“911 (A. G. Cook Remix)” is a remix of Lady Gaga’s song 911 from her sixth studio album Chromatica. It features vocals by British singer-songwritter Charli XCX and additional production by A. G. Cook.

Charli revealed the idea of the remix and it’s unsuccessful happening during her Twitter Q&A when she was asked about Chromatica:

Bloodpop, one of the original producers then replied to the tweet with screenshot of his messages with Charli:
Later in April 2021, Bloodpop confirmed that he’s working on to make everything happen:

In May 2021, Charli confirmed that she’s begun the process of recording the remix:
In August 2021, Bloodpop was again asked about the song and if Charli’s frequent collaborator A. G. Cook was involved. He replied with enthusiasm and in past tense implying that it’s already finished:

Later that month few hours after the remix album was announced, producer A. G. Cook shared a snippet of the song on his Instagram stories.