Claude Code v2.1.90 Released - /powerup Command and Resume Cache Bug Fix

Anthropic released Claude Code v2.1.90. This update introduces an interactive learning feature and important bug fixes.

Changes

/powerup Command

A new interactive system that teaches users about 10 lesser-known features of Claude Code through animated demos. The /powerup command provides an effective way to learn various capabilities.

Resume Cache Bug Fix

A significant bug present since v2.1.69 has been fixed. This bug caused a full prompt cache miss on the first request for users with deferred tools, MCP servers, or custom agents, leading to increased API costs due to wasted tokens.

Other Improvements

• Faster resume flows
• Improved startup memory usage

Recent Claude Code Updates

Claude Code has introduced several major features in early 2026:

• Computer Use: Claude can control user’s mouse, keyboard, and screen to operate any application directly
• Scheduled Tasks (/loop): Recurring and scheduled tasks turn Claude Code into a background worker
• Voice Mode: Voice mode supporting 20 languages via /voice command
• Interactive Visualizations: Interactive charts, diagrams, and visualizations

Transparency Concerns

The v2.1.88 release had a packaging issue where .map files were included in the npm package. Anthropic stated it was “a release packaging issue caused by human error, not a security breach,” and confirmed no sensitive customer data or credentials were involved. This incident raised transparency concerns from the community.