docs: qwen38-fp8 expert-offload tuning — prefetch off hits 37.4-40.6 tok/s (target met)

Measured campaign on the ad hoc qwen-fp8 container (tcclaviger RDNA4
fork, 2x R9700, TP=2): telemetry (with_stack=false) measured the
prefetcher at 36% precision — ~half of gather traffic wasted; deleting
--expert-prefetch: 26.8 -> 40.57/37.44/37.57 tok/s. Prefetch-on shape
survived every other challenger (gather geometry, spec depth, TunableOp
[corrupts numerics], MNBT, concurrency, ngram [PLE fork bug]). 256k ctx
boots at 4.5 GiB KV (36.65/34.21/34.77, arena -14%). New runbook +
index links + log entry.

serverAppConfigs-docs/LLM/index.md

@@ -101,6 +101,16 @@ frank-small, port 7771]
   bound, ~23 tok/s ceiling at today's residency). Includes the Affinity
   V4-Flash-to-V4.1 port assessment — reusable expert tiering, four
   architecture gaps, one of them a silent-wrongness trap on the Engram key
+- [[dankserver-qwen38-fp8-expert-offload-tuning]] — VERIFIED 2026-09-29:
+  the flag-level decode-tuning campaign on the ad hoc qwen-fp8 container
+  (tcclaviger RDNA4 fork, orcarouter/Qwen3.8-Flash-Next-Uncensored-FP8,
+  TP=2 across both R9700s). **>35 tok/s MET: 37.44-40.57 tok/s with
+  `--expert-prefetch` DELETED** — telemetry measured the prefetcher at
+  36% precision, wasting ~half the gather traffic (the LRU itself runs at
+  82.45% hit). Prefetch-on incumbent 26.8 survived every other challenger
+  (geometry, spec depth, TunableOp-corrupts, batch knobs, concurrency,
+  ngram-fork-bug); the residual gap to ~60 tok/s is the fork's gather
+  read path (6.5-9.5 GB/s effective vs 22.7 at the same slab size)
 - [[frank-medium-radiance-mxfp4]] — RETIRED 2026-09-26 (replaced by
   [[frank-primary-lucebox-ds4]], then
   [[frank-primary-llamacpp-qwen38-flash-next-q8]]): vllm-radiance 0.9.3