fix(cyberprev-seat): serve coherent v2 quant from name-repaired source; wire gateway

The first cyberprev quant served pure gibberish despite passing every structural
check. Root cause: the hotdogs/Qwen3.8-27B-abliterated-cyber-preview checkpoint
ships broken -- 850 of 1199 tensors (the whole transformer body) carry a TRIPLED
`language_model.` prefix, confirmed present in the upstream HF index (an unsloth
export bug, not our download). transformers silently loaded the unmapped tensors
as random-init, the pipeline quantized noise, and structural verification passed
because it inspects the output config, never that input names mapped. A plain
greedy coherence smoke caught it; nothing structural could.

Fix: rewrite tensor names against a known-good reference of the same architecture
(qwen38-27b-uncensored-bf16), verified the repaired name-set == reference name-set
exactly (1199 tensors, 0 collisions), and re-quantized from the corrected source
(cyberprev-bf16-fixed). v2 is coherence-verified (spec off AND live with dflash):
Paris/Berlin/Rome, correct arithmetic precedence, primes, clean cyber-domain chat
with a proper thinking split. dflash k=7 measured at 2.77 mean acceptance length.

Seat serves cyberprev-27b / cyberprev-27b-thinking on :8025/GPU0 with dflash k=7,
displacing the retired sentinel-r3. Gateway: removed the retired sentinel-r3 /
sentinel-r3-reasoning aliases and added cyberprev-27b / cyberprev-reasoning -- NOT
repointed, since serving cyberprev weights under sentinel's name is silent
substitution. Verified end-to-end through the gateway; sentinel-r3 now 400s.

Playbook gains a superseded-claims row: structural verification does not imply a
good quant; a coherence smoke is the load-bearing gate, and third-party sources
must have their tensor names diffed against a reference before quantizing.

Broken v1 quant dir removed.

docs/pfi/model-quantization-playbook.md

@@ -777,6 +777,7 @@ day if followed:
 | "NVFP4 W4A4 is infeasible, no 4-bit wins both axes, FP8 is the Blackwell answer" | `reference_nvfp4_w4a4_granite_infeasible` | **NARROWED.** True for *uniform* W4A4 (measured on Granite-8B at 30k ctx). W4A4 on bulk MLPs **with FP8 on attention and late layers** is fine and is the current default (§2). |
 | "The Qwen3.8 MTP corruption is fixed by disabling prefix caching while keeping MTP; the gen seat runs APC-off" | this playbook §3.7 (now marked), earlier auto-memory | **SUPERSEDED 2026-08-17, and the staleness was only caught 2026-08-26.** APC-off passed a synthetic 7-turn probe and the operator still saw severe degeneration in real use; reverted the same day. The real cause was the **AEON W4A4 quant being defective** (~15-20% degenerate generations), with MTP / prefix-caching / gateway merely AMPLIFYING it (§3.8). The gen seat runs **MTP ON and prefix-caching ON** on the in-house mixed NVFP4+FP8 build — verified against the live container 2026-08-26. ⚠ The lesson inside the lesson: a *passing multi-turn probe* was not sufficient evidence either. |
 | "transformers' Qwen3.5 DeltaNet linear-attention NaNs in bf16 without causal-conv1d; it is precision-driven cancellation and fp32 resolves it" | `services/coldfusion-abliteration/README.md`, `persistent-memory.d/2026-08-20-coldfusion-abliteration-capture.md` | **SUPERSEDED 2026-08-20.** Precision was never the variable. The NaN came from **multi-GPU sharding** and **`expandable_segments`** (§3.9, §3.10); fp32 only made it rarer, which is worse than failing. On one GPU with a plain allocator, **bf16 is exactly deterministic through all 64 layers and generates coherent prose** — at 50 GB and 4.3× the throughput of the 111 GB fp32 it replaced. |
+| "Structural verification of a quant (layer split, MTP graft, ignore list, tensor dtypes all correct) means the quant is good" | general belief | **FALSE — cost a full cutover of a gibberish seat 2026-09-14.** The `cyberprev` quant passed every structural check AND matched the reference config exactly, yet served pure gibberish, because the SOURCE checkpoint (`hotdogs/Qwen3.8-27B-abliterated-cyber-preview`, an unsloth export) had 850/1199 body tensors carrying a **tripled `language_model.` prefix** — verified present in the UPSTREAM HF index, not our download. transformers silently loaded the unmapped tensors as random-init, quantized noise, and every structural check passed because it inspected the OUTPUT config, never that INPUT names mapped. **A plain greedy coherence smoke (spec off) is the load-bearing gate and caught it; structure never can.** Fix: rewrite tensor names to a known-good reference of the same arch (exact 1199-tensor match), re-quant. Add a name-set diff of the bf16 SOURCE against a reference BEFORE quantizing. |
 | "A checkpoint with an FP8 PLE table but no `ple_embedding_dtype` declaration cannot be loaded; compressed-tensors qwen4_exp needs a vLLM source patch" | `stacks/flash-next-seat/README.md`, `persistent-memory.d/2026-09-14-fv-seat-reorg-and-orca-blocker.md` | **SUPERSEDED 2026-09-14.** `from_quant_config` checks `ple_embedding_dtype` as **branch 1, before any quant-config type check**, and its `NotImplementedError` is scoped to the **PLE path only**. Declaring the FP8 PLE bypasses it on stock mainline — a **one-key config fix**, not a source build. Proven live: orcarouter (compressed-tensors) serves on gen-large after converting its bf16 PLE to FP8 + declaring it. ⚠ Declare only what is TRUE — declaring FP8 over a bf16 table is the gorbatjovy failure in reverse. |
 
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