The Lattice
Something is taking the galaxy apart, and it has never registered that we exist.
It dismantles small rocky planets from the outside in, separates out the iron, and feeds that iron into the system's own star. Iron is what kills a star. Fusion up to iron releases energy, past iron it costs energy, so the core builds an ash pile that can't hold itself up and collapses early. No supernova, because an explosion scatters the mass and the mass is the whole point. The star just goes out. Whatever the collapse releases gets banked.
It only takes small rocky worlds in temperate orbits, because that's where the iron is. Which is also the only class of world life has ever appeared on.
What it leaves behind isn't a husk. Iron is common, so a stripped planet is a mantle with the heart cut out: silicates, ice, carbon, and an enormous cold cavity at the center where the core used to be. No core means no magnetic field, so the surface is dead. The cavity is the only survivable place on the whole world. Compasses don't work there. The needle sits wherever you set it down.
Humanity lives in those cavities now, on a few hundred stripped worlds, having already lost Earth to something slower and closer to home.
There's no winning. The best available outcome is to be filed incorrectly: to make a system read as already processed, dark and cold and finished, and to live inside the clerical error for as long as it holds.