fix: serve studio preview fallbacks without 404

inferedgelab/studio/routes.py

@@ -12,6 +12,7 @@
 from fastapi import Body
 from fastapi.responses import FileResponse
 from fastapi.responses import RedirectResponse
+from fastapi.responses import Response
 
 from inferedgelab.compare.comparator import compare_results
 from inferedgelab.compare.judgement import judge_comparison
@@ -61,6 +62,26 @@ def studio_korean_particle_redirect() -> RedirectResponse:
 
 @router.get("/studio/static/{asset_name}", include_in_schema=False)
 def studio_static(asset_name: str) -> FileResponse:
+    return _studio_static_response(asset_name)
+
+
+@router.get("/app.js", include_in_schema=False)
+def studio_file_preview_app() -> Response:
+    return _studio_file_preview_placeholder(
+        "application/javascript",
+        "// Local server placeholder: /studio/static/app.js owns Studio initialization.\n",
+    )
+
+
+@router.get("/style.css", include_in_schema=False)
+def studio_file_preview_style() -> Response:
+    return _studio_file_preview_placeholder(
+        "text/css",
+        "/* Local server placeholder: /studio/static/style.css owns Studio styling. */\n",
+    )
+
+
+def _studio_static_response(asset_name: str) -> FileResponse:
     media_type = STATIC_ASSETS.get(asset_name)
     if media_type is None:
         raise HTTPException(status_code=404, detail="studio asset not found")
@@ -71,6 +92,14 @@ def studio_static(asset_name: str) -> FileResponse:
     )
 
 
+def _studio_file_preview_placeholder(media_type: str, content: str) -> Response:
+    return Response(
+        content=content,
+        media_type=media_type,
+        headers={"Cache-Control": "no-store"},
+    )
+
+
 @router.get("/studio/api/jobs", include_in_schema=False)
 def studio_jobs(request: Request) -> dict[str, Any]:
     store = _get_studio_job_store(request)

tests/test_studio_routes.py

@@ -5,6 +5,7 @@
 
 from fastapi.responses import FileResponse
 from fastapi.responses import RedirectResponse
+from fastapi.responses import Response
 
 import inferedgelab.api as api
 
@@ -100,6 +101,26 @@ def test_studio_static_assets_are_served():
     assert "pipeline-flow" in Path(style_response.path).read_text(encoding="utf-8")
 
 
+def test_studio_file_preview_asset_fallbacks_are_served():
+    app = api.create_app()
+    app_route = _get_route(app, "/app.js")
+    style_route = _get_route(app, "/style.css")
+
+    app_response = app_route.endpoint()
+    style_response = style_route.endpoint()
+
+    assert isinstance(app_response, Response)
+    assert isinstance(style_response, Response)
+    assert app_response.status_code == 200
+    assert style_response.status_code == 200
+    assert app_response.headers["cache-control"] == "no-store"
+    assert style_response.headers["cache-control"] == "no-store"
+    assert app_response.media_type == "application/javascript"
+    assert style_response.media_type == "text/css"
+    assert b"/studio/static/app.js owns Studio initialization" in app_response.body
+    assert b"/studio/static/style.css owns Studio styling" in style_response.body
+
+
 def test_studio_static_assets_include_redesigned_ui_contracts():
     app = api.create_app()
     route = _get_route(app, "/studio/static/{asset_name}")