Who wrote the משנה ברורה?

 

Daf Yomi כתובות ל"ד המבשל בשבת       Who wrote the משנה ברורה? The משנה ברורה שי"ח ס"ק י"ד ) writes " Food that was cooked for a sick person on Shabbos, even healthy people may eat it immediately on Motzei Shabbos. (Since it was cooked בהיתר  there is no problem of בישול עכו"ם & no need of בכדי שיעשו)  The Dirshu Mishna Berurah quotes from the  (שביתת השבת & שונה הלכות (ר' חיים קניבסקי שליט"א who ask from the מ"ב שכ"ח ס"ק סג "Food cooked for a חולה on Shabbos may not be eaten on Motzei Shabbos even for the חולה, since you can cook for him fresh food on Motzei Shabbos." The שביתת השבת & שונה הלכות answer various answers to solve the contradiction in the מ"ב. In the ספר כל ספרי החפץ חיים ח"ג There is a chapter written by the son of the Chofetz Chaim הרב אריה לייב הכהן זצ"ל. He writes that the Chofetz Chaim paid him a monthly salary of 20 Rubles so that he will help him with writing the מ"ב. *The first volume of the מ"ב and most of volume 3 were written entirely by the Chofetz Chaim.  The rest of the מ"ב R. Aryeh used to send to the Chofetz Chaim his pieces of Mishna Berurah & Biur Halacha. The Chofetz Chaim reviewed (edited) and entered them in the Sefer. When the Chofetz Chaim wasn't satisfied he rejected it and  entered his own פסק. There were times when a הלכה somehow slipped through and was entered even though the Chofetz Chaim was not in agreement with it. Therefore you will find at times contradictions in the מ"ב.  One such example is the סתירה in the מ"ב between סימן שי"ח & סימן שכ"ח  R Aryeh writes that in שי"ח is the Psak of the Chofetz Chaim who allowed eating the food immediately after Shabbos. In שכ"ח is his own Psak where he argues with his father and forbids food cooked by an עכו"ם on Shabbos to be eaten after Shabbos. *Most of the מ"ב was written by R.Aryeh Zt"l & edited by the Chofetz Chaim