Add API routes directly to Gradio's FastAPI app - no monkey-patch needed

app.py

@@ -3,11 +3,9 @@ import platform
 import sys
 import shutil
 import tempfile
-import traceback
 import torch
 import torchaudio
 import gradio as gr
-from fastapi import FastAPI
 from fastapi.responses import JSONResponse
 from einops import rearrange
 from huggingface_hub import login
@@ -127,66 +125,58 @@ def generate_audio(prompt, duration, steps, cfg_scale, seed, model_name):
 
 
 # ---------------------------------------------------------------------------
-# Gradio UI (built inside a function to keep it out of global scope)
+# Gradio UI
 # ---------------------------------------------------------------------------
 
-def _build_ui():
-    with gr.Blocks(title="Respite API") as ui:
-        gr.Markdown("# Respite API - Music & SFX Generation")
-        gr.Markdown(
-            "Generate music and sound effects using "
-            "Stability AI's Stable Audio 3 Small models."
-        )
-
-        with gr.Row():
-            with gr.Column():
-                model_name = gr.Dropdown(
-                    choices=["small-music", "small-sfx"],
-                    value="small-music", label="Model",
-                )
-                prompt = gr.Textbox(
-                    label="Prompt",
-                    placeholder="Describe the music or sound effect you want to generate...",
-                    lines=2,
-                )
-                duration = gr.Slider(minimum=1, maximum=120, value=30, step=1, label="Duration (seconds)")
-                steps = gr.Slider(minimum=1, maximum=50, value=8, step=1, label="Steps")
-                cfg_scale = gr.Slider(minimum=0.0, maximum=10.0, value=1.0, step=0.1, label="CFG Scale")
-                seed = gr.Number(value=-1, label="Seed (-1 for random)")
-                btn = gr.Button("Generate", variant="primary")
-
-            with gr.Column():
-                audio_output = gr.Audio(label="Generated Audio", type="filepath")
-
-        btn.click(
-            fn=generate_audio,
-            inputs=[prompt, duration, steps, cfg_scale, seed, model_name],
-            outputs=audio_output,
-        )
-
-    return ui
+with gr.Blocks(title="Respite API") as demo:
+    gr.Markdown("# Respite API - Music & SFX Generation")
+    gr.Markdown(
+        "Generate music and sound effects using "
+        "Stability AI's Stable Audio 3 Small models."
+    )
+
+    with gr.Row():
+        with gr.Column():
+            model_name = gr.Dropdown(
+                choices=["small-music", "small-sfx"],
+                value="small-music", label="Model",
+            )
+            prompt = gr.Textbox(
+                label="Prompt",
+                placeholder="Describe the music or sound effect you want to generate...",
+                lines=2,
+            )
+            duration = gr.Slider(minimum=1, maximum=120, value=30, step=1, label="Duration (seconds)")
+            steps = gr.Slider(minimum=1, maximum=50, value=8, step=1, label="Steps")
+            cfg_scale = gr.Slider(minimum=0.0, maximum=10.0, value=1.0, step=0.1, label="CFG Scale")
+            seed = gr.Number(value=-1, label="Seed (-1 for random)")
+            btn = gr.Button("Generate", variant="primary")
+
+        with gr.Column():
+            audio_output = gr.Audio(label="Generated Audio", type="filepath")
+
+    btn.click(
+        fn=generate_audio,
+        inputs=[prompt, duration, steps, cfg_scale, seed, model_name],
+        outputs=audio_output,
+    )
 
 
 # ---------------------------------------------------------------------------
-# FastAPI application with discovery routes
+# Add discovery routes directly to Gradio's internal FastAPI app.
+# demo.app exists as a FastAPI-compatible app after the Blocks context exits.
 # ---------------------------------------------------------------------------
 
-app = FastAPI(title="Respite API")
-
-
-@app.get("/respite/resources")
-def resources():
+@demo.app.get("/respite/resources")
+def _resources():
     return JSONResponse({"resources": API_RESOURCES})
 
 
-@app.get("/respite/specs")
-def specs():
+@demo.app.get("/respite/specs")
+def _specs():
     return JSONResponse({**API_SPECS, "runtime": _get_runtime_specs()})
 
 
-# Mount the Gradio UI onto the FastAPI app.
-# The HF Spaces Gradio runner should detect `app` (FastAPI) as the
-# entrypoint and serve it directly.
-app = gr.mount_gradio_app(app, _build_ui(), path="/")
+_log("Respite API routes registered")
 
-_log("Respite API application initialized")
+demo.queue(max_size=4, default_concurrency_limit=1)