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Specifications
Context windowHow much information the model can work with in one request, measured in tokens — pieces of words or other data. This includes your question, attachments, conversation and reply. Limits can vary by model variant and provider.
400k—
Benchmarks
Next.js EvalsNext.js coding — Vercel's open eval of how well AI coding agents build and migrate real Next.js apps — measured as the share of tasks the agent completes successfully. Higher is better.
46%82%
Overview
CompanyOpenAISpaceXSI
Release dateDec 18 2025May 18 2026
AccessClosedClosed
Model detailsView modelView model

Frequently asked questions

Composer 2.5 leads GPT-5.2-Codex on 1 of the 1 benchmark they both report (Next.js Evals). GPT-5.2-Codex shipped 151 days before Composer 2.5, so benchmark comparisons should account for the intervening progress.

Published specifications for these two models are limited — see each model page for the latest details.

On Next.js Evals, Composer 2.5 leads at 82% vs GPT-5.2-Codex at 46%.