OpenAI still calls a February model its best coder — and it knows nothing written after August 2025

OpenAI's documentation describes GPT-5.3-Codex as "the most capable agentic coding model to date". It went on sale on 24 February 2026. Six months later that sentence still stands, because nothing has replaced it: the dedicated Codex line has not had a new member since. The general line has not stood still in the same period. GPT-5.5 arrived on 24 April and the three-model GPT-5.6 family — Sol, Terra and Luna — on 9 July, and OpenAI's own catalogue entry for GPT-5.6 Sol now reads "start here for complex reasoning and coding". The specialist and the generalist are being pointed at the same job. The gap between them is not marketing. GPT-5.6 Sol carries a 1,050,000-token context window against the Codex model's 400,000, and a knowledge cutoff of 16 February 2026 against 31 August 2025. For a coding model the second number matters more than it looks: a cutoff of August 2025 means the tool writing your dependency call has never seen a year of releases, deprecations and breaking changes in the libraries it is calling. What the older model keeps is price. GPT-5.3-Codex costs $1.75 per million input tokens and $14 per million output, against $4 and $20 for GPT-5.6 Sol — a bit over half the input rate. It is also narrower by design: the Codex line runs only on the Responses API, with no Chat Completions, no batch, no fine-tuning. That leaves a choice OpenAI does not spell out anywhere in one place. The cheap specialist is frozen in time; the expensive generalist is current. Nothing in the documentation says the Codex line has been retired, and no shutdown date has been published for it — which is exactly why the six-month silence is worth noticing rather than assuming. Figures in this article come from OpenAI's own model cards and pricing tables, read on 26 August 2026; the release dates were cross-checked against an independent model registry, because OpenAI does not date its model cards.