feat(frank-archon): move the endpoint to radiance 1.8.1 and its budget model

The decode stall is step contention (measured: 18.7 ms decode-only steps
against 317 ms steps that carry a prefill chunk, decode at 13 t/s median
while prefill runs), and the two engine knobs that fix it arrived after this
endpoint's pin. Moving to 1.8.1 (2026-10-18) brings both, and brings two CLI
breaks with them:

  - --vram-weights-mib / --vram-kv-mib were REMOVED at 1.3.0. The per-card
    split between the expert slab and the KV pool is now derived by the
    engine's budget resolver from --gpu-headroom-mib, the cache bound
    (--max-model-len, --max-num-seqs) and --host-pool-mib, and the cache may
    lend idle blocks to the expert slab. The slab size and the pool's token
    count are boot-ledger lines from here on, so the capacity contract
    (3 x 200,000 fp8) is verified live by the probe's capacity leg instead of
    computed from an env number.
  - The prefix cache has no disk tier any more: --prefix-cache-dir and
    --prefix-cache-disk-mib are refusals and --prefix-cache-host-mib is
    --prefix-cache-mib. 64 GiB of parked KV on NVMe becomes re-prefill, so
    prefix_hit_rate is the thing to watch after this boot.

env: image re-pinned to the 1.8.1 digest; the pair and the disk tier dropped;
FRANK_ARCHON_PREFIX_CACHE_MIB replaces the host/disk pair; new
FRANK_ARCHON_BUSY_PREFILL_CHUNK=auto (explicit, because auto vs off is the
difference between decode waiting one chunk and waiting a whole step) and
FRANK_ARCHON_PREFILL_INTERLEAVE=0 (opt-in through a guarded argv array).

serve: argv follows the new CLI, /data mount and the pre-created kvcache path
go with the disk tier, and the retired env keys are no longer required (they
would abort ExecStart). autoresearch-frank-archon.sh takes the same CLI, with
a cold prefill now coming from --prefix-cache-mib 0 instead of a per-run disk
directory. run-swift15-bf16.sh is untouched: it pins its own engines by design.

tests: the two budget-arithmetic seams asserted knobs that no longer exist and
are replaced by one seam that asserts the retired knobs are ABSENT from env and
argv - a stale line is a boot refusal, not a no-op. The container-contract seam
now asserts the tune mount and the absence of /data.

scripts/autoresearch-frank-archon.sh

@@ -29,10 +29,10 @@
 # The scratch mirrors the production container contract exactly (serve-frank-
 # primary.sh): --network host, --init, seccomp=unconfined (io_uring for the
 # n-gram table), memlock unbounded (the ~132 GiB pinned ledger), /dev/kfd +
-# /dev/dri, the .rad ro, the state dir rw, the tune cache mount. The ONLY
-# differences: the container name (arbench, so prod's identity is untouched)
-# and a FRESH prefix-cache disk tier (arbench/, wiped per run) so the cold
-# prefill is cold — the prod tier at kvcache/frank-archon is left intact.
+# /dev/dri, the .rad ro, the tune cache mount. The ONLY differences: the
+# container name (arbench, so prod's identity is untouched) and the prefix cache
+# switched OFF (--prefix-cache-mib 0), so every prefill is cold — the tier is
+# host RAM now, there is no per-run disk directory to wipe.
 set -uo pipefail
 
 ENV_FILE="${1:-/home/dank/serverAppConfigs/scripts/frank-archon.env}"
@@ -60,9 +60,8 @@ set -a; . "$ENV_FILE"; set +a
 sudo systemctl stop frank-archon >/dev/null 2>&1 || true
 podman rm -f "$SCRATCH" >/dev/null 2>&1 || true
 
-# --- fresh prefix-cache tier for a cold prefill (prod's tier untouched) ------
-FRESH_KV="$FRANK_ARCHON_STATE_DIR/kvcache/$SCRATCH"
-rm -rf "$FRESH_KV"; mkdir -p "$FRESH_KV"
+# --- the prefix cache is switched off below, so there is no scratch KV tree ---
+# to wipe; the cold prefill comes from --prefix-cache-mib 0.
 mkdir -p "$FRANK_ARCHON_STATE_DIR/tune"
 
