frank-primary: pin the expert host region to 120 GiB (--expert-offload-mem)

The host region was the ONE arena-plan term still autofitting per boot: with
no cap the planner binds it to MemAvailable AT BOOT minus PLE/process/api/
margin terms (boot 2026-10-05: 237.97 GiB -> 159.39 GiB usable; the same host
reads 75.4 GiB available while running). Demand is 105.48 GiB
(52.74/rank x 2 ranks, 23,040 swap-target experts); a boot where co-tenant
RAM squeezed the bound near that silently pins next-hottest experts VRAM-only
(pinned_extra warning, smaller swap region, no flag change). 120 GiB =
measured demand + 14% headroom on 246.1 GiB total. Semantics verified in the
shipped image: cap binds as the bound, exceedance only warns.

The GPU-side arena is unchanged (deterministic arithmetic over the same
constants): verify after boot that host reads '--expert-offload-mem' and
slots stay 7,762. Seam: red first (wiring + value), then green; full suite
368+1 green.

scripts/frank-primary.env

@@ -213,6 +213,22 @@ FRANK_PRIMARY_UTIL=0.982
 FRANK_PRIMARY_CUDAGRAPH_BASE_MB=0
 FRANK_PRIMARY_CUDAGRAPH_PER_GRAPH_MB=12
 
+# HOST-region cap — the last arena-plan term that still autofit per boot. With
+# no cap the planner's host bound is MemAvailable AT BOOT minus PLE 47.68 -
+# 2 x 7.0 process - 5.0 api/engine - 5% margin (measured boot 2026-10-05:
+# MemAvailable 237.97 -> 159.39 GiB usable across 2 ranks; the demand is 105.48
+# = 52.74/rank x 2 ranks, 23,040 swap-target experts). The same host reads 75.4
+# GiB available while running — the bound tracks whatever the co-tenants hold at
+# boot, and a boot where that drops near the demand silently pins next-hottest
+# experts VRAM-only instead (smaller swap region; the pinned_extra warning is
+# the only trace). Pin 120 GiB: measured demand + 14% headroom, on a host with
+# 246.1 GiB total. If a boot ever logs "expert-offload-mem … exceeds
+# MemAvailable at plan time", THAT is the contract being broken — look at the
+# co-tenant RAM before touching this number. Plan semantics verified in the
+# shipped image (offloader/expert_plan.py): the cap binds as the bound, an
+# exceedance only warns.
+FRANK_PRIMARY_EXPERT_OFFLOAD_MEM=120
+
 # --- optional engine knobs (unset == the flag is absent) ---------------------
 # FRANK_PRIMARY_SPEC holds the WHOLE --speculative-config JSON; setting it adds
 # the flag. THE RETIREMENT VERDICT WAS INVALID: c1248d4 (2026-10-02) retired MTP

scripts/serve-frank-primary.sh

@@ -156,6 +156,7 @@ podman run -d --name "$FRANK_PRIMARY_CONTAINER" \
   --max-num-seqs "$FRANK_PRIMARY_SEQS" \
   ${FRANK_PRIMARY_MNBT:+--max-num-batched-tokens "$FRANK_PRIMARY_MNBT"} \
   ${FRANK_PRIMARY_PRECISE_MEMORY:+--expert-precise-memory} \
+  ${FRANK_PRIMARY_EXPERT_OFFLOAD_MEM:+--expert-offload-mem "$FRANK_PRIMARY_EXPERT_OFFLOAD_MEM"} \
   --gpu-memory-utilization "$FRANK_PRIMARY_UTIL" \
   --kv-cache-memory-bytes "$FRANK_PRIMARY_KV_BYTES" \
   --kv-cache-dtype "$FRANK_PRIMARY_KV_DTYPE" \

