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WASI preview 3 llegó como estándar estable a finales de 2025 y ha tenido unos meses para demostrar si realmente desbloquea los casos que preview 2 se quedaba cortos. Recorrido honesto por adopciones reales, bibliotecas maduras y patrones que empiezan a funcionar en producción.
WASI 0.3, also known as preview 3, was ratified on June 11, 2026, adding native asynchronous concurrency to the WebAssembly component model through streams, futures, and async functions. It fixes old fragmentation across languages and runtimes, enables real composition between Wasm services, and paves the way for cooperative threads planned in upcoming 0.3.x releases.
WASI 0.2 reached GA in January 2024, bringing WebAssembly's Component Model into production: typed WIT interfaces that let Rust, Go, and JavaScript code compose without manual glue code. That shift makes edge functions with sub-1 ms cold start, secure plugins, and untrusted-code sandboxing viable today, though it does not replace containers for traditional apps.
WASI Preview 2 redefines how WebAssembly interacts with the operating system. It introduces the Component Model with typed WIT interfaces and granular capabilities, enabling modules written in different languages to compose without manual serialisation. The full standard arrives in 2024 with direct impact on edge functions, plugins, and serverless.
WebAssembly is moving beyond the browser through WASI, the standard system interface, and the component model, which defines declarative WIT interfaces so modules written in different languages can compose with each other. Cold start lands around 1 ms versus roughly 500 ms for a container, a key difference for serverless and edge computing teams.
