A set of options in the File ▸ Watch allows the creation of various types of watched folders linked to external applications. The result is a form of AutoFetch operation.
Multiple watched folders of the same source type (e.g. more than one Notes folder) are allowed though be mindful heavy use of this feature may affect overall performance, i.e. the feature is not designed as a fully-synced system but rather for importing/updating some external data.
A watched folder is always added at root level in a document (and should not be moved elsewhere). This is for necessary design considerations re performance. Likewise the watched destination is envisaged as a single item or small collection of items and not a large hierarchy of folders/files.
The prototypes of watched notes specify that watched notes are imported with a $TextBackgroundColor of white, even if dark styles, since external documents are most likely compatible with light background colours.
Notes imported from watch folders respect ziplinks-style '[[' markup. To disable ziplinks in a watched folder note, set $Ziplinks to false. To disable ziplinks throughout a watch folder, set $Ziplinks for the folder to false.
Refresh timing: all watched folders are refreshed when the TBX document is opened. Then, while the document remains open, the folders are refreshed periodically on their own cycle. The frequency of that cycle is not documented and no force refresh mechanism is known.
There are currently 3 forms of watched folder: