How Platform Service APIs Work

WebAssembly code cannot directly call JavaScript promises or provider SDKs. Uzumibi adapter crates define Ruby methods and Wasm imports; the generated host implements those imports with the platform’s native APIs.

For Cloudflare Workers:

Ruby API
   |
uzumibi-cloudflare-ext
   |
Wasm import
   |
generated src/index.js
   |
Workers API or binding

Cloudflare operations such as outbound fetch, KV access, and Queue sends are asynchronous. The enable-external build applies Asyncify with wasm-opt and uses asyncify-wasm so the Ruby call can suspend while JavaScript awaits the Workers API.

The base Cloudflare HTTP template does not enable those asynchronous imports. The queue feature enables the external Rust feature as part of the Queue build.

API names can be shared by another adapter, but their exact provider semantics and configuration may differ. Treat each platform guide as the compatibility contract.