serverAppConfigs-docs/LLM/dankserver-qwen38-fp8-expert-offload-tuning.md

@@ -286,6 +286,7 @@ FRANK_PRIMARY_MNBT=2048       --max-num-batched-tokens 2048 (arena-free, see sha
 FRANK_PRIMARY_UTIL=0.982      budget = total x util, the law (1.0 unbootable, see below)
 FRANK_PRIMARY_CUDAGRAPH_BASE_MB=0 / _PER_GRAPH_MB=12  -e VLLM_CUDAGRAPH_MEM_*
 FRANK_PRIMARY_PRECISE_MEMORY=1      --expert-precise-memory (overhead 7.60 -> 5.25 GiB)
+FRANK_PRIMARY_EXPERT_OFFLOAD_MEM=120  --expert-offload-mem (host-region cap, explicit)
 FRANK_PRIMARY_GPU_MAX_HW_QUEUES=2   -e GPU_MAX_HW_QUEUES=2 (HSA queues/GPU)
 FRANK_PRIMARY_CACHE_DIR=/home/dank/.cache/frank-primary   mounted at /root/.cache
 R4D_LRU_GATHER_CHUNKS=32 / R4D_LRU_GATHER_LANES=64  (container env)
@@ -343,6 +344,20 @@ boot at 0.13 GiB free; the 5x262144 boot at "0 bytes free" on a real
 inside the image (the fork's log line says exactly that: *"Update the
 registry entry if this drifts"*), not a deploy.
 
+**The host region was the last arena-plan term still autofitting per boot —
+now it is a literal (2026-10-04).** With no `--expert-offload-mem` the planner
+binds the host region to `MemAvailable` AT BOOT minus `PLE 47.68 - 2 x 7.0
+process - 5.0 api/engine - 5% margin`: the 2026-10-05 boot read 237.97 GiB and
+offered 159.39 GiB usable, while the same host reads **75.4 GiB available while
+running** — the bound tracks whatever the co-tenants hold at that moment. The
+demand is 105.48 GiB (52.74 GiB/rank x 2, 23,040 swap-target experts), and a
+boot where the bound drops near it silently converts next-hottest experts to
+VRAM-only (the `pinned_extra` warning is the only trace).
+`FRANK_PRIMARY_EXPERT_OFFLOAD_MEM=120` pins it: measured demand + 14% headroom,
+on a host with 246.1 GiB total. Semantics verified in the shipped image
+(`offloader/expert_plan.py`): the cap binds as the bound, an exceedance only
+warns, and the plan rewrites the field to the cap it met (+1 MiB/rank).
+
 **MNBT 1024 -> 2048 is free on every axis the plan can see.** The registry
 overhead model is `base + 0.22 GiB x max(0, (nbt - 4096)/1024)` anchored at
 nbt 4096, so any rung up to 4096 charges the identical 5.25 GiB; the fitted 5.25

tests/frank_primary_unit.bats

@@ -188,6 +188,14 @@ DOWNLOAD="$REPO_ROOT/scripts/download-frank-primary.sh"
     grep -q -- '-e VLLM_CUDAGRAPH_MEM_PER_GRAPH_MB="$FRANK_PRIMARY_CUDAGRAPH_PER_GRAPH_MB"' "$SERVE"
     grep -q '^FRANK_PRIMARY_CUDAGRAPH_BASE_MB=0$' "$ENV_FILE"
     grep -q '^FRANK_PRIMARY_CUDAGRAPH_PER_GRAPH_MB=12$' "$ENV_FILE"
+    # The host region is the ONE plan term that autofits per-boot: with no cap
+    # the bound is MemAvailable at that moment (boot 2026-10-05: 237.97 GiB ->
+    # 159.39 GiB usable, while the running host later reads 75.4 GiB available).
+    # An explicit --expert-offload-mem cap makes the plan deterministic whatever
+    # the co-tenant RAM state is at boot; 120 GiB covers the measured 105.48
+    # GiB of swappable experts (52.74/rank x 2) with 14% headroom.
+    grep -q -- '${FRANK_PRIMARY_EXPERT_OFFLOAD_MEM:+--expert-offload-mem "$FRANK_PRIMARY_EXPERT_OFFLOAD_MEM"}' "$SERVE"
+    grep -q '^FRANK_PRIMARY_EXPERT_OFFLOAD_MEM=120$' "$ENV_FILE"
 }
 
 @test "tools and reasoning are wired — the client contract is served" {