frank-primary: 3 slots x 200704, fp8, pool sized for 2 contexts

Re-applies the desired shape incrementally on the proven-good fp8 3x262144
base, after bisecting why the first attempt (30904ba) crash-looped.

Root cause: `--max-num-seqs 2` cannot compile on this model. AOT
build_guards(strict_error=True) inside profile_run -> _dummy_run specializes
`query_start_loc`'s width to SEQS + 1 (3 at SEQS 2, 4 at SEQS 3) and the
ConstraintViolationError kills engine init ~7 min in. MNBT is orthogonal:
SEQS 2 failed at MNBT 1024 AND 2048; SEQS 3 passed at both. KV dtype was a
red herring. Measured by four single-variable boot probes.

Arena lever measured: the expert arena is sized from `max_model_len` via the
registry-priced KV reserve (9190 B/token x max_model_len), NOT from
--kv-cache-memory-bytes. 262144 -> 14.30 GiB / 6,248 slots; 200704 ->
14.87 GiB / 6,496 slots. The 6.1e9 -> 3.15e9 pool cut bought zero arena and
is a runtime-headroom lever.

Shape: MAXLEN 200704, SEQS 3 (unchanged - the only slot count that compiles),
KV_BYTES 3.15e9/rank = 2.04x full-length concurrency at 7,701 B/token fp8,
MNBT 1024, gather 32x64, no spec decode, no prefetch, no precise-memory.

scripts/serve-frank-primary.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 # serve-frank-primary.sh — frank-primary endpoint (tcclaviger RDNA4 vLLM fork,
-# orcarouter Qwen3.8-Flash-Next-Uncensored-FP8 + MTP4 spec decode, 2x R9700,
+# orcarouter Qwen3.8-Flash-Next-Uncensored-FP8, 2x R9700,
 # dankserver :7770; 2026-09-29 cutover from the R9V radiance fork — git tag
 # frank-primary-r9v-q8-20260929 is the pre-cutover state).
 #
@@ -11,14 +11,17 @@
 # every flag here was qualified by boot probe on 2026-09-29 — see
 # frank-primary.env for the qualification record).
 #
-# Shape (2026-10-01 bf16 cutover): MAXLEN 262144 x 3 sessions (786,432
-# tokens), KV UNQUANTIZED (--kv-cache-dtype auto = bf16; the fp8 q8/q8 shape
-# is retired to git tag frank-primary-fp8-mtp-20261001), KV_BYTES
-# 11,047,010,304 PER RANK (the engine measured 798,280 tokens of capacity /
-# 3.05x concurrency), NO speculative decode, --max-num-batched-tokens 1024
-# (Frank's lock), MoE gather geometry R4D_LRU_GATHER_CHUNKS=32 /
-# R4D_LRU_GATHER_LANES=64 (+18.7% decode, grows with depth), prefix caching,
-# expert prefetch OFF (36% precision measured), TunableOp off.
+# Shape (2026-10-02 shape D): MAXLEN 200704 x 3 slots, fp8 KV, KV_BYTES
+# 3,150,000,000 PER RANK — the POOL, not the slot count, caps resident
+# conversations at ~2 full-length (2.04x); shorter requests use the spare
+# blocks. --max-num-seqs stays 3 because SEQS=2 CANNOT boot this model
+# (torch.fx ConstraintViolationError on query_start_loc, measured at both
+# MNBT 1024 and 2048 — the 2x2 lives in frank-primary.env). NO speculative
+# decode, --max-num-batched-tokens 1024 (Frank's lock), MoE gather geometry
+# R4D_LRU_GATHER_CHUNKS=32 / R4D_LRU_GATHER_LANES=64 (+18.7% decode, grows
+# with depth), prefix caching, expert prefetch OFF (36% precision measured),
+# TunableOp off. The native-262144 and fp8+MTP4 shapes are retired to git tag
+# frank-primary-fp8-mtp-20261001.
 #
 # The root unit (scripts/frank-primary.service, User=dank,
 # LimitMEMLOCK=infinity) grants the pin budget for the tiered-expert host