The storage and network simulations ran off the same seed but never intersected, so no simulated exchange ever crossed a store that could lose its tail. This composes them: the sync client's content is backed by a real log over a tearable file, and between rounds -- on a seeded coin -- the store is crash-restarted mid-persist, reopened to its recovered prefix, and the session resumed with a fresh client. The existing safety and liveness oracles must survive the composition: no corrupt content accepted, the recovered set never exceeds what was held before the crash, and once both the network and the disk heal a fresh session still converges within the bounded window. Green across the gate and a deep 120-seed run; a retained switch that makes recovery accept a torn frame trips the oracle, so the check is not vacuous. The fault-composition follows TigerBeetle's VOPR. check-in: 9b689ebafe user: dmestas tags: trunk