frank-primary: V4.1 launch shape (feat/ds41-engine source)

The deepseek41 architecture exists only on Luce-Org/lucebox's
feat/ds41-engine branch; main rejects the checkpoint with
"unsupported model architecture 'deepseek41'". Re-aim the image build at
that branch and fix the launch shape, which had been copied from the V4
DS4.md recipe:

- drop --ds4-fused-decode and --ds4-fused-verify-f16-kv, and use
  --ds4-prefill dense: V4.1's validate_model_features refuses the V4-only
  prefill/fused paths (layer split and --mmproj too).
- --chunk 4096 (the V4.1 dense-prefill measurement point), --max-ctx
  131072 (the V4.1 default window), --prefix/--prefill-cache-slots 0 as
  the DS41.md bring-up recipe.
- drop --cache-type-k/v: the DeepSeek4 backend ignores them; the MLA
  compressed caches are F16 by design.
- expose BOTH R9700s and set LUCE_EXPERT_STREAM_DEVICE=1, so hip:0 owns
  the dense weights plus the hot expert stack while hip:1 holds the
  streamed-expert slot cache instead of competing with it.
- quadlet: 384 routed experts per layer, Engram tables, 40 layers.

dankserver/frank-primary/frank-primary-entrypoint.sh

@@ -8,22 +8,37 @@
 # C++ server reads LUCE_* environment variables straight from the process
 # environment, so no env plumbing is needed here.
 #
-# LAUNCH SHAPE (server/docs/DS4.md, server/docs/RECOMMENDED_SETUPS.md):
-#   --ds4-fused-decode     requests a monolithic GPU load; on a 377 GiB model
-#                          that allocation fails and the backend falls back
-#                          to hybrid expert placement + layered decode (dense
-#                          work on the R9700, routed experts computed on CPU
-#                          from the mmapped page cache). That fallback IS the
-#                          intended serving mode on this host.
-#   --ds4-prefill sparse   the batched prefill; use for prompts beyond a few
-#                          hundred tokens (exact is token-wise decode cost).
-#   --ds4-expert-top-k 6   the model default. Do NOT reduce on adaptive
-#                          (qtype-105/106) artifacts: measured degenerate
-#                          output at top-4 (DS4.md, 2026-08-05).
-#   --chunk 8192           the qualified Strix Halo profile's chunk.
-#   --max-ctx 131072       the qualified Strix Halo window; DS4's MLA KV is
-#                          compressed, so the pool is small.
-#   --cache-type-k/v q4_0  the qualified launch's KV dtype.
+# SOURCE BRANCH. The `deepseek41` architecture exists only on the
+# `feat/ds41-engine` branch of Luce-Org/lucebox: main carries `deepseek4`
+# alone and rejects this checkpoint with "unsupported model architecture
+# 'deepseek41'" (server/src/common/backend_plan.cpp). The image is built from
+# that branch — see serverAppConfigs-docs/LLM/frank-primary-lucebox-ds41.md.
+#
+# LAUNCH SHAPE (server/docs/DS41.md — the V4.1 page, not the V4 DS4.md one):
+#   --ds4-prefill dense   the V4.1 batched prefill. The default `exact` walks
+#                         the prompt token by token, and the V4-only modes are
+#                         REFUSED for V4.1: `sparse`, --ds4-fused-decode,
+#                         --ds4-fused-verify-f16-kv, layer split and --mmproj
+#                         all fail validate_model_features at load.
+#   --chunk 4096          the chunk the V4.1 dense-prefill numbers were taken
+#                         at; the runtime caps it to what the device holds.
+#   --max-ctx 131072      the V4.1 default window. The MLA compressed caches
+#                         are F16 by design and stay small; --cache-type-k/v
+#                         are ignored by the DeepSeek4 backend, so they are
+#                         not passed.
+#   --prefix-cache-slots 0 --prefill-cache-slots 0
+#                         the DS41.md bring-up recipe (the server default is
+#                         32 prefix slots). Lift them once capacity under load
+#                         has been measured, not before.
+#
+# EXPERT PLACEMENT. 377 GiB of weights against 64 GiB of VRAM: only the dense
+# weights, the compressed caches and a hot expert stack fit on hip:0, and the
+# remaining routed experts are streamed out of the mmapped page cache/NVMe by
+# the hybrid expert tier. LUCE_EXPERT_STREAM_DEVICE=1 moves the streamed-
+# expert slot cache onto the second R9700 — it defaults to the target device,
+# where it would compete with the hot stack. Both the owner stack and the
+# slot cache then auto-size to their device's free memory minus the 1.5 GiB
+# discrete headroom.
 #
 # No DSpark draft is published for DeepSeek-V4.1-Flash, so this is plain
 # autoregressive decode (no --draft, no LUCE_DS4_SPEC).
@@ -32,6 +47,12 @@ set -euo pipefail
 MODEL="${FRANK_PRIMARY_MODEL:-/models/DeepSeek-V4.1-Flash/DeepSeek-V4.1-Flash-ROCMFP23.gguf}"
 BIN="${FRANK_PRIMARY_BIN:-/opt/lucebox-hub/server/build/luce_server}"
 
+# The second R9700 holds the streamed-expert slot cache and computes them.
+export LUCE_EXPERT_STREAM_DEVICE="${LUCE_EXPERT_STREAM_DEVICE:-1}"
+# rocBLAS/BLAS dispatch and queue depth, as the fleet's other ROCm servers.
+export ROCBLAS_USE_HIPBLASLT="${ROCBLAS_USE_HIPBLASLT:-0}"
+export GPU_MAX_HW_QUEUES="${GPU_MAX_HW_QUEUES:-8}"
+
 if [[ ! -f "$MODEL" ]]; then
     echo "frank-primary: model missing at $MODEL" >&2
     exit 1
@@ -47,9 +68,7 @@ exec "$BIN" "$MODEL" \
     --model-name frank-primary \
     --target-device hip:0 \
     --max-ctx 131072 \
-    --chunk 8192 \
-    --cache-type-k q4_0 \
-    --cache-type-v q4_0 \
-    --ds4-fused-decode \
-    --ds4-prefill sparse \
-    --ds4-expert-top-k 6
+    --chunk 4096 \
+    --ds4-prefill dense \
+    --prefix-cache-slots 0 \
+    --prefill-cache-slots 0