@habemus-papadum/aiui-pencil

A pencil: pressure/tilt/azimuth-driven textured strokes, erasing, and vanishing ink, on a three-tier raster surface — plus the whole remote pencil: the relay backend/sidecar, the host and client sessions (WebRTC video + ink intent), and the iPad client app.

Install

npm install @habemus-papadum/aiui-pencil

The entries

Subpath	What it is
.	the instrument (PencilSurface, params/presets, telemetry, splines, dabs, grain) and the session layer (HostSession, ClientSession, the wire protocol)
./client	the remote client kit (Solid): PencilRemoteApp and the pieces it composes
./server	the relay backend (createPencilBackend)
./sidecar	the channel sidecar (pencilSidecar) — serves the client app at /pencil/ and relays /pencil/host ↔ /pencil/client

The remote client: one app, per-application presentation

There is ONE served client app (client/, built to assets/client, served by the sidecar at GET /pencil/) — and two ways to customize it (owner, 2026-07-17):

• The paved road: a host declares a RemotePresentation when it registers — { title, accent, tools, modes, undo, clear, navigation, color, size } — and the shared app renders from it: which tools and presets the strip offers, whether the brush color/size knobs exist, whether two-finger gestures emit scroll/zoom intents. Absent fields default to fully-featured (the Lab). The intent client, for example, registers { tools: ["draw"], modes: ["write"], color: false, size: false } — a markup surface, not a paint studio.
• Full control: compose your own page from the kit — RemoteView (the display: video, letterbox plane, preview crossfade — all the coordinate correctness that must never be rebuilt), SessionPicker, PencilStrip, bindPenInput, createPlaneTracker.

Presentation is presentation: the host stays authoritative. Brush-knob choices ride each strokeBegin as overrides and the host merges them over its own resolved preset (and can clamp outright — the intent client forces draw + the write preset host-side).

Hosting a session

import { HostSession } from "@habemus-papadum/aiui-pencil";

const session = new HostSession({
  url: hostRelayUrl(),           // ws://…/pencil/host
  label: "my app",
  presentation: { tools: ["draw"], color: false, size: false },
  surface: () => pencilSurface,  // where remote strokes land
  size: () => plane,             // MUST equal the captured frame (see host-session.ts)
  stream: () => captureStream,
});
session.connect();

aiui pencil url prints where an iPad should point its browser, per running channel.

Developing

• pnpm lab — the Lab rig (the reference host; serves the built client at /pencil/).
• pnpm dev:client — HMR loop on the client app alone.
• pnpm build:client — the servable artifact (assets/client), what ships.