[BUG]

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When a bash command outputs a data:image/svg+xml;base64,... string to stdout, Claude Code detects it as image data and attempts to send it to the Claude API as a vision/image content block. The Claude API
rejects SVG format (only PNG, JPEG, GIF, WebP are supported), returning:

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"},"request_id":"req_011CZMWyw4DGdP72BBp5VRYm"}

What Should Happen?

Either:

• SVG data URLs should not be intercepted as image data (since the API doesn't support SVG), or
• Claude Code should check the MIME type before sending and only intercept supported formats (PNG, JPEG, GIF, WebP), or
• If the API rejects the image, Claude Code should gracefully fall back to treating the output as plain text rather than crashing

Error Messages/Logs

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"},"request_id":"req_011CZMWyw4DGdP72BBp5VRYm"}

Steps to Reproduce

1. Open Claude Code in any project containing an SVG file
2. Ask Claude to convert the SVG to a base64 data URL
3. Claude runs a bash command like:

python3 -c "
import base64
with open('path/to/image.svg', 'rb') as f:
b64 = base64.b64encode(f.read()).decode()
print(f'data:image/svg+xml;base64,{b64}')
"

1. The output is detected as image data: [Image data detected and sent to Claude]
2. API returns 400: "Could not process image"

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.81 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_