What's new in ReSharper 2026.3

• Claude Agent and Codex are supported in the AI Assistant.

• Full support for C# 15, covering union types, closed class hierarchies, collection expression arguments, extension indexers, and labeled break and continue statements.

• Parameter information now groups related overloads by their shared parameter prefixes, keeping similar signatures together.

• Improvements in unit testing support:

  • Support for xUnit v3 version 4.0. and NUnit 5.0.

  • Test discovery is more reliable for MSTest 4 projects.

  • Playwright settings in your .runsettings file, such as LaunchOptions, are now applied when you run tests, so you can run browser tests with the browser window visible.

  • Microsoft Testing Platform support is now enabled by default, so tests for frameworks like TUnit are discovered without changing any settings.

• Support for .NET 11 runtime-async methods in decompiled code and IL Viewer.

• New features in C++:

  • New code inspections that enforce the restrictions of the CUDA Tile programming model.

  • Support for new language features:

    • C++23 delimited escape sequences: \x{...}, \o{...}, and \u{...}.

    • C++26 user-generated static_assert messages.

    • C++26 offset parameter of the #embed directive.

    • C++26 #line directives before module declarations.

  • The new Class Layout tool window shows how a class, struct, or union is laid out in memory.

  • Refactoring improvements:

    • The new Introduce Using Directive refactoring replaces namespace qualifiers with a using namespace directive.

    • Change Signature now works for constructors.

    • Extract Method now has the Place in and Make constexpr options.

  • The bundled Clang-Tidy and Clang-Format have been updated to LLVM 23.

  • Error messages for failed requires expressions, deleted constructors, and failed destructibility checks now explain the full chain of reasons.