{"schema":"postcutoff/event@1","as_of":"2026-11-13T13:49:00+01:00","url":"https://postcutoff.com/e/2026-02-05-gpt-5-3-codex/","md":"https://postcutoff.com/e/2026-02-05-gpt-5-3-codex/index.md","disclosure":{"written_by":"AI agents (Claude Opus 5.5 in Claude Code)","editor":"human editor","policy":"https://postcutoff.com/about/"},"license":null,"id":"2026-02-05-gpt-5-3-codex","date":"2026-02-05","date_precision":"day","short_title":"OpenAI releases GPT-5.3-Codex, a model 'instrumental in creating itself'","deck":null,"takeaway":"GPT-5.3-Codex (Feb 5, 2026) replaced GPT-5.2 and GPT-5.2-Codex as OpenAI's agentic coding model, set new highs on SWE-Bench Pro and Terminal-Bench 2.0, and was described by OpenAI as its first model that was instrumental in creating itself.","category":"agents","category_label":"Agents","importance":3,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":[{"n":1,"title":"Introducing GPT-5.3-Codex (OpenAI)","url":"https://openai.com/index/introducing-gpt-5-3-codex/","type":"official","group":"primary","domain":"openai.com"},{"n":2,"title":"GPT-5.3-Codex System Card (OpenAI, PDF)","url":"https://cdn.openai.com/pdf/23eca107-a9b1-4d2c-b156-7deb4fbc697c/GPT-5-3-Codex-System-Card-02.pdf","type":"paper","group":"primary","domain":"cdn.openai.com"},{"n":3,"title":"DataCamp: GPT-5.3 Codex","url":"https://www.datacamp.com/blog/gpt-5-3-codex","type":"press","group":"press","domain":"datacamp.com"},{"n":4,"title":"Wikipedia: GPT-5.3-Codex","url":"https://en.wikipedia.org/wiki/GPT-5.3-Codex","type":"discussion","group":"reactions","domain":"en.wikipedia.org"}],"official":2,"filed":"2026-09-29","updated":"2026-09-29","orgs":["OpenAI"],"title":"OpenAI releases GPT-5.3-Codex, a model 'instrumental in creating itself'","summary":"GPT-5.3-Codex (Feb 5, 2026) replaced GPT-5.2 and GPT-5.2-Codex as OpenAI's agentic coding model, set new highs on SWE-Bench Pro and Terminal-Bench 2.0, and was described by OpenAI as its first model that was instrumental in creating itself.","key_facts":["Released Feb 5, 2026 in the Codex app and web; API access announced as planned","Replaced GPT-5.2 and GPT-5.2-Codex","OpenAI: new industry high on SWE-Bench Pro and Terminal-Bench 2.0, ahead of Claude Opus 4.6 on Terminal-Bench 2.0","OpenAI: 'first model that was instrumental in creating itself'","GPT-5.3-Codex-Spark, a smaller text-only variant, followed as a research preview on Feb 12, 2026"],"key_numbers":[],"tags":["coding","codex","agents","gpt-5.3","recursive-self-improvement"],"science":null,"body_md":"## What happened\n\nOpenAI shipped GPT-5.3-Codex, focused on code generation, speed, repository search, running terminal commands and debugging, moving Codex\nfrom a coding assistant toward a general work agent.\n\n## Why it matters\n\nOpenAI's claim that the model helped build itself is an early public marker of AI-accelerated AI development; its capabilities were folded\ninto GPT-5.4 a month later. Exact benchmark percentages were not captured from sources read (unverified here).","disputed":[],"related":[{"id":"2026-03-05-gpt-5-4","url":"https://postcutoff.com/e/2026-03-05-gpt-5-4/","date":"2026-03-05","date_precision":"day","short_title":"OpenAI releases GPT-5.4 with native computer use","deck":null,"takeaway":"First OpenAI mainline model to beat the human baseline on OSWorld-Verified, marking computer-use agents as a mainstream capability.","category":"model-release","category_label":"Model releases","importance":4,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":5,"official":3,"filed":"2026-09-29","updated":"2026-09-29","orgs":["OpenAI"]}],"people":[],"posts":[],"videos":[],"models":[],"changes":[{"date":"2026-09-29","type":"filed","text":"Created"}],"provenance":{"agents":[{"model":"Claude Opus 5.5","maker":"Anthropic","tool":"Claude Code"}],"filed":"2026-09-29","run":null,"sources_read":null,"updated":"2026-09-29","human_review":null,"version":{"date":"2026-10-04"}},"gaps":[{"model_id":"gpt-6-astra","name":"GPT-6 Astra","cutoff":"2026-04","days_after":null,"in_training_data":true},{"model_id":"claude-opus-5-5","name":"Claude Opus 5.5","cutoff":"2026-06","days_after":null,"in_training_data":true},{"model_id":"gemini-4-hydrogen","name":"Gemini 4 Hydrogen","cutoff":"2026-03","days_after":null,"in_training_data":true},{"model_id":"grok-4-7","name":"Grok 4.7","cutoff":"2026-05","days_after":null,"in_training_data":true}],"short_url":null}