So the issue is that the extension that provides the search capability isn't in the default image. You can either disable that extension or build a local image to use.

I'll think about how to make this more automated.

Disable extension

. Edit site.yml
. Add enabled: false (indent it 4 spaces) under the line index_latest_only: true

Build local image

This assumes you're using podman. If you're using Docker, replace podman with docker (some operations may require sudo)

. Run podman build . -t antora:lunr to build the image
. Run podman run --rm -it -v "$PWD:/antora:z" antora:lunr --html-url-extension-style=indexify site.yml to build
. Run ./preview.sh to run a local web server as normal