This project makes use of Eagle, provided by Mistachkin Systems.
Eagle: Secure Software Automation

The "/builtin" page:

Return one of many built-in content files. Query parameters:
Return the single file whose name is FILENAME.
Override the mimetype in the returned file to be TYPE. If this query parameter is omitted (the usual case) then the mimetype is inferred from the suffix on FILENAME
IDLIST is a comma-separated list of integers that specify multiple javascript files to be concatenated and returned all at once.
Version number of the "builtin" files. Used for cache control only.

At least one of the name= or m= query parameters must be present.

If the id= query parameter is present, then Fossil assumes that the result is immutable and sets a very large cache retention time (1 year).