Migration to Responses

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Mental Model Shift

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When To Stay On Chat Completions

• you already have a large OpenAI chat integration that would gain little from migration right now
• your SDK wrappers are deeply tied to choices[0].message

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When To Migrate

• you are adding new tools or richer multimodal flows
• you want the primary platform surface going forward
• you want docs and examples that match the main product path

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Field mapping

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Simple request conversion

{
  "model": "gpt-4.1-mini",
  "messages": [
    {
      "role": "user",
      "content": "Summarize this pull request in three bullets."
    }
  ]
}

{
  "model": "gpt-4.1-mini",
  "input": "Summarize this pull request in three bullets."
}

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Tool-calling migration notes

• tool_calls become function_call items in output[]
• follow-up tool results become function_call_output items in the next input
• do not assume the final assistant text is always output[0]

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Streaming migration notes

• Chat Completions streams chat deltas
• Responses streams semantic events such as response.output_text.delta
• if your client parses raw delta text today, update it before switching APIs

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Next steps

• Responses API
• Responses Streaming
• Responses Tool Calling