ImageGenToolCall omits returned image metadata fields

Source reports

• https://github.com/openai/openai-python/issues/2580
• https://github.com/openai/openai-python/issues/2649
• openai/openai-go#675

Current specification gap

Affected surface: POST /responses; ImageGenToolCall output.

The linked Python and Go reports identify action, background, output_format, quality, revised_prompt, and size on image_generation_call outputs. The current public component exposes only type, id, status and result.

Specification reviewed at b61ced9.

Minimal shape

{
  "background": "opaque",
  "output_format": "png",
  "quality": "high",
  "revised_prompt": "A rewritten image prompt",
  "size": "1024x1536"
}

This is a sanitized illustration of the reported shape, not a new live API capture.

Expected reconciliation

Add the supported returned metadata with accurate optionality and types. Preserve the individual source field lists and avoid SDK-only edits.

Verification scope

Reviewed the source reports, relevant comments, and current published schema. No new live API request was made. This mirrors the specification gap and preserves the original reproduction; it does not claim that a fix has shipped.

The Go report additionally preserves the missing action field; the Python reports preserve size alongside the shared field list. Validate both source lists together.

Start in openapi.yaml at the ImageGenToolCall definition near line 42240, then compare it with the linked Python and Go reports. Reconcile the returned metadata fields, including action and size, with accurate optionality and types while preserving the existing source field lists. Done means the public POST /responses schema represents the reported image_generation_call shape without SDK-only edits.