> Every struct or bare fn now needs (2) fields/parameters by default.

Storing interfaces a field in structs is becoming a bit of an an anti-pattern in Zig. There are still use cases for it, but you should think twice about it being your go-to strategy. There's been a recent shift in the standard library toward "unmanaged" containers, which don't store a copy of the Allocator interface, and instead Allocators are passed to any member function that allocates.

Previously, one would write:

    var list: std.ArrayList(u32) = .init(allocator);
    defer list.deinit();
    for (0..count) |i| {
        try list.append(i);
    }

    var list: std.ArrayList(u32) = .empty;
    defer list.deinit(allocator);
    for (0..count) |i| {
        try list.append(allocator, i);
    }

    var list: std.ArrayList(u32) = .empty;
    defer list.deinit(allocator);
    try list.ensureUnusedCapacity(allocator, count); // Allocate up front
    for (0..count) |i| {
        list.appendAssumeCapacity(i); // No try or allocator necessary here
    }

I think a good compromise between a DI framework and having to pass everything individually would be some kind of Context object. It could be created to hold an Allocator, IO implementation, and maybe a Diagnostics struct since Zig doesn't like attaching additional information to errors. Then the whole Context struct or parts of it could be passed around as needed.

Yes, and it's good that way.

Please, anything but a dependency injection framework. All parameters and dependencies should be explicit.

I think and hope that they don’t do that. As far as I remember their mantra was „no magic, you can see everything which is happening“. They wanted to be a simple and obvious language.