 # --- boot the scratch: the production run line, scratch name + fresh KV ------
@@ -73,7 +72,6 @@ podman run -d --name "$SCRATCH" \
   --ulimit memlock=-1:-1 \
   --device /dev/kfd --device /dev/dri \
   -v "$FRANK_ARCHON_MODEL_DIR":/models:ro \
-  -v "$FRANK_ARCHON_STATE_DIR":/data \
   -v "$FRANK_ARCHON_STATE_DIR/tune":/opt/radiance/share/radiance/tune \
   -v "$FRANK_ARCHON_TEMPLATE":/templates/template.jinja:ro \
   "$FRANK_ARCHON_IMAGE" \
@@ -87,12 +85,9 @@ podman run -d --name "$SCRATCH" \
   --placement "$FRANK_ARCHON_PLACEMENT" \
   --host-pool-mib "$FRANK_ARCHON_HOST_POOL_MIB" \
   --gpu-headroom-mib "$FRANK_ARCHON_GPU_HEADROOM_MIB" \
-  --vram-weights-mib "$FRANK_ARCHON_VRAM_WEIGHTS_MIB" \
-  --vram-kv-mib "$FRANK_ARCHON_VRAM_KV_MIB" \
   --kv-cache-dtype "$FRANK_ARCHON_KV_DTYPE" \
-  --prefix-cache-host-mib "$FRANK_ARCHON_PREFIX_HOST_MIB" \
-  --prefix-cache-dir "/data/kvcache/$SCRATCH" \
-  --prefix-cache-disk-mib "$FRANK_ARCHON_PREFIX_DISK_MIB" \
+  --prefix-cache-mib 0 \
+  --busy-prefill-chunk "${FRANK_ARCHON_BUSY_PREFILL_CHUNK:-auto}" \
   --ngram-placement "$FRANK_ARCHON_NGRAM_PLACEMENT" \
   --num-speculative-tokens "$FRANK_ARCHON_SPEC_TOKENS" \
   --max-num-batched-tokens "$FRANK_ARCHON_MAX_BATCHED_TOKENS" \

