ADR-012: Browser as First-Class Node

Status

Exploring

Context

The browser should not be a lite client that talks to a server. It should run the same engine — same parser, same execution. This means both kern (OCaml) and the Rust engine need to compile to WASM and run in the browser.

The problem

kern (OCaml) compiles to WASM via wasm_of_ocaml, which outputs WasmGC instructions. The Rust engine compiles to WASM via wasm-bindgen. Both need to run in the browser and talk to each other.

WasmGC support

• Browsers: Chrome 119+, Firefox 122+, Safari 18.2+ — all support WasmGC
• wazero (Go): does not support WasmGC, no timeline (#1860)
• wasmtime (Rust): supports WasmGC since v27.0 (November 2024)

This is why the browser path works but the Go server path doesn't for OCaml WASM.

Composition

Two WASM modules (kern + Rust engine) need to call each other in the browser. The WASM Component Model (Wasm 3.0, September 2025) is designed for this — typed interfaces between modules. Whether this is the right mechanism needs investigation.

Open questions

• Is the Component Model the right composition mechanism, or is there something simpler?
• What does the interface between kern.wasm and qntx.wasm look like?
• IndexedDB as the browser-side storage backend (replacing SQLite)?
• Offline-first: what subset of the engine runs without a server?