[New Model] Gemma 4 (#21952)

Signed-off-by: Xinyuan Tong <xinyuantong.cs@gmail.com>
Co-authored-by: Pengyu Chen <pychen96@gmail.com>
Co-authored-by: kpham-sgl <khoa.pham@radixark.ai>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Andy Luo <andy.luo@amd.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: adarshxs <adarsh.shirawalmath@gmail.com>

python/sglang/lang/chat_template.py

@@ -404,6 +404,19 @@ register_chat_template(
     )
 )
 
+register_chat_template(
+    ChatTemplate(
+        name="gemma-4-it",
+        default_system_prompt=None,
+        role_prefix_and_suffix={
+            "system": ("", ""),
+            "user": ("<|turn>user\n", "<turn|>\n"),
+            "assistant": ("<|turn>assistant\n", "<turn|>\n"),
+        },
+        style=ChatTemplateStyle.PLAIN,
+    )
+)
+
 register_chat_template(
     ChatTemplate(
         name="dbrx-instruct",
@@ -611,8 +624,10 @@ def match_chat_yi(model_path: str):
 
 
 @register_chat_template_matching_function
-def match_gemma_it(model_path: str):
-    if re.search(r"gemma.*it", model_path, re.IGNORECASE):
+def match_gemma(model_path: str):
+    if re.search(r"gemma-4.*it", model_path, re.IGNORECASE):
+        return "gemma-4-it"
+    if re.search(r"(gemma.*it)|(gemma-3)", model_path, re.IGNORECASE):
         return "gemma-it"
 
 
@@ -636,12 +651,6 @@ def match_granite_instruct(model_path: str):
         return "granite-3-instruct"
 
 
-@register_chat_template_matching_function
-def match_gemma3_instruct(model_path: str):
-    if re.search(r"gemma-3", model_path, re.IGNORECASE):
-        return "gemma-it"
-
-
 @register_chat_template_matching_function
 def match_internvl_chat(model_path: str):
     if re.search(r"internvl2_5", model_path, re.IGNORECASE):