No clue what's causing this to error.

[stray yew]

//root.zig
const std = @import("std");
const z = @import("zalgebra");
const c = @cImport({
    @cInclude("SDL3/SDL.h");
});
pub const Renderer = struct {
    window: *c.SDL_Window,
    pub fn init() void {
        _ = c.SDL_Init(c.SDL_INIT_VIDEO);
    }
    pub fn deinit() void {
        c.SDL_Quit();
    }
};
//main.zig
const std = @import("std");
const zig_cpugame = @import("zig_cpugame");
const root = @import("root.zig");
pub fn main() !void {
    var game = root.Renderer.init();
    game.deinit();
}

error: the following build command failed with exit code 1:
.zig-cache/o/36be8f30a32fd66c643c996d90074232/build /home/alpha/.config/VSCodium/User/globalStorage/ziglang.vscode-zig/zig/x86_64-linux-0.15.2/zig /home/alpha/.config/VSCodium/User/globalStorage/ziglang.vscode-zig/zig/x86_64-linux-0.15.2/lib /home/alpha/zig_cpugame .zig-cache /home/alpha/.cache/zig --seed 0x6e850313 -Z26a7d3b1a937618e run

[gleaming pike]

i'm not sure why you're not getting an error, but the problem is that src/root.zig is in both the main executable module, and the other one

    const mod = b.addModule("zig_cpugame", .{
        // The root source file is the "entry point" of this module. Users of
        // this module will only be able to access public declarations contained
        // in this file, which means that if you have declarations that you
        // intend to expose to consumers that were defined in other files part
        // of this module, you will have to make sure to re-export them from
        // the root file.
        .root_source_file = b.path("src/root.zig"),
        // Later on we'll use this module as the root module of a test executable
        // which requires us to specify a target.
        .target = target,
    });

this module includes the src/root.zig file, since its specified as the root source file

main.zig also includes src/root.zig, because of the line
const root = @import("root.zig");