diff --git a/AGENTS.md b/AGENTS.md
index f25c7fb..a902255 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -208,13 +208,27 @@ archive.
 
 **STOP the production service BEFORE benchmarking** — these servers serve
 real users, and a bench beside a live service starves the GPU and corrupts
-results. Use the runtime's own harness: `llama-bench` for every llama.cpp
-endpoint (all three are llama.cpp now). Rolling your own bench
+results. Use the runtime's own harness: `llama-bench` for the llama.cpp
+endpoints, `gufo bench` for frank-large. Rolling your own bench
 requires asking first.
 Scratch ports are not used on LLM hosts — a
 test process cannot share the single GPU anyway; validate against the service
 itself.
 
+**`gufo bench` cannot rank speculative-decode settings, and will invert the
+ranking.** Measured 2026-09-28 on frank-large at depth 32768: its corpus
+reports `acceptance=0.933 ± 0.000` with an **identical trace sha256** across
+draft widths, i.e. the same highly-predictable text every run, and 93 % of
+every proposal accepted. It reported 29–37 t/s decode where real traffic
+gives ~15 t/s, and it made `--draft-tokens 16` look 6 % faster than 7 when
+real text made it 14 % *slower*. Use it for shape, not for A/B. For an A/B,
+replay **real** text through the live server and read the `Server-Timing`
+header — but note the unit rides in the **name** half (`ttft;dur=402.485`),
+so splitting on `=` alone keys the dict `ttft;dur` and every lookup silently
+returns nothing. Generate **at least 128 tokens** for the measurement: at 8
+tokens, `inter_token` is first-token noise and the run-to-run spread swamps
+every real difference.
+
 This covers **any GPU experiment, not just benchmarks** — including a bare
 2-rank RCCL/`torch.distributed` probe. On 2026-09-16 one such probe was run
 against the live service "because it only needs 200 MB of VRAM"; the host went
diff --git a/serverAppConfigs-docs/LLM/frank-large-gufo-qwen38-27b.md b/serverAppConfigs-docs/LLM/frank-large-gufo-qwen38-27b.md
index cedbb77..c53f1b9 100644
--- a/serverAppConfigs-docs/LLM/frank-large-gufo-qwen38-27b.md
+++ b/serverAppConfigs-docs/LLM/frank-large-gufo-qwen38-27b.md
@@ -179,6 +179,40 @@ unchanged by the payload swap.
   Short-prompt decode is gufo's *winning* regime; see the depth table above
   before quoting it as the endpoint's number.
 
+### Tuning: the served flags are already optimal (2026-09-28)
+
+Frank asked for iterative decode/prefill improvement at a 32k working point
+without touching the model or the quantization. **Result: no win exists at
+this engine's served settings, and nothing was changed.** Measured on real
+repo prose and shell sources at **32,762 prompt tokens**, salted per run so
+a warm prefix cache could not help, 3–5 repetitions each.
+
+| lever | range swept | outcome |
+|---|---|---|
+| `--prefill-chunk` | 512 → 8192 | **no effect** — 410.7–412.4 t/s prefill across a 16× change |
+| `--draft-tokens` | 5 → 10 | **flat** — 13.79–15.86 t/s decode, inside run-to-run noise |
+| `--draft-policy` | fixed vs adaptive | 35.90 vs 35.50 (bench) — no effect |
+| `--min-draft-tokens` | — | **rejected by the engine**: "DFlash2 requires … 1" |
+| MTP backend | — | **unsupported for Q8**: `token_embd.weight` is Q8_0 |
+| `--context` 262144 → 40960 | diagnostic | 13.93 vs 14.71 t/s — no gain, and it would break the declared client context |
+
+The confirmation round at 5 reps **reversed** the 3-rep leaders: the pair
+that looked best (`dt9 + chunk4096`) came last at 12.86 t/s, and the
+**deployed configuration came first at 14.71 t/s**. Every difference sits
+inside the noise band.
+
+What *does* move the number is speculative decoding itself: **6.65 t/s off →
+~15 t/s on, a 5.3× step** — and that is already switched on. Prefill is
+insensitive to everything tried, which is consistent with gufo's own
+`EXPERIMENTS.md`, where dozens of kernel-level alternatives are recorded as
+rejected for "no release throughput improvement".
+
+**Do not repeat this investigation without new information.** Two traps
+cost most of the time, and both are in AGENTS.md's benchmarking policy:
+`gufo bench` reports `acceptance=0.933 ± 0.000` on an identical trace hash
+and **inverts** the draft-width ranking; and a live A/B needs ≥128 generated
+tokens or `inter_token` is first-token noise.
+
 ## The template law: Qwen-Sharp is gone
 
