By default, TextrudeInteractive stores all text within the project file. However, below each input and output pane is a set of file linkage controls which can be used to establish links to files on disk.
A link is established by using either the load from file or save to file buttons. From that point the file path will appear in the path section. The file can then be reloaded or saved with a single button press.
Breaking the link can be done with the break link button.
Note that linked files are not automatically reloaded or saved. You can use the Inputs/Reload linked or Outputs/Save linked menu items to save multiple inputs or outputs.