Developer Newsletter: Fable 5.1 and maximizing the value of Claude Code sessions

Dropping this month: Claude Haiku 5.5, Code Review general availability, and a new API version with major SDK releases.

Feature releases

All the code that’s fit to ship.

Feature Highlight: We’re introducing Claude Haiku 5.5, the cheapest, fastest, and most capable small model we’ve ever released. It’s designed for high-volume, cost-sensitive tasks, pairs well with Opus 5.5 and Sonnet 5.5 as a subagent on coding work, and on average costs around 75% less to run than Haiku 4.5. Learn more.

Claude Code:

• Run more sessions side by side on desktop. Start Claude Code sessions faster, split work across parallel sessions, and see at a glance which ones need your attention.
• Code Review is now generally available. Catch more bugs that matter, with faster reviews that you can tune to each of your repositories. Available on Team and Enterprise plans.
• Cloud sessions are now generally available. Start a session from your browser, phone, desktop app, or terminal. Close your device, and Claude keeps running. You can pick up sessions later from wherever you are.

Claude Platform:

• Agent observability on the Claude Platform (beta). Send OpenTelemetry (OTel) traces from Claude Managed Agents, the Messages API, and Anthropic SDKs to any OTel tool to follow each step your agents take.
• Computer use and browser use in the Anthropic SDKs (beta). Run computer use and browser use agents in your own code with the Anthropic Python and TypeScript SDKs. Use them to automate work in apps that have no API, like form filling and data entry.
• API version 2026-10-21. Claude API version 2026-10-21 is now available. It’s opt-in, and requests on 2023-06-01 continue to work as they do today. Upgrade to the new major version of the Anthropic SDKs when you’re ready.
• Agent Skills joins the Agentic AI Foundation. We’re donating Agent Skills to the AAIF at the Linux Foundation, where it joins MCP as an open, vendor-neutral standard. At the AAIF, anyone building with skills can help shape what’s next. Engineers from Anthropic and other companies will maintain it.

Claude Apps:

• Introducing Claude Duet (research preview). Work with Claude as a proactive agent that surfaces what needs your attention, keeps working when you step away, and checks with you before it acts on your behalf. Join the waitlist, starting with US Pro and Max subscribers.
• Claude Security now scans continuously and tracks fixes (beta). Keep up with your repositories as code changes and track findings until fixed. Claude Security learns from your team’s context and connects to your tools. Admins for Claude Enterprise can enable this in the admin console. Claude Enterprise organizations receive up to $25,000 in usage credits to use on Claude Security for two months. The offer applies to usage through December 31, 2026. Terms apply.
• Build live dashboards and animate explainers with Claude (beta). Turn data from tools like BigQuery, Databricks, Snowflake, and Salesforce into live dashboards and your ideas into animated explainers. Dashboards are on paid plans, and animated explainers are on Team and Enterprise.
• Claude now works with Google Docs, Sheets, and Slides (beta). Work with Claude for Google Workspace in your open Docs, Sheets, and Slides files, and new connectors let Claude create and edit Google files without moving between tools. Available on paid Claude plans.

TIL

Sharing Claude resources from Anthropic and our developer community.

• How the Claude Code team does code review. How do you review code when agents produce more of it than your team can read? Learn how the Claude Code team uses Claude to manage code review, with reverts and incidents as the guardrail.
• Getting started with Claude Code mods. Our best practices for building your first Claude Code mod.
• Building effective agent automations. A reference implementation that walks through how to use Claude Managed Agents to build a monitoring agent that checks your sources on a schedule and posts what changed.

Claude Community

From the terminal to IRL, the Claude Community is meeting around the world. Check out our calendar and register to join fellow builders in your city, including:

Humans who ship

Spotlights on the founders, builders, and programmers who ship with Claude.

This month, we’re highlighting five projects to show how our community is building with Claude:

• CityPulse — An interactive smart-city traffic simulator that maps out how adaptive traffic lights reduce congestion. Built by Zakaria Adnane and Achraf Salki.
• Ballast — A Claude Code plugin that keeps your rules, decisions, and verified facts in files instead of the conversation. Correct Claude once, and a hook delivers that rule with every request it matches. Built by @woogie_o.
• Math-Animals — Ten animal illustrations built entirely in code with Claude Code and rendered in Canvas 2D, each generated from the published science behind its form. Built by Sanju Sunny.
• Satradar — A satellite tracking and visualization app. Built by Euan Brown, winner of the Claude Founder House Builder Showcase in London.
• Telephone Detective — A murder mystery you solve by talking to AI characters through a converted 1940s rotary phone. Built by Georg Luif, winner of the Claude Founder House Builder Showcase in Stockholm.

Resources

Discord | Release Notes | Docs | Anthropic Academy | X | Blog