I tried setting up the extension on an existing project.  The directory has a file at .eclipse/.bazelproject.  I'm using version  1.25.101230444.
 
~/project ± ● main
❯ ls -all .eclipse
total 8
drwxr-xr-x@  3 dan  staff   96 Feb 16 17:14 .
drwxr-xr-x  24 dan  staff  768 Feb 16 17:14 ..
-rw-rw-rw-@  1 dan  staff  121 Feb 16 18:14 .bazelproject