Esposter
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Prior art

Surveyed projects and why each does or doesn't fit. Keeps the landscape from being re-derived.

Filesystem layer — adopt

  • node:vfs (nodejs/node#61478, open) — official core virtual filesystem. Provider-based, full fs API compat, mount prefixes, overlay mode, module loading from virtual files. The end state virrun targets.
  • @platformatic/vfs (MIT) — the same work extracted to userland. Memory / Sqlite / RealFS providers, overlay mode, patches require/import/fs. Adopted now, swap to node:vfs later — one module owns the import (execution backends). Filesystem only; explicitly cannot run processes, native binaries, or npm install.

Shell layer — optional reuse

  • just-bash (vercel-labs, Apache-2.0) — TS bash interpreter, ~80 commands reimplemented in JS, WASM Python/JS/sqlite. Cannot run system binaries, no package-manager support, no VM isolation. Reusable only for its bash parser + builtins; never as the exec engine — pure-JS exec is rejected.

Runtime / sandbox — study, don't adopt wholesale

  • WebContainers (@webcontainer/api, StackBlitz) — node compiled to WASM, runs in-process/in-browser, pnpm install works. No native binaries, CPU-slow. Deferred as a backend.
  • e2b — TS SDK over Firecracker microVMs; real native support, but in their cloud / a Firecracker host you operate. Closest commercial analogue — evaluate before ever building the microVM path.
  • Firecracker + jailer (AWS) — microVM, sub-second boot, snapshotting. The reference design for an untrusted/multi-tenant backend (deferred).
  • CRIU — Linux checkpoint/restore; the candidate for true process-state warm-fork if FS-only snapshotting ever proves insufficient (snapshot and fork).
  • Turborepo — task cache prior art (skip unchanged builds); virrun's task cache is the same idea content-keyed on lockfile + working tree + command.

Names checked (rejected)

mirage (taken in-domain — strukto-ai/mirage, MirageOS), bare wisp/skiff/husk (all taken on npm). Settled on virrun — a contraction of virtual runner, short, unclaimed, published unscoped.