A desktop canvas site builder where an Owner starts from one Template Seed, edits positioned design primitives with AI help, switches deterministic Style Kits, and publishes to a real Published Address that updates open Visitor tabs immediately.

▶️ Watch the full walkthrough → (replace VIDEO_ID with your YouTube video id)

One Cloudflare Worker. Three kinds of human (Owner, Collaborator, Visitor) converge on a single document model; AI mutates it through a validate-gate; publish is a column split, audited on every write by a six-check a11y pass that reports to the Owner (advisory — a deliberate ship-fast call, not a hard gate).

flowchart TB
  Own((Owner))
  Col((Collaborator))
  Vis((Visitor))

  subgraph DOC["§1 · Document model"]
    direction LR
    D1[EditableSite tree]
    D2[15-atom union]
  end

  subgraph EDIT["§2 · Co-edit ★"]
    direction LR
    D3[Yjs CRDT]
    D4[SiteRoom DO]
  end

  subgraph AI["§3 · AI surfaces ★"]
    direction LR
    D5[Agent validate-gate]
    D6[Image preview-before-persist]
  end

  subgraph VER["§4 · Versioning"]
    D7[Y.Doc snapshot]
  end

  subgraph REC["§5 · Recipes"]
    D8[Regenerative factories]
  end

  subgraph COMP["§6 · Composition ★"]
    direction LR
    D9[Site Import]
    D10[Template clone]
  end

  subgraph PUB1["§7 · Publish split"]
    D11[editable ⇄ published]
  end

  subgraph PUB2["§8 · A11y audit (advisory) ★"]
    D12[6-check audit]
  end

  Own ==> DOC
  Col ==> EDIT
  Own ==> AI

  D2 --> D1
  D1 <==> D3
  D3 ==> D4
  D4 -. fan-out .-> Vis
  D3 ==> D7

  D5 ==> D1
  D6 ==> D1

  D8 --> D1
  D9 ==> D1
  D10 ==> D1
  D9 <-. same two-pass pattern .-> D10

  D1 ==> D11
  D11 ==> D12
  D11 -- published --> Vis
  D12 -. advisory report .-> Own

Bold arrows carry primary data flow; dotted arrows are cross-cutting relationships. ★ marks the four subsystems that carry the non-obvious decisions. Full contributor tour: docs/key-architecture.md · canonical decisions: docs/adr/.

Engineering substance over vanity metrics — every figure below is sourced from the repo or the production database, not estimated.

• 61 architecture decision records · 103 colocated *.smoke.ts tests + 4 Playwright e2e journeys · 21 schema migrations
• 495 TypeScript modules — one Cloudflare Worker plus its separately-built editor and dashboard client bundles
• Document model exercised in production: 1,090 design primitives across 124 sections / 33 pages, 31 deterministic version snapshots, 3 sites published live
• Every publish runs a six-check accessibility audit (advisory — reports to the dashboard, deliberately non-blocking); an audit crash surfaces as an explicit issue, never a silent skip

Open the dashboard, name a site, and drop into a canvas pre-populated from one Template Seed. Drag positioned design primitives, ask the AI agent for a previewed edit, swap deterministic Style Kits live, and click Publish — the Published Address (<subdomain>.opencanvas.aayushman.dev) updates in every open Visitor tab within a few hundred milliseconds. One Cloudflare Worker hosts the dashboard, the editor, the canvas API, the AI agent endpoint, the publish snapshot store, and the public host that serves Visitors.

The product is live — the demo is the real thing, not a recording:

• Try it: opencanvas.aayushman.dev — sign in, start from a Template Seed, edit on the canvas, publish.
• Guided walkthrough: docs/demo/act-1-script.md scripts the flagship beat — an indie founder rebrands the Apogee template into Briar and publishes it to a live address.
• Engineering tour: docs/key-architecture.md walks the five non-obvious decisions behind it, diagram by diagram.

• Cloudflare Workers + Hono JSX (single bundle)
• Drizzle ORM + Neon serverless Postgres (HTTP driver)
• Clerk auth (single origin, no token handoff)
• Durable Object: SiteRoom — publish broadcasts + presence
• Gemini adapter for previewed AI edits
• Vanilla browser JS in the editor (no client framework)

Most site builders are template hosts: you pick a layout, fill predefined slots, pay for hosting, and republish to push a change live. Open Canvas is built on a different premise — a free-form canvas, an agent at the cursor, and a live document the whole team shares. The table below maps the differences axis by axis.

The throughline: the previous generation lets you fill in a layout. Open Canvas lets you, an agent, and your whole team design on one live canvas — and ships the result as clean, accessible, framework-free HTML.

bun install
bun.cmd run dev            # wrangler dev — http://localhost:8787

/ renders the Post-Aero landing. /health returns a JSON heartbeat. /dashboard is gated by Clerk.

bun.cmd run typecheck       # tsc --noEmit
bun.cmd run lint            # eslint .
bun.cmd run canvas:smoke    # canvas schema + validator + renderer round-trip
bun.cmd run canvas-agent:smoke   # canvas-agent tool surface + op application
bun.cmd run review:smoke    # publish + visitor-update integration
bun.cmd run build           # wrangler deploy --dry-run

Live at opencanvas.aayushman.dev and under active development. Issues and PRs welcome.

• FEATURES.md — exhaustive feature reference
• docs/adr/ — 66 architecture decision records (the reasoning behind every major choice)
• CONTEXT.md — domain language and core concepts

Pull requests welcome. See CONTRIBUTING.md for the dev loop and PR checklist, plus CODE_OF_CONDUCT.md and SECURITY.md for reporting vulnerabilities.

MIT (c) 2026 Aayushman Singh