I’ll use Ghostty as an example because that’s the only software I use that I know is written in Zig. It’s also a moderately complex project not a toy project.

Its Zig 0.15 effort started in August and was only complete in October (see first PR at https://github.com/ghostty-org/ghostty/pull/8372). And many issues were encountered and solved along the way. And of course during all of this they also encountered an issue in Zig itself: https://github.com/ziglang/zig/issues/24627

The huge change that will be passing Io objects around like you have with Allocator.

0.16 changes things around dramatically.