TIL that AMD64 instructions generally don't support immediates greater than 32-bit: https://c9x.me/notes/2015-09-19.html
If you really need a large immediate value, you need to use MOV into a register first.
I'm pretty impressed with Cursor: I've successfully asked it to perform codebase transforms in English, and it's worked!
E.g. "Replace all calls foo(..., true) with foo_immediate(...) define a foo_immediate function".
I'm still reading the diff and checking tests -- it's still AI after all.