Function is_effectful_return 

pub fn is_effectful_return(r: &TypeRef) -> bool

P6.50 (design/tracks/the-ir.md §6b): a return type’s own syntactic Effect[...] wrapper — TypeRef::Effect(_, _), not the resolved Ty::Effect(_) shape lower_handler_signature_ir reads above via cx.program.ty_intern. Relocated here from emitter/emit.rs (its original home, #[allow(dead_code)]-free and with eight call sites across emit.rs/workers.rs/workers_entry.rs) because lower_service_handler_signature_ir below was already calling up into it (bynk_emit::emitter::is_effectful_return) — the Ast → Ir boundary running backwards, an Ir-side lowering function reaching into the emitter module it should only ever be called from. emit.rs and friends now call bynk_lower::is_effectful_return instead (relocated again at the P7.12 crate carve — emitter/ir::lower are now separate crates, bynk-emit/bynk-lower respectively).