Old Is Not False: Valid-Time Memory for Interactive Video World Models

arXiv:2611.00758v1 Announce Type: new Abstract: Interactive video world models draw each frame from a memory bank of earlier frames stamped with their capture times. With frames, weights and noise fixed, reversing the timestamps of two views flips the state that generators of two families draw: they take the newest timestamp as the truth. That reading is right as long as states never return. After an agent undoes an action, the newest view of a region is outdated and the only view of the present is older; memories for changing worlds delete that older view, and memories that keep it hand the generator the past. Temporal databases separate when a record is stored from when its content holds, its valid time. ReDate keeps every frame and dates each retrieved token by its valid time, read from the agent's action log. The frozen generator then reads a reverted region as one that has just reached a new state, so ReDate needs no training. We prove that trusting the newest timestamp is right exactly when every current view is dated after every outdated one, that without a view taken after the return only the action log tells a reverted region from an up-to-date one, and that a generator able to draw from its own prediction gains more from re-dating than from deletion when the moved tokens keep little weight. After an undo, ReDate raises the share of FAR's steps showing the current state from 0.36 to 0.62 and HY-WorldPlay's from 0.003 to 0.19. We also propose a calibrated state metric to test any memory after undos.