fix: Add ephemeral file upload support (#12300)

* add image temporary field to backend

* [autofix.ci] apply automated fixes

* fix tests files

* fix file upload component test

* merge fix from rc branch

---------

Co-authored-by: Hanzo Dev <[email protected]>

src/backend/base/langflow/api/v2/files.py

@@ -137,6 +137,7 @@ async def upload_user_file(
     settings_service: Annotated[SettingsService, Depends(get_settings_service)],
     *,
     append: bool = False,
+    ephemeral: bool = False,
 ) -> UploadFileResponse:
     """Upload a file for the current user and track it in the database."""
     # Get the max allowed file size from settings (in MB)
@@ -299,6 +300,12 @@ async def upload_user_file(
             # General error saving file or getting file size
             raise HTTPException(status_code=500, detail=f"Error accessing file: {e}") from e
 
+        if ephemeral:
+            # Ephemeral uploads: file is saved to storage (servable for chat history)
+            # but no UserFile record is created (won't appear in "My Files")
+            file_path = f"{current_user.id}/{stored_file_name}"
+            return UploadFileResponse(id=file_id, name=root_filename, path=file_path, size=file_size)
+
         if append and existing_file:
             existing_file.size = file_size
             session.add(existing_file)

src/backend/tests/unit/api/v2/test_files.py

@@ -149,6 +149,43 @@ async def test_upload_file(files_client, files_created_api_key):
     assert "id" in response_json
 
 
+async def test_should_not_persist_in_my_files_when_upload_is_ephemeral(files_client, files_created_api_key):
+    """Ephemeral uploads save the file to storage but do NOT create a UserFile DB record.
+
+    This is the expected behavior for chat playground uploads in Desktop,
+    where the file must be servable (for chat history) but should not
+    appear in the user's 'My Files' list.
+    """
+    headers = {"x-api-key": files_created_api_key.api_key}
+
+    # Upload with ephemeral=true
+    response = await files_client.post(
+        "api/v2/files",
+        files={"file": ("playground_image.png", b"fake image content")},
+        params={"ephemeral": "true"},
+        headers=headers,
+    )
+    assert response.status_code == 201, f"Expected 201, got {response.status_code}: {response.text}"
+
+    upload_response = response.json()
+    assert "path" in upload_response
+
+    # The file must NOT appear in the user's file list
+    list_response = await files_client.get("api/v2/files", headers=headers)
+    assert list_response.status_code == 200
+    file_names = [f["name"] for f in list_response.json()]
+    assert "playground_image" not in file_names, (
+        f"Ephemeral file should not appear in My Files, but found: {file_names}"
+    )
+
+    # The file is saved in storage and the response includes a valid path
+    file_path = upload_response["path"]
+    assert file_path, "Ephemeral upload should return a non-empty path"
+    # Path format: {user_id}/{stored_file_name}
+    parts = file_path.split("/")
+    assert len(parts) == 2, f"Expected path format 'user_id/filename', got: {file_path}"
+
+
 async def test_should_return_path_with_forward_slashes_when_uploading_file(files_client, files_created_api_key):
     """Upload response path must use forward slashes on all platforms.