---
title: "A shared whiteboard with live cursors, built by Claude Code on Elements"
author: "@chris"
author_url: https://elements.dev/u/@chris
published: 2026-09-30T19:31:16.157Z
url: https://elements.dev/demos/a-shared-whiteboard-with-live-cursors-built-by-claude-code-uyko0qoc
kind: post
format: article
---

# A shared whiteboard with live cursors, built by Claude Code on Elements

by [@chris](https://elements.dev/u/@chris) · 2026-09-30

## Description

Sticky notes, pen, shapes and arrows on shared boards, with named live cursors, real-time edits and per-person undo.

Sketchmoor needed boards that several people draw on at once, named cursors that follow each person's pointer, strokes that appear as they are drawn, undo for each person and accounts with shared links. Each of those is a part of Elements, so the agent spent its 22 minutes on the whiteboard itself.

- **Shapes that sync.** Shapes are a LiveTable, one view per board. Notes, pen strokes, rectangles, arrows and text are rows, and the board adds and moves them straight through the view, so every open copy updates as each edit lands.
- **Cursors and strokes in flight.** A channel carries what is seen but never stored: each person's named cursor, the stroke under their pen and a shape mid-drag. Each browser drops its own echo.
- **Undo for each person.** Erasing marks a shape as deleted, so it can come back. Each person keeps their own undo and redo steps, applied through the same view.
- **Shared by link.** Opening a board's link adds the signed-in user to its members, and every edit checks that membership.
- **Thumbnails from the data.** The board list shows each board drawn as an SVG from its shapes, cached until the next edit.
- **Data and sessions from SQL.** Migrations define the boards and seed three demo accounts sharing two boards, a sprint retro of sticky notes and an architecture sketch. Each person signs in with a session.