docs: update SGLang quickstart

README.md

@@ -318,108 +318,41 @@ The source checkout is immutable at `d9fd5f11423a1a5628fe29e7296ceb9de91aac3c`.
 
 ### SGLang
 
-The SGLang stack is pinned to public commit [`ffb41d77`](https://github.com/LLM360/sglang/commit/ffb41d77d8b96b8a953351cb4d66d6bf4ed061a7). The setup applies a hash-guarded namespace migration to expose the public `K2Horizon` classes and `k2_horizon` parser identifiers, then verifies both registries before launch. That source locks PyTorch 2.9.1, CUDA Python 12.9, Transformers 5.3.0, sglang-kernel 0.4.1, and FlashInfer 0.6.7.post2; the PyTorch wheel uses CUDA 12.8, and Safetensors 0.8.0 is selected independently. Its declared `flash-attn-4` dependency has only beta candidates, so the reproducible install removes exactly that unused metadata line, assigns the stable local version `0.5.10+ffb41d77.stableonly`, and explicitly selects stable FA3 from sglang-kernel. Keep this source-patched stack in its own environment.
+Native K2 Horizon support is provided by
+[sgl-project/sglang#37654](https://github.com/sgl-project/sglang/pull/37654).
+Use a `lmsysorg/sglang:dev` image built after that PR is merged. Once support is
+included in a tagged SGLang release, use the corresponding versioned image.
 
 <details>
-<summary>Show SGLang setup and serving commands</summary>
+<summary>Show the SGLang serving command</summary>
 
 ```bash
-git clone https://github.com/LLM360/sglang.git
-cd sglang
-git checkout ffb41d77d8b96b8a953351cb4d66d6bf4ed061a7
-python - <<'PY'
-from hashlib import sha256
-from pathlib import Path
-
-path = Path("python/pyproject.toml")
-source = path.read_text(encoding="utf-8")
-if sha256(source.encode()).hexdigest() != "b3c46337e6852f4febc45087e96c26543bab7a1cc835276246290de152a1f532":
-    raise RuntimeError("unexpected pinned SGLang pyproject hash")
-unstable = '  "flash-attn-4>=4.0.0b4",\n'
-if source.count(unstable) != 1:
-    raise RuntimeError(f"unexpected flash-attn-4 metadata in {path}")
-patched = source.replace(unstable, "")
-if sha256(patched.encode()).hexdigest() != "69a86d23327737ad8cb16e0bb81dde8a1c530d93af997e7af32248a43a2efa1d":
-    raise RuntimeError("unexpected stable-only SGLang pyproject hash")
-path.write_text(patched, encoding="utf-8")
-
-old_class = "K2" + "V3"
-old_id = "k2" + "_v3"
-old_label = "K2-" + "v3"
-contracts = (
-    (
-        Path("python/sglang/srt/parser/reasoning_parser.py"),
-        "8bd1894b7d8c2935d4800e44616ba18c8eebaedde9d7c95c5d270864e928a25c",
-        "e448c562fd5a994dec67a3ebf5d6539a4acbac0bbc2204d67ba801dd502ca7f5",
-    ),
-    (
-        Path("python/sglang/srt/function_call/function_call_parser.py"),
-        "0957d87b0e5dbcf761dc4871f4e48a7cc1f8c7e0a7badbfb5d3982b10f4d10eb",
-        "177dabfc3c73461ecbb7da14c4009e4b6c109502a1d6bed65de0dfba6f9e7785",
-    ),
-    (
-        Path("python/sglang/srt/function_call/multi_format_detector.py"),
-        "306d310748ba84d3c2084d111a23fb6e2dead2e316bd0bdf69356b3c6e6eeab1",
-        "b6e5650366afe8f7abf878172e70bdde527df1e1484514625e49178606ba847e",
-    ),
-)
-replacements = (
-    (old_class, "K2Horizon"),
-    (old_id, "k2_horizon"),
-    (old_label, "K2-Horizon"),
-)
-for source_path, original_hash, migrated_hash in contracts:
-    text = source_path.read_text(encoding="utf-8")
-    if sha256(text.encode()).hexdigest() != original_hash:
-        raise RuntimeError(f"unexpected pinned SGLang parser source: {source_path}")
-    for old, new in replacements:
-        text = text.replace(old, new)
-    if sha256(text.encode()).hexdigest() != migrated_hash:
-        raise RuntimeError(f"unexpected Horizon parser migration: {source_path}")
-    source_path.write_text(text, encoding="utf-8")
-PY
-
-export SETUPTOOLS_SCM_PRETEND_VERSION_FOR_SGLANG="0.5.10+ffb41d77.stableonly"
-python -m pip install ./python "safetensors==0.8.0"
-python -m pip check
-python - <<'PY'
-from importlib.metadata import metadata, version
-
-from packaging.version import Version
-from sglang.srt.function_call.function_call_parser import FunctionCallParser
-from sglang.srt.parser.reasoning_parser import ReasoningParser
-
-assert not Version(version("sglang")).is_prerelease
-requirements = metadata("sglang").get_all("Requires-Dist") or []
-assert not any(requirement.lower().startswith("flash-attn-4") for requirement in requirements)
-assert "k2_horizon" in ReasoningParser.DetectorMap
-assert "k2_horizon_legacy" in ReasoningParser.DetectorMap
-assert "k2_horizon" in FunctionCallParser.ToolCallParserEnum
-PY
-
-export MODEL_ID="IFM/K2-Horizon-7B"
-export MODEL_REVISION="mid_4"
-export TP_SIZE=1
-export CONTEXT_LENGTH=131072
-
-python -m sglang.launch_server \
-  --model-path "$MODEL_ID" \
-  --revision "$MODEL_REVISION" \
-  --model-impl transformers \
-  --tp "$TP_SIZE" \
-  --trust-remote-code \
-  --dtype bfloat16 \
-  --context-length "$CONTEXT_LENGTH" \
-  --attention-backend fa3 \
-  --reasoning-parser k2_horizon \
-  --tool-call-parser k2_horizon \
-  --mem-fraction-static 0.85 \
-  --disable-piecewise-cuda-graph
+docker run --gpus all \
+  --shm-size 32g \
+  -p 30000:30000 \
+  -v ~/.cache/huggingface:/root/.cache/huggingface \
+  --ipc=host \
+  lmsysorg/sglang:dev \
+  python3 -m sglang.launch_server \
+    --model-path "IFM/K2-Horizon-7B" \
+    --revision main \
+    --tp 1 \
+    --dtype bfloat16 \
+    --context-length 131072 \
+    --attention-backend fa3 \
+    --reasoning-parser k2_horizon \
+    --tool-call-parser k2_horizon \
+    --mem-fraction-static 0.85 \
+    --host 0.0.0.0 \
+    --port 30000
 ```
 
 </details>
 
-The example starts at 131,072 tokens and explicitly selects stable FA3 from sglang-kernel 0.4.1; FlashInfer 0.6.7.post2 remains installed for compatible alternate paths. The source is launched through SGLang's Transformers backend so the repository's self-contained remote code remains the architecture source of truth. Piecewise CUDA graphs are disabled because this experimental path can trigger an illegal-memory-access failure while warming up XLLM MoVA layers; ordinary serving remains available. The installation preflight verifies the migrated `k2_horizon`, `k2_horizon_legacy`, and tool-parser registrations before the server starts.
+This uses SGLang's native `K2HorizonForCausalLM` implementation; no
+`--trust-remote-code`, source patch, or external parser plugin is required. The
+131,072-token limit is a conservative starting point; increase it only after
+measuring KV-cache capacity.
 
 ### Reasoning and Tool Parsers