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The Agent Couldn’t Move Until Its Twin Replayed the Past

An executable world model cleared 179 of 183 hidden-rule levels after every prediction mismatch became a counterexample for repair.

Published Updated Story ID: mp-2026-08-17-001
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Summary

An executable world model cleared 179 of 183 hidden-rule levels after every prediction mismatch became a counterexample for repair.

Twin made a coding agent earn each real action by first reproducing every transition it had already observed inside an executable test-time world model. When the model predicted a result that the environment contradicted, the mismatch became a counterexample and the agent repaired the twin before continuing. Across the reported ARC-AGI-3 runs, the system cleared 179 of 183 levels and inferred the goal before receiving a reward on 156 of the levels it cleared.

The same base model scored 7.8 percent when playing directly, 61.1 with an off-the-shelf harness and 93.3 with the twin-world harness across 25 games. Those figures come from one benchmark family whose grid-game prior is unusually amenable to executable modeling; they do not establish a general recipe for unconstrained physical environments. The sharper result is procedural: prediction errors were not merely logged—they blocked action until the accumulated history could be replayed.

Why it matters

An executable world model cleared 179 of 183 hidden-rule levels after every prediction mismatch became a counterexample for repair.

Limits and context

  • Those figures come from one benchmark family whose grid-game prior is unusually amenable to executable modeling; they do not establish a general recipe for unconstrained physical environments.
  • The sharper result is procedural: prediction errors were not merely logged—they blocked action until the accumulated history could be replayed.

Key claims

  1. An executable world model cleared 179 of 183 hidden-rule levels after every prediction mismatch became a counterexample for repair.

    Qualification: Those figures come from one benchmark family whose grid-game prior is unusually amenable to executable modeling; they do not establish a general recipe for unconstrained physical environments.

    Evidence: source-2026-08-17-001

Sources

  1. arXiv preprint 2608.14490arXiv · primary research

Corrections

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