feat: add XL (4B DiT) turbo as default model + acemusic banner

- Default model 1: acestep-v15-xl-turbo (was acestep-v15-turbo)
- Default model 2: acestep-v15-turbo (was acestep-v15-turbo-shift3)
- Add XL model entries to MODEL_REPO_MAPPING for auto-download
- Enhanced acemusic.ai banner with gradient background
- Update README frontmatter with XL model

README.md

@@ -9,6 +9,7 @@ python_version: 3.11
 pinned: false
 models: 
  - ACE-Step/Ace-Step1.5
+ - ACE-Step/acestep-v15-xl-turbo
 license: mit
 app_file: app.py
 short_description: Music Generation Foundation Model v1.5

acestep/gradio_ui/interfaces/__init__.py

@@ -64,7 +64,14 @@ def create_gradio_interface(dit_handler, llm_handler, dataset_handler, init_para
         gr.HTML(f"""
         <div class="main-header">
             <h1>{t("app.title")}</h1>
-            <p>{t("app.subtitle")}, try more on <a href="https://acemusic.ai" target="_blank">acemusic.ai</a></p>
+            <p>{t("app.subtitle")}</p>
+            <div style="background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); padding: 10px 20px; border-radius: 8px; text-align: center; margin: 8px auto; max-width: 600px;">
+                <span style="color: white; font-size: 15px;">
+                    🚀 Want faster &amp; more stable experience? Try 
+                    <a href="https://acemusic.ai" target="_blank" style="color: #ffd700; font-weight: bold; text-decoration: underline;">acemusic.ai</a>
+                    — 100% free!
+                </span>
+            </div>
             <p style="margin-top: 0.5rem;">
                 <a href="https://ace-step.github.io/ace-step-v1.5.github.io/" target="_blank">Project</a> |
                 <a href="https://huggingface.co/collections/ACE-Step/ace-step-15" target="_blank">Hugging Face</a> |

acestep/handler.py

@@ -135,6 +135,10 @@ class AceStepHandler:
         "acestep-v15-base": "ACE-Step/acestep-v15-base",
         "acestep-v15-sft": "ACE-Step/acestep-v15-sft",
         "acestep-v15-turbo-shift3": "ACE-Step/acestep-v15-turbo-shift3",
+        # XL (4B) DiT models
+        "acestep-v15-xl-turbo": "ACE-Step/acestep-v15-xl-turbo",
+        "acestep-v15-xl-base": "ACE-Step/acestep-v15-xl-base",
+        "acestep-v15-xl-sft": "ACE-Step/acestep-v15-xl-sft",
     }
     
     # Default fallback repository for unknown models

app.py

@@ -166,10 +166,10 @@ def main():
     # Service mode configuration from environment variables
     config_path = os.environ.get(
         "SERVICE_MODE_DIT_MODEL",
-        "acestep-v15-turbo"
+        "acestep-v15-xl-turbo"
     )
     # Second DiT model - default to turbo-shift3 for two-model setup
-    config_path_2 = os.environ.get("SERVICE_MODE_DIT_MODEL_2", "acestep-v15-turbo-shift3").strip()
+    config_path_2 = os.environ.get("SERVICE_MODE_DIT_MODEL_2", "acestep-v15-turbo").strip()
     
     lm_model_path = os.environ.get(
         "SERVICE_MODE_LM_MODEL",