The fault simulator only ever corrupted at crash and restart boundaries. It could not model a latent sector error: bit rot that surfaces during a read of a store that opened clean. A new read_rot_pct knob does that -- a read returns payload-derived, never-self-healing corruption for a frame that is intact on disk -- and a sweep reopens a healthy store, arms it, and reads every held hash. The oracle: each read returns exactly the stored bytes or a declared corruption error, never wrong bytes as success. The append open path re-runs the whole-frame checksum per read, so it catches the rot; the sweep is green and a companion test proves the sweep can fail by reading through the checksum-skipping read-only open. The knob is inert at zero, so every existing seed keeps its byte stream. The crash-point fault technique follows TigerBeetle's storage fault model. check-in: ba805e5913 user: dmestas tags: trunk