Pace3D: Controlling Structural Progress in 3D Editing

Training-free 3D editors typically stop at a fixed sampling endpoint, implicitly assuming elapsed time implies structural completion. This can fail in hierarchical 3D generators: sparse-structure latents evolve continuously, while decoded support changes discretely as occupancy logits cross thresholds. Sampling can therefore end with incomplete target support, unrecoverable by downstream feature generation. We call this failure *structural progress–clock mismatch*. **Pace3D** uses the structure decoder as an online progress sensor. A target-conditioned proxy provides a structural reference; when decoded structure lags behind its reference phase, Pace3D rewinds the clock while retaining the current latent. Source Alignment stabilizes the extended trajectory, while Cross-Condition Consensus preserves unchanged source features. Diagnostics show that larger terminal phase lag corresponds to more missing target structure. On Eval3DEdit, Pace3D further achieves the best target alignment while maintaining strong source fidelity.