 `scripts/qwen-sharp-v22.4.0.jinja` is the fleet's chat template — it is
diff --git a/serverAppConfigs-docs/log.md b/serverAppConfigs-docs/log.md
index c49a0f2..349caf6 100644
--- a/serverAppConfigs-docs/log.md
+++ b/serverAppConfigs-docs/log.md
@@ -1,6 +1,51 @@
 # Bundle Change Log
 
 
+## 2026-09-29
+- **frank-large tuning investigation: a measured NEGATIVE result, nothing
+  changed.** Frank asked for iterative decode/prefill improvement at a 32k
+  working point without touching the model or quantization. **No win exists
+  at gufo's served settings**, so no config change was shipped. frank-large
+  was stopped for the whole investigation (~4h) per the benchmarking policy
+  and restored healthy in 9s afterwards.
+  - Measured on the repo's own prose and shell sources at **32,762 prompt
+    tokens**, salted per run so a warm prefix cache could not flatter a
+    later run, 3–5 repetitions per configuration.
+  - **`--prefill-chunk` is dead**: 512 → 8192 moves prefill 410.7–412.4 t/s.
+    A 16x change in chunk size, 0.4% out.
+  - **`--draft-tokens` is flat**: 5 → 10 gives 13.79–15.86 t/s decode, all
+    inside the run-to-run noise band. The 5-rep confirmation round
+    **reversed** the 3-rep leaders — `dt9 + chunk4096` looked best and came
+    **last** (12.86), while the **deployed config came first** (14.71).
+  - `--draft-policy` fixed vs adaptive: no effect. `--min-draft-tokens`:
+    **rejected by the engine** ("DFlash2 requires ... 1"). MTP: **unsupported
+    for Q8 targets** (`Unsupported Qwen MTP tensor type for
+    token_embd.weight: Q8_0`).
+  - `--context 262144 → 40960` was tested as a diagnostic (the deployed value
+    preallocates KV ~8x larger than a 32k conversation needs): **no gain**
+    (13.93 vs 14.71 t/s), and it would break `models.yml`'s declared
+    `contextWindow: 262144`. Not shipped.
+  - **What actually moves the number is speculation itself: 6.65 t/s off →
+    ~15 t/s on, 5.3x** — already enabled. Prefill is insensitive to
+    everything tried, consistent with gufo's own `EXPERIMENTS.md` where
+    dozens of kernel variants are recorded rejected for "no release
+    throughput improvement".
+  - **Two traps are now in AGENTS.md's benchmarking policy**, because they
+    cost most of the wall time and both produced *false* results:
+    (1) **`gufo bench` cannot rank speculative settings and inverted the
+    ranking** — its corpus reports `acceptance=0.933 +/- 0.000` with an
+    identical trace sha256 across draft widths (the same highly-predictable
+    text every run, 93% of proposals accepted). It reported 29–37 t/s where
+    real traffic gives ~15, and made dt16 look 6% faster than dt7 when real
+    text made it 14% slower. (2) **A live A/B needs >=128 generated tokens**;
+    at 8, `inter_token` is first-token noise and the first pass of the sweep
+    produced a nonsense ordering that the 128-token pass reversed.
+  - Also worth recording: the `Server-Timing` header is
+    `ttft;dur=402.485` — the unit is in the **name** half, so splitting on
+    `=` keys the dict `ttft;dur` and every lookup silently returns nothing.
+    Four configurations reported "no Server-Timing" while the header was
+    present on all of them.
+
 ## 2026-09-28
 - **Dankclaw model cleanup** (disk was at 93%, 137 G free). Frank asked to
   clean up old models. **510 G staged** to