# Claude Code v1.0.42

> Claude Code v1.0.42, released 3 Jul 2025 (2025-07-03). 10 entries read out of the shipped bundle. Unofficial, and not affiliated with Anthropic.

Web version: https://changelogs.core-directive.com/v/1.0.42

## Changes

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

# Claude Code v1.0.42 Changelog

### Enhanced Configuration File Locking

- **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

### Configuration Backup System

- **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

### Improved Symlink Support

- **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

### Enhanced URL and URLSearchParams Implementation

- **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

### Better Error Handling

- **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

### Debug Logging Enhancements

- **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

### Working with Multiple Instances

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`

### Configuration Safety

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`

## Notes

- 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)