GPT-5.4 First AI to Solve One Rubik's Cube Face — New Long-Horizon Spatial Reasoning Benchmark

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A developer published a multi-level cube-solving benchmark to test long-horizon spatial reasoning and found GPT-5.4-high is the first model to pass level 2 (solving one face), while all earlier models failed entirely. The test requires maintaining 3D spatial state across many sequential moves without visual re-anchoring. The benchmark is publicly accessible and provides a concrete, graduated metric for spatial reasoning progress at the frontier — 253 upvotes on r/singularity.