tiddlywebplugins.twimport now implements some of the functionality
from bimport. The rules go like this (for twanager twimport bag_name
filename) where filename is:

• .{wiki,html} import as a tiddlywiki
  

note: i suggest also to include '.htm' for importing tiddlywikis

• .{tid,tiddler,js} import as various forms of tiddler
  

.tid is tiddlyweb text store style
.js and .tiddler are Cook formats

• .{recipe} import the expansion of a recipe
  
  

• .<anything else> import as a "binary" tiddler, attempting
  

to deduce the content-type

twimport is include with the latest tiddlywebwiki dependencies