Run the fast, read-only supported-toolchain check from the repository root:

ruby script/toolchain_preflight.rb

The command accepts the currently tested x86_64 environments:

Platform Ruby Bundler Premake Build driver Native compiler Formatter
Linux x86_64 3.3.12, 3.4.9, or 4.0.5 2.7.2 5.0.0-beta8 Premake gmake and make g++ clang-format
macOS x86_64 3.3.12 2.7.2 5.0.0-beta8 Premake gmake and make clang++ Homebrew llvm@18 clang-format in CI
Windows x86_64 3.3.12 2.7.2 5.0.0-beta8 Premake gmake and make g++ clang-format

Premake can be selected with PREMAKE, and clang-format can be selected with CLANG_FORMAT. The preflight reports the resolved paths and detected versions. Compiler, make, and clang-format release numbers are reported but are not pinned because the current CI contract only proves their availability on the named runners.

Success means that the environment and repository metadata match the supported contract. Failure reports all detected missing, unsupported, or drifted prerequisites before the build begins. The command does not install or download tools, modify or generate files, clean the checkout, build Dab, or run tests. Run the complete validation gate when the preflight and inherited build/test/documentation gate should run together.