feat(openai): Responses API

[mattmcdev]

This change migrates OpenAI from /chat/completions to the new Responses API.

I believe it is (almost) non-breaking, and the only newly introduced features are support for the new previous_response_id argument and truncation argument when passed in providerMeta.

The only breaking change - the callId property of ToolCall I've renamed to id because OpenAI now requires both an id and call_id for tool calling, so it was that or something like callCallId. To avoid making this breaking, perhaps setting callId equal to id when it's not provided ?

I also changed the providerMeta function in HasProviderMeta to return null when the valuePath can't be found. I assume it's meant to return the entire object when valuePath is null, which it still does with this change. Before it also returned the entire object when valuePath was set but the path returned null - I couldn't see anywhere that seemed to want that behaviour - maybe it was a bug ?

Why this change ? As well as supporting the previous_response_id to help easily keep context in long threads, the Responses API is also their recommended option for new users.

⚠️ Tests are currently failing because I've not updated the streaming fixtures - if you're happy with this proposed change I'll get those updated to the new format and document previous_response_id

[sixlive]

I'll take a closer look at this later today. I haven't done any research on the responses API yet.

[mattmcdev]

I'll take a closer look at this later today. I haven't done any research on the responses API yet.

Thank you - I think there's other provider metadata that could be supported, but wanted to keep this mainly focused on switching to the Responses API and then build upon that. Just added previous_response_id and truncation because they're an immediate fix for a chat thread length issue I've been having !

[kinsta]

Preview deployments for prism ⚡️

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Commit: 04a0aff955203c9bfba5f6b15db4e1a242355f05

Deployment ID: fb34d344-5f3b-409f-85e3-056bd7c42845

Static site name: prism-97nz9