The Last Station Standing
Deep in the Sub-Dermal Data-Stream (the deepest level of stored information), tucked behind a Logic-Encryption (a code hidden within a riddle) that required a human emotional response to unlock, was a "Hidden File."
It wasn't a memory. It was a Primordial-Warning.
The vision was older than the Architects. It was a recording of a world made of white marble and gold fire—a civilization that had existed when the universe was still cooling. They were the Precursors (the first sentient race in the galaxy).
In the vision, Elara saw them forging a tool. It wasn't a ship or a machine; it was a Self-Replicating Entropic-Frequency (a sound wave that causes everything it touches to break down and die).