Images shared in VS Code chat cause 400 'Could not process image' error and crash conversation

Description

When sharing a screenshot/image in the Claude Code VS Code extension chat, the conversation crashes with a 400 error. The image is never processed and the chat becomes unusable for that turn.

Steps to reproduce

1. Open Claude Code in VS Code
2. Attach or paste a screenshot/image into the chat
3. Send the message

Expected behavior

Image is processed and Claude responds normally.

Actual behavior

The API returns a 400 error and the conversation crashes.

Error from VS Code Output panel (Claude Code)

[ERROR] API error (attempt 1/11): 400 400 {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"},"request_id":"req_011CaCqkoVLCccbDrxc6D1Tk"}
[ERROR] Error in API request: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"},"request_id":"req_011CaCqkoVLCccbDrxc6D1Tk"}

Environment

• Client: Claude Code VS Code extension
• OS: Windows 11 Enterprise 10.0.26100
• Request ID (for Anthropic lookup): req_011CaCqkoVLCccbDrxc6D1Tk