Claude Code v2.1.63: HTTP Hooks and a Massive Memory Leak Cleanup

Anthropic has released Claude Code v2.1.63, and this one’s worth paying attention to. Alongside a handful of new features — HTTP hooks, bundled slash commands, and cross-worktree config sharing — the release tackles a staggering number of memory leaks that had been quietly eating RAM during long coding sessions.

HTTP Hooks: Webhooks for Claude Code

The headline feature is HTTP hooks. Until now, Claude Code’s hook system was limited to running shell commands. With v2.1.63, hooks can POST JSON to a URL and receive JSON back, opening the door to direct integration with external web services and APIs without the overhead of spawning shell processes.

New Slash Commands: /simplify and /batch

Two new bundled slash commands join the lineup. /simplify does what you’d expect — asks Claude to reduce complexity in selected code. /batch enables grouping multiple operations into a single command, useful for repetitive refactoring tasks.

Git Worktree Config Sharing

For developers who work across multiple git worktrees of the same repository, project configs and auto-memory are now shared automatically. No more duplicating .claude/ settings across worktrees.

The Memory Leak Reckoning

The real story of this release is the sheer volume of memory leak fixes. Anthropic’s team clearly went on a hunt, and they found problems everywhere:

• Bridge polling loop listener leak
• MCP OAuth flow cleanup leak
• Hooks configuration menu navigation leak
• Interactive permission handler listener leak during auto-approvals
• Bash command prefix cache unbounded growth
• MCP tool/resource cache leak on server reconnect
• WebSocket transport listener leak on reconnect
• Git root detection cache unbounded growth in long sessions
• JSON parsing cache unbounded growth over time
• Teammates retaining all messages after conversation compaction
• MCP server fetch caches not cleared on disconnect
• Subagent progress payloads retained during context compaction

For anyone running extended Claude Code sessions — and especially those using MCP servers with frequent reconnections or heavy subagent workflows — this release should deliver noticeable improvements in memory consumption.

Other Improvements

• MCP OAuth fallback: Manual URL paste when localhost redirect fails
• ENABLE_CLAUDEAI_MCP_SERVERS=false: New env var to opt out of claude.ai MCP servers
• /model command: Now shows the currently active model in the menu
• /copy command: Added “Always copy full response” option
• /clear fix: Cached skills are now properly reset
• VS Code: Remote sessions appear in conversation history; session rename/remove added
• REPL bridge: Fixed race condition causing message ordering issues during initial connection

How to Update

npm install -g @anthropic-ai/claude-code

After v2.1.59’s auto-memory feature and several stability patches, v2.1.63 represents a significant quality-of-life release. The memory leak fixes alone make it a must-upgrade for power users running long sessions.