I need to change the type for a large number of tiddlers (from text/plain to text/markdown). I hoped that the Commander plugin might be able to do this but cannot find the option there. Is there some other way of achieving this?
Additionally, if I am importing an external file by dragging it into TW, how can I ensure that the Type is set to text/markdown?
There is a config tiddler
$:/plugins/kookma/commander/config/systemfields
It defines which system fields will be excluded from some operations in Commander. Edit this tiddler and remove type from it, then you should be able to edit the type field by Commander.
Is @vilc suggestion working for you?
Can you list the tiddlers to change with a filter so you don’t change others.
Since you already have the Commander plugin: you should see a “batch Edit” button after performing the import. That will enable you to apply your change to exactly the imported batch — once you allow Commander to “see” the type field, of course, as suggested by @vilc.