Introducing Claude Haiku 4.5: our latest small model.

Five months ago, Claude Sonnet 4 was state-of-the-art. Today, Haiku 4.5 matches its coding performance at one-third the cost and more than twice the speed. Haiku 4.5 surpasses Sonnet 4 on computer use tasks, making Claude for Chrome even faster.

In Claude Code, it makes multi-agent projects and rapid prototyping markedly more responsive.

This morning we announced several upgrades to Claude Code.

We also launched two new features for managing context on the Claude Developer Platform.

Here’s what’s new: The Claude Agent SDK gives you access to the same core tools, context management systems, and permissions frameworks that power Claude Code.

Read how devs are building agents with the SDK:
anthropic.com/engineering/bu…

Introducing Claude Sonnet 4.5—the best coding model in the world.

It's the strongest model for building complex agents. It's the best model at using computers. And it shows substantial gains on tests of reasoning and math. We're also releasing upgrades for Claude Code.

The terminal interface has a fresh new look, and the new VS Code extension brings Claude to your IDE.

The new checkpoints feature lets you confidently run large tasks and roll back instantly to a previous state, if needed.

We've published a detailed postmortem on three infrastructure bugs that affected Claude between August and early September.

In the post, we explain what happened, why it took time to fix, and what we’re changing: In early August, some users began reporting degraded responses.

It was initially hard to distinguish this from normal variation in user feedback. But the increasing frequency and persistence prompted us to open an investigation.

A roundup of what’s new in Claude Code: Output styles and Learning mode:

https://x.com/claudeai/status/1956038897793716228

Over the last two weeks, 200+ members of r/ClaudeAI shared products, apps, and projects they’ve built with Claude.

Announcing the Built with Claude contest winners: u/Legitimate-Gene-7047, a dentist, developed a professional cephalometric analysis app to replace the one they used in their clinic.

“I said to myself that even I could make an app that works better than this.”

How (and why) agents in Claude Code help you write better code, faster:

Agents allow you to deploy specialized experts for every task. It's like managing a team rather than collaborating 1-on-1. To get started, launch Claude Code, run /agents and select "Create new agent."

Define it by describing what the agent should do and when it should be used. Be specific but not overly prescriptive.

Today we're launching new ways to learn in Claude Code and the Claude app.

First up: Claude Code now lets you customize communication styles with /output-style We're introducing two output styles to help students and developers build skills:

- Explanatory: Claude explains its reasoning step-by-step
- Learning: You take turns coding with Claude

We just shipped automated security reviews in Claude Code. Catch vulnerabilities before they ship with two new features:

- /security-review slash command for ad-hoc security reviews
- GitHub Actions integration for automatic reviews on every PR The /security-review command runs security analysis directly from your terminal.

Claude checks for vulnerabilities like:
- SQL injection risks
- XSS vulnerabilities
- Insecure data handling

Found a vulnerability? Simply ask Claude to fix it.