fix: fix serve command without diffusion dependency (#13246)

python/sglang/cli/generate.py

@@ -1,15 +1,15 @@
 import argparse
 
 from sglang.cli.utils import get_is_diffusion_model, get_model_path
-from sglang.multimodal_gen.runtime.entrypoints.cli.generate import (
-    add_multimodal_gen_generate_args,
-    generate_cmd,
-)
 
 
 def generate(args, extra_argv):
     # If help is requested, show generate subcommand help without requiring --model-path
     if any(h in extra_argv for h in ("-h", "--help")):
+        from sglang.multimodal_gen.runtime.entrypoints.cli.generate import (
+            add_multimodal_gen_generate_args,
+        )
+
         parser = argparse.ArgumentParser(description="SGLang Multimodal Generation")
         add_multimodal_gen_generate_args(parser)
         parser.parse_args(extra_argv)
@@ -18,6 +18,11 @@ def generate(args, extra_argv):
     model_path = get_model_path(extra_argv)
     is_diffusion_model = get_is_diffusion_model(model_path)
     if is_diffusion_model:
+        from sglang.multimodal_gen.runtime.entrypoints.cli.generate import (
+            add_multimodal_gen_generate_args,
+            generate_cmd,
+        )
+
         parser = argparse.ArgumentParser(description="SGLang Multimodal Generation")
         add_multimodal_gen_generate_args(parser)
         parsed_args = parser.parse_args(extra_argv)