Anthropic AI Updates: April 2, 2026

1. Claude Code v2.1.90 Adds Interactive Lessons and Fixes Key Bugs

Anthropic. Claude Code version 2.1.90, tagged on April 1, 2026, introduces interactive lessons that teach Claude Code features with animated demos via the /powerup command, along with .husky directory protection in acceptEdits mode and an environment variable for offline plugin environments. The release also resolves a significant infinite loop where the rate-limit options dialog repeatedly auto-opened after hitting usage limits, fixes Edit/Write failures caused by PostToolUse format-on-save hooks rewriting files, and corrects a UI crash from malformed tool input in permission dialogs. Performance improvements include JSON.stringify elimination and SSE transport optimizations, plus an improved /resume all-projects view with parallel session loading. Source

2. Claude Code v2.1.89 Adds Deferred Permissions and Fixes Widespread Bugs

Anthropic. Claude Code version 2.1.89, also released on April 1, 2026, adds a "defer" permission decision for PreToolUse hooks that allows headless session pauses, named subagents in @ mention typeahead suggestions, and a CLAUDE_CODE_NO_FLICKER=1 environment variable for flicker-free rendering. The release fixes a StructuredOutput schema cache bug causing roughly a 50% failure rate, a memory leak from large JSON inputs retained as LRU cache keys, prompt history silently dropping CJK and emoji characters at 4KB boundaries, and claude-cli:// deep links not opening on macOS. PreToolUse and PostToolUse hooks now receive file_path as an absolute path, and autocompact detection was improved for context refill loops. Source

3. Anthropic API Deprecating 1M Token Context Window Beta for Older Models on April 30

Anthropic. Anthropic announced it is retiring the 1M token context window beta for Claude Sonnet 4.5 and Claude Sonnet 4 on April 30, 2026, giving developers roughly a month to migrate. After that date, requests exceeding the standard 200k-token context window will return an error for those models. Users who need 1M context windows should migrate to Claude Sonnet 4.6 or Claude Opus 4.6, which support the full 1M token context window at standard pricing without a beta header. Source