image generation fails with gpt-image-2: Unknown parameter 'response_format'

Description

Image generation fails when using the openai/gpt-image-2 model with the following error:

Image generation failed: Unknown parameter: 'response_format'

The error occurs because the image generation code passes a response_format parameter to the OpenAI API that is not supported by the gpt-image-2 model.

Steps to Reproduce

1. Set image generation model to openai/gpt-image-2

2. Send a message that triggers image generation (e.g. "generate an image of ...")

3. Image generation fails with the error above

Expected Behavior

Image generation should work with gpt-image-2 without passing unsupported parameters.

Root Cause

The gpt-image-2 model (newer OpenAI image API) does not accept the response_format parameter. This parameter was used by older models like dall-e-3 (values: url or b64_json), but the newer model API schema differs.

The image generation implementation likely hardcodes or defaults response_format in the API request body, causing the request to be rejected.

Suggested Fix

• Omit response_format when the selected model is gpt-image-2 (or any model that doesn't support it)

• Alternatively, detect the model family and only include supported parameters

Environment

• Alma version: v0.0.810

• Model: openai/gpt-image-2

• Platform: macOS (ARM64)