File include would be a replacement for the current system used to define what files are synchronized by the server.

Currently, the directory management list is used to determine what files should be served, this should change to a more standard file include/ignore list pair.

directories: [...] // Directory management modes
files: {
  include: [...] // Glob patterns to include
  ignore: [...] // Glob patterns to ignore
}

• Directory patterns should be automatically transformed to their glob equivalent
• Included files/directories should be added to the manifest
• Ignored files should not be added to the manifest

The initial draft of this feature is available in alpha 6|
https://github.com/rheimus/ServerSync/releases/tag/3.7.0-alpha.6