8 months of iterating ATLAS: pushing a small model toward frontier coding without touching weights

itigges22 · reddit · 2026-09-18

A developer details 8 months of building ATLAS, testing whether system design (not weight changes) can bring a small model close to frontier performance on code. V2 added Best-of-K candidate generation, a 'Geometric Lens' cost field trained on code embeddings and execution pass/fail labels (inspired by Anthropic's representation-geometry work), a confidence router (later dropped), and PageIndex-based retrieval with a pattern cache. V3 rearchitected it into a Go proxy managing tools, session state, permissions and budgets, with a Python pipeline for generation/repair and llama.cpp inference, extensible beyond a coding harness into a general verification runtime. arXiv references throughout.

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