Every Claude change, once a week.
Claude changes almost daily — new Claude Code versions, new features, API updates. Every Friday we send one short email with everything that changed that week, each explained in a sentence or two, with a link if you want more.
What goes in it
These are the most recent changes we covered — the kind of thing you’d get on Friday:
- Claude Opus 5.5 launches with 1M context, always-on thinking, and API changes
Claude Opus 5.5 is a new model for long-running agentic coding and knowledge work, featuring a 1M token context window, 128k max output tokens, always-on adaptive thinking, and a lower price than Claude Opus 5. Several API behaviors have changed, including mandatory thinking and restricted tool_choice types.
- Claude Code 2.1.280: Opus 5.5 default, dozens of fixes
Version 2.1.280 adds Claude Opus 5.5 as the new default Opus model with 1M context, introduces several UI and hook improvements, and ships an unusually large batch of bug fixes across terminal, VSCode, web, and Slack integrations.
- Claude Code 2.1.278: Auto Mode Now Defaults to Server-Side Classifier
Claude Code's auto mode now defaults to the server-side classifier for Claude API, Enterprise, Bedrock, Vertex, Foundry, and gateway users, eliminating classifier overhead charges. A new 'Auto mode server' row in `/status` shows whether the current session uses server-side classification.
- Claude Code 2.1.277: AGENTS.md support, gateway proxy controls, and 60+ fixes
Version 2.1.277 adds AGENTS.md as a fallback project-instructions file, two new Claude apps gateway proxy options, and resolves over 60 bugs spanning crashes, tool errors, plugin management, Windows path issues, and VS Code/web/Slack integrations.
- Claude Code 2.1.276: Proxy compatibility fix
Version 2.1.276 fixes a regression introduced in 2.1.275 that caused every request to fail with a 400 error when using a custom proxy or gateway via ANTHROPIC_BASE_URL.
- Claude Code 2.1.275: Send-Now Key, Account Skill Sync, Plugin Marketplace Install
Version 2.1.275 adds a send-now shortcut (Ctrl+Enter or Ctrl+X Ctrl+S) to interrupt and flush queued messages, syncs claude.ai skills and plugins to terminal sessions, and introduces `/plugin install --marketplace` for one-step marketplace-and-plugin setup. The release also ships dozens of bug fixes across the terminal, VS Code, web, Slack (Claude Tag), and Code Review surfaces.
See every past change on the changelog.
The small print
- Free. One email on Fridays — nothing is sent in a week with no changes.
- You’ll also get a welcome email and three short tips emails in your first week.
- Every email has a one-click unsubscribe that stops all Claude Master email. We never share your address.
- Claude Master is independent and not affiliated with or endorsed by Anthropic.