Fix openai streaming decoding error when using provider webSearch tool

[tensor2077]

Type

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update

Description

When sending a stream request, OpenAiClient.streamRequest decodes each SSE event.data into ResponseStreamEvent(OpenAiClient.ts:1803).

However, in real streams, ResponseOutputItemAddedEvent can emit a
web_search_call item before it’s fully populated: the action field is not present yet (it only shows up later in response.output_item.done). This can cause an early decode failure while
OpenAiLanguageModel.makeStreamResponse is processing the tool-call stream parts.

effect/packages/ai/openai/src/OpenAiClient.ts

Lines 402 to 421 in 65e9e35

	export class ResponseOutputItemAddedEvent extends Schema.Class<ResponseOutputItemAddedEvent>(
	"@effect/ai-openai/ResponseOutputItemAddedEvent"
	)({
	/**
	* The type of the event. Always `"response.output_item.added"`.
	*/
	type: Schema.Literal("response.output_item.added"),
	/**
	* The sequence number for this event.
	*/
	sequence_number: Schema.Int,
	/**
	* The index of the output item that was added.
	*/
	output_index: Schema.Int,
	/**
	* The output item that was added.
	*/
	item: Generated.OutputItem
	}) {}

Proposed Fix

I currently work around this by relaxing the schema to accept web_search_call without action in ResponseOutputItemAddedEvent, so it can accept an in-progress web_search_call item without action. (status="in_progress").

what do you think is the most appropriate way to model/handle this situations? @IMax153

Reproduce

You can reproduce this by enabling the web_search tool and asking the model to perform a search in streaming mode.

Toolkit.make(
  OpenAI.OpenAiTool.WebSearch({
    search_context_size: 'medium'
  })
)

[changeset-bot]

🦋 Changeset detected

Latest commit: 213c49f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@effect/ai-openai	Patch

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[tensor2077]

A follow-up issue #5939

[IMax153]

@tensor2077 - thank you for the detailed pull request.

It doesn't feel quite right to implement this fix in the OpenAiClient - feels a little bit like a "hack", since if more tools are added in the future that require similar fixes this could become unmaintainable. But I also don't think there's a better short-term fix right now so I'm willing to move this forward.

The good thing is that in Effect v4, our OpenAPI generator will be much more robust, so we can actually generate the streaming output types, which should alleviate the need for these patches.