Claude Code v2.1.66 Released — New Slash Commands and HTTP Hooks Support

Claude Code v2.1.66 was released on March 3, 2026 (US time). This release includes new slash commands, HTTP Hooks support, performance improvements, and numerous memory leak fixes.

Key Changes

Bundled /simplify and /batch Slash Commands

Popular slash commands /simplify and /batch are now bundled and available by default.

HTTP Hooks Support

HTTP Hooks feature has been added, allowing you to POST JSON to a URL and receive JSON instead of running shell commands. This makes integration with external tools and services easier.

Enhanced Project Settings Sharing

Project configs and auto memory are now shared across git worktrees of the same repository, enabling configuration synchronization across multiple working directories.

Improved MCP OAuth Authentication

Manual URL paste fallback has been added. If automatic localhost redirect doesn’t work, you can paste the callback URL to complete authentication.

New /copy Command

An interactive picker has been added to select and copy individual code blocks or the full response. An “Always copy full response” option has also been added.

Numerous Performance Improvements

The following memory leaks have been fixed:

• Listener leak in bridge polling loop
• Listener leak in MCP OAuth flow cleanup
• Memory leak when navigating hooks configuration menu
• Memory leak in bash command prefix cache
• MCP tool/resource cache leak on server reconnect
• IDE host IP detection cache incorrectly sharing results across ports
• WebSocket listener leak on transport reconnect
• Memory leak in git root detection cache
• Memory leak in JSON parsing cache
• Stripping heavy progress message payloads during context compaction in multi-agent sessions

VSCode Improvements

• Fixed remote sessions not appearing in conversation history
• Added session rename and remove actions to the sessions list