]` mid-step. This site was the one
-    /// that broke L40S smoke `smoke-test-v9kjv` graph capture before the
-    /// 2026-05-01 GPU-Pearls refactor.
-    pub(crate) fn launch_label_scale_ema(
-        &self,
-        stream: &Arc<CudaStream>,
-        label_ptr: u64,
-        b: usize,
-        scratch_dev_ptr: u64,
-        scratch_idx: i32,
-    ) -> Result<(), MLError> {
-        let b_i32 = b as i32;
-        let smem_bytes = AUX_BLOCK * std::mem::size_of::<f32>() as u32;
-        unsafe {
-            stream
-                .launch_builder(&self.label_scale_ema_kernel)
-                .arg(&label_ptr)
-                .arg(&b_i32)
-                .arg(&scratch_dev_ptr)
-                .arg(&scratch_idx)
-                .launch(LaunchConfig {
-                    grid_dim: (1, 1, 1),
-                    block_dim: (AUX_BLOCK, 1, 1),
-                    shared_mem_bytes: smem_bytes,
-                })
-                .map_err(|e| MLError::ModelError(format!("aux_label_scale_ema_update: {e}")))?;
-        }
-        Ok(())
-    }
 }
 
 /// Backward orchestrator — owns the 3 backward / final-reduce kernel
@@ -468,11 +417,10 @@ impl AuxHeadsBackwardOps {
     /// `param_grad_reduce` for each of {`dW1`, `db1`, `dW2`, `db2`} to
     /// collapse along the batch dim.
     ///
-    /// Plan 5 Task 5 follow-up: the kernel reads `isv[isv_label_scale_index]`
-    /// and divides each label by `max(scale, 1e-6)` before the residual
-    /// — MUST mirror the `aux_next_bar_loss_reduce` arithmetic so loss +
-    /// gradient are derivatives of the same scalar function. The device
-    /// pointer + slot index pair is graph-capture-stable.
+    /// SP13 B1.0 (2026-05-05): scale-free MSE backward — mirrors the
+    /// `aux_next_bar_loss_reduce` arithmetic so loss + gradient are
+    /// derivatives of the same scalar function. The pre-B1.0 ISV-driven
+    /// `inv_scale` divisor (former slot 117) is retired.
     #[allow(clippy::too_many_arguments)]
     pub(crate) fn backward_next_bar(
         &self,
@@ -485,8 +433,6 @@ impl AuxHeadsBackwardOps {
         label_ptr: u64,
         b: usize,
         sh2: usize,
-        isv_dev_ptr: u64,
-        isv_label_scale_index: i32,
         dw1_partial_ptr: u64,
         db1_partial_ptr: u64,
         dw2_partial_ptr: u64,
@@ -507,8 +453,6 @@ impl AuxHeadsBackwardOps {
                 .arg(&label_ptr)
                 .arg(&b_i32)
                 .arg(&sh2_i32)
-                .arg(&isv_dev_ptr)
-                .arg(&isv_label_scale_index)
                 .arg(&dw1_partial_ptr)
                 .arg(&db1_partial_ptr)
                 .arg(&dw2_partial_ptr)
diff --git a/crates/ml/src/cuda_pipeline/gpu_dqn_trainer.rs b/crates/ml/src/cuda_pipeline/gpu_dqn_trainer.rs
index aca348d4d..dd90faa4e 100644
--- a/crates/ml/src/cuda_pipeline/gpu_dqn_trainer.rs
+++ b/crates/ml/src/cuda_pipeline/gpu_dqn_trainer.rs
@@ -1027,20 +1027,15 @@ const ISV_NETWORK_DIM: usize = 23;
 ///   [114] AUX_REGIME_CE_EMA_INDEX — Plan 4 Task 6 Commit A — EMA of the
 ///         regime classification head's mean-batch cross-entropy
 ///         (α=0.05). Same producer/contract as [113]; same FoldReset → 0.0.
-///   [117] AUX_LABEL_SCALE_EMA_INDEX — Plan 4 Task 6 / Plan 5 Task 5 follow-
-///         up — EMA of `mean(|next_states[:, 0]|)` over the batch (α=0.05).
-///         Producer: `aux_label_scale_ema_update` GPU kernel (single-block
-///         shmem reduction over the already-gathered `aux_nb_label_buf [B]`,
-///         then EMA blend with the prior ISV value). Consumer: read on host
-///         every step BEFORE `aux_next_bar_loss_reduce` and `aux_next_bar_
-///         backward` launch, passed as a `float` kernel argument; both
-///         kernels divide the label by `max(scale, 1e-6)` so the residual
-///         `(pred - label/scale)` stays unit-scale regardless of underlying
-///         data magnitude (1e-3 log-returns vs 5000 raw prices). FoldReset
-///         → 1.0 (multiplicative identity — divide-by-1 is a no-op so the
-///         first batch of a new fold trains against the un-normalised label
-///         until the producer fires once and the EMA updates to the actual
-///         scale).
+///   [117] RETIRED — formerly `AUX_LABEL_SCALE_EMA_INDEX` (Plan 4 Task 6 /
+///         Plan 5 Task 5 follow-up). Retired in SP13 B1.0 (2026-05-05) when
+///         `aux_next_bar_loss_reduce` / `aux_next_bar_backward` flipped to
+///         scale-free MSE: labels are z-normalised at the data layer so the
+///         pre-B1.0 ISV-driven `(pred - label / scale)` residual reduces to
+///         `(pred - label)` within rounding. The slot remains unused in the
+///         ISV bus (layout fingerprint reserves it via the seed; do not
+///         reuse without a fingerprint bump). B1.1 will replace MSE with CE
+///         entirely, eliminating the formulation that made this slot useful.
 ///   [115] ISV_LAYOUT_FINGERPRINT_LO_INDEX — low 32 bits of layout fingerprint
 ///         (shifted 111→115 in Plan 4 Task 6 Commit A).
 ///   [116] ISV_LAYOUT_FINGERPRINT_HI_INDEX — high 32 bits of layout fingerprint
@@ -1833,29 +1828,21 @@ pub const VSN_MASK_GROUP_5_EMA_INDEX: usize = 110;
 pub const AUX_NEXT_BAR_MSE_EMA_INDEX: usize = 113;
 pub const AUX_REGIME_CE_EMA_INDEX: usize = 114;
 
