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xAI: a GIF image gets 400 invalid_image and breaks the session (v2) #53786
Description
Description
xAI only accepts JPEG, PNG and WebP images. When a GIF is sent to an xAI model, either attached by the user or returned by the read tool, the request fails with 400 invalid_image. The GIF stays in the session, so every later turn fails the same way and the session is stuck.
The API returns the same error for a plain request, while the same request with a PNG works:
curl https://api.x.ai/v1/chat/completions -H "Authorization: Bearer $XAI_API_KEY" -H "Content-Type: application/json" \
-d '{"model":"grok-4.7","messages":[{"role":"user","content":[{"type":"text","text":"What is in this image?"},{"type":"image_url","image_url":{"url":"data:image/gif;base64,'"$(base64 < shapes.gif | tr -d '\n')"'"}}]}]}'
# 400 {"code":"invalid_image","error":"... Downloaded response does not contain a valid JPG, PNG, WebP, or ICO image."}Plugins
none
OpenCode version
v2 branch (5183ea4)
Steps to reproduce
- Put a GIF at
assets/shapes.gif opencode run -m xai/grok-4.7 -f assets/shapes.gif "What shapes are in this image?"fails with 400invalid_imageopencode run -m xai/grok-4.7 --continue "Just reply OK."fails the same way, because the GIF is sent again
Reading the GIF with the read tool fails the same way.
Screenshot and/or share link
Test GIF: 
Operating System
macOS 26
Activity
opencode-agent commentedon Oct 7, 2026
Thanks for the detailed report. I reproduced this on v2.0.24 using a local stand-in for the xAI endpoint that returns xAI's
invalid_image400 for GIFs:opencode run -m xai/grok-4.7 -f assets/shapes.gif "What shapes are in this image?": the GIF is sent asdata:image/gif;base64,...and the request fails withImage could not be processed: Downloaded response does not contain a valid JPG, PNG, WebP, or ICO image.opencode run -m xai/grok-4.7 --continue "Just reply OK.": the stored GIF is sent again and the turn fails the same way, so the session stays stuck.OpenCode only checks whether a model accepts images at all, not which image formats a provider accepts, so a GIF goes to xAI unchanged. Your PR #53787 targets this, and #53014 proposes a more general way to recover from rejected attachments.