Version 1.0.42

Based on my analysis of the diff for version 1.0.42, here's the detailed changelog:

# Claude Code v1.0.42 Changelog

• Improved multi-instance handling: Added file locking mechanism when saving configuration to prevent conflicts between multiple Claude instances
• Automatically acquires a lock on the config file (config.json.lock) before modifications
• Displays warning if lock acquisition takes longer than 100ms: "Lock acquisition took longer than expected - another Claude instance may be running"
• Shows process ID (PID) when acquiring locks for better debugging

• Automatic config backups: Creates a backup of the configuration file before making changes
• Provides safety net for configuration modifications
• Debug messages indicate when backups are created

• Better symlink handling: Enhanced detection and handling of symbolic links in file paths
• Shows where symlinks point to in debug messages
• More robust handling of symlinked configuration files

• Standards-compliant URL handling: Updated internal URL and URLSearchParams implementations
• Better error messages for invalid arguments (e.g., "Failed to execute 'append' on 'URLSearchParams': 2 arguments required")
• Improved validation for URL operations
• Enhanced Unicode domain name handling with proper xn-- prefix support

• More descriptive errors: Enhanced error messages throughout the codebase
• Type validation errors now provide clearer context
• Better BigInt conversion error messages
• Improved range enforcement for numeric values

• More detailed debug output: Added comprehensive debug logging for configuration operations
• Shows lock acquisition timing
• Indicates when config is re-read after acquiring lock
• Logs atomic write operations for configuration files

If you're running multiple Claude Code instances, you'll now see helpful debug messages:

Acquiring lock on /path/to/config.json.lock for config save (PID: 12345)
Lock acquired successfully after 150ms
Lock acquisition took longer than expected - another Claude instance may be running

The new backup system automatically protects your configuration:

Creating backup of config at /path/to/config.json.backup
Backup created successfully
Writing config to /path/to/config.json atomically
Config written successfully

• This update focuses on improving reliability when multiple Claude instances are running simultaneously
• Configuration operations are now atomic and protected by file locking
• Enhanced internal URL handling provides better standards compliance
• Debug messages provide more visibility into configuration operations (visible when debug mode is enabled)