01 / DECIDE
Architecture decision
Use it when a new model, a changed default, or a retirement notice forces saved configuration, custom agents, scripts, and scheduled tasks to move together.
GPT-6 Astra, GPT-6 Sol, GPT-6 Luna, and GPT-6.1 Sol all reached Codex during September 2026, so a pinned model identifier is a dated dependency rather than a settled choice. Map input, output, state, and side effects as one observable path before deciding which layer owns treat a model change as a reversible migration.
02 / BUILD
Three-step implementation
- 01
Frame the contract
Write down the caller, data classification, success condition, timeout, cancellation, and ownership. Use it when a new model, a changed default, or a retirement notice forces saved configuration, custom agents, scripts, and scheduled tasks to move together.
- 02
Build one narrow path
Implement one end-to-end path with request correlation, typed state, and reversible failure handling. GPT-6 Astra, GPT-6 Sol, GPT-6 Luna, and GPT-6.1 Sol all reached Codex during September 2026, so a pinned model identifier is a dated dependency rather than a settled choice.
- 03
Prove the outcome
Turn acceptance into a repeatable fixture, contract test, or browser test. The migration holds when no configuration still selects a retired identifier such as gpt-5.3-codex-spark, gpt-5.4, gpt-5.4-mini, or gpt-5.5 under ChatGPT sign-in, and a familiar task passes on the replacement model and effort.
03 / BOUND
Production boundary
Reasoning efforts do not map exactly between model generations, GPT-6 Luna supports efforts up to Max but not Ultra, and Enterprise or Edu workspaces keep a new model off until an administrator enables it.
04 / PROVE
Acceptance evidence
The migration holds when no configuration still selects a retired identifier such as gpt-5.3-codex-spark, gpt-5.4, gpt-5.4-mini, or gpt-5.5 under ChatGPT sign-in, and a familiar task passes on the replacement model and effort.
SOURCE / HTTP
Reproducible source probe
curl -fsSI 'https://learn.chatgpt.com/docs/models' | sed -n '1,5p'