In Canary, there is a new dedicated Sass module for a more improved Sass authoring and debugging workflow. One common problem (still present in stable) is for line number (and filename) mappings to disappear upon CSS editing.
In Canary, this use case is fixed, but also the workflow is significantly improved and will enable a tighter integration between Sass and compiled CSS.
Warning: This is an in-development feature currently in Canary! Things are likely to change.