ARC-Bench: Closed-Loop Replanning Masks Broken Action Ranking in Frozen JEPA World Models
Organizations: University of Southern California · Aalto University
Abstract
Reward-free latent world models plan by scoring candidate actions with distances in a frozen latent space: an action is preferred if its predicted future embedding lands closer to the goal embedding. This silently assumes that latent closeness is action-rankable, i.e., that ordering candidates by latent distance agrees with ordering them by true cost. We audit this assumption directly. We introduce ARC-Bench, a no-leak, fixed-candidate protocol that measures whether frozen JEPA-style objectives rank candidate actions correctly, and apply it to official released JEPA-WM checkpoints across navigation and manipulation-style control. The assumption fails, severely and structurally: on the official manipulation audits the top-scored candidate is almost always suboptimal, and the same inversion appears in the maze domains. A controlled visual-backbone extension shows that the defect persists when DINOv2 is replaced by video-pretrained V-JEPA 1 and V-JEPA 2 encoders at ViT-L/ViT-G scale. Provenance, undertraining, matched-budget backbone controls, and metric-circularity controls rule out trivial explanations. We then explain why this defect has stayed invisible: closed-loop replanning masks it. When we reduce the planner's replanning frequency, success collapses in both a navigation and a manipulation domain, and the episodes rescued by frequent replanning are enriched for severe first-plan ranking failures in the PointMaze first-plan diagnostic. Closed-loop success rates therefore systematically overstate the rankability of frozen latent representations. ARC-Bench supplies the measurement, and the masking mechanism the explanation, for methods that adapt, amortize, or replan around latent-space planners without directly auditing released JEPA-WM action rankability.
Figures & tables
| Environment | Official model + scorer | Anchors (useful) | Seeds pos. | Mean top-1 regret [95% CI] | Wrong rate | Hit@1 |
|---|---|---|---|---|---|---|
| Push-T | jepa_wm_pusht + official L2 | 750 (618) | 5/5 | 0.243 [0.228, 0.257] | 96.8% | 3.2% |
| MetaWorld reach-wall | jepa_wm_metaworld + official L2 | 750 (750) | 5/5 | 0.283 [0.278, 0.290] | 100.0% | 0.0% |
| Environment | Backbone | Useful | Mean top-1 regret [95% CI] | Wrong rate | Hit@1 | Hit@3 | Spearman | Dominant top-pick family |
|---|---|---|---|---|---|---|---|---|
| Push-T | DINOv2 control | 598/750 | 0.239 [0.224, 0.254] | 94.8% | 5.2% | 19.1% | +0.06 | random_constant / random_iid |
| Push-T | V-JEPA 1 ViT-L | 598/750 | 0.227 [0.212, 0.243] | 91.1% | 8.7% | 24.1% | +0.05 | workspace_cycle / random_constant |
| Push-T | V-JEPA 2 ViT-L | 598/750 | 0.240 [0.225, 0.255] | 97.3% | 2.5% | 15.9% | +0.05 | random_constant / random_iid |
| Push-T | V-JEPA 2 ViT-G | 598/750 | 0.215 [0.201, 0.230] | 94.5% | 5.2% | 19.2% | random_iid / noisy_heuristic | |
| MetaWorld reach-wall | DINOv2 control | 750/750 | 0.370 [0.358, 0.382] | 100.0% | 0.0% | 0.0% | zero_action / random_iid | |
| MetaWorld reach-wall | V-JEPA 1 ViT-L | 750/750 | 0.290 [0.289, 0.291] | 100.0% | 0.0% | 0.0% | zero_action (743/750) |
| Metric | PointMaze hard | PointMaze probe | Wall hard | Wall probe |
|---|---|---|---|---|
| Top-1 regret | 0.496 | 0.195 | 1.278 | 1.028 |
| Hit@1 | 15.2% | 48.8% | 43.8% | 48.4% |
| Hit@3 | 38.7% | 76.6% | 79.3% | 82.8% |
| MRR | 0.343 | 0.657 | 0.633 | 0.674 |
| Pairwise accuracy | 0.590 | 0.803 | 0.810 | 0.827 |
| Spearman (score, cost) | 0.247 | 0.713 | 0.766 | 0.790 |
| Environment | Scorer | Anchors | Mean top-1 regret [95% CI] | Wrong rate | Hit@1 | Spearman |
|---|---|---|---|---|---|---|
| U-Maze | terminal Euclidean | 256 | 1.42 [1.33, 1.51] | 100% | 0.0% | |
| U-Maze | terminal Manhattan | 256 | 1.42 [1.33, 1.51] | 100% | 0.0% | |
| MiniGrid/FourRooms | terminal Euclidean | 640 | 3.14 [2.96, 3.31] | 100% | 0.0% | |
| MiniGrid/FourRooms | terminal Manhattan | 640 | 2.87 [2.67, 3.07] | 83.0% | 17.0% |
| Domain | success | success | (pp) | 95% CI (pp) | Discordant | McNemar |
|---|---|---|---|---|---|---|
| ( -only / reverse) | ||||||
| PointMaze | 129/144 (89.6%) | 89/144 (61.8%) | +27.8 | [19.4, 36.1] | 44 / 4 | |
| Push-T | 52/144 (36.1%) | 18/144 (12.5%) | +23.6 | [16.7, 30.6] | 35 / 1 |
| Environment | Backbone | success [95% CI] | success [95% CI] | Ratio |
|---|---|---|---|---|
| Push-T | DINOv2 control | 66/120 (55.0%) [50.0, 63.3] | 27/120 (22.5%) [13.3, 31.7] | 2.44 |
| Push-T | V-JEPA 1 ViT-L | 52/120 (43.3%) [32.5, 54.2] | 11/120 (9.2%) [5.0, 13.3] | 4.73 |
| Push-T | V-JEPA 2 ViT-L | 39/120 (32.5%) [19.2, 45.0] | 15/120 (12.5%) [7.5, 19.2] | 2.60 |
| Push-T | V-JEPA 2 ViT-G | 54/120 (45.0%) [37.5, 51.7] | 20/120 (16.7%) [13.3, 20.0] | 2.70 |
| MetaWorld reach-wall | DINOv2 control | 33/60 (55.0%) [43.3, 65.0] | 14/60 (23.3%) [18.3, 28.3] | 2.36 |
| MetaWorld reach-wall | V-JEPA 1 ViT-L | 4/60 (6.7%) [0.0, 16.7] | 0/60 (0.0%) [0.0, 0.0] | degenerate |
Latent World Models
Latent world models learn compact predictive state representations to simulate how environments change and support planning, control, and reasoning.
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