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lab-link

lab-link is a small synchronization library for laboratory control software. It keeps Python instrument services authoritative while giving browser UIs a typed, reactive view of state.

Because browser pages can attempt cross-origin WebSocket connections to localhost and private-network addresses, lab-link also provides server-side origin validation, persistent passphrase sessions, one-use invitations, and scoped API tokens. See Why lab-link includes access control for the laboratory-control threat model and the boundary between the library and an application's UI.

The core protocol is simple:

  1. A browser connects over WebSocket and receives a state snapshot.
  2. The server broadcasts JSON Patch updates with version and command metadata.
  3. The browser sends commands.
  4. The server validates, performs side effects, commits state, then sends patch and command acknowledgement or a structured command error.

Packages

lab-link is intentionally split into two packages:

  • lab-link on PyPI: the Starlette/Pydantic backend runtime and Python sync client.
  • lab-link on npm: framework-neutral browser runtime plus Svelte and React adapters.

Publish both packages from the same git tag and keep their versions aligned. That makes app dependency constraints easy to reason about: backend and frontend protocol changes share one semantic version.

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