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OpenAINew version

gpt-5.3-codex

New version, announced 24 February 2026. Rerun the suite: Run your agent cases against gpt-5.3-codex, and decide whether your harness should record the phase label so intermediate messages stop being scored as answers.

What OpenAI says changed

OpenAI released gpt-5.3-codex to the Responses API. The same entry added the phase parameter, which OpenAI says labels an assistant message as intermediate commentary or final answer.

OpenAI: API changelog

announced 2026-02-24 . verified 2026-09-22

This section restates the provider. It adds no judgement the provider did not make, and it contains no measurement of ours.

Entry

Provider
OpenAI
Models
gpt-5.3-codex
Change type
New version
Announced
2026-02-24
Verified
2026-09-22

What this kind of change typically touches

  • Agent

    Future AGI describes scoring an agent at four resolutions, end to end, trajectory, step and turn, writes that a high end to end score can hide bad tool calls, and warns that strong per step scores can still miss that the agent pursued the wrong goal. A label that separates intermediate commentary from the final answer is read at those resolutions.

    Future AGI

What to do this week

Rerun the suite

Run your agent cases against gpt-5.3-codex, and decide whether your harness should record the phase label so intermediate messages stop being scored as answers.

If you are on a plan

A tracked provider update triggers a rerun of your suite within 2 business days of the announcement, and you get a written verdict. That is one of the six guarantees on every plan.

See plansRead EV-RERUN

Other OpenAI changes

OpenAINew version

gpt-6-astra

OpenAI released GPT-6 Astra, which it describes as its most capable model for end to end work, covering reasoning, coding, computer use and tools. It is available in the Responses API and the Chat Completions API.

Rerun the suiteAdd gpt-6-astra as a second model in your next scheduled suite run alongside the one you serve today, and read the differences before changing any default.

Source: OpenAI, OpenAI API changelog . verified 2026-09-22

OpenAITool change

slow_down, server_is_overloaded

OpenAI wrote that a rapid increase in traffic can now return a 429 error with the slow_down code, and that temporary overload can return a 503 error with the server_is_overloaded code.

Rerun the suiteCheck that your client and your eval harness treat these two codes as a signal to back off rather than as failures, then run a batch large enough to exercise that path.

Source: OpenAI, API changelog . verified 2026-09-22

OpenAIDeprecation

whisper-1, gpt-4o-transcribe, gpt-4o-mini-transcribe, gpt-4o-transcribe-diarize

OpenAI announced on August 26, 2026 that whisper-1, gpt-4o-transcribe, gpt-4o-mini-transcribe and gpt-4o-transcribe-diarize are scheduled to shut down on February 26, 2027. The recommended replacements are gpt-live-transcribe and gpt-transcribe.

Plan a migrationFind every call to one of the four ids, run a held out set of recordings through gpt-transcribe or gpt-live-transcribe, and keep both transcripts so the step after them can be compared before February 26, 2027.

Source: OpenAI, Deprecations . verified 2026-09-22

Questions

How do I know this is accurate?
The entry links to OpenAI's own page, and the date we read it is on this page. If the provider's page and this page disagree, the provider's page is right and we want to hear about it.
Does this mean my feature broke?
No. It means a thing your feature depends on changed. Whether anything about your output changed is a question only a rerun against your own dataset can answer, and that is what the recommended action is for.
Why is there no score or benchmark here?
Because we publish none. This site restates provider announcements and cites published practitioner guides. Any measurement we make belongs to the customer whose dataset produced it.

Sources

Change-log entries restate provider announcements with sources and dates. Impact notes cite public practitioner reports. The site publishes no measurements of its own on any model.

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