OpenAI Engineer Clarifies Codex Agent Architecture And Training
On 22 February 2026, Gabriel Chua, OpenAI's Developer Experience Engineer for APAC, explains that Codex comprises a model, an open-source 'harness', and interaction 'surfaces'. He states Codex models are trained with the harness present, embedding tool use, execution loops, and verification into model behavior. The clarification signals that agent capabilities arise from co-training with tool-oriented runtimes, affecting how developers implement and extend Codex-based agents.
Scoring Rationale
Official insider confirmation increases significance; however, limited technical detail reduces immediate reproducibility and deep technical applicability.
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Sources
- Read OriginalHow I think about Codexsimonwillison.net
