Macro export_runtime 

export_runtime!() { /* proc-macro */ }

Emit the runtime symbols every WeaveFFI library exports, prefixed with the crate’s name: {prefix}_abi_version, {prefix}_error_set, {prefix}_error_set_payload, {prefix}_error_clear, {prefix}_error_free, {prefix}_alloc, {prefix}_free_bytes, the four {prefix}_cancel_token_* functions, and {prefix}_debug_live.

Invoke it exactly once, at the crate root of the cdylib. It takes no arguments.