@tropel/core-wasm

Tropel's core tier for browser embedders — the pure compute every API client page needs, compiled to wasm32-unknown-unknown with a wasm-bindgen surface. No QuickJS, no WASI, no scenario runner: that is the separate heavy tier (@tropel/runtime-wasm / tropel_web.wasm).

Today it ships the dynamic-variable catalog ({{$guid}}, {{$timestamp}}, {{$randomHexColor}}, 35+ variables — the same DynamicCatalog the native runner uses, so the website, the extension and the CLI can never drift). Next residents: auth signing, OpenAPI/Postman import parsing, declarative assertions.

Why it exists

API_CLIENT_WEB_PAYLOAD.md §2.3 (two-tier wasm):

core tier    variables · auth signing · import parse        ~450 KB raw
             NO QuickJS — loaded eagerly

script tier  QuickJS + sandbox + shims (tropel-web)          ~2.5 MB
             extension/native only (or loaded only when a
             request actually has scripts)

A website/web app always executes scripts in the browser's own JS engine (@tropel/shims) and hits APIs through a CORS relay — it never needs the QuickJS tier. See KnockPort's WEB_EXTENSION_RUNTIME_SPLIT.md.

Usage

import { initCoreWasm, resolveDynamicVariables, getPredefinedVariableNames } from "@tropel/core-wasm";

await initCoreWasm();                                    // app boot
const out = resolveDynamicVariables("id={{$guid}}");     // sync, wasm-backed
const names = getPredefinedVariableNames();              // for editor autocomplete

initCoreWasm accepts { wasmUrl } or { wasmBytes } (Node/tests); by default it fetches pkg/tropel_core_wasm_bg.wasm relative to the package. Until (or if) init succeeds, resolveDynamicVariables degrades to a passthrough — {{$…}} survive literal and nothing throws.

Building

bash scripts/build.sh        # cargo release-wasm → wasm-bindgen → wasm-opt -Oz → smoke → pack dry-run

Requires the wasm32-unknown-unknown target and a modern wasm-opt (npm binaryen; wasm-pack's pinned 171374efd61df962 predates reference-types and cannot parse the output). Rust tests live in the crate (cargo test -p tropel-core-wasm); the JS smoke test runs in Node: node smoke.mjs.

Size

465,677 B raw after wasm-opt -Oz --strip-debug (155 KB brotli, measured, 234,323 B headroom under the 700 KB gate). ✅MEAS