The "fileedit-glob" setting:

The VALUE of this setting is a list of GLOB patterns matching files which are allowed to be edited using the /fileedit page. An empty list suppresses the feature. Example: *.md,*.txt The parsing rules are complex; see https://fossil-scm.org/home/doc/trunk/www/globs.md#syntax Note that /fileedit cannot edit binary files, so the list should not contain any globs for, e.g., images or PDFs.