Mutating generated files in later steps

The gist of what I’m trying to do is: I’m making an ISO file by calling an external command, and then I’m trying to modify that ISO file by calling another command that isn’t actually external but for the purposes of this question we can pretend that it is. Here’s how I’ve implemented this in my build.zig: const iso_staging_dir = b.addWriteFiles(); // ...set up the ISO filesystem hierarchy... const build_iso_cmd = b.addSystemCommand(&.{ "xorriso", "-as", "mkisofs" }); // ...what feels like tw...