BTVS's showrunners history

For the first 5 seasons,the showrunner was Joss Whedon. In season 6,when the show changed network (going from WBtv to UPN),Joss decided to leave the role of showrunner to Marti Noxon,who acted as showrunner during that season,while Whedon was preparing the pilot for the tv show "Firefly". Then,Marti Noxon left the show because she was pregnant and went into materinity leave,so during season 7 its kinda obscure who was the showrunner. I didnt find any official article about it. Whedon wrote and directed several episode of season 7,as it was Buffy's final season,so he wanted to take care of it. But its also true that,especially in the first half of the season,he was also busy with Firefly and other projects,so he was probably not so much present in the set at the time. Maybe it was Jane Espenson or David Fury,as they were the most expert Buffy writers at the time? Quick recap:

-Seasons 1-5: Joss Whedon
-Season 6: Marti Noxon
-Season 7: Joss Whedon,Jane Espenson,David Fury