Programs that use configuration files should provide ways to: show which sources of config data were used: files, CLI, env vars, etc. with --verbos

Programs that use configuration files should provide ways to: show which sources of config data were used: files, CLI, env vars, etc. with --verbose, also show which potential sources were not used show any conflicts or overrides from config sources show config settings differing from program defaults in the same format as their source, or in an appropriate format for a config file For the last item, it should be possible to capture the output showing non-default settings and append it to a config file, without any editing or processing, to reproduce the program configuration state exactly.