Joy was pervasive Sunday at Pitchfork Music Festival. Maybe that’s odd considering the national mood lately has been characterized by hostility, despair, and righteous fury — even more so considering the contentious role that Chicago, the city that hosts this event every summer at Union Park, tends to play in that discourse. Maybe a lineup that erred on the side of visceral, sharp-edged aggression would be more in keeping with that mood. Maybe the people at Pitchfork programmed Sunday’s lineup as a conscious rejection of it. I don’t know how they assemble these things. I do know the result was nonstop merrymaking.

An abundance of Chicago hip-hop acts on the main stages — Noname, Smino, Ravyn Lenae, Kweku Collins, and Nnamdi Ogbonnaya, plus Moor Mother’s experimental jazz act Irreversible Entanglements — turned the festival’s early and middle hours into an exuberant local music showcase-cum-pep rally. DRAM was there, being DRAM. At one point late in the day Chaka Khan and Japandroids advanced competing notions of feel-good music from opposite ends of the park; to stand at the midpoint between them was to witness an especially jubilant soundclash.

None of these acts were surprising sources of joy. They all have a reputation for it. I was not prepared, however, to be walloped by posi vibes from Japanese Breakfast.

Go figure: A project that emerged out of grieving her mother has become an outlet for Michelle Zauner’s broadest smiles. Looking back on photos from other gigs this year, it appears that this is normal for a Japanese Breakfast performance. Whether slinging a guitar or forgoing it to stalk the stage with a microphone, Zauner is often dancing, bouncing, beaming, rejecting the serious-artiste posturing you’d expect from a critical darling out of America’s current cool-kid music capital. Her demeanor transforms her songs. Although they remain shaded in melancholy, they burst from the stage with a delighted enthusiasm.

Perhaps “Everybody Wants To Love You” should have tipped me off. Even then, on 2016 debut Psychopomp — an album named after “creatures, spirits, angels, or deities in many religions whose responsibility is to escort newly deceased souls from Earth to the afterlife” — she slid a moment of pure buoyancy onto the tracklist. Onstage Sunday, the song’s vision of dream-pop beauty filling out the edges of a big happy rock song was the most in-tune with the vibe of Zauner and her bandmates.

“Diving Woman,” which opens last year’s Soft Sounds From Another Planet, worked even better kicking off a concert. Its spaced-out bass groove and ceaseless vamp gave Zauner and friends ample opportunity to swing their headstocks and hop in time with the beat. The live context brought out the heartier rock elements of “In Heaven,” its dreamy aspects downplayed in favor of temperate guitar rock á la Wilco’s “Pot Kettle Black.” It wasn’t the only time Wilco crossed my mind. “Heft,” another early shoegaze-rocker, even featured a guitar solo from Japanese Breakfast’s very own Nels Cline character, who turned right around and laid another one on the grandiose and graceful ’50s prom dance “Boyish.”

(I’m talking guitar solos that would have been laughed out of indie rock a few years ago for being too corny — spotlight moments on the bridge built to let a six-string hero shine, like you’d hear on a country song or a classic rock radio hit. Is this … cool now?)

Whenever Zauner set herself free from the guitar, as on “Woman That Loves You” and the set-closing robo-romance “Machinist,” she proved she’s adept at the tactics of a Gwen Stefani or Hayley Williams, punching the sky and venturing out to the far reaches of the stage to rally her audience. Even the ethereal swoon “Road Head” became a commanding groove with Zauner going full pop-star. It speaks to her versatility that she can toggle between this and strapping the guitar back on for a ’90s alt-rock homage like “Body Like A Blade” — or actual ’90s alt-rock via a cover of the Cranberries’ “Dreams” — and it all feels of a piece, like furniture that you’d think would clash but actually ties a room together. Hearing her creation come to life like this, Zauner had reason to be joyful, and so did the rest of us.