RFC 0001: Vooya Component Islands

Status

Accepted for the Stage 0 architecture validation.

Problem

Some JavaScript UI components spend material time in state derivation, list reconciliation, and event-heavy rendering. Rewriting an entire existing application in another framework is usually disproportionate. Vooya investigates whether a Rust/WASM component can replace only the expensive subtree while remaining an ordinary component from the host framework's perspective.

Decision

Vooya components compile from Rust to wasm32-unknown-unknown. A host adapter mounts one component into one host-owned element. Once mounted, Vooya owns every DOM node below that element. The host owns the element itself and its place in the application tree.

The first host is Vue 3 through a Vite plugin and @vooya/vue. The core is not allowed to depend on Vue APIs.

Host framework             Adapter                 Vooya runtime
--------------             -------                 ------------
props -------------------> compact ABI ----------> state + render
unmount -----------------> dispose --------------> release state/listeners
events <------------------ CustomEvent <---------- component dispatch

Component events are dispatched on the host element with a vooya- prefix and bubbles: false. The adapter listens directly on that element and forwards the payload through the framework's component-event mechanism. This prevents an ancestor DOM listener or another island from observing an island event.

Non-goals for Stages 0-4

• Reimplementing Vue, React, routing, or global state management.
• Rendering into DOM nodes owned by the host framework.
• Vue slots, arbitrary host VNodes, provide/inject, or deep reactive object synchronisation.
• Server-side rendering, hydration, or a standalone Vooya application framework.
• Claiming that WASM improves ordinary DOM-bound UI without measurement.
• A global CLI or a CLI bundled into runtime packages.

Build decision

Use Cargo plus wasm-bindgen directly. wasm-pack is a useful publishing wrapper but does not own Vooya's Vite-oriented development workflow, incremental cache, or generated component module shape. The future Vite plugin will invoke the build pipeline; users will not need a global CLI.

The initial release profile uses size-oriented optimization and must be compared against opt-level = 3 on measured workloads before a default is chosen.

ABI and component boundary

The first ABI supports JSON-compatible props and event payloads. JavaScript calls into WASM only for mount, prop update, and dispose. DOM updates and event delegation remain inside the component where possible. This avoids treating individual DOM calls across the JS/WASM boundary as a performance strategy.

Deferred decisions

• Rust component syntax and macro design.
• DOM renderer architecture: retained tree versus direct incremental updates.
• HMR state preservation semantics. The Stage 2 plugin rebuilds the Rust core and requests a full page reload when Rust source changes; it does not claim state preservation.
• CSS scoping and asset loading.
• A React adapter, to be reconsidered only after Stage 4.