Function upload_answer_files 

async fn upload_answer_files(
    pool: Data<PgPool>,
    exercise_task_id: Path<Uuid>,
    payload: Multipart,
    file_store: Data<dyn FileStore>,
    user: AuthUser,
    app_conf: Data<ApplicationConfiguration>,
) -> ControllerResult<Json<Vec<ExerciseServiceUploadResultEntry>>>

POST /api/v0/files/answer-uploads/:exercise_task_id Used to upload the files a student is attaching to an answer for the given exercise task.

Unlike POST /api/v0/files/:exercise_service_slug this binds every stored file to the uploader and the task’s exercise, which is what lets a later submission verify that the answer only names files the submitter uploaded for that exercise.

Returns

An ordered list of file_uploads ids and stored URLs, in the order the parts were sent.