scripts/frank-archon.env

@@ -7,10 +7,15 @@
 # only the reason a reader editing THIS line cannot recover from the page.
 # Where the two disagree, this file wins on values; the boot ledger arbitrates
 # the engine shape.
-FRANK_ARCHON_IMAGE=stilldeadcode/radiance@sha256:4c3f484564bb2872784e46b0a59cbd71becc9c1e746e301a3596ffae253c322e
-# 1.0.13 is pinned by digest on purpose: 1.2.0 is a DEAD END on this payload
-# (acceptance 0.7123 vs 0.7549 — the page's Dead ends section names the suspect).
-# The .rad file mounted under /models; /data holds the prefix-cache disk tier.
+FRANK_ARCHON_IMAGE=stilldeadcode/radiance@sha256:d590e300234bf6d2f942a0b8d456d183153fd808f28820e6c2fa69c9389178ed
+# 1.8.1 (2026-10-18), pinned by digest. Two CLI breaks sit between it and the
+# 1.0.13 line this endpoint ran for two eras, and both are boot refusals, not
+# warnings: --vram-weights-mib/--vram-kv-mib were REMOVED at 1.3.0 (the card is
+# now split by the engine's budget resolver — see below), and the prefix cache
+# lost its disk tier. Draft acceptance has to be re-scored on any pin past 1.2.0:
+# 1.2.0's MoE weight rotation measured 0.7123 against the 0.7549 control, and the
+# suspect is untangled (the page's Dead ends section names it).
+# The .rad file mounts under /models; the tune cache mounts separately below.
 # The model dir holds ONLY .rad files — the HF download and staging stay beside it.
 FRANK_ARCHON_MODEL_DIR=/home/dank/models/rad
 FRANK_ARCHON_MODEL_FILE=qwen3.8-next-flash-fp8-iq4r-moe.rad
@@ -52,21 +57,25 @@ FRANK_ARCHON_MAX_SEQS=3
 # sequence.
 FRANK_ARCHON_MAX_MODEL_LEN=200000
 FRANK_ARCHON_PLACEMENT=expert_tiered
-# Pinned host pool for expert rows that do not fit VRAM. It moves WITH
-# VRAM_WEIGHTS: the pair and this pool serve the per-rank resident set together,
-# so cutting the slab spills here — under-sizing it is a boot failure (36,864
+# Pinned host pool for expert rows that do not fit VRAM. Under the budget
+# resolver this is ALSO the lever that decides which experts stay on the card:
+# the card's leftover goes to the expert plane first and the KV cache takes the
+# rest, so growing the pool moves experts off the card and shrinking it spills
+# them onto VRAM the cache wanted. Under-sizing it is a boot failure (36,864
 # refused a boot). The ledger's coverage line is the referee, not this file.
 FRANK_ARCHON_HOST_POOL_MIB=44928
 # VRAM left unclaimed per card (publisher default 96 MiB); the engine's settle
 # floor is built from it.
 FRANK_ARCHON_GPU_HEADROOM_MIB=96
-# ONE budget per card: VRAM_WEIGHTS + VRAM_KV <= 30,969 MiB, the ceiling the
-# engine's own budget table prints (derivation and the slab/pool price: the
-# page's VRAM laws). Idle KV VRAM is ALSO the expert cache's spillover, so a
-# bigger pool pays twice — which is why the pool sits at the contract and the
-# slab takes the rest.
-FRANK_ARCHON_VRAM_WEIGHTS_MIB=25600
-FRANK_ARCHON_VRAM_KV_MIB=5120
+# There is no VRAM pair any more. --vram-weights-mib/--vram-kv-mib were removed
+# at 1.3.0: the engine takes capacity - already-held - GPU_HEADROOM - arena,
+# puts the static (non-expert) weights off the top, then divides the rest between
+# the expert plane and the KV cache — experts first when the cache has no idle
+# blocks to lend, and never less than ONE MAX_MODEL_LEN sequence for the cache.
+# What moves the split from here is HOST_POOL_MIB (which experts stay resident),
+# MAX_MODEL_LEN/MAX_SEQS (the cache bound) and GPU_HEADROOM_MIB. The slab size
+# the prefill-slope law cares about is a boot-ledger line now, not a knob: read
+# it after every resize instead of asserting it here.
 # fp8 is the ONLY rung below bf16 on this engine: one kv_dtype for the whole
 # cache, so llama.cpp's exact-K/quantized-V split (frank-zealot) is unservable
 # here. bf16 costs 1.89x fp8, not 2x — the QSA block-key plane is dtype-fixed.
@@ -75,11 +84,25 @@ FRANK_ARCHON_KV_DTYPE=fp8
 # 2, and 3 x (1+2) = 9 rows stays inside the wht6 25-row exactness bound.
 FRANK_ARCHON_SPEC_TOKENS=2
 FRANK_ARCHON_MAX_BATCHED_TOKENS=2048
-# Prefix cache tiers. The host tier is sized in ENTRIES and one entry tracks the
-# cache dtype (58.50 KiB at fp8), so a dtype change re-sizes the parked set
-# without touching these numbers.
-FRANK_ARCHON_PREFIX_HOST_MIB=8192
-FRANK_ARCHON_PREFIX_DISK_MIB=65536
+# Step sharing. A prefill chunk that shares a step with decoding sequences holds
+# the device for the chunk's whole time, and every decode row in that step waits
+# that long for its next token (the census: [[LLM Performance Diagnosis]] §9).
+# `auto` leaves each decode row behind the chunk a row plus its draft window and
+# keeps a share for whatever is waiting to be admitted; a number pins the chunk's
+# cap; `off` is the pre-1.4 behaviour this endpoint ran for two eras, where the
+# chunk took the step and admission never ran. Interleave inserts N decode-only
+# steps after a chunk step taken beside decoders: it protects their cadence and
+# holds a waiting request out of those steps, so it stays 0 until the post-migration
+# decode-vs-prefill buckets say it is wanted.
+FRANK_ARCHON_BUSY_PREFILL_CHUNK=auto
+FRANK_ARCHON_PREFILL_INTERLEAVE=0
+# Prefix cache: pinned host memory only. The disk tier was removed outright
+# (--prefix-cache-dir and --prefix-cache-disk-mib are refusals), so what used to
+# be restored from NVMe is now re-prefilled. The tier is sized in ENTRIES and one
+# entry tracks the cache dtype (58.50 KiB at fp8). Watch prefix_hit_rate after
+# this change: a drop is extra prefill, and prefill is exactly the traffic that
+# costs decode its cadence.
+FRANK_ARCHON_PREFIX_CACHE_MIB=8192
 # Frank's pin law: the PLE n-gram table serves from pinned host RAM the cards
 # read. `ram` REFUSES the start if memlock is too small — the unit's
 # LimitMEMLOCK=infinity is the other half of this law.