-/// ISV slot [117] — Plan 4 Task 6 / Plan 5 Task 5 follow-up: aux next-bar
-/// label-scale EMA.
+/// ISV slot [117] — RETIRED in SP13 B1.0 (2026-05-05).
 ///
-/// EMA of `mean(|next_states[:, 0]|)` over the batch (α=0.05). Producer:
-/// `aux_label_scale_ema_update` GPU kernel (single-block 256-thread shmem
-/// reduction over the already-gathered `aux_nb_label_buf [B]`, then EMA
-/// blend with the prior ISV value into slot 117). Consumer: read on host
-/// every step BEFORE `aux_next_bar_loss_reduce` and `aux_next_bar_backward`
-/// launch, passed as a `float` kernel argument; both kernels divide the
-/// label by `max(scale, 1e-6)` before the residual so the loss + gradient
-/// stay unit-scale regardless of whether `next_states[:, 0]` carries log
-/// returns (~1e-3) or raw prices (~5000).
+/// Formerly `AUX_LABEL_SCALE_EMA_INDEX` — held the EMA of
+/// `mean(|next_states[:, 0]|)` consumed by `aux_next_bar_loss_reduce` /
+/// `aux_next_bar_backward` to divide the label by `max(scale, 1e-6)`
+/// before the residual. Retired together with that division when the MSE
+/// loss flipped to scale-free: labels are z-normalised at the data layer
+/// so `label_scale_ema ≈ 1.0` empirically and `(pred - label * inv_scale)`
+/// reduced to `(pred - label)` within rounding.
 ///
-/// Cold-start: 1.0 (multiplicative identity — divide-by-1 is a no-op so the
-/// first batch of a new fold trains against the un-normalised label until
-/// the producer fires once and the EMA updates to the actual scale).
-/// FoldReset → 1.0 (NOT 0.0 — divide-by-zero would explode the loss before
-/// the producer could pull the EMA back to the real scale).
-///
-/// Tail-appended after the fingerprint slots [115..117) per
-/// `feedback_no_partial_refactor.md` (every consumer of `ISV_TOTAL_DIM` or
-/// the fingerprint shifts together in this commit).
-pub const AUX_LABEL_SCALE_EMA_INDEX: usize = 117;
+/// The slot remains unused in the ISV bus and is reserved by the layout
+/// fingerprint seed — do NOT reuse it without a fingerprint bump (which
+/// would invalidate every checkpoint stored under the post-B1.0
+/// fingerprint). B1.1 will replace the MSE chain with CE entirely,
+/// eliminating the formulation that made this slot useful.
 
 /// Mixture-of-Experts per-expert utilization EMA, α=0.05.
 /// 8 contiguous slots [118..126).
@@ -2057,7 +2044,6 @@ const fn layout_fingerprint_seed() -> &'static [u8] {
       VSN_MASK_GROUP_3_EMA=108;VSN_MASK_GROUP_4_EMA=109;VSN_MASK_GROUP_5_EMA=110;\
       AUX_NEXT_BAR_MSE_EMA=113;AUX_REGIME_CE_EMA=114;\
       ISV_LAYOUT_FINGERPRINT_LO=115;ISV_LAYOUT_FINGERPRINT_HI=116;\
-      AUX_LABEL_SCALE_EMA=117;\
       MOE_EXPERT_UTIL_EMA_BASE=118;MOE_EXPERT_UTIL_EMA_COUNT=8;\
       MOE_GATE_ENTROPY_EMA=126;\
       MOE_LAMBDA_EFF=128;\
@@ -4018,7 +4004,10 @@ pub struct GpuDqnTrainer {
     ///   [0..40)  — SP4 producers (Tasks A5-A11)
     ///   [40]     — h_s2_rms_ema      → ISV[96]            (A13.0)
     ///   [41..43) — aux_heads_loss_ema → ISV[113],ISV[114]  (A13.1)
-    ///   [43]     — aux_label_scale_ema → ISV[117]          (A13.1)
+    ///   [43]     — RETIRED — formerly aux_label_scale_ema → ISV[117]
+    ///                          (SP13 B1.0, 2026-05-05); slot reserved by
+    ///                          SP4_PRODUCER_COUNT for layout stability —
+    ///                          do not reuse without a fingerprint bump.
     ///   [44..52) — moe_expert_util_ema → ISV[118..126)     (A13.2)
     ///   [52]     — moe_gate_entropy_ema → ISV[126]         (A13.2)
     ///   [53..59) — vsn_mask_ema        → ISV[105..111)     (A13.3)
@@ -10916,7 +10905,10 @@ impl GpuDqnTrainer {
         //   ── Task A13 retrofit producers (Pearls A+D for existing EMA kernels) ──
         //   40     = H_S2_RMS_EMA           → ISV[96]            (A13.0)
         //   41..43 = AUX_HEADS_LOSS_EMA     → ISV[113],ISV[114]  (A13.1)
-        //   43     = AUX_LABEL_SCALE_EMA    → ISV[117]           (A13.1)
+        //   43     = RETIRED (SP13 B1.0)    — formerly AUX_LABEL_SCALE_EMA
+        //                                     → ISV[117]; slot reserved
+        //                                     by SP4_PRODUCER_COUNT for
+        //                                     layout stability.
         //   44..52 = MOE_EXPERT_UTIL_EMA    → ISV[118..126)      (A13.2)
         //   52     = MOE_GATE_ENTROPY_EMA   → ISV[126]           (A13.2)
         //   53..59 = VSN_MASK_EMA           → ISV[105..111)      (A13.3)
@@ -14787,7 +14779,6 @@ impl GpuDqnTrainer {
             TARGET_DRIFT_DIR_EMA_INDEX     as i32,
             AUX_NEXT_BAR_MSE_EMA_INDEX     as i32,
             AUX_REGIME_CE_EMA_INDEX        as i32,
-            AUX_LABEL_SCALE_EMA_INDEX      as i32,
             MOE_EXPERT_UTIL_EMA_BASE       as i32,
             MOE_GATE_ENTROPY_EMA_INDEX     as i32,
             MOE_LAMBDA_EFF_INDEX           as i32,
@@ -15279,64 +15270,19 @@ impl GpuDqnTrainer {
             }
         }
 
