[MODEL] Claude Opus 4.5** (model ID: `claude-opus-4-5-20251101`)

Preflight Checklist

• [x] I have searched existing issues for similar behavior reports
• [x] This report does NOT contain sensitive information (API keys, passwords, etc.)

Type of Behavior Issue

Other unexpected behavior

What You Asked Claude to Do

Initial trigger:** Large HTML paste (Gmail view source)

1. Failure mode: Repeated error on any subsequent prompt
2. No recovery path: Couldn't clear the bad state or continue working
3. Lost work: Session context/progress potentially lost

This suggests the bad input gets stuck in the conversation history and keeps causing failures on every new request. There should be:

• Input validation before adding to context
• A way to "undo" or clear the last message
• Graceful degradation, not total lockout

I'm not sure how relevant this is, but I'm using Claude Code through the Zed IDE. Pure effing magic!!!

What Claude Actually Did

Locked up, and became completely unresponsive. I also had this issue when CC tries to read Base 64 image data through the n8n MCP. I sort of expected bad results from that mine field; however, a gmail markup file in a fresh context window was unexpected. I have a work around where I simply copy/paste the markup file in a local, accessible, directory. I just wanted to report this issue in the chance that an improvement may be sought. Just wondering if there is a way to prevent a catastrophic crash situation.

Expected Behavior

Allowed a graceful method for recovering from the context window overflow.

Files Affected

No mods.

Permission Mode

Accept Edits was ON (auto-accepting changes)

Can You Reproduce This?

Yes, every time with the same prompt

Steps to Reproduce

Paste, or have CC read, a file that is large enough to overload the context window.

Claude Model

Opus

Relevant Conversation

Initial trigger:** Large HTML paste (Gmail view source)
2. **Failure mode:** Repeated error on any subsequent prompt
3. **No recovery path:** Couldn't clear the bad state or continue working
4. **Lost work:** Session context/progress potentially lost

This suggests the bad input gets stuck in the conversation history and keeps causing failures on every new request. There should be:
- Input validation *before* adding to context
- A way to "undo" or clear the last message
- Graceful degradation, not total lockout

Impact

Low - Minor inconvenience

Claude Code Version

claude-opus-4-5-20251101

Platform

Other

Additional Context

_No response_