scripts/serve-frank-archon.sh

@@ -15,12 +15,13 @@
 # log states every budget before anything is allocated (weights vs KV
 # split, the expert host pool's coverage of the worst case, the PLE pin,
 # the P2P answer per pair) — read it after every resize.
-# Deployed shape (2026-10-13): THREE decode slots x 200,000 tokens, fp8
-# (quantized) KV in a 5,120 MiB pool (contract 3 x 200,000 + 1.3 %) and a
-# 25,600 MiB resident expert slab — 30,720 MiB of the 30,969 MiB the engine's
-# own budget table makes claimable, spent on the slab because prefill is
-# slab-limited. 44 GiB/rank pinned expert pool, MTP depth 2, prefix cache host
-# 8 GiB + disk 64 GiB, PLE pinned in RAM.
+# Deployed shape (2026-10-19, radiance 1.8.1): THREE decode slots x 200,000
+# tokens, fp8 KV, 44 GiB/rank pinned expert pool, MTP depth 2, prefix cache in
+# pinned host RAM, PLE pinned in RAM. The per-card split between the expert slab
+# and the KV pool is NO LONGER an operator number — 1.3.0 removed the VRAM pair
+# and the budget resolver derives it from headroom, the cache bound and the host
+# pool, so the slab size and the pool's token count are LEDGER lines: after every
+# boot read them out of the log and check the pool still backs 3 x 200,000.
 #
 # The root unit (scripts/frank-archon.service, User=dank,
 # LimitMEMLOCK=infinity) grants the pin budget: 2 x 44 GiB expert pools +
@@ -56,13 +57,11 @@ set +a
 : "${FRANK_ARCHON_PLACEMENT:?FRANK_ARCHON_PLACEMENT must be set}"
 : "${FRANK_ARCHON_HOST_POOL_MIB:?FRANK_ARCHON_HOST_POOL_MIB must be set}"
 : "${FRANK_ARCHON_GPU_HEADROOM_MIB:?FRANK_ARCHON_GPU_HEADROOM_MIB must be set}"
-: "${FRANK_ARCHON_VRAM_WEIGHTS_MIB:?FRANK_ARCHON_VRAM_WEIGHTS_MIB must be set}"
-: "${FRANK_ARCHON_VRAM_KV_MIB:?FRANK_ARCHON_VRAM_KV_MIB must be set}"
+: "${FRANK_ARCHON_BUSY_PREFILL_CHUNK:?FRANK_ARCHON_BUSY_PREFILL_CHUNK must be set (auto|off|N)}"
 : "${FRANK_ARCHON_KV_DTYPE:?FRANK_ARCHON_KV_DTYPE must be set}"
 : "${FRANK_ARCHON_SPEC_TOKENS:?FRANK_ARCHON_SPEC_TOKENS must be set}"
 : "${FRANK_ARCHON_MAX_BATCHED_TOKENS:?FRANK_ARCHON_MAX_BATCHED_TOKENS must be set}"
-: "${FRANK_ARCHON_PREFIX_HOST_MIB:?FRANK_ARCHON_PREFIX_HOST_MIB must be set}"
-: "${FRANK_ARCHON_PREFIX_DISK_MIB:?FRANK_ARCHON_PREFIX_DISK_MIB must be set}"
+: "${FRANK_ARCHON_PREFIX_CACHE_MIB:?FRANK_ARCHON_PREFIX_CACHE_MIB must be set}"
 : "${FRANK_ARCHON_NGRAM_PLACEMENT:?FRANK_ARCHON_NGRAM_PLACEMENT must be set}"
 : "${FRANK_ARCHON_TTM_MIN_MIB:?FRANK_ARCHON_TTM_MIN_MIB must be set}"
 : "${FRANK_ARCHON_TTM_TARGET_MIB:?FRANK_ARCHON_TTM_TARGET_MIB must be set}"
@@ -103,19 +102,12 @@ if [ ! -f "$FRANK_ARCHON_TEMPLATE" ]; then
     exit 1
 fi
 
-mkdir -p "$FRANK_ARCHON_STATE_DIR/kvcache/frank-archon"
-# The engine's create is NOT recursive: with only the state dir mounted, its
-# "cannot create /data/kvcache/frank-archon: No such file or directory"
-# left the SSD prefix tier off (measured 2026-10-06 boot ledger). Pre-create
-# the full path on the host so the tier opens on first boot.
-
 mkdir -p "$FRANK_ARCHON_STATE_DIR/tune"
 # rad-tune's kernel-selection cache (see the runbook's "Tuning levers"):
 # the engine's selector reads $RADIANCE_HOME/tune/<machine>.tune at boot;
 # $RADIANCE_HOME defaults to /opt/radiance, which lives in the image, so
 # the cache must ride a host mount or it dies with the --rm container
-# that wrote it. The dir is pre-created for the same reason as kvcache
-# (the engine's create is not recursive).
+# that wrote it. The engine's create is not recursive, so the dir is pre-created.
 