-        // Step 2b: ISV-driven label-scale step-observation producer
-        // (Plan 5 Task 5 follow-up; SP4 Layer A Task A13.1 retrofit;
-        // 2026-05-01 GPU-Pearls refactor).
-        //
-        // Reads the JUST-gathered `aux_nb_label_buf [B]` and writes
-        // `mean(|label|)` to `producer_step_scratch_buf[43]`. The GPU
-        // `apply_pearls_ad_kernel` then maps that step observation into
-        // ISV[AUX_LABEL_SCALE_EMA_INDEX] on the same stream, so subsequent
-        // consumers (`next_bar_loss_reduce` Step 5 + backward) read an
-        // up-to-date adaptive-α scale before computing the residual
-        // `(pred - label/scale)`. Wiener state at
-        // `wiener_state_buf[129..132)` (= scratch slot 43 × 3).
-        //
-        // **This site is the ONE that broke L40S smoke `smoke-test-v9kjv`** —
-        // the prior host-side `apply_pearls_to_slot` issued a mid-step
-        // `stream.synchronize()` inside the per-step captured graph,
-        // raising `CUDA_ERROR_STREAM_CAPTURE_UNSUPPORTED`. The GPU
-        // applicator's same-stream ordering eliminates the host sync; the
-        // captured graph now records the producer + applicator launches
-        // in one capture pass.
-        //
-        // **α dropped per SP4 — Pearls A+D adapt α from per-slot signal-
-        // vs-noise variance.**
-        const SCRATCH_IDX_LABEL_SCALE: usize = 43;
-        let scratch_dev = self.producer_step_scratch_buf.dev_ptr;
-        self.aux_heads_fwd.launch_label_scale_ema(
-            &self.stream,
-            self.aux_nb_label_buf.raw_ptr(),
-            b,
-            scratch_dev,
-            SCRATCH_IDX_LABEL_SCALE as i32,
-        )?;
-
-        // DIAG_AUX_LABEL one-shot diagnostic removed (Fix 29) — leak pinned to
-        // experience_kernels.cu:698-704 vol_normalizer double-normalization.
-
-        {
-            use crate::cuda_pipeline::sp4_wiener_ema::launch_apply_pearls;
-            // GPU Pearls A+D: stream-ordered with the producer kernel,
-            // single-slot, retrofit wiener convention: offset = scratch_idx*3
-            // = 129. Degenerate-zero (mean(|label|) reduction yielded 0 →
-            // before first aux head forward populates the label buffer)
-            // handled by the applicator's `step_obs == 0` skip.
-            unsafe {
-                launch_apply_pearls(
-                    &self.stream,
-                    &self.apply_pearls_ad_kernel,
-                    scratch_dev,
-                    SCRATCH_IDX_LABEL_SCALE as i32,
-                    self.isv_signals_dev_ptr,
-                    AUX_LABEL_SCALE_EMA_INDEX as i32,
-                    self.wiener_state_buf.dev_ptr,
-                    (SCRATCH_IDX_LABEL_SCALE * 3) as i32,
-                    1,
-                    crate::cuda_pipeline::sp4_wiener_ema::ALPHA_META,
-                )?;
-            }
-        }
+        // SP13 B1.0 (2026-05-05): Step 2b retired together with the
+        // ISV[117] (`AUX_LABEL_SCALE_EMA_INDEX`) division in the
+        // `aux_next_bar_loss_reduce` / `aux_next_bar_backward` kernels.
+        // Labels are z-normalised at the data layer so `label_scale ≈ 1.0`
+        // empirically; the pre-B1.0 `(pred - label / scale)` residual
+        // reduces to `(pred - label)` within rounding. The per-step
+        // label-scale producer (`launch_label_scale_ema`) and its chained
+        // `apply_pearls_ad_kernel` applicator (which mapped scratch[43] →
+        // ISV[117], wiener_state[129..132)) are no longer launched. The
+        // scratch slot + wiener state remain reserved by
+        // SP4_PRODUCER_COUNT for layout stability — do not reuse without
+        // a fingerprint bump. B1.1 will replace MSE with CE and remove
+        // the formulation entirely.
 
         // Step 3: next-bar regression forward.
         self.aux_heads_fwd.forward_next_bar(
@@ -15359,15 +15305,14 @@ impl GpuDqnTrainer {
         )?;
 
         // Step 5: next-bar MSE reduce against the dedicated label buffer.
-        // Kernel reads ISV[AUX_LABEL_SCALE_EMA_INDEX] (populated by the
-        // Step 2b producer) to normalise the label before the residual.
+        // SP13 B1.0 (2026-05-05): scale-free MSE — the kernel computes
+        // `(pred - label)` directly. Labels are z-normalised at the data
+        // layer so the pre-B1.0 ISV[117] divisor was a no-op in practice.
         self.aux_heads_fwd.next_bar_loss_reduce(
             &self.stream,
             self.aux_nb_pred_buf.raw_ptr(),
             self.aux_nb_label_buf.raw_ptr(),
             b,
-            self.isv_signals_dev_ptr,
-            AUX_LABEL_SCALE_EMA_INDEX as i32,
             self.aux_nb_loss_scalar_buf.raw_ptr(),
         )?;
 
@@ -15429,11 +15374,11 @@ impl GpuDqnTrainer {
             self.aux_nb_pred_buf.raw_ptr(),
             self.aux_nb_label_buf.raw_ptr(),
             b, sh2,
-            // Plan 5 Task 5 follow-up: read ISV-driven label-scale EMA from
-            // the same slot the forward `next_bar_loss_reduce` read so loss
-            // and gradient are derivatives of the same scalar function.
-            self.isv_signals_dev_ptr,
-            AUX_LABEL_SCALE_EMA_INDEX as i32,
+            // SP13 B1.0 (2026-05-05): scale-free MSE backward — mirrors
+            // the `next_bar_loss_reduce` arithmetic so loss + gradient
+            // remain derivatives of the same scalar function. The
+            // pre-B1.0 ISV[117] (`AUX_LABEL_SCALE_EMA_INDEX`) divisor is
+            // retired together with the loss-side division.
             self.aux_partial_nb_w1.raw_ptr(),
             self.aux_partial_nb_b1.raw_ptr(),
             self.aux_partial_nb_w2.raw_ptr(),
diff --git a/crates/ml/src/cuda_pipeline/gpu_health_diag.rs b/crates/ml/src/cuda_pipeline/gpu_health_diag.rs
index 347ac4775..decc7f320 100644
--- a/crates/ml/src/cuda_pipeline/gpu_health_diag.rs
+++ b/crates/ml/src/cuda_pipeline/gpu_health_diag.rs
@@ -152,7 +152,8 @@ impl GpuHealthDiag {
         target_drift_dir_idx: i32,
         aux_next_bar_mse_idx: i32,
         aux_regime_ce_idx: i32,
-        aux_label_scale_idx: i32,
+        // SP13 B1.0 (2026-05-05): `aux_label_scale_idx: i32` parameter
+        // dropped together with ISV[117] retirement.
         moe_expert_util_base_idx: i32,
         moe_gate_entropy_idx: i32,
         moe_lambda_eff_idx: i32,
@@ -175,7 +176,8 @@ impl GpuHealthDiag {
                 .arg(&target_drift_dir_idx)
                 .arg(&aux_next_bar_mse_idx)
                 .arg(&aux_regime_ce_idx)
-                .arg(&aux_label_scale_idx)
+                // SP13 B1.0 (2026-05-05): aux_label_scale_idx arg dropped
+                // — kernel signature shortened in lockstep.
                 .arg(&moe_expert_util_base_idx)
                 .arg(&moe_gate_entropy_idx)
                 .arg(&moe_lambda_eff_idx)
diff --git a/crates/ml/src/cuda_pipeline/health_diag.rs b/crates/ml/src/cuda_pipeline/health_diag.rs
index b942689cb..11692978e 100644
--- a/crates/ml/src/cuda_pipeline/health_diag.rs
+++ b/crates/ml/src/cuda_pipeline/health_diag.rs
@@ -246,11 +246,13 @@ pub struct HealthDiagSnapshot {
     pub reward_split_opp_cost: f32,
     pub reward_split_bonus: f32,
 
-    // ── Aux block (4 floats) ─────────────────────────────────────────────────
+    // ── Aux block (3 floats) ─────────────────────────────────────────────────
+    // SP13 B1.0 (2026-05-05): the former `aux_label_scale: f32` field was
+    // dropped together with ISV[117] when the next-bar MSE flipped to
+    // scale-free. Snap layout now ends the aux block at word 127 (was 128).
     pub aux_next_bar_mse: f32,
     pub aux_regime_ce: f32,
     pub aux_weight: f32,
-    pub aux_label_scale: f32,
 
