The Pulse
JetBrains adds Claude Agent and Codex to ReSharper
ReSharper 2026.3 brings Claude Agent and Codex into its AI Assistant window in Visual Studio. The release also adds support for .NET 11, C# 15 and updated testing frameworks.
AI.info Team · Written with AI · fact-checked ·
JetBrains has added Claude Agent and Codex to ReSharper 2026.3, giving Visual Studio users two more coding agents in the AI Assistant tool window, according to the company’s release announcement. The agents join Junie, which arrived in the preceding ReSharper release.
Users can ask the selected agent to write or edit code, run terminal commands or explain unfamiliar parts of a solution. The release also supports.NET 11 and C# 15 and updates the ReSharper test runner for newer framework versions.
Agents in the editor
The agents connect through the Agent Client Protocol, which links coding agents to editors. In the AI Assistant window, users can select Claude Agent, Codex or Junie and send a prompt without switching to a separate application.
ReSharper asks for consent before installing Claude Agent or Codex the first time either is used. It also installs Node.js if that software is not already present on the machine. AI Assistant must be selected in the ReSharper installer to use the tool window.
All three agents can use ReSharper’s refactoring skill to perform operations such as renaming symbols or moving types to other namespaces. The skill lets an agent run those refactorings rather than edit files individually.
Subscriptions and access
Claude Agent and Codex require a JetBrains AI subscription and consume its quota. Junie also uses that quota unless the user selects Junie Lite, a free model tier.
Junie Lite is available in ReSharper to anyone signed in with a JetBrains Account, including people without a ReSharper license. The free tier does not require a trial.
ReSharper no longer offers JetBrains AI Pro trials, although people who have already started one can continue using it until it ends. Regional restrictions apply to AI features in mainland China.
Language and code tools
C# 15 support covers union types, closed class hierarchies, collection expression arguments, extension indexers, and labeled break and continue statements. Code analysis, completion and navigation work with the new syntax, alongside inspections and quick-fixes for existing code.
The release also supports the memory safety redesign preview, recognizing the safe modifier and unsafe expressions. It highlights missing or redundant unsafe contexts and offers fixes. For runtime-async methods, which remain a preview feature in.NET 11, the decompiler displays an ordinary async method and the IL Viewer marks it with the async keyword.
Additional inspections flag issues including character values used as array lengths or indices, culture-sensitive operations and using statements that dispose of a task instead of its result. For C++, the release adds a class layout view, format-string checks, refactoring options and CUDA inspections.
Testing updates
The test runner now supports xUnit v3 4.0 and NUnit 5.0. Test discovery is also improved for MSTest 4 projects.
ReSharper applies Playwright settings from a project’s.runsettings file, including launch options that allow browser tests to run with the browser window visible. Microsoft.Testing.Platform support is enabled by default, allowing tests for frameworks such as TUnit to be discovered without changing settings.