Session-killing crash: oversized screenshot cannot be deleted, no recovery possible

Bug Description

When a screenshot exceeds 2000 pixels in either dimension and there are multiple images in the conversation, the API returns error 400:

messages.16.content.0.image.source.base64.data: At least one of the image dimensions exceed max allowed size for many-image requests: 2000 pixels

Once this happens, the session is permanently dead. Every subsequent message attempt fails with the same error because the oversized image is stuck in the conversation history. There is no way to recover.

Impact

• Complete session loss — all unsaved work in the conversation is gone
• No recovery mechanism — cannot delete the offending image, cannot skip past it
• Happens during normal use — taking a screenshot on a 1920x1080 monitor produces images over 2000px
• Especially painful for long sessions — losing hours of context and work

Expected Behavior

At minimum, ONE of these should exist:

1. Auto-resize images before sending to the API (downscale to max 2000px)
2. Delete button for messages/images in the conversation so users can remove the bad image
3. Graceful error recovery — skip the bad image and continue the session instead of killing it
4. Warning before sending — if an image is too large, warn the user instead of sending it

Steps to Reproduce

1. Have a conversation with several screenshots already in context
2. Take or paste a screenshot from a monitor with resolution >= 1920px
3. Session crashes with the above error
4. All subsequent messages fail — session is unrecoverable

Environment

• Claude Code 2.1.34
• Windows 11
• Claude in Chrome extension (screenshots via browser automation)
• Also happens when users paste screenshots directly

Workaround

Resize the browser window to under 2000px before taking screenshots. But this requires users to know about the limit in advance, and doesn't help when users paste screenshots from their clipboard.