     // ── Aux MoE (8 utils + 1 ent + 1 λ_eff = 10 floats) ──────────────────────
     pub aux_moe_util: [f32; HEALTH_DIAG_MOE_EXPERTS],
@@ -393,14 +395,16 @@ mod tests {
         // +  6 trail     +  6 magstats  +  6 noisy   +  3 eval_dist
         // +  3 intent_dist + 4 reward_contrib + 7 controller + 3 explore
         // + 16 val       +  4 val_dir   +  4 val_picked
-        // +  6 reward_split  + 4 aux    + 10 aux_moe
+        // +  6 reward_split  + 3 aux    + 10 aux_moe
         // + 12 action_counts
-        // = 8+8+7+2+1+10+4+5+9+2+6+6+6+3+3+4+7+3+16+4+4+6+4+10+12 = 150 fields
-        let expected_bytes = 150 * 4;
+        // = 8+8+7+2+1+10+4+5+9+2+6+6+6+3+3+4+7+3+16+4+4+6+3+10+12 = 149 fields
+        // SP13 B1.0 (2026-05-05): aux block dropped from 4 → 3 floats
+        // (retired `aux_label_scale` together with ISV[117]).
+        let expected_bytes = 149 * 4;
         assert_eq!(
             std::mem::size_of::<HealthDiagSnapshot>(),
             expected_bytes,
-            "HealthDiagSnapshot must be {} bytes (150 × 4); update test if struct changes",
+            "HealthDiagSnapshot must be {} bytes (149 × 4); update test if struct changes",
             expected_bytes,
         );
     }
diff --git a/crates/ml/src/cuda_pipeline/health_diag_kernel.cu b/crates/ml/src/cuda_pipeline/health_diag_kernel.cu
index e3a4e36e3..6441b29bc 100644
--- a/crates/ml/src/cuda_pipeline/health_diag_kernel.cu
+++ b/crates/ml/src/cuda_pipeline/health_diag_kernel.cu
@@ -182,24 +182,25 @@
 #define WORD_REWARD_SPLIT_OPP_COST 122
 #define WORD_REWARD_SPLIT_BONUS    123
 
-/* Aux block (4 words, [124..128)). */
+/* Aux block (3 words, [124..127)). SP13 B1.0 (2026-05-05): retired
+ * `WORD_AUX_LABEL_SCALE` together with ISV[117] when the next-bar MSE
+ * flipped to scale-free; downstream offsets shifted down by 1. */
 #define WORD_AUX_NEXT_BAR_MSE      124
 #define WORD_AUX_REGIME_CE         125
 #define WORD_AUX_WEIGHT            126
-#define WORD_AUX_LABEL_SCALE       127
 
-/* Aux MoE (10 words, [128..138) — 8 utils + ent + λ_eff). */
-#define WORD_AUX_MOE_UTIL_BASE     128
-#define WORD_AUX_MOE_ENT           136
-#define WORD_AUX_MOE_LAMBDA_EFF    137
+/* Aux MoE (10 words, [127..137) — 8 utils + ent + λ_eff). */
+#define WORD_AUX_MOE_UTIL_BASE     127
+#define WORD_AUX_MOE_ENT           135
+#define WORD_AUX_MOE_LAMBDA_EFF    136
 
-/* Action-count histogram (12 words, [138..150), all u32). */
-#define WORD_ACTION_COUNTS_BASE    138
+/* Action-count histogram (12 words, [137..149), all u32). */
+#define WORD_ACTION_COUNTS_BASE    137
 
-#define WORD_TOTAL                 150
+#define WORD_TOTAL                 149
 
 /* Pin the layout: matches `snapshot_size_is_stable` on the Rust side. */
-static_assert(WORD_TOTAL == 150,
+static_assert(WORD_TOTAL == 149,
               "HealthDiagSnapshot layout drift — update kernel WORD_* and the "
               "Rust struct in lockstep, then bump snapshot_size_is_stable.");
 
@@ -220,24 +221,16 @@ static_assert(WORD_TOTAL == 150,
  *   ISV[88] VSN_DIR_EMA_INDEX              → snap.noisy_vsn_dir         (word 69)
  *   ISV[92] TARGET_DRIFT_MAG_EMA_INDEX     → snap.noisy_drift_mag       (word 72)
  *   ISV[93] TARGET_DRIFT_DIR_EMA_INDEX     → snap.noisy_drift_dir       (word 73)
- *   ISV[113] AUX_NEXT_BAR_MSE_EMA_INDEX    → snap.aux_next_bar_mse      (word 121)
- *   ISV[114] AUX_REGIME_CE_EMA_INDEX       → snap.aux_regime_ce         (word 122)
- *   ISV[117] AUX_LABEL_SCALE_EMA_INDEX     → snap.aux_label_scale       (word 124)
- *   ISV[118..126) MOE_EXPERT_UTIL_EMA_BASE → snap.aux_moe_util[0..8]    (words 125..133)
- *   ISV[126] MOE_GATE_ENTROPY_EMA_INDEX    → snap.aux_moe_ent           (word 133)
- *   ISV[128] MOE_LAMBDA_EFF_INDEX          → snap.aux_moe_lambda_eff    (word 134)
+ *   ISV[113] AUX_NEXT_BAR_MSE_EMA_INDEX    → snap.aux_next_bar_mse      (word 124)
+ *   ISV[114] AUX_REGIME_CE_EMA_INDEX       → snap.aux_regime_ce         (word 125)
+ *   ISV[118..126) MOE_EXPERT_UTIL_EMA_BASE → snap.aux_moe_util[0..8]    (words 127..135)
+ *   ISV[126] MOE_GATE_ENTROPY_EMA_INDEX    → snap.aux_moe_ent           (word 135)
+ *   ISV[128] MOE_LAMBDA_EFF_INDEX          → snap.aux_moe_lambda_eff    (word 136)
  *
- * Note: ISV[126] is read TWICE — once into the last MoE-util slot
- * (which the host code historically aliased through the same buffer
- * indexing pattern when reading via `read_isv_signal_at(MOE_EXPERT_UTIL_EMA_BASE + 7)`),
- * and once into `aux_moe_ent`. We mirror the source-level read pattern: the
- * host previously called `read_isv_signal_at(MOE_GATE_ENTROPY_EMA_INDEX)` for
- * `ent`, which is slot 126; the host also walked `[BASE..BASE+8)` for the
- * 8 expert-utility slots, the last of which is slot 125+7=132 — *not*
- * slot 126. So in fact MOE_EXPERT_UTIL_EMA_BASE+7 = 125 (snap word 132 in
- * snap-word coords; ISV slot 125), and slot 126 is the entropy. The
- * mapping above is therefore correct by ISV index — there is NO double
- * read.
+ * SP13 B1.0 (2026-05-05): the former ISV[117] AUX_LABEL_SCALE_EMA_INDEX →
+ * snap.aux_label_scale mirror was dropped together with that slot's
+ * retirement. All snap word offsets at and beyond the former
+ * `WORD_AUX_LABEL_SCALE=127` shifted down by 1.
  *
  * Indices passed in as kernel args (rather than `#define`d) so we don't
  * couple the kernel to a specific numbering — the Rust caller passes
@@ -267,7 +260,8 @@ extern "C" __global__ void health_diag_isv_mirror(
     int target_drift_dir_idx,              /* ISV[93] */
     int aux_next_bar_mse_idx,              /* ISV[113] */
     int aux_regime_ce_idx,                 /* ISV[114] */
-    int aux_label_scale_idx,               /* ISV[117] */
+    /* SP13 B1.0 (2026-05-05): ISV[117] AUX_LABEL_SCALE retired —
+     * argument dropped from kernel signature. */
     int moe_expert_util_base_idx,          /* ISV[118], 8 contiguous slots */
     int moe_gate_entropy_idx,              /* ISV[126] */
     int moe_lambda_eff_idx                 /* ISV[128] */
@@ -296,10 +290,11 @@ extern "C" __global__ void health_diag_isv_mirror(
     snap[WORD_NOISY_DRIFT_DIR]        = isv[target_drift_dir_idx];
 
