With the release of lunr.py 0.6.0, the lunr pipeline is now configurable. See my feature request there.

This means you can now generate a pre-built search index with, e.g., disabled stemming.

It would be nice to integrate this functionality in the search plugin, so we can modify the pipeline when using prebuilt_index, as outlined here:

- search:
    prebuild_index: python
    pipeline:
        - stemmer: false
        - trimmer: true
        - stopWordFilter: true

Currently, themes that modify the pipeline can only do this when the index is not pre-built, leading to inconsistent search behavior depending on whether prebuilt_index is enabled or not.