PW Kindle library wont recognize new .mobi files

[AmarettoWill]

I'm trying to set up automatic wireless daily delivery of news to my hacked kindle. I've set up Calibre so that at 3am everyday it fetches news, builds custom .mobi files, and I have a bash script on the Kindle which pulls the files over local WiFi and drops them in /mnt/base-us/documents/.

That works fine, but the Kindle's native library doesn't register the new .mobi files in the library. I can view the files using KOReader through KUAL instead of the native Kindle ebook reader, but KOReader screws up Calibre's nice formatting, so it's a less desirable option. Any ideas for how to get Kindle's native library to recognize the newly added .mobi files?