Atrium plan · v0.2
Exploration plan · June 2026

Atrium

An open-source home for AI-generated HTML & Markdown artifacts: permanent URLs, inline comments, revision history, and an agent loop that works from Claude Code, Codex, and every LLM app. Self-host it on boring standard tech, or use our hosted tier.

Open source · Apache-2.0 Self-host · Postgres + S3 + 1 container Any agent · CLI / MCP / API Hosted tier · flat pricing

Executive summary

The bet, in five sentences

1
Artifacts are the new unit of work.Every model now ships HTML/MD things — specs, dashboards, reports, prototypes — dozens of times a day. Shopify's internal "Quick" hit 50,000+ sites in months.
2
They have no durable, neutral home.Native publish is vendor-locked and feature-poor; Vercel/Netlify are built for apps; display.dev is closed SaaS with no self-host.
3
The product is a loop, not a host.Publish → humans comment inline → agent reads threads back over MCP → republishes v2 at the same URL. The artifact becomes a living spec.
4
Open + self-hostable is the moat.Every LLM vendor will build their own silo; none can be neutral about rivals or ship self-host. We can — that's the empty quadrant.
5
Monetize convenience, not the core.Full engine is OSS. Revenue = hosted tier (flat, unlimited viewers) + enterprise self-host support/SSO/SLA — the Sentry/GitLab model.

Why now

HTML is overtaking Markdown as agents' preferred serious-output format, and every coding agent gained the ability to write full interactive pages this year.

display.dev just proved teams will pay for exactly this loop — but built it closed. The window to plant the open standard is before their protocol becomes the de-facto one.

Enterprise AI rollouts are hitting governance walls: "where does agent output live?" has no good answer today. Self-hostable + auditable is the answer procurement wants to hear.

The plan

Seven briefs, one argument

Decision log

What's settled, what's leaning, what's open

Positioning
One open, vendor-neutral home for artifacts from every LLM tool — the commons, not another silo. Differentiate on open source + self-host + open protocol, never on the loop alone.
Decided
Artifact kinds
All static content just works: single HTML/MD files and full build outputs (Astro, Vite, Next export, mdBook — any dist/ folder or zip), with SPA fallback routing. The unit is a bundle, not a file — Quick's core lesson.
Decided
Comments & versions in v1
Non-negotiable — they're what make this a workspace instead of a pastebin, and the basis of the agent loop.
Decided
Stack
One container, embedded SQLite + local blobs by default (docker run, 90 seconds); Postgres + S3 as config upgrades; same image for hosted tier. TypeScript core (Go single-binary kept as a fallback if self-host friction demands it).
Decided
License
Apache-2.0 for maximum enterprise adoption. Risk: hyperscaler re-hosting. Mitigation: the hosted tier competes on convenience and the protocol is the moat — revisit only if it becomes real.
Leaning
Name
Atrium (working). Bare-word domains taken everywhere; useatrium.ai and atrium.host confirmed available, foyer.build/hangar.