Taylor Swift will release “The Life of a Showgirl: The Encore,” an extended edition of her 12th studio album, on Friday. The new version adds four tracks, including the freshly announced single “Patient Zero.”

Swift announced the project on social media with a note explaining its origins. “About a year ago, you guys did a truly unfathomable thing. Something that completely blew my mind … You gave The Life of a Showgirl the biggest first week for an album in history,” she wrote. To celebrate, she traveled to Sweden with her two collaborators on the album, producers Max Martin and Shellback.

“Really we just wanted to reflect and take in how grateful we were for the moment we were in, but there was a studio there and we did what we do when we feel anything at all: We wrote more songs,” Swift wrote. She closed the note: “I hope you love them, because they were born out of pure gratitude for your exuberance for and celebration of the album we made.”

The release reverses a stance Swift took when the album came out on October 3. At the time, she insisted the record was complete at 12 tracks. “There’s not a 13th, there’s not other ones coming,” Swift said during an appearance on “New Heights,” the podcast hosted by her husband, Travis Kelce. “Every single song is on this album for hundreds of reasons, you know, and you couldn’t take one out and it’d be the same album. You couldn’t add one. It’s just right.”

She doubled down at the time: “I wanted to do an album that was so focused on quality and on the theme and everything fitting together like a perfect puzzle, that these 12 songs for my 12th album, I feel like we achieved that, and I’m really happy about that.”

Swift confirmed the new single “Patient Zero” on Tuesday. She did not initially declare it the lead single for the deluxe edition, but fans noticed that the album’s logo appeared under CD single versions on her official website — a signal that more was coming.

The website itself changed from a sparkly orange to a dark gray and began offering three CD versions of “Patient Zero,” each with a different cover image of Swift in black. In her Instagram post announcing the track, she also wore a black high-neck tank top. Swift changed her profile picture across social media as well — a move that has historically signaled the start of a new era for the singer. By Wednesday, the profile picture showed the cover of “The Life of a Showgirl: The Encore.”

The extended edition brings the track list to 16 songs, with “Patient Zero” joined by “Cleveland!,” “Pink Clouding” and “Babylon” after the original dozen.

The full track list:

1. “The Fate of Ophelia”
2. “Elizabeth Taylor”
3. “Opalite”
4. “Father Figure”
5. “Eldest Daughter”
6. “Ruin the Friendship”
7. “Actually Romantic”
8. “Wi$h Li$t”
9. “Wood”
10. “Cancelled!”
11. “Honey”
12. “The Life of a Showgirl”
13. “Patient Zero”
14. “Cleveland!”
15. “Pink Clouding”
16. “Babylon”

The Friday release, arriving nearly a year to the month after the original album, gives fans the first new Swift recordings since the record-breaking debut — and tests whether gratitude, as she puts it, can top the biggest first week in album history.