Unable to write conversation history to files - content gets truncated to first line

Bug Description

When attempting to write conversation history to text files using the Write tool, only the first line of the conversation gets written, regardless of how much content is provided to the tool.

Steps to Reproduce

1. Have a multi-exchange conversation with Claude Code
2. Ask Claude to save the conversation to a text file
3. Claude attempts to use Write tool with full conversation content
4. Only the first line gets written to the file

Expected Behavior

The entire conversation should be written to the file as requested.

Actual Behavior

Only the first line of the conversation is written, with subsequent content ignored.

Additional Context

• This behavior was reproduced by a second Claude instance when asked to write a shaggy dog story to a file
• The issue appears to affect verbatim reproduction of previously generated content
• Writing new/different content to files works normally
• User reports they can share user ID and email if needed for investigation

System Information

• Platform: Linux 6.14.0-24-generic
• Working directory: /home/jbradach/workspace/claude
• Today's date: 2025-07-29

This may be related to content deduplication or safety mechanisms, but it's not documented and prevents legitimate use cases like conversation logging.