docs: upstream-first KV-cache guidance (q8_0/q4_0, mainline Hadamard rotation); fork demoted to experimental

README.md

@@ -15,6 +15,23 @@ inference: false
 > **Status (2026-07-07): no weights published yet.** This repository currently contains only the model card — it marks a planned variant that has not been released. Follow the repo to be notified when files land.
 <!-- status-note -->
 
+> [!TIP]
+> **KV-cache quantization without any fork (recommended, 2026):** upstream
+> llama.cpp/Ollama now cover this natively — use `-ctk q8_0 -ctv q8_0`
+> (~half KV memory, negligible quality loss: perplexity +0.002–0.05) or
+> `-ctk q4_0 -ctv q4_0` (~quarter memory, ≈7.6% perplexity increase). In
+> Ollama: `OLLAMA_KV_CACHE_TYPE=q8_0` with `OLLAMA_FLASH_ATTENTION=1`. Keep
+> K and V types symmetric to stay on the fast fused Flash-Attention path.
+> Since April 2026, mainline llama.cpp also applies Hadamard rotation to
+> KV activations ([PR #21038](https://github.com/ggml-org/llama.cpp/pull/21038)),
+> which greatly improves low-bit KV quality (opt-out:
+> `LLAMA_ATTN_ROT_DISABLE=1`).
+>
+> The RotorQuant/TurboQuant fork flow below is **experimental/legacy**: the
+> TurboQuant llama.cpp PR was closed without merging (June 2026) and the fork
+> is unmaintained relative to mainline. It is NOT required to use this model.
+<!-- kv-upstream-note -->
+
 # Nemotron-3-Nano-Omni-30B-A3B-Reasoning - mmproj-F16
 
 Multimodal projector split file for `Nemotron-3-Nano-Omni-30B-A3B-Reasoning`. Required by `llama-mtmd-cli`