Bug: image >2000px crashes entire turn (not just rejected upload)

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?

Bug: image >2000px crashes entire turn (not just rejected upload)

Repro:

1. Paste screenshot >2000px in Claude Code chat
2. Error "An image in the conversation exceeds the dimension limit for many-image requests (2000px)"
3. EVERY subsequent message in same session fails with same error — even text-only

Platform: Claude Code CLI on Windows 11
Model: Opus 4.7

What Should Happen?

reject the oversized image, let conversation continue
Actual: whole session blocked until restart, losing context

Impact: forces new session + full context reload every time. On long technical sessions this is painful.

Suggestion: strip/downscale oversized image automatically, or at minimum allow follow-up messages without re-sending the offending image.

Error Messages/Logs

An image in the conversation exceeds the dimension limit for many-image requests (2000px)

Steps to Reproduce

1. Open a chat session in Claude Desktop (Windows 11, Opus 4.7 model)
2. Paste or attach a screenshot/image with height or width greater than 2000px
3. Send the message — API returns error:

"An image in the conversation exceeds the dimension limit
for many-image requests (2000px). Start a new session with fewer images."

1. Try to send ANY follow-up message in the same session, even plain text with no image
2. Every subsequent turn fails with the same error — the session is permanently blocked

Expected: the oversized image is rejected (or auto-downscaled), but the conversation continues normally.

Actual: entire session is stuck. Only workaround is starting a brand-new session, losing all prior context — painful on long technical work sessions where rebuilding context takes significant time.

Suggestion: either auto-downscale images above 2000px client-side before sending, or drop the offending image from the conversation history so follow-up messages can proceed.

Screenshots of the error attached.

<img width="740" height="259" alt="Image" src="https://github.com/user-attachments/assets/77dd2e11-28ab-4985-a360-94b2260b69e2" />

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude Code CLI on Windows 11

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_