frank-medium: step 3 -- the skew is the balance, and equality is off-limits

The 38:27 skew folded into the DSpark swap already does what step 3 asks: the
draft-carrying card sits 2.08 GiB above the other (5.49 / 3.41 GiB free) instead
of the ~9 GiB a 1:1 split would leave.

Chasing an exact balance is a mistake worth recording: 39:26 measured tighter
(3.86 / 4.69 GiB free) but that server died on its eighth request with SDMA0
UTCL2 page faults in the amdgpu driver -- "ROCm error: an illegal memory access
was encountered" -> ggml_abort, in the cross-card boundary copy that is the
layer split's hot path. 38:27 has since served the whole e2e gate and 12 varied
requests with no fault, so the residual 2.08 GiB gap is the safe side of this
trade. Comment-only: no restart needed.

scripts/frank-medium.env

@@ -77,6 +77,16 @@
 # common_speculative_impl_draft_dflash::process).  Handing three target layers
 # to ROCm0 buys back ~3 GiB of headroom on both cards at the full window.
 #
+# EQUALITY WAS TRIED AND REJECTED.  39:26 levels the cards more closely (3.86 /
+# 4.69 GiB free -- an 0.83 GiB gap, against 2.08 GiB here), but that server
+# died on its eighth request: the amdgpu driver logged SDMA0 UTCL2 page faults
+# and the engine surfaced `ROCm error: an illegal memory access was
+# encountered` -> ggml_abort, i.e. a fault in the cross-card boundary copy,
+# which is this layer split's hot path.  38:27 has since served the whole e2e
+# gate plus a burst of varied requests with none.  Do not chase an exact
+# balance: take the skew that fits and leave the drafter's card on the safe
+# side of the gap.
+#
 # WARNING: do not name any variable TEMP, HOST, or GPU_MAX_HEAP_SIZE (HIP reads
 # those bare vars; 2026-08-13 incident).  llama.cpp takes --host/--port/--temp
 # as flags only.
@@ -103,8 +113,10 @@ DEVICES=ROCm0,ROCm1
 SPLIT_MODE=layer
 
 # Skewed 38:27 rather than 1:1: ROCm1 also carries the drafter and the whole of
-# its KV, so it must hold fewer target layers for the cards to end level.  See
+# its KV, so it must hold fewer target layers for the cards to end level -- at
-# SIZING above -- this is measured, not computed.
+# 1:1 the drafter's card would sit ~9 GiB above the other.  This is the measured
+# point that keeps BOTH cards above a 3 GiB floor at the full window; a tighter
+# balance was tried and rejected (see SIZING above).
 TENSOR_SPLIT=38,27
 
 NGL=999