Impossible Research's Schema Harness Hits 99% on ARC‑AGI‑3 with Claude Opus 4.8 + Fable 5
The new Schema harness from Impossible Research claims a 99% RHAE score on the ARC‑AGI‑3 public set by pairing Claude Opus 4.8 with the Fable 5 model, and 95.35% using GPT‑5.6 Sol. It achieves this without altering model weights, instead reshaping observation gathering, hypothesis formation, and iterative code refinement.