Patchpit

Patchpit is a browser shell for trusted HTML apps sharing an Automerge-backed filesystem. It projects an app folder into an immutable file snapshot, stores that snapshot in Cache Storage, and launches it through a same-origin service-worker mount so normal relative HTML, CSS, and module URLs work.

The current same-origin app profile is for trusted plugins. See packages/sandbox/SECURITY.md for its boundary.

Development

Prerequisites: Node >=24.12.0, pnpm@10.33.2, and Chromium for the browser harnesses.

pnpm install
pnpm dev
pnpm build
pnpm build:sandbox-compat
pnpm preview
pnpm typecheck
pnpm lint
pnpm test
pnpm test:browser
pnpm test:dev
pnpm test:preview
pnpm test:browser -- --case=fetch-relative-json

Set PLAYWRIGHT_CHROMIUM_EXECUTABLE=/path/to/chromium when Chromium is not at /usr/bin/chromium.

pnpm build produces the static site in dist, including the sandbox service worker. pnpm build:sandbox-compat builds the standalone compatibility fixture. Set PATCHPIT_BASE for a subpath deployment:

PATCHPIT_BASE=/patchpit/ pnpm build

The Pages workflow runs typecheck, lint, Node tests, both browser harnesses, and a /patchpit/ preview before uploading dist to GitHub Pages.

Workspace packages export TypeScript source. Direct Node imports use the repo loader:

node --import ./scripts/register-ts-loader.mjs your-script.mjs