[xperiandri]

Summary

Stacked on #56. The branch contains the commits of #56 and of the pull requests before it, so the last 1 commit is new here.

This pull request raises the C# language version from 12.0 to 14.0 in Directory.Build.props, for the extension and the tests. It needs no other pull request to work: LangVersion is read by every C# project, whatever its format; it sits behind #56 only for the order of the commits. The matching update of the instructions is part of the last pull request of the chain (#69), because the instructions live in the files that #54 adds. The code does not change.

Chain, changes, things to know and verification

Chain

This pull request is part of a chain of small pull requests that all target main. After #53 the chain has two branches that do not depend on each other: the AI agent files (#54) and the modernization of the build (#55 to #58). The last pull request (#69) merges both and updates the instructions, which live in the files of the AI branch. The branch of each pull request contains the commits of the ones it is stacked on, so GitHub lists those commits here until they are merged. Merge in this order and review only the commits that are new in each pull request:

1. Switch the solution to the .slnx format #53 – Switch the solution to the .slnx format (first in the chain, no dependencies)
2. Add instructions, skills and MCP configuration for AI coding agents #54 – Add instructions, skills and MCP configuration for AI coding agents (stacked on Switch the solution to the .slnx format #53)
3. Convert the projects to the SDK style #55 – Convert the projects to the SDK style (stacked on Switch the solution to the .slnx format #53)
4. Move the package versions to central package management #56 – Move the package versions to central package management (stacked on Convert the projects to the SDK style #55)
5. Set the C# language version to 14 #57 – Set the C# language version to 14 (stacked on Move the package versions to central package management #56) – this pull request
6. Build with dotnet build #58 – Build with dotnet build (stacked on Set the C# language version to 14 #57)
7. Update the instructions for the SDK-style projects, central package management, C# 14 and dotnet build #69 – Update the instructions for the SDK-style projects, central package management, C# 14 and dotnet build (stacked on Build with dotnet build #58 and Add instructions, skills and MCP configuration for AI coding agents #54)

Changes

• Directory.Build.props sets LangVersion to 14.0 for both projects; it was 12.0.

Things to know

• C# 14 needs the .NET SDK 10 or Visual Studio 2026 on a development machine. The windows-2022 image of the CI has the .NET SDK 10, so the workflows need no change; the build of this pull request ran on it.
• The code compiles to the same types and methods as with 12.0, with the same warnings. The language features that the runtime must support (record with init, Index and Range, default interface members) still need polyfills or are unavailable on .NET Framework 4.8.1; the instructions already say so.

Verification

• With the .NET SDK 10.0.402, Debug and Release build without errors, with the same 26 distinct warnings; the fingerprints of both assemblies (every type and method with the IL size) are identical to the build with 12.0; the 4 tests pass.
• CI: the workflows of this repository wait for the approval of a maintainer on a pull request from a fork, so the commit ran in a fork on a clean windows-2022 runner: Build builds the solution with LangVersion 14.0 and runs the 4 tests, which pass. As on the unchanged main (run), the step Publish Test Results fails there: the third-party action EnricoMi/publish-unit-test-result-action finds no Python interpreter on the image. This pull request neither causes nor changes it.

🤖 Generated with Claude Code

• After the chain was re-cut so that this pull request no longer contains the files of Add instructions, skills and MCP configuration for AI coding agents #54, the tip was built again locally with the MSBuild of Visual Studio 2026 (no errors, the same distinct warnings as the pull request before it).