There’s a telling admission about a minute and a half into Code Girl, the riveting new double album by Mary Halvorson. It arrives after she sets a mood on guitar, using pedal effects to loop her lines into a web — a tactic you’ll recognize if you know her heralded work as an improviser.
“It is not predictable, my mind,” goes the line in question, from a song called “My Mind in Time.” And the message in that refrain, sung with penetrating calm by Amirtha Kidambi, feels almost self-fulfilling. Halvorson’s music has always had the capacity to surprise, but Code Girl amounts to the most startling move in her solo career. It’s clearly the work of an unpredictable mind, and a personality drawn at once to unruly possibility and fastidious detail.