 if [ ! -e /dev/kfd ] || [ ! -d /dev/dri ]; then
     echo "ERROR: GPU device nodes absent (/dev/kfd, /dev/dri)" >&2
@@ -148,6 +140,15 @@ done
 LOG=/home/dank/logs/frank_archon.log
 mkdir -p "$(dirname "$LOG")"
 
+# Interleave is opt-in: 0 is the engine's default and passing it anyway would put
+# a flag in argv that changes nothing but the record. The sharing cap is always
+# explicit because `auto` vs `off` is the difference between decode waiting one
+# chunk and waiting the whole step.
+PREFILL_ARGS=()
+if [ "${FRANK_ARCHON_PREFILL_INTERLEAVE:-0}" -gt 0 ]; then
+    PREFILL_ARGS=(--prefill-interleave "$FRANK_ARCHON_PREFILL_INTERLEAVE")
+fi
+
 # Publisher-vetted container contract (docs/DOCKER.md, compose/common.yaml):
 # --network host (the server binds the host's addresses directly, no NAT),
 # --init (the engine releases the cards on SIGTERM), seccomp=unconfined
@@ -156,8 +157,9 @@ mkdir -p "$(dirname "$LOG")"
 # makes for host memory), memlock unbounded (the pinned ledger — legal
 # because the root unit grants LimitMEMLOCK=infinity to this dank process),
 # /dev/kfd + /dev/dri (render/video groups are moot for a root container).
-# The template rides a single-file mount; the .rad dir is ro; /data holds
-# the prefix-cache disk tier.
+# The template rides a single-file mount and the .rad dir is ro. The prefix cache
+# has no disk tier any more, so the only host state this container writes is the
+# rad-tune cache under /opt/radiance/share/radiance/tune.
 podman run -d --name "$FRANK_ARCHON_CONTAINER" \
   --network host \
   --init \
@@ -165,7 +167,6 @@ podman run -d --name "$FRANK_ARCHON_CONTAINER" \
   --ulimit memlock=-1:-1 \
   --device /dev/kfd --device /dev/dri \
   -v "$FRANK_ARCHON_MODEL_DIR":/models:ro \
-  -v "$FRANK_ARCHON_STATE_DIR":/data \
   -v "$FRANK_ARCHON_STATE_DIR/tune":/opt/radiance/share/radiance/tune \
   -v "$FRANK_ARCHON_TEMPLATE":/templates/template.jinja:ro \
   "$FRANK_ARCHON_IMAGE" \
@@ -179,15 +180,13 @@ podman run -d --name "$FRANK_ARCHON_CONTAINER" \
   --placement "$FRANK_ARCHON_PLACEMENT" \
   --host-pool-mib "$FRANK_ARCHON_HOST_POOL_MIB" \
   --gpu-headroom-mib "$FRANK_ARCHON_GPU_HEADROOM_MIB" \
-  --vram-weights-mib "$FRANK_ARCHON_VRAM_WEIGHTS_MIB" \
-  --vram-kv-mib "$FRANK_ARCHON_VRAM_KV_MIB" \
   --kv-cache-dtype "$FRANK_ARCHON_KV_DTYPE" \
-  --prefix-cache-host-mib "$FRANK_ARCHON_PREFIX_HOST_MIB" \
-  --prefix-cache-dir /data/kvcache/frank-archon \
-  --prefix-cache-disk-mib "$FRANK_ARCHON_PREFIX_DISK_MIB" \
+  --prefix-cache-mib "$FRANK_ARCHON_PREFIX_CACHE_MIB" \
   --ngram-placement "$FRANK_ARCHON_NGRAM_PLACEMENT" \
   --num-speculative-tokens "$FRANK_ARCHON_SPEC_TOKENS" \
   --max-num-batched-tokens "$FRANK_ARCHON_MAX_BATCHED_TOKENS" \
+  --busy-prefill-chunk "$FRANK_ARCHON_BUSY_PREFILL_CHUNK" \
+  "${PREFILL_ARGS[@]}" \
   ${FRANK_ARCHON_EXTRA_ARGS:+$FRANK_ARCHON_EXTRA_ARGS} \
   > "$LOG" 2>&1