TextMate bundles
There may be cases when it is required to have code highlighting with Smart Mode off, or when the language you need is not supported.

For such cases, JetBrains Fleet provides the ability to add custom TextMate bundles.
Navigate to one of the following path depending on your operating system:
Windows
%APPDATA%
\JetBrains \Fleet Linux
~
/.config /JetBrains /Fleet macOS
~
/Library /Application Support /Jetbrains /Fleet In the Fleet directory, create the textmate directory, and place the required TextMate bundles there.
In this procedure, we use the ziglang/Zig.tmbundle repository at GitHub to enable support for the Zig language. We clone the whole repository to the textmate directory. The full path to the bundle is the following:
~
/Library /Application Support /Jetbrains /Fleet /textmate /Zig.tmbundle / Restart JetBrains Fleet.
After you restart JetBrains Fleet, it will pick up the provided bundles and add the highlighting for the respective file types.

Thanks for your feedback!