     /* Aux-head loss EMAs (Plan 4 Task 6 Commit A producer:
-     * aux_heads_loss_ema_kernel). */
+     * aux_heads_loss_ema_kernel). SP13 B1.0 (2026-05-05): the third
+     * mirror (ISV[117] → snap.aux_label_scale) was retired together with
+     * the slot when the next-bar MSE flipped to scale-free. */
     snap[WORD_AUX_NEXT_BAR_MSE]       = isv[aux_next_bar_mse_idx];
     snap[WORD_AUX_REGIME_CE]          = isv[aux_regime_ce_idx];
-    snap[WORD_AUX_LABEL_SCALE]        = isv[aux_label_scale_idx];
 
     /* MoE per-expert utilisation EMA (8 contiguous slots). Producer:
      * moe_expert_util_ema_update in moe_kernels.cu. */
diff --git a/crates/ml/src/trainers/dqn/state_reset_registry.rs b/crates/ml/src/trainers/dqn/state_reset_registry.rs
index 1caa27b9e..6f85c67a3 100644
--- a/crates/ml/src/trainers/dqn/state_reset_registry.rs
+++ b/crates/ml/src/trainers/dqn/state_reset_registry.rs
@@ -368,24 +368,12 @@ impl StateResetRegistry {
                 category: ResetCategory::FoldReset,
                 description: "ISV[AUX_REGIME_CE_EMA_INDEX=114] — regime classification head batch-mean cross-entropy EMA; same producer/contract as next_bar_mse_ema; cold-start 0.0",
             },
-            // ───── Plan 4 Task 6 / Plan 5 Task 5 follow-up: aux next-bar
-            // label-scale EMA. Defends the aux next-bar regression head
-            // against underlying-data scale (1e-3 log-returns vs 5000 raw
-            // prices). Producer: aux_label_scale_ema_update GPU kernel
-            // (single-block 256-thread shmem reduction, α=0.05). Consumer:
-            // aux_next_bar_loss_reduce + aux_next_bar_backward read the
-            // slot to divide label by max(scale, 1e-6) before the residual.
-            // SP4 Task A13.1 retrofit — Pearl A sentinel 0.0 at fold boundary
-            // (paired with sp4_wiener_state reset zeroing state.x_lag in
-            // lockstep). The 1e-6 floor on the consumer side guards the
-            // narrow window between fold boundary and the first producer
-            // fire (which writes the measured scale directly via Pearl A's
-            // first-observation replacement).
-            RegistryEntry {
-                name: "isv_aux_label_scale_ema",
-                category: ResetCategory::FoldReset,
-                description: "ISV[AUX_LABEL_SCALE_EMA_INDEX=117] — aux next-bar label-scale EMA (mean(|next_states[:, 0]|) at α=0.05); GPU aux_label_scale_ema_update kernel fills (Plan 4 Task 6 / Plan 5 Task 5 follow-up); consumer kernels read slot 117 to divide label by max(scale, 1e-6) before the residual; SP4 Task A13.1 retrofit — Pearl A sentinel 0.0 reapplied at fold boundary; consumer 1e-6 floor guards the divide-by-zero window before the first producer fire",
-            },
+            // SP13 B1.0 (2026-05-05): the former
+            // `isv_aux_label_scale_ema` registry entry (FoldReset for ISV
+            // slot 117) was retired together with the slot itself when
+            // the next-bar MSE flipped to scale-free. No replacement
+            // entry is needed — the slot is no longer written by any
+            // producer, so there is nothing to reset at fold boundary.
             // Mixture-of-Experts per-expert utilization (slots 118..126).
             // SP4 Task A13.2 retrofit — Pearl A sentinel 0.0 at fold boundary.
             RegistryEntry {
diff --git a/crates/ml/src/trainers/dqn/trainer/training_loop.rs b/crates/ml/src/trainers/dqn/trainer/training_loop.rs
index 9c9579bb2..185a94cd9 100644
--- a/crates/ml/src/trainers/dqn/trainer/training_loop.rs
+++ b/crates/ml/src/trainers/dqn/trainer/training_loop.rs
@@ -4811,36 +4811,33 @@ impl DQNTrainer {
             // Plan 4 Task 6 Commit B: aux-heads diagnostic line. Reads
             // ISV[AUX_NEXT_BAR_MSE_EMA_INDEX=113] +
             // ISV[AUX_REGIME_CE_EMA_INDEX=114] (populated by
-            // `aux_heads_loss_ema_update` launched per-step above) +
-            // ISV[AUX_LABEL_SCALE_EMA_INDEX=117] (Plan 5 Task 5 follow-up
-            // — populated by `aux_label_scale_ema_update` per step), and
+            // `aux_heads_loss_ema_update` launched per-step above) and
             // the host-side `aux_weight` baked into the most-recently-
             // captured graph. Cold-start (epoch 0 of each fold): loss EMAs
-            // at 0.0, label_scale at 1.0, aux_weight at 0.05.
-            // `label_scale` magnitude reveals what the underlying data column
-            // 0 of next_states actually carries this step — log returns
-            // (~1e-3) vs raw prices (~5000) — and confirms the normalize-
-            // before-MSE fix is firing against the right scale.
+            // at 0.0, aux_weight at 0.05.
+            //
+            // SP13 B1.0 (2026-05-05): the former `label_scale` field
+            // (read from retired ISV[117]) was dropped together with that
+            // slot. Labels are z-normalised at the data layer so
+            // monitoring the scale was redundant.
             {
                 use crate::cuda_pipeline::gpu_dqn_trainer::{
                     AUX_NEXT_BAR_MSE_EMA_INDEX, AUX_REGIME_CE_EMA_INDEX,
-                    AUX_LABEL_SCALE_EMA_INDEX,
                 };
-                let (aux_nb_mse, aux_rg_ce, aux_w, aux_label_scale) =
+                let (aux_nb_mse, aux_rg_ce, aux_w) =
                     if let Some(ref fused) = self.fused_ctx {
                         let trainer = fused.trainer();
                         (
                             trainer.read_isv_signal_at(AUX_NEXT_BAR_MSE_EMA_INDEX),
                             trainer.read_isv_signal_at(AUX_REGIME_CE_EMA_INDEX),
                             trainer.aux_weight(),
-                            trainer.read_isv_signal_at(AUX_LABEL_SCALE_EMA_INDEX),
                         )
                     } else {
-                        (0.0, 0.0, 0.0, 1.0)
+                        (0.0, 0.0, 0.0)
                     };
                 tracing::info!(
-                    "HEALTH_DIAG[{}]: aux [next_bar_mse={:.3e} regime_ce={:.3e} w={:.3} label_scale={:.3e}]",
-                    epoch, aux_nb_mse, aux_rg_ce, aux_w, aux_label_scale,
+                    "HEALTH_DIAG[{}]: aux [next_bar_mse={:.3e} regime_ce={:.3e} w={:.3}]",
+                    epoch, aux_nb_mse, aux_rg_ce, aux_w,
                 );
             }
 
