Create .scalafmt.conf at the repo root (may be empty). And add to the WORKSPACE
load("@rules_scala3//rules/scalafmt:config.bzl", "scalafmt_repositories")
scalafmt_default_config()And in BUILD
load("@rules_scala3//rules:scalafmt.bzl", "scala_format_test")
scala_format_test(
name = "format",
srcs = glob(["**/*.scala"]),
)Then
# check format, with diffs and non-zero exit in case of differences
$ bazel test :format
# format files in-place
$ bazel run :format