Lumencast

The missing standard for server-driven displays.

Reactive scenes. Live state. Leaf-grain updates over a tiny LSDP WebSocket protocol. Drop a mount() on any browser, OBS browser source, CEF wrapper, or embedded frame, and your display becomes a thin reactive client of your backend.

GitHub npm Spec

Install

pnpm add @lumencast/runtime @lumencast/protocol

Or load directly in a browser via the npm CDN :

<script type="module">
  import { mount } from "https://cdn.lumencast.dev/@lumencast/runtime@0.1.0/dist/lumencast.js";
  mount({
    target: document.getElementById("stage"),
    serverUrl: "wss://example.com/lsdp/v1",
    token: "<jwt>",
    mode: "broadcast",
  });
</script>

The surface

One protocol (LSDP/1), one declarative scene format (LSML 1.1), a runtime that mounts in three lines.

Leaf-grain reactivity. The server pushes a single { path, value } patch ; only the bound primitive re-renders. No virtual DOM diffing the world.
Snapshot + delta resume. Reconnect with since_sequence and the server replays missed deltas. No re-fetching the world to recover from a flaky link.
Animations declared, not coded. Per-leaf transition directives, keyframe sequences, and repeat.stagger_ms are first-class in the protocol — not bolted on per-runtime.
Multi-language SDKs. TypeScript (this repo), Go, Rust, and Python share a single conformance suite — 33 scenarios that every implementation must pass.

Packages

Package	What it does
`@lumencast/runtime`	Browser runtime — `mount()`, transport, store, primitives.
`@lumencast/server`	Node server kit — HTTP+WS, scene composition, leaf store, adapters.
`@lumencast/protocol`	Pure protocol code — codec, sequence, types. No IO.
`@lumencast/dev-server`	Mock server for tests — WS + HTTP + `/__mock/*` control plane.
`@lumencast/runtime-svelte`	Headless Svelte adapter — leaf state as Svelte stores.
`@lumencast/runtime-vue`	Headless Vue 3 adapter — leaf state as Vue refs.
`@lumencast/compiler`	LSML 1.1 → flat RenderBundle compiler.