twin-wasm-extract.ts

Overview

@file Extract the WASM module embedded in web-twin/twin.js into src/twin.wasm. /twin runs the compiled firmware inside a Cloudflare Worker, not a browser. workerd refuses runtime WASM code generation from a byte array (WebAssembly.instantiate(bytes, …) — the exact path twin.js's own findWasmBinary()/instantiateArrayBuffer() take — fails there with "Wasm code generation disallowed by embedder"; confirmed directly against wrangler dev, see docs/twin-worker-phase0.md). A WASM module imported as a build-time module resource (import wasmModule from "./twin.wasm") is compiled ahead of time instead, which workerd does allow, and Emscripten's Module["instantiateWasm"] hook lets a caller supply that precompiled module without twin.js ever reaching its own embedded-bytes path. This script produces that file — once, checked in — by requiring the real, unmodified twin.js under Node (where runtime WASM codegen is allowed) and capturing the exact bytes its own WebAssembly.instantiate call receives. twin.js is never edited, forked, or re-encoded; only observed. Run after any web-twin/twin.js rebuild: npm run twin-extract in bot/, then commit src/twin.wasm and src/twin.lock.json together. npm test's drift guard (test/twin-wasm-drift.test.ts) fails if twin.js changes without a matching re-extraction.

flowchart TD
  main --> sha256