docs/sycl: PF_XMX=2 Alchemist default approved by the owner 2026-10-18 (comment and INTEL.md heading only)

docs/INTEL.md

@@ -759,7 +759,7 @@ Measured on an Arc A750 (8 GB, `i915`, PCIe 4.0) with the Flash-Next IQ3_XXS in
   8192 --prefill-repeat 5` for the time of both kernels. Not taken: the same kernel with its state in SLM (no register
   spills, the same bits, ~4x slower: 13.7 vs 3.1-3.3 ms at T=1000).
 
-### Prompt speed on Alchemist: the grouped XMX expert launch is the default (0.1.48, `STRATA_PF_XMX`)
+### Prompt speed on Alchemist: the grouped XMX expert launch is the default (0.1.48, `STRATA_PF_XMX`; owner approved 2026-10-18)
 
 The A750's prompt path decodes and multiplies a group of experts in one fused launch on the XMX units (`STRATA_PF_XMX=2`, `sycl/src/prefill/xmx_moe.dp.cpp`)
 instead of dequantizing each expert to FP16 and calling oneMKL. It is the default on Alchemist cards; `STRATA_PF_XMX=0` turns it off and `=1` is the

sycl/src/prefill/xmx_moe.dp.cpp

@@ -150,7 +150,7 @@ int mode() {
     // sub-group 16 (Xe2, Battlemage).
     static const int v = [] {
         const char* e = std::getenv("STRATA_PF_XMX");
-        // 0.1.48: mode 2 (the fused grouped XMX launch) is the default on Arc Alchemist (A-series): A750 prompts +30..39% (4K), +32..35% (1-2K tokens),
+        // 0.1.48 (owner approved 2026-10-18): mode 2 (the fused grouped XMX launch) is the default on Arc Alchemist (A-series): A750 prompts +30..39% (4K), +32..35% (1-2K tokens),
         // first-token KL 0.002 against a 0.0005 floor, HumanEval / reasoning / agent / CJK / needles inside the run-to-run spread; Battlemage is
         // 7-11% slower with it, so it stays off there.  STRATA_PF_XMX=0 turns it off, 1 is the dequantize + grouped XMX variant.
         const bool alchemist = strata::intel_gpu_gen(strata::q_of(nullptr)->get_device()) == strata::IntelGpuGen::Alchemist;