loki

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Loki lets an AI agent run an entire website at runtime — content schema, content, code, routes, and design — through a single MCP endpoint. No repo to clone, no build pipeline, no deploy step. The agent writes TSX, previews it at a real URL, and publishes by repointing a version. Rollback is instant. A failed publish never touches the live site.

Loki is a single Cloudflare Worker built on agent-cms (agent-first headless CMS: D1, GraphQL, MCP) and Dynamic Workers (the Worker Loader API, open beta). Site code lives in the database, compiles at write time, and executes in sandboxed V8 isolates loaded on demand.

Why

Agents are already good at building websites. What slows them down is the ceremony around the code: branches, pull requests, CI, deploys — a loop designed for humans coordinating with humans. agent-cms moved schema and content into the runtime loop; Loki moves the rest of the site there too. "Deploy" collapses into a database write, and the whole edit → preview → publish cycle happens inside one conversation.

The safety you lose by skipping CI is re-created where an agent can actually use it:

• Publish-time validation — every GraphQL query in the site is validated against the live schema; a smoke render runs in a throwaway sandbox. Errors come back precise (routes/index.tsx#gql0: Cannot query field "subtitle" on type "BlogPostRecord". Did you mean "title"?) and the live site stays untouched.
• Immutable versions — publishing snapshots the compiled site; rollback_site repoints a pointer.
• A migration guard — Loki records which schema fields each published version queries (its footprint). Destructive schema operations that would break the live site are rejected with an error that teaches the expand → backfill → publish → contract order.

Architecture

flowchart LR
    A[Your agent] -- MCP --> M["/mcp (merged endpoint)"]
    subgraph W [Loki · one Cloudflare Worker]
        M -- site tools --> S[(D1: site files,\nversions, footprints)]
        M -- CMS tools, guarded --> C[agent-cms\nschema · content · GraphQL]
        S --> L[Worker Loader]
        L -- loopback GraphQL --> C
    end
    V[Visitors] --> L

• Merged MCP endpoint. Loki exposes one /mcp: its own site tools plus every agent-cms tool, proxied in-process. Destructive schema calls pass through the migration guard first.
• Site ring. Source files (TSX/TS/CSS) are stored in D1 and transpiled on write (sucrase). Publishing snapshots a compiled module map into a version row.
• Serving. Public traffic loads the published version into a V8 isolate via LOADER.get("site:v<N>") — milliseconds on cold start, cached while warm. The isolate gets exactly two capabilities: a loopback GraphQL binding into the CMS and nothing else (globalOutbound: null).
• Preview. preview_site mints a 30-minute token; the draft tree serves at the real domain behind an HttpOnly cookie, with draft content included in queries.

The authoring model

The agent writes Preact routes with file-based routing:

// routes/posts/[slug].tsx
import { gql, query, renderStructuredText } from "loki/runtime";

const POST = gql`
  query Post($slug: String!) {
    blogPost(filter: { slug: { eq: $slug } }) {
      title
      body { value }
    }
  }
`;

export async function loader({ env, params }) {
  const data = await query(env, POST, { slug: params.slug });
  return { post: data.blogPost };
}

export const head = (props) => ({ title: props.post?.title ?? "Post" });

export default function Post({ post }) {
  return (
    <article>
      <h1>{post.title}</h1>
      {renderStructuredText(post.body?.value)}
    </article>
  );
}

routes/index.tsx → /, routes/posts/[slug].tsx → /posts/:slug, styles.css → linked stylesheet. A main.ts default-exporting a fetch handler is the escape hatch from file routing. The full guide lives in the site_help tool — the endpoint documents itself.

Tools

On top of the full agent-cms toolset (models, fields, records, publishing, assets, search), Loki adds:

Tool	What it does
site_write / site_read / site_list / site_delete	Edit the draft tree; writes transpile immediately and reject on error
site_asset_import / site_asset_write	Add design images and one-off files (favicon, OG image, hero, downloads) by URL or bytes; returns the exact URL to paste
site_diff	Draft vs. published: added / changed / removed, code and assets
graphql_query	Explore the content API (introspection included) before writing route queries
preview_site	Token URL serving the draft at the real domain
publish_site	Validate queries → extract footprint → smoke render → snapshot → go live
site_versions / rollback_site	List immutable versions; repoint the live pointer
site_help	The authoring guide, served by the endpoint itself

Beyond static pages, routes can export an action to handle form POSTs, write to allowlisted content models (env.RECORDS), and push to WebSocket channels (env.REALTIME) — and any component can become a hydrated Preact island (<Island client="visible">) for client-side interactivity, served with no bundler via native ES modules and import maps. A live realtime guestbook, forms, and design assets all run this way today.

Quickstart

You need a Cloudflare account on Workers Paid (for Worker Loader, open beta), pnpm, and wrangler logged in.

git clone https://github.com/jokull/loki && cd loki
pnpm install && pnpm vendor

wrangler d1 create loki-cms        # put the new database_id in wrangler.jsonc
wrangler d1 migrations apply loki-cms --remote
wrangler secret put WRITE_KEY      # any long random string
wrangler deploy

Connect your agent (Claude Code shown; any MCP client works):

claude mcp add loki https://loki.<your-subdomain>.workers.dev/mcp \
  --transport http --header "Authorization: Bearer <WRITE_KEY>"

Then ask for a website:

Read site_help. Create a blog with a few posts about anything, design it nicely, preview it, and publish.

In the first end-to-end test, an agent given nothing but the endpoint URL and the key did exactly that — schema, content, routes, stylesheet, dark mode — and shipped it, self-correcting from the validation errors along the way.

The migration guard

The part CI can't do for you. Each published version stores the set of GraphQL types and fields it queries. When the agent later tries delete_field on something the live site depends on:

Blocked by Loki migration guard: The published site (version v5) still queries
field "slug" (GraphQL BlogPostRecord.slug) on model "blog_post".
Follow the expand -> contract migration order:
  1. EXPAND: add the replacement field
  2. BACKFILL: migrate content
  3. UPDATE SITE CODE: publish a site version that no longer queries it
  4. CONTRACT: retry this operation

The same check covers the REST API (409). Non-breaking updates (labels, validators, hints) pass through untouched.

Status & roadmap

This is a working experiment, not a product. Rough edges are documented by the tools themselves.

Working today: schema + content + code + design at runtime, immutable versions with rollback, the migration guard, preview at a real URL, Preact islands (partial hydration, no bundler), form actions with scoped record writes, realtime channels (WebSocket-backed Durable Objects), and content-addressed static/design assets in R2 (version-pinned, served with ETag/304).

Planned:

• Cloudflare Artifacts as the site-code store (git-compatible branches, diffs, and a git clone escape hatch) once it exits private beta — D1 is the store today
• Code Mode on the merged endpoint (one code tool instead of forty)
• Serve-time image transforms via the Cloudflare Images binding (resize/format from one stored original)
• Rate limiting for public write routes; presigned direct-to-R2 for large human uploads
• Durable Object Facets for per-feature state (agent-built apps with their own SQLite)

License

MIT © Jökull Sólberg