diff --git a/backend/apps/outputs/outputs.py b/backend/apps/outputs/outputs.py
index 80cb42f3..4bdc1284 100644
--- a/backend/apps/outputs/outputs.py
+++ b/backend/apps/outputs/outputs.py
@@ -671,6 +671,8 @@ async def create_output(body: OutputCreate):
         input_schema=body.input_schema,
         files=body.files,
         thumbnail=body.thumbnail,
+        # The request model has carried this since the workspace era; the route dropped it, so an API caller's app had no workspace and its card said the files were missing.
+        workspace_id=body.workspace_id,
         created_at=now,
         updated_at=now,
     )
diff --git a/backend/tests/test_output_create_workspace.py b/backend/tests/test_output_create_workspace.py
new file mode 100644
index 00000000..be6e87ab
--- /dev/null
+++ b/backend/tests/test_output_create_workspace.py
@@ -0,0 +1,12 @@
+"""`POST /api/outputs/create` advertises `workspace_id` in its request model and used to drop it on the
+floor: an API caller's app had no workspace, its card said the files were missing, and the Windows
+CI round trip exported an empty app before it ever reached the importer (2026-09-04)."""
+
+import inspect
+
+from backend.apps.outputs import outputs
+
+
+def test_create_carries_the_workspace_id_into_the_record():
+    src = inspect.getsource(outputs.create_output)
+    assert "workspace_id=body.workspace_id" in src