See PHI1394. Currently, if you run `arc diff` from a working directory with: more than 255 characters; or (probably) non-UTF8 characters, the operation fails:
> {"result":null,"error_code":"ERR-CONDUIT-CORE","error_info":"#1406: Data too long for column 'sourcePath' at row 1"}
The desired path forward here is //likely// to remove `sourcePath` and `host`. Previously, see T838.
(These fields do power some `arc` behavior today so we can't strictly just rip them out, and it's possible that unusual/niche workflows care about them.)