Mount Gradio OAuth routes for canvas sign-in

app.py

@@ -309,6 +309,9 @@ with gr.Blocks(title="Workflow Studio", analytics_enabled=False, fill_width=True
     api_run.click(generate, [api_scalars["preset_id"], api_scalars["prompt"], first, last,
                             api_scalars["canvas"], api_scalars["duration"], api_scalars["seed"]],
                   [video, result], api_name="generate", concurrency_limit=None)
+    # The canvas has its own sign-in button; this hidden one makes Gradio mount
+    # the /login/huggingface OAuth routes it uses.
+    gr.LoginButton(visible=False)
     runtime = gr.JSON(visible=False)
     gr.Button(visible=False).click(health, outputs=runtime, api_name="health", queue=False)
     generate_index = next(i for i, fn in demo.fns.items() if fn.api_name == "generate")