@terrariumlabs/evm

npm install @terrariumlabs/evm      # you rarely install it directly: @terrariumlabs/core depends on it

revm 43 compiled to WebAssembly, as the execution engine of Terrarium. About 1.5 MB of wasm, no C dependencies (k256 for secp256k1, arkworks for bn254/bls12-381, pure-Rust KZG), built with wasm-bindgen --target web. pkg/ is committed so JavaScript users need no Rust toolchain.

What it does, and only that

It executes one transaction per call. Everything else stays in JavaScript: accounts, code and storage, checkpoints and reverts, blocks and receipts, persistence, fork recording. The engine asks the host for what it reads and returns a state diff to apply:

Two entry points: run(host, request) executes one transaction and returns its state diff; estimate(host, request) runs reth's gas estimation (a run at the cap, the optimistic 64/63 probe, a bisection from ~3× the gas used, within 1.5 %) in one call against a read cache, committing nothing. Analysed bytecode is cached by code hash across calls: host.account(address, wantCode) may omit code when wantCode is false (never answer '0x' for a contract). Built with wasm-opt -O3 and panic = "abort": 1.29 MB, 463 KB gzipped.

import init, { run, estimate, version } from '@terrariumlabs/evm';
await init({ module_or_path: wasmBytesOrUrl });
const result = JSON.parse(run(host, JSON.stringify({ tx, block, cfg })));
// result: { success, reason, gasUsed, gasRefunded, output, created, logs, state, sloads }

host is a plain object with synchronous methods account(address), storage(address, slot), blockHash(number). If the host cannot answer synchronously it throws { missing: true }; run throws "missing", the caller loads the state and calls again. Reads are recorded, so re-runs are exact. cfg.traceSloads returns every SLOAD (address, slot) — how Terrarium's deal finds a token's balance slot. Field-by-field schema: docs/api.md.

Build

rustup target add wasm32-unknown-unknown
cargo install wasm-bindgen-cli          # 0.2.127 at the time of writing; must match the wasm-bindgen crate version
npm run build                           # cargo build --release --target wasm32-unknown-unknown && wasm-bindgen --target web --out-dir pkg
node smoke.mjs                          # deploy PEPE, call balanceOf, trace the balance slot — PASS

getrandom is pinned with its js feature: wasm32-unknown-unknown has no OS entropy source.

Fidelity and speed

npm run test:uniswap (repo root) runs a 14-transaction Uniswap V2 scenario on this engine and on Anvil: every transaction hash, receipt, log, call result and revert payload is byte-identical, every block's header hash and roots recompute from the RPC output. The scenario takes ≈135 ms here (≈35 ms inside the wasm) versus ≈75 ms on native Anvil. test/unit/wasm.test.mjs pins the run / host contract described above. Since terrarium 0.3 this is the only execution engine.