The announcement Sept. 5 of a forthcoming boxed set devoted to the early work of Hüsker Dü, “Savage Young Dü,” immediately prompted yet another wave of nostalgia for the pioneering punk band on social media. Old-school fans once again daydreamed aloud: As one of the very few legendary bands of the era never to reunite, could this be a first step?

Few but a handful of close followers knew just how impossible that dream had become, with Grant Hart suffering from the final stages of cancer. In the early morning hours of Sept. 14, the news broke that Hart had passed away at age 56.

With his soulful vocals and rapid-fire drumming, Hart was a hero to an entire “alt” generation, with many considering Hüsker Dü one of the all-time greatest bands in the genre, and 1984’s sprawling and ambitious “Zen Arcade” to be one of the most expansive albums produced by an American band in that decade. They were a band of firsts — the first to come above-ground from the hardcore scene, perhaps, to explore such rich melodies or sometimes odd subject matter, and the first to controversially exit their punk indie imprint for a corporate major label. They were also a band of lasts — as in being just about the last major band in rock to refuse to give in to reunion fever even for a one-off, so acrimonious was their ’87 split.

Bob Mould was the most visible member of the trio, as the primary singer and songwriter for Hüsker Dü’s first few albums. But some fans identified more with Hart, the underdog who pushed his way from having only a couple of his songs make it onto some of the band’s mid-period albums to claiming nine out of 20 on their two-LP swan song, “Warehouse: Stories and Songs.” (There may have been significance to those numbers; in a typical gripe, Hart claimed that, at the end, Mould had a policy of not letting him take the lead on more than 45 percent of an album.)

By the time of “New Day Rising” in 1985, Hart was rising within the group, offering a more melodious voice than Mould’s in blistering yet hook-driven tracks like “The Girl Who Lives on Heaven Hill,” even as he brought an odder lyrical sensibility to numbers like “Terms of Psychic Warfare” and “Books About UFOs,” in the best Syd Barrett tradition of weirdo pop. “As (for) our embrace of pop;” Hart said, “we weren’t the only band that went more pop-sounding, but as far as making that travel from where we originated to where ended up, it was a great leap.”

For a season, at least, he wrote some more straightforward material, including songs that were covered by bands they influenced (and which became much more well-known than they were). When Green Day covered a Hüsker Dü song, it was Hart’s modern-rock radio fave “Don’t Want to Know if You Are Lonely.” When the Foo Fighters did one, it was Hart’s “Never Talking to You Again.” (He was at his most cantankerous when asked about Dave Grohl’s hero-worshipping cover: “I do not care for the Foo version of ‘Never’,” he said in a 2013 interview with the Music Universe. “I think they never made too much effort… Honestly, I am glad those fellows are free to do something else.”)

Depending on whose stories fans listened to, the band came to an end either over Hart’s anger at Mould’s control issues or Mould’s outrage over Hart’s heroin habit at the time. Until recently, the three never again shared a space or got beyond the most perfunctory and sporadic business emails, although there is one sort-of exception: In 2004, minus Husker bassist Greg Norton, Hart and Mould did manage to smoke the peace pipe just long enough to perform two songs together at a Minneapolis benefit for cancer-stricken Soul Asylum member Karl Mueller. But practically within minutes, they seemed to have retreated to their separate corners, Mould all but spitting on the idea of a band reunion, and Hart leaving the door open but responding to Mould’s slights with ever pithier retorts.

Asked about being treated dismissively in Mould’s memoir, Hart said that the book “really sounds like it was written by the President of the Bob Mould Fan Club rather than by Bob Mould.” And: “I think he has burned more bridges than the interstate highway system ever built.” Yet he occasionally let some sorrow over the fissure show: “Bob’s got some hurt to put behind him yet. I think the world of the guy, but he doesn’t even want to talk about the pain that I’ve been able to work out by talking to other people, and if I sincerely wounded him, you know, I’d like that put that right. This is supposed to be the part of a person’s life where they start thinking about how they’ve lived their life, who they’ve touched and who they’ve affected.”

But Hart came off as at least as determined to be forward-facing. “Nobody has ever loved Bob Mould like I have,” he said in a 2013 Facebook chat. “I scaled great heights with him musically. Our admiration for each other, never physical, brought forth a new way of music.” (The “never physical” aside was another confirmation to inquiring minds that Hart, a bisexual, and Mould, a gay man, had never been romantically involved.) “Wouldn’t there be unfair pressure on the two of us if we made music live again?… The reunion fad seems to be energized by mid-life crisis. I am sure Bob would agree with me on this. I would rather have Grant Hart fans coming to my own shows than Hüsker Dü fans… I want people coming that don’t feel like they are settling for something less. My shows are not compromises with the past. My shows are as much about the future as I can make them. And the future is right f—ing now!”

He took the words out of some other sages’ mouths in a 2012 interview with the Village Voice, saying, “I’ve always lived with the doctrine of Patti Smith: ‘I don’t f— much with the past but I f— plenty with the future.’ I tend to like that philosophy. I like the way John Cage used to sign his correspondence: he would just write: ‘Looking forward.’”

By some accounts the pair were on improved terms in recent months; Mould wrote his former friend and bandmate a touching tribute early Thursday. (Article continues below.)

Some musicians react to a split in a panicked way, by turning to ever more accessible fare to prove their commercial bona fides on their own. That may have factored into Mould’s post-Dü stint as the leader of the radio-friendly Sugar, but it hardly characterized Hart’s solo career, as he continued to challenge himself in provocative ways over the succeeding three decades. Take his last released solo album, 2013’s “The Argument” — not just an 89-minute adaptation of John Milton’s “Paradise Lost,” but an adaptation as filtered through the ideas of William S. Burroughs, with whom Hart had had a passing acquaintanceship and picked up some additional Miltonian tips. Hart said it was his intention to condense the sprawling “Paradise Lost” into an hour and a half in part by leaving out all the Old Testament elements — not so much because he had no use for religion, though that certainly was the case, but because he figured listeners already knew all the biblical stuff.

Or, take the project that Hart was reportedly working on in his final year: “From what I understand, his new record is a concept piece based on the life of [Unabomber] Ted Kaczynski,” Norton recently told Rolling Stone.

Hart made what was apparently his final on-stage appearance two and a half months ago, at the Hook and Ladder Theater & Lounge in his hometown. It had been billed as a gig with Hart headlining, but when he showed up, he was surprised to find it had turned into a tribute show full of local all-stars, organized by Babes in Toyland drummer Lori Barbero. “They managed, by some Olympian feat, to keep this [tribute] unknown to me until I arrived at 8:00 tonight. I was truly flabbergasted,” Hart was quoted as saying in The Current. It may have been partly an act of mercy to turn most of the show over to others, as Hart had to cut his own participation short when he grew weak. But the guest list was illustrious: Soul Asylum’s Dave Pirner sang “Terms of Psychic Warfare” and other Hart numbers, echoing the moment in 2004 when Hart played a beat-cancer benefit for a Soul Asylum member. Joining Pirner on stage: the other long estranged member of Hüsker Dü, Greg Norton.

“The sweet sound of music. They’ll never take that away from us,” Hart was said to have uttered, as one of the makeshift tribute bands played on. For the length of one touching last hurrah, his fellow Minnesotans helped prove that a reunion of affectionate hearts can overwhelm any longing for original lineups.