Tools This Week: October 30, 2026 - Copilot Fusion

This week's Tools This Week list has five developer tools. GitHub made Copilot Fusion generally available, so Copilot can now pick and combine models for you. Mistral released the weights of its largest model, and Google shipped Android Studio Rabbit 2 with support for outside coding agents. OpenSSL 4.1.0 arrived, and the Node.js project put out the first Node.js 27 alpha, which bundles it. This edition covers October 24 to Friday, October 30.

This week's tools at a glance

Tool	What it does	Price
GitHub Copilot Fusion	Routes and combines AI models per coding task	All Copilot plans; models billed at standard rates, 30% off for a limited time on paid plans
Android Studio Rabbit 2	Android IDE that runs 40+ outside coding agents	Pricing not stated
Mistral Large 4	1-trillion-parameter open-weight model	API $0.70 input, $2.10 output per million tokens
OpenSSL 4.1.0	Encryption library, now with DTLS 1.3	License not stated on the page
Node.js 27 alpha	First test build of the next Node.js	Pricing not stated

AI coding tools

Copilot Fusion became generally available on October 28. Instead of choosing one model, you pick Fusion and Copilot decides which models to use. It has three effort levels, Standard, High and Max. It also has three ways of working: one model alone, a cheap model that escalates when a check fails, or one model drafting while another reviews. GitHub says Fusion Max scored 60 on the Artificial Analysis Coding Agent Index, within two points of Claude Code with Opus 5.5 Max, at about half the cost per task. It works in VS Code, the Copilot app, the Copilot CLI and JetBrains IDEs. Read our Copilot Fusion story.

Android Studio Rabbit 2 makes Bring Your Own Agent stable. That lets the IDE run more than 40 coding agents that speak the Agent Client Protocol (ACP), a common standard for plugging agents into editors. A new Change Review feature reviews pending agent edits, and you can call it with /review. The Android CLI gained android preview, which renders Compose previews without an emulator. Google says that was 77% faster with up to 3x fewer tokens in its own tests. See our Android Studio Rabbit 2 story.

Models

Mistral published open weights for Mistral Large 4, a 1-trillion-parameter model that uses 49 billion active parameters per token. It has three reasoning modes, Low, Medium and High. The weights come under the Mistral Ecosystem Open-Weight License, a modified MIT license. Anyone can use and fine-tune them, but selling the model as a hosted service needs a separate commercial license. Through Mistral's API it costs $0.70 per million input tokens, $0.07 for cached input and $2.10 for output. More in our Mistral Large 4 story.

Runtimes and libraries

OpenSSL 4.1.0, released October 23, adds DTLS 1.3, the secure-connection protocol used over UDP, plus GREASE, a trick that keeps TLS software from breaking on unknown values. It also brings AVX-512 speedups on x86_64. Watch the breaking changes. The tsget script now needs the Net::Curl::Easy Perl module, and the no-ecdsa and no-ecdh build options are gone in favor of no-ec. See our OpenSSL 4.1 story.

Node.js 27.0.0-alpha.0.0.0 arrived on October 29. It is the first build under Node's new plan of one major release a year. It updates V8 to 15.6, bundles npm 12.1.0 and OpenSSL 4.1.0, and requires OpenSSL 3 or later. About 100 commits are semver-major. It is not meant for production. Read our Node.js 27 alpha story.

What this means for developers

• Try Copilot Fusion on one repo. Pay attention to the bill. Each model Fusion uses is charged at its normal rate, and the 30% discount is temporary.
• Point Android Studio at the agent you already use. If your team runs Claude Code or Codex, Rabbit 2 can now host it inside the IDE instead of a side terminal.
• Read the Mistral license before you build a product on it. Self-hosting for your own app is allowed. Reselling the model as a hosted API is not, without a deal.
• Check OpenSSL build scripts. If your build passes no-ecdsa or no-ecdh, it will fail on 4.1.0 until you switch to no-ec.
• Add the Node.js 27 alpha to CI. You have until April 2027 to fix what it breaks, and native addons need a rebuild.

The previous edition is Tools This Week: October 23, 2026. The current list always lives on the Tools This Week page.