docs: sync legacy docs/-only updates into docs_new (Mintlify) (#27308)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs_new/docs/sglang-diffusion/quantization.mdx

@@ -14,8 +14,10 @@ Use these paths:
 - `--model-path`: the base or original model
 - `--transformer-path`: a quantized transformers-style transformer component directory that already contains its own `config.json`
 - `--transformer-weights-path`: quantized transformer weights provided as a single safetensors file, a sharded safetensors directory, a local path, or a Hugging Face repo ID
+- `--quantization`: apply online quantization to unquantized models at load time (activations are quantized dynamically)
+- `--quantization-ignored-layers` layer name patterns to keep unquantized (e.g. `attention.to_`)
 
-Recommended example:
+Recommended example for pre-quantized checkpoints:
 
 ```bash
 sglang generate \
@@ -65,7 +67,15 @@ backend.
   </thead>
   <tbody>
     <tr>
-      <td><code>fp8</code></td>
+      <td><code>fp8</code> / <code>mxfp4</code> (online quantization)</td>
+      <td>Unquantized checkpoint (offline via AMD Quark coming soon)</td>
+      <td><code>--quantization &#123;fp8,mxfp4&#125;</code></td>
+      <td>Z-Image-Turbo (validated), others likely work. More support coming soon.</td>
+      <td>MXFP4: <code>aiter</code> on ROCm</td>
+      <td>MXFP4 requires ROCm and MI350+ (gfx95x). Weights quantized at load time, activations quantized to <code>fp8</code> / <code>mxfp4</code> dynamically.</td>
+    </tr>
+    <tr>
+      <td><code>fp8</code> (offline quantization)</td>
       <td>Quantized transformer component folder, or safetensors with <code>quantization_config</code> metadata</td>
       <td><code>--transformer-path</code> or <code>--transformer-weights-path</code></td>
       <td>ALL</td>
@@ -107,6 +117,58 @@ backend.
   </tbody>
 </table>
 
+## Online Quantization
+
+Online quantization applies quantization to unquantized models at load time. This is useful for when pre-quantized checkpoints are not available.
+
+### FP8 Online Quantization
+
+Apply FP8 quantization to any unquantized model:
+
+```bash
+sglang generate \
+  --model-path Tongyi-MAI/Z-Image-Turbo \
+  --quantization fp8 \
+  --prompt "a beautiful sunset" \
+  --save-output
+```
+
+### MXFP4 Online Quantization
+
+MXFP4 provides aggressive 4-bit compression with online quantization. **Note: Requires ROCm and MI350+ (gfx95x) GPU.**
+
+```bash
+sglang generate \
+  --model-path Tongyi-MAI/Z-Image-Turbo \
+  --quantization mxfp4 \
+  --prompt "a beautiful sunset" \
+  --save-output
+```
+**Note:** Requires `aiter` package with MXFP4 kernel support
+
+### Skipping Layers
+
+By default, online quantization quantizes every linear layer in
+the transformer. However, `--quantization-ignored-layers` can be used to keep specific layers in their original precision:
+
+```bash
+sglang generate \
+  --model-path Tongyi-MAI/Z-Image-Turbo \
+  --quantization fp8 \
+  --quantization-ignored-layers attention.to_ \
+  --prompt "a beautiful sunset" \
+  --save-output
+
+sglang generate \
+  --model-path Tongyi-MAI/Z-Image-Turbo \
+  --quantization mxfp4 \
+  --quantization-ignored-layers attention.to_ \
+  --prompt "a beautiful sunset" \
+  --save-output
+```
+
+Each pattern is matched against the full layer prefix (e.g. `layers.0.attention.to_q`). A layer is skipped and left unquantizd if its prefix contains any of the given patterns.
+
 ## Validated ModelOpt Checkpoints
 
 This section is the canonical support matrix for the nine diffusion ModelOpt