Still, she is enjoying the spoils of her hits — she recently toured a $3.4 million home in the Los Angeles area in what the listing described as a “highly desirable celebrity neighborhood” — along with the perks of obscurity. “I love my day to day,” Starrah said. “I don’t want it to be crowded, or to ever affect me going home, being with my family, taking my nieces bowling or to the skating rink.”

The next afternoon, she was back in the studio, as if it were any other day job. While the producers Jason Evigan — with whom Starrah wrote Maroon 5’s recent Top 10 hit “What Lovers Do” — and Cirkut plinked around with a moody ’80s synth line, Starrah sat silently in a corner, tapping lyrics into her phone. (While many modern songwriters — from Migos to Sia to Ed Sheeran — tend to start with melodies, using gibberish as lyrics and then fit words in retroactively, Starrah writes lyrics first and then molds them to the production.)

After barely 10 minutes of hearing the looped riff, she stood up: “Ready?”

Cirkut laughed. “She out-wrote the beat,” he said, rushing to finish his part as Starrah made her way to the darkened vocal booth.

What she delivered, filtered through Auto-Tune, was a rush of tangled syllables and rat-a-tat repetition that somehow sounded familiar and was instantly hummable. In another half an hour, she had a first verse, chorus and post-chorus down, and she left the microphone to write some more. Mr. Jarjour estimated that Starrah had up to 800 such sketches.

She paced the room searching for more inspiration, but not too hard. In an imperceptible instant, she decided it just wasn’t happening that afternoon, exchanged a few pleasantries with her producers and was gone. Just as easily as she’d conjured future radio catnip, Starrah had clocked out.