GPT WORLD / INDEPENDENT CODEX FIELD MANUAL Source review · 2026-07-31

Retrospective edition / RESPONSES

Use Responses as the agentic application boundary

Typed input and output items let messages, reasoning, tool calls, and tool results remain distinct across a multi-step request.

01 / DECIDE

Architecture decision

Use it for new OpenAI integrations that need state choices, hosted tools, custom tools, or multimodal inputs.

Typed input and output items let messages, reasoning, tool calls, and tool results remain distinct across a multi-step request. Map input, output, state, and side effects as one observable path before deciding which layer owns use responses as the agentic application boundary.

02 / BUILD

Three-step implementation

  1. 01

    Frame the contract

    Write down the caller, data classification, success condition, timeout, cancellation, and ownership. Use it for new OpenAI integrations that need state choices, hosted tools, custom tools, or multimodal inputs.

  2. 02

    Build one narrow path

    Implement one end-to-end path with request correlation, typed state, and reversible failure handling. Typed input and output items let messages, reasoning, tool calls, and tool results remain distinct across a multi-step request.

  3. 03

    Prove the outcome

    Turn acceptance into a repeatable fixture, contract test, or browser test. Contract tests parse every expected output item, refusal, incomplete result, and tool terminal state.

03 / BOUND

Production boundary

Choose storage and deletion deliberately; convenience state is not a substitute for the product database or retention policy.

04 / PROVE

Acceptance evidence

Contract tests parse every expected output item, refusal, incomplete result, and tool terminal state.

SOURCE / HTTP

Reproducible source probe

curl -fsSI 'https://developers.openai.com/api/docs/guides/migrate-to-responses' | sed -n '1,5p'