OpenAI’s coding agent, which runs software tasks in sandboxed environments from the terminal, IDE and cloud (product page). It opens the corpus’s recursive-self-improvement strand when its product lead says it is beginning to babysit its own training runs; by February a Codex engineering manager says the product now pretty much builds itself, and OpenAI ships GPT-5.3-Codex, described as instrumental in creating itself.
AISystem
OpenAI Codex
OpenAI's software-engineering agent, the system reported babysitting its own training runs and later said by its own team to build itself.
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- Welcome to December 15, 2025 (theinnermostloop.substack.com)
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