RFC 0005: Island events and lifecycle diagnostics

Status

Implemented for the Rust-file source-authoring path used by the Vite adapter. The earlier .voo implementation was an exploratory intermediate and is not the current authoring contract.

Component events

An event declared in a component's events: block is emitted from Rust through the generated context.events.<event>(...) method. The generated method dispatches a CustomEvent on that component's framework-provided host element:

• its name is vooya-<event>;
• bubbles is false;
• zero parameters use undefined as detail;
• one parameter uses that primitive value as detail;
• multiple parameters use an array in declaration order as detail.

The Vue adapter listens on the same host and forwards the values to Vue emit. The React adapter listens on the same host and forwards the values to the corresponding onXxx callback. These events are an island-to-adapter boundary; they are not a DOM bubbling channel for ancestors or other islands.

Adapters install component-event listeners before calling mount. They remove them before disposal. If mount throws, both adapters remove those listeners immediately.

Failed mount cleanup

Generated component context contains a cleanup scope for one mount attempt. Component code can call context.cleanup.defer(...) to register a callback for a resource created before mount returns. If mount returns an error, the generated binding runs these callbacks in reverse registration order and removes host children appended during that mount attempt. On success it disarms the scope and the returned component handle owns its normal disposal.

This does not track or automatically undo arbitrary direct web_sys side effects that were not registered in the cleanup scope. Component authors remain responsible for such resources.

Development lifecycle diagnostics

In development builds, adapters dispatch host-local, non-bubbling events:

• vooya:mount
• vooya:update
• vooya:dispose
• vooya:error for failed load, mount, update, or disposal

Each event detail has only component, abiVersion, phase, and non-negative duration. Error diagnostics additionally contain error with truncated name and message. They do not include props, component-event payloads, stacks, or the original Error object. Production builds do not emit these diagnostics.

Diagnostics are observations for development tooling; the component runtime does not depend on a listener or a DevTools package.

Compatibility

This RFC does not change the Rust-file syntax, generated WASM export names, ABI version, or the Vue and React adapter public APIs.