Right now it requires the toolchain be installed because it hardcodes the path to python in the installed v4 toolchain. It also tries to use clang-tidy from the bazel toolchain. While that may be desireable, it currently adds an extra second to every run to invoke bazel to locate the toolchain. And it only works with the main execroot, not the compiledb execroot. We may want to move to the bazel toolchain long term, but until we work out the details, since we are requiring the installed toolchain for some ide integrations, we should probably still use the installed version here and save that second. It is often something that people will be waiting for if they want to see if a warning went away after saving.