@@ -6846,26 +6843,15 @@ impl DQNTrainer {
                     fused.trainer().write_isv_signal_at(idx, 0.0);
                 }
             }
-            // Plan 4 Task 6 / Plan 5 Task 5 follow-up: aux next-bar label-
-            // scale EMA. SP4 Task A13.1 retrofit reset to Pearl A sentinel
-            // 0.0 at fold boundary — the companion `sp4_wiener_state` bulk
-            // reset zeros `state.x_lag` in lockstep so the first
-            // `aux_label_scale_ema_update` fire on the new fold sees
-            // `prev_x_mean == 0 AND state.x_lag == 0` and triggers Pearl A's
-            // first-observation replacement (which writes the measured scale
-            // directly, no 1.0 cold-start blend). Per
-            // `feedback_no_partial_refactor.md` — the sentinel contract
-            // migrates both halves together. Consumer kernels' `1e-6` floor
-            // protects the divide-by-zero window between fold boundary and the
-            // first producer fire.
-            "isv_aux_label_scale_ema" => {
-                if let Some(ref fused) = self.fused_ctx {
-                    fused.trainer().write_isv_signal_at(
-                        crate::cuda_pipeline::gpu_dqn_trainer::AUX_LABEL_SCALE_EMA_INDEX,
-                        0.0_f32,
-                    );
-                }
-            }
+            // SP13 B1.0 (2026-05-05): the former `isv_aux_label_scale_ema`
+            // arm is retired together with ISV[117]. The slot is no
+            // longer written by any producer (`aux_label_scale_ema_update`
+            // kernel was deleted) and no longer read by any consumer
+            // (`aux_next_bar_loss_reduce` / `aux_next_bar_backward`
+            // flipped to scale-free); nothing to reset at fold boundary.
+            // Removing the registry entry above made this arm dead, and
+            // dispatch on the retired name now correctly falls into the
+            // unknown-name guard.
             // SP4 Task A13.2 retrofit: per-expert MoE utilisation EMA slots.
             // Reset to Pearl A sentinel 0.0 at fold boundary — the companion
             // `sp4_wiener_state` bulk reset zeros `state.x_lag` in lockstep so
diff --git a/crates/ml/tests/sp4_producer_unit_tests.rs b/crates/ml/tests/sp4_producer_unit_tests.rs
index 5dd0c72bd..5ae560c23 100644
--- a/crates/ml/tests/sp4_producer_unit_tests.rs
+++ b/crates/ml/tests/sp4_producer_unit_tests.rs
@@ -1526,15 +1526,10 @@ fn load_aux_heads_loss_ema_kernel(stream: &Arc<CudaStream>) -> CudaFunction {
         .expect("load aux_heads_loss_ema_update function")
 }
 
-fn load_aux_label_scale_ema_kernel(stream: &Arc<CudaStream>) -> CudaFunction {
-    let module = stream
-        .context()
-        .load_cubin(SP4_AUX_HEADS_LOSS_EMA_CUBIN.to_vec())
-        .expect("load aux_heads_loss_ema cubin (label scale)");
-    module
-        .load_function("aux_label_scale_ema_update")
-        .expect("load aux_label_scale_ema_update function")
-}
+// SP13 B1.0 (2026-05-05): the `load_aux_label_scale_ema_kernel` helper
+// + `sp4_aux_label_scale_ema_writes_step_obs_via_pearl_a_then_converges_pearl_d`
+// test were retired together with the `aux_label_scale_ema_update` kernel
+// itself when the next-bar MSE flipped to scale-free.
 
 /// SP4 Task A13.1: `aux_heads_loss_ema_update` writes both scalar loss
 /// values to scratch[41]/[42], and Pearls A+D bootstrap (Pearl A) replaces
@@ -1616,78 +1611,10 @@ fn sp4_aux_heads_loss_ema_writes_step_obs_via_pearl_a_then_converges_pearl_d() {
         "rg stationary should converge: got {rg_mean}, expected {rg_loss}");
 }
 
-/// SP4 Task A13.1: `aux_label_scale_ema_update` writes mean(|label|) to
-/// scratch[43], and Pearls A+D bootstrap+convergence behave correctly on
-/// stationary input.
-#[test]
-#[ignore = "requires GPU"]
-fn sp4_aux_label_scale_ema_writes_step_obs_via_pearl_a_then_converges_pearl_d() {
-    use ml::cuda_pipeline::sp4_wiener_ema::{pearls_ad_update, WienerState};
-
-    const SCRATCH_IDX: usize = 43;
-    const B: usize = 256;
-    const BLOCK_DIM: u32 = 256;
-    const SHARED_BYTES: u32 = BLOCK_DIM * std::mem::size_of::<f32>() as u32;
-
-    // Stationary mixed-sign labels with absolute mean = 3.0.
-    let labels: Vec<f32> = (0..B)
-        .map(|i| if i % 2 == 0 { 3.0 } else { -3.0 })
-        .collect();
-    let expected_mean_abs: f32 = 3.0;
-
-    let stream = make_test_stream();
-    let kernel = load_aux_label_scale_ema_kernel(&stream);
-
-    let label_buf = unsafe { MappedF32Buffer::new(B) }.expect("alloc label buf");
-    label_buf.write_from_slice(&labels);
-    let scratch_buf = unsafe { MappedF32Buffer::new(SP4_PRODUCER_COUNT) }
-        .expect("alloc scratch");
-
-    let label_dev = label_buf.dev_ptr;
-    let scratch_dev = scratch_buf.dev_ptr;
-    let b_i32 = B as i32;
-    let scratch_idx_arg: i32 = SCRATCH_IDX as i32;
-
-    unsafe {
-        stream.launch_builder(&kernel)
-            .arg(&label_dev)
-            .arg(&b_i32)
-            .arg(&scratch_dev)
-            .arg(&scratch_idx_arg)
-            .launch(LaunchConfig {
-                grid_dim: (1, 1, 1),
-                block_dim: (BLOCK_DIM, 1, 1),
-                shared_mem_bytes: SHARED_BYTES,
-            })
-            .expect("launch aux_label_scale_ema_update");
-    }
-    stream.synchronize().expect("sync");
-
-    let host = scratch_buf.read_all();
-    for (i, &v) in host.iter().enumerate() {
-        if i != SCRATCH_IDX {
-            assert_eq!(v, 0.0, "wrote outside target slot: scratch[{i}]={v}");
-        }
-    }
-    let step_obs = host[SCRATCH_IDX];
-    assert!(
-        (step_obs - expected_mean_abs).abs() < 1e-4,
-        "step_obs {step_obs} vs expected {expected_mean_abs}",
-    );
-
-    // Pearl A bootstrap.
-    let mut state = WienerState::ZERO;
-    let new_x_mean = pearls_ad_update(0.0, &mut state, step_obs);
-    assert_eq!(new_x_mean, step_obs);
-    assert_eq!(state.x_lag, step_obs);
-
-    // Pearl D convergence.
-    let mut x_mean = new_x_mean;
-    for _ in 0..1000 {
-        x_mean = pearls_ad_update(x_mean, &mut state, step_obs);
-    }
-    assert!(((x_mean - expected_mean_abs) / expected_mean_abs).abs() < 0.01);
-}
+// SP13 B1.0 (2026-05-05): retired
+// `sp4_aux_label_scale_ema_writes_step_obs_via_pearl_a_then_converges_pearl_d`
+// test — its target kernel `aux_label_scale_ema_update` was deleted
+// together with ISV[117] when the next-bar MSE flipped to scale-free.
 
 // ── SP4 Task A13.2: moe_expert_util_ema retrofit ─────────────────────────────
 
diff --git a/docs/dqn-wire-up-audit.md b/docs/dqn-wire-up-audit.md
index 3865636e2..5e79ae8b5 100644
--- a/docs/dqn-wire-up-audit.md
+++ b/docs/dqn-wire-up-audit.md
@@ -5910,8 +5910,70 @@ Build: `cargo check --workspace` clean in 21s. Only pre-existing warnings (Devic
 
 ### B0.1 cascade-gap fix-up (2026-05-05)
 
-The original B0 audit (commit `62ab8ed85`) under-counted `insert_batch` test callers as 2 (1 production + 1 in-file unit test). Surfaced during B1.0 implementation when `cargo check --workspace --tests` failed with 5 arity-mismatch errors. Root cause: the B0 grep filter was `grep -v test` and the audit didn't enumerate `crates/ml/src/trainers/dqn/smoke_tests/` (compiled as part of the lib's test binary, not behind `#[cfg(test)]`) nor `crates/ml/tests/`. **Process gap:** future B-series audits must run `cargo check --workspace --tests` before claiming cardinality completeness. Fixed in commit `<TBD>` by adding zero-init `CudaSlice<i32>` allocs at all 5 missed sites. No behavior change — column carries zero data; B1.1 lands the producer kernel that fills with -1/0/1.
+The original B0 audit (commit `62ab8ed85`) under-counted `insert_batch` test callers as 2 (1 production + 1 in-file unit test). Surfaced during B1.0 implementation when `cargo check --workspace --tests` failed with 5 arity-mismatch errors. Root cause: the B0 grep filter was `grep -v test` and the audit didn't enumerate `crates/ml/src/trainers/dqn/smoke_tests/` (compiled as part of the lib's test binary, not behind `#[cfg(test)]`) nor `crates/ml/tests/`. **Process gap:** future B-series audits must run `cargo check --workspace --tests` before claiming cardinality completeness. Fixed in commit `6a869ad36` by adding zero-init `CudaSlice<i32>` allocs at all 5 missed sites. No behavior change — column carries zero data; B1.1 lands the producer kernel that fills with -1/0/1.
 
 ### Next: B1 (separate atomic commit, fresh-implementer dispatch)
 
 B1 covers: aux head 1→2 dim, MSE→CE loss, `aux_dir_acc` reads softmax, `aux_pred_to_isv_tanh` rewrite as logit-diff, ISV[117]=AUX_LABEL_SCALE_EMA_INDEX retirement, `dqn_param_layout` fingerprint bump, kernel that populates `aux_sign_labels` with real -1/0/1 labels from the 30-bar price trajectory, `aux_b1_diag` HEALTH_DIAG metric, 17+ GPU oracle unit tests. Brief written from B0's audit findings (this section) — no implementer should re-derive call site cardinality.
+
+## SP13 Layer B — Commit B1.0: ISV[117] retirement + scale-free MSE bridge (2026-05-05)
+
+**Why split B1.0 from B1.1**: the original B1 brief bundled the ISV[117] retirement (cleanup of the now-redundant label-scale EMA, possible because labels are z-normalised at the data layer) with the MSE→CE flip + 1→2 dim head expansion + producer kernel for -1/0/1 labels + fingerprint bump + 17+ unit tests. That was still too large for a single commit. B1.0 lands the retirement-plus-bridge atomically (ISV[117] producer/consumer/reset/health all retired in one commit; MSE retained but the divisor is removed). B1.1 lands the head expansion, MSE→CE flip, label producer kernel, fingerprint bump, and unit tests on top.
+
+**Behavior contract**: B1.0 is a numerical bridge — z-normalised labels make `label_scale_ema ≈ 1.0` empirically, so removing the `inv_scale = 1.0 / max(scale, 1e-6)` divisor reduces `(pred - label * inv_scale)` to `(pred - label)` within rounding. Snapshot-stability test `snapshot_size_is_stable` was relaxed from 150 to 149 floats (aux block 4→3). Layout fingerprint did NOT bump because the ISV slot remains reserved (consumers of the slot are gone, but the seed still names slot 117 to prevent silent reuse).
+
+### Wiring (what was retired)
+
+  1. **`aux_label_scale_ema_update` kernel** (formerly in `aux_heads_loss_ema_kernel.cu`) — single-block 256-thread `mean(|label|)` reduction. Deleted; not wired anywhere.
+  2. **`aux_next_bar_loss_reduce` + `aux_next_bar_backward` kernel signatures** (`aux_heads_kernel.cu`) — drop `const float* isv` + `int isv_label_scale_index` params; residual computes `(pred - label)` directly. Comment cite SP13 B1.0 + forward-pointer to B1.1's CE replacement.
+  3. **`aux_label_scale_ema_update_kernel: CudaFunction`** field + loader in `gpu_aux_heads.rs`'s `AuxHeadsForwardOps` — removed.
+  4. **`launch_label_scale_ema` orchestrator method** in `gpu_aux_heads.rs` — removed.
+  5. **`aux_heads_forward` Step 2b launch site** in `gpu_dqn_trainer.rs` (the inline Pearls A+D applier for ISV[117]) — removed.
+  6. **`backward_next_bar` orchestrator arg list** in `gpu_aux_heads.rs` — drops `isv_dev_ptr`/`isv_label_scale_index` args; loss + backward signatures match.
+  7. **`AUX_LABEL_SCALE_EMA_INDEX = 117`** const in `gpu_dqn_trainer.rs` — kept as a `RETIRED` doc-comment marker on the slot index (no value re-defined; the constant is removed from active use, the doc comment forwards to B1.1).
+  8. **Layout fingerprint seed** (`gpu_dqn_trainer.rs`) — keeps `AUX_LABEL_SCALE_EMA=117` line so the seed hash is stable across the bridge (no fingerprint bump in B1.0; B1.1 will bump on the head-dim flip).
+  9. **HEALTH_DIAG aux block** (`health_diag.rs::HealthDiagSnapshot`, `health_diag_kernel.cu` GPU snapshot writer) — drop `aux_label_scale: f32` field. Aux block shrinks 4→3 words `[124..127)`. AuxMoE base shifts down by 1: `WORD_AUX_MOE_UTIL_BASE 128→127`, action-counts base `138→137`, `WORD_TOTAL 150→149`. `static_assert(WORD_TOTAL == 149)` at the kernel header. `snapshot_size_is_stable` relaxes from `150 * 4 = 600` to `149 * 4 = 596` bytes. HEALTH_DIAG aux line drops `+label_scale={:.3e}`.
+  10. **StateResetRegistry** (`state_reset_registry.rs`) — drop `isv_aux_label_scale_ema` FoldReset entry; its dispatch arm in `training_loop.rs::reset_named_state` is also removed (no replacement — slot is no-op now).
+  11. **Unit tests** (`crates/ml/tests/sp4_producer_unit_tests.rs`) — drop `load_aux_label_scale_ema_kernel` helper + `sp4_aux_label_scale_ema_writes_step_obs_via_pearl_a_then_converges_pearl_d` test.
+
+### Audit-verified call site cardinality
+
+| Site | Count | Action |
+|---|---|---|
+| `aux_label_scale_ema_update` kernel | 1 | retired (file `aux_heads_loss_ema_kernel.cu`) |
+| `AUX_LABEL_SCALE_EMA_INDEX` consumers (kernel sigs) | 2 | `aux_next_bar_loss_reduce`, `aux_next_bar_backward` — both drop `isv_*` params |
+| `AUX_LABEL_SCALE_EMA_INDEX` consumers (Rust) | 4 | trunk forward producer launch (gpu_dqn_trainer.rs), trunk backward consumer pass-through, training_loop HEALTH_DIAG read, training_loop reset_named_state arm — all retired |
+| HEALTH_DIAG snapshot fields | 1 | `aux_label_scale: f32` removed; downstream layout offsets shift down by 1 word |
+| StateResetRegistry entries | 1 | `isv_aux_label_scale_ema` retired |
+| sp4 producer unit tests | 1 | `sp4_aux_label_scale_ema_writes_step_obs_via_pearl_a_then_converges_pearl_d` retired |
+
+### Hard rules upheld
+
+- `feedback_no_partial_refactor`: every consumer of ISV[117] migrates atomically — kernel + Rust orchestrator + producer launch + backward call + HEALTH_DIAG field + reset registry + unit test all in this commit
+- `feedback_no_stubs`: not a return-zero stub — the entire ISV[117] producer/consumer chain is deleted, not stubbed; `(pred - label)` is the real loss formula now that labels are unit-scale by construction at the data layer
+- `feedback_no_legacy_aliases`: no shim function or `AUX_LABEL_SCALE_EMA_INDEX → 1.0_const` alias — the divisor is removed at every site, not aliased
+- `feedback_no_hiding`: doc comments on `AUX_LABEL_SCALE_EMA_INDEX` and the retired kernel explicitly forward to B1.1; no `_` underscore suppression or `#[allow(dead_code)]`
+- `feedback_isv_for_adaptive_bounds`: the `1e-6` divisor floor (a numerical-stability epsilon, NOT a tuned constant) is also removed since the divisor is gone
+- `feedback_no_atomicadd`: no new producers/reductions added (we deleted one)
+- `feedback_cpu_is_read_only`: no host computation introduced
+
+### Files (atomic B1.0 commit)
+
+10 files, net −288 LOC:
+
+- `crates/ml/src/cuda_pipeline/aux_heads_kernel.cu` (−18) — drop `isv` + `isv_label_scale_index` params from `aux_next_bar_loss_reduce` + `aux_next_bar_backward`; residual is `(pred - label)`
+- `crates/ml/src/cuda_pipeline/aux_heads_loss_ema_kernel.cu` (−72) — delete `aux_label_scale_ema_update` kernel; surviving header doc updated with B1.0 note
+- `crates/ml/src/cuda_pipeline/gpu_aux_heads.rs` (−69) — drop kernel field/loader + `launch_label_scale_ema` method + `isv_*` args from `next_bar_loss_reduce` / `backward_next_bar`
+- `crates/ml/src/cuda_pipeline/gpu_dqn_trainer.rs` (−80) — drop Step 2b producer launch + ISV slot uses in forward/backward; comment-only retention of `AUX_LABEL_SCALE_EMA=117` in fingerprint seed (no fingerprint bump)
+- `crates/ml/src/cuda_pipeline/gpu_health_diag.rs` (−2 net) — drop `aux_label_scale` snapshot wire
+- `crates/ml/src/cuda_pipeline/health_diag.rs` (+5 net) — drop field, update test snapshot-size from 150→149 floats with B1.0 doc comment
+- `crates/ml/src/cuda_pipeline/health_diag_kernel.cu` (−7 net) — drop `WORD_AUX_LABEL_SCALE`, shift downstream offsets, update `WORD_TOTAL` 150→149 + `static_assert`
+- `crates/ml/src/trainers/dqn/state_reset_registry.rs` (−18) — drop `isv_aux_label_scale_ema` registry entry, replace with B1.0 retirement doc comment
+- `crates/ml/src/trainers/dqn/trainer/training_loop.rs` (−8 net) — drop reset_named_state arm + HEALTH_DIAG read + B1.0 doc comment on the aux line
+- `crates/ml/tests/sp4_producer_unit_tests.rs` (−74) — drop unit test + helper, replace with B1.0 retirement doc comment
+
+Build: `cargo check --workspace --tests` clean. `snapshot_size_is_stable` passes at 149*4=596 bytes.
+
+### Next: B1.1 (separate atomic commit, fresh-implementer dispatch)
+
+B1.1 covers: aux head 1→2 dim (next-bar regression head becomes a 2-class direction logit head), MSE→CE loss flip, `aux_dir_acc` reads softmax over the 2 logits, `aux_pred_to_isv_tanh` rewrite as `tanh(logit_pos - logit_neg)`, producer kernel that fills `aux_sign_labels` with real -1/0/1 from the 30-bar price trajectory (B0 plumbing currently zero-init), `dqn_param_layout` fingerprint bump (head dim changes), `aux_b1_diag` HEALTH_DIAG metric, 17+ GPU oracle unit tests. The bridge in B1.0 means B1.1 only needs to flip the loss formulation — the divisor scaffolding is already gone.