docs: GGML_HRX_LOG_DISPATCH changes behaviour, so say it where the pages teach the instrument (#2143)

docs/determinism.md

@@ -244,6 +244,12 @@ comparators and `logprob_agree.py`'s prompts, so it measures what this page docu
 
 ### What the `hrx` width gate is, by name
 
+> **It is not a behaviour-neutral instrument (engine#2143).** With this flag set, an 18,782-token request
+> *completes* where the same binary, model and request **fails** without it, and NaN-logit incidents went from 2
+> to 0; a plain 18.6k prefill measured **271.75 t/s** unset against **118.86 t/s** set. A 2.3x gap is not
+> "logging cost" — it is a different code path. So a rate taken with the flag is not comparable to one taken
+> without it, and an A/B that sets it on one arm only is not an A/B.
+
 `GGML_HRX_LOG_DISPATCH=1` prints each dispatch registration the first time it matches
 (`dispatch_registry/dispatch-registry.cpp`), so the set of registrations a serve logs is the set of
 kernels its graphs actually ran. Keying that log on the root node's shape as well — a throwaway local
@@ -256,6 +262,7 @@ step splits into two disjoint sets:
 | 1 (solo, and any sequential history) | `hip.qkv_rope`, `kquant.mul_mat.decode_f32`, `hip.dense_kquant_swiglu`, `hip.gemv_add_norm`, `common.mul_mat.f32_f32_decode` |
 | 2 (concurrent) | `hip.kquant_tokens.mm`, `hip.kquant_tokens.mm_add`, `hip.kquant_tokens.swiglu`, `common.rmsnorm_binary_f32` |
 
+
 Seventeen more registrations match at both widths, including the attention kernel
 (`common.flash_attention_decode_split_next_q8`): on `hrx`, unlike on `cpu`, attention is *not* where
 the width dependence comes from. What changes is the **fusion boundaries**. The residual add and

docs/zyphra.md

@@ -264,6 +264,7 @@ have been measured in three windows and answered differently every time.
   prefill drop noted below, and it is why a throughput row here is inseparable from *which quantizer built it*. **Measured here on 2026-11-08**: two arms
   that differ *only* in the adapter tensors' type (F16 ×26 vs Q6_K ×13 + Q8_0 ×13), benched back to back in one ticket and one window —
 
+
   | shape | F16 pairs | block-quantized pairs | cost |
   |---|---|---|---|
   | `pp8` | 114.19 tok/s | 14.03 tok/s | **8.1×** |
@@ -279,6 +280,13 @@ have been measured in three windows and answered differently every time.
   per tensor: asking for `ffn_gate_up_adapter=q6_K` yields `_a` = Q6_K but `_b` = **Q8_0**, because the `[128, 28672]` pair's contraction has
   `input_size = 128` and HRX's block-format admission needs `>= 256` while the float predicate needs only `>= 4`. So the pair leaves the device for *any*
   block type, including the substitute — the same "the label is not evidence" rule this page applies to arm names, applied to the tensors inside them.
+
+> **It is not a behaviour-neutral instrument (engine#2143).** With this flag set, an 18,782-token request
+> *completes* where the same binary, model and request **fails** without it, and NaN-logit incidents went from 2
+> to 0; a plain 18.6k prefill measured **271.75 t/s** unset against **118.86 t/s** set. A 2.3x gap is not
+> "logging cost" — it is a different code path. So a rate taken with the flag is not comparable to one taken
+> without it, and an A/B that sets it on one arm only is not an A/B.
+
 - **A control on 2026-11-08 shows how far a single reading can be off, and it retire the A/B this page would need.** One file whose form cause 2
   did **not** touch (`Zamba-7B-v1` `Q6_K`) was re-benched on a current build: `pp512 211.16 (sd 170.84)`, `pp4096 47.14 (sd 12.73)`, `tg128 4.26
   (sd 3.04)` against its own published `108.07 / 92.28 / 12.20`. **The same bytes, 2-2.9× apart, with 71 % sd on decode.** So the rows in this