update quantization code owner and document quantization contributions (#26784)

Co-authored-by: ronnie_zheng <zl19940307@163.com>

.github/CODEOWNERS

@@ -32,7 +32,8 @@
 /python/sglang/srt/hardware_backend/mlx @yeahdongcn
 /python/sglang/srt/hardware_backend/musa @yeahdongcn
 /python/sglang/srt/hardware_backend/npu @ping1jing2 @iforgetmyname @whybeyoung
-/python/sglang/srt/hardware_backend/npu/quantization @OrangeRedeng @TamirBaydasov @iforgetmyname
+/python/sglang/srt/hardware_backend/gpu/quantization @Alisehen
+/python/sglang/srt/hardware_backend/npu/quantization @OrangeRedeng @TamirBaydasov @Alisehen
 /python/sglang/srt/layers @merrymercy @Ying1123 @Fridge003 @ispobock @HaiShaw @ch-wan @BBuf @Edwardf0t1
 /python/sglang/srt/layers/attention @merrymercy @Fridge003 @ispobock @Qiaolin-Yu @hebiao064 @HaiShaw
 /python/sglang/srt/layers/attention/fla @yizhang2077 @hebiao064 @yuan-luo
@@ -40,7 +41,7 @@
 /python/sglang/srt/layers/attention/mamba @yizhang2077 @hebiao064
 /python/sglang/srt/layers/attention/dsa @1am9trash @hubertlu-tw @kkHuang-amd @HaiShaw @Fridge003 @YAMY1234 @rainj-me
 /python/sglang/srt/layers/attention/vision.py @mickqian @yuan-luo @yhyang201
-/python/sglang/srt/layers/quantization @ch-wan @BBuf @Edwardf0t1 @FlamingoPg @AniZpZ @HaiShaw @b8zhong
+/python/sglang/srt/layers/quantization @ch-wan @BBuf @Edwardf0t1 @FlamingoPg @AniZpZ @HaiShaw @b8zhong @OrangeRedeng @TamirBaydasov @Alisehen
 /python/sglang/srt/layers/quantization/quark @kkHuang-amd @yichiche @hubertlu-tw @1am9trash @BowenBao
 /python/sglang/srt/lora @Ying1123 @Fridge003 @lifuhuang @yushengsu-thu @jybsuper
 /python/sglang/srt/managers @merrymercy @Ying1123 @hnyls2002 @xiezhq-hermann

docs_new/docs.json

@@ -809,7 +809,8 @@
                 "group": "Development",
                 "pages": [
                   "docs/developer_guide/development_guide_using_docker",
-                  "docs/developer_guide/development_jit_kernel_guide"
+                  "docs/developer_guide/development_jit_kernel_guide",
+                  "docs/developer_guide/quantization_contribution_guide"
                 ]
               },
               {

docs_new/docs/developer_guide/overview.mdx

@@ -6,6 +6,7 @@ description: Contributing to SGLang — development setup, benchmarking, and eva
 - [Contribution Guide](./contribution_guide)
 - [Development Guide (Docker)](./development_guide_using_docker)
 - [JIT Kernels](./development_jit_kernel_guide)
+- [Quantization Contribution Guide](./quantization_contribution_guide)
 - [Benchmark and Profiling](./benchmark_and_profiling)
 - [Bench Serving](./bench_serving)
 - [Evaluating New Models](./evaluating_new_models)

docs_new/docs/developer_guide/quantization_contribution_guide.mdx

@@ -0,0 +1,96 @@
+---
+title: "Quantization Contribution Guide"
+metatags:
+    description: "Guidance for contributing SGLang quantization methods, schemes, backend kernels, tests, and validation results."
+---
+
+This guide describes how to add or refactor quantization support in SGLang. It focuses on the common structure used by weight-only and weight-activation quantization methods such as AWQ, GPTQ, compressed-tensors, ModelSlim, Quark, and related backend kernels.
+
+## Design Goals
+
+Quantization code should keep the quantization format semantics separate from hardware-specific execution. This makes it easier to add new formats, reuse kernels across formats, and review platform-specific changes independently.
+
+Follow the architecture proposed in [Quantization Modifications](https://github.com/sgl-project/sglang/issues/15194):
+
+- **Config**: parses model and runtime quantization parameters, validates supported options, and selects the proper scheme.
+- **Scheme**: owns quantized weight creation, weight loading, post-processing, and quantized layer wiring for Linear, MoE, embedding, or other module types.
+- **Backend kernel**: wraps hardware-specific execution, layout conversion, kernel selection, and kernel calls for GPU (CUDA/HIP/XPU), NPU, or other backends.
+
+Avoid putting config parsing, weight loading, and backend kernel calls in a single monolithic file. If a method needs multiple formats or backends, add a package under `python/sglang/srt/layers/quantization/<method>/` and split schemes into `schemes/`.
+
+## Recommended File Layout
+
+Use this layout for a quantization method that has multiple schemes or backend-specific execution paths:
+
+```text
+python/sglang/srt/layers/quantization/<method>/
+  __init__.py
+  <method>.py
+  schemes/
+    __init__.py
+    <method>_scheme.py
+    <method>_linear.py
+    <method>_moe.py
+    <method>_<variant>.py
+```
+
+Backend kernels should live under the hardware backend they target:
+
+```text
+python/sglang/srt/hardware_backend/gpu/quantization/<method>_kernels.py
+python/sglang/srt/hardware_backend/npu/quantization/<method>_kernels.py
+```
+
+Keep shared method selection in the quantization package and keep backend imports narrow. This prevents circular imports and keeps non-target platforms from importing unavailable kernel dependencies.
+
+## Adding or Refactoring a Quantization Method
+
+1. Define the config entry point and register it through `python/sglang/srt/layers/quantization/__init__.py` when needed.
+2. Add explicit scheme selection helpers such as `get_linear_scheme` and `get_moe_scheme`.
+3. Move layer-specific weight creation and weight loading into scheme classes.
+4. Move GPU (CUDA/HIP/XPU), NPU, or other hardware kernel calls into backend kernel modules.
+5. Keep Linear, MoE, embedding, and non-linear module handling explicit. Do not assign a Linear quantization method to a module type that needs different semantics.
+6. Preserve compatibility for existing quantized checkpoints and runtime flags.
+7. Add tests that cover both config parsing and execution paths touched by the change.
+
+For examples, see the AWQ and GPTQ refactors:
+
+- [PR #21126](https://github.com/sgl-project/sglang/pull/21126): splits AWQ schemes, weight initialization, and backend kernel calls.
+- [PR #26402](https://github.com/sgl-project/sglang/pull/26402): applies the same scheme/kernel split to GPTQ.
+
+## Tests and Validation
+
+Quantization changes can affect both accuracy and performance. Include validation that matches the blast radius of the change.
+
+For Python-only structure changes:
+
+```bash
+ruff check <changed-python-files>
+git diff --check
+```
+
+For quantized model behavior:
+
+- Launch at least one representative model for each touched quantization method.
+- Send a `/generate` request and confirm the output path succeeds.
+- Run an accuracy sanity test if the change can affect numerics.
+- Include warmup-aware benchmark results when the change affects kernel calls, layout conversion, or dispatch.
+
+For backend-specific changes:
+
+- Validate GPU changes on a supported GPU environment (NVIDIA, AMD, or Intel).
+- Validate NPU changes on a supported Ascend environment.
+- Include the exact model, quantization flag, backend flag, hardware, and command used in the PR description.
+
+## PR Checklist
+
+Before requesting review, make sure the PR description includes:
+
+- The quantization method and backend paths changed.
+- The issue, design proposal, or roadmap item the PR follows.
+- Any compatibility notes for existing checkpoints or flags.
+- Accuracy results when model outputs can change.
+- Benchmark or profiling results when runtime performance can change.
+- The exact local checks and model launch tests that were run.
+
+Use the general [Contribution Guide](./contribution_guide) for source setup, formatting, unit tests, CI triggering, and review process details.