To me ownership composability means you can express ownership locally without it infecting anything outside of that local scope. However, ownership is not alway

To me ownership composability means you can express ownership locally without it infecting anything outside of that local scope. However, ownership is not always tied to lexical scope and in those cases it doesn’t compose. In other words, you can add all the annotations you want locally and a) the code will still be incorrect b) the code may not compile as you show in your other snippet because now the function signature needs to contain the ownership sigil which then results in all callers needing the ownership sigil. Disabling it partially only emulates composition if the callers are in external files compiled with alternate options / skipping ownership validation. If you have local calls to the newly annotated function, you’ll be back into needing to fix the entire file’s annotations. Unless I misunderstood what OP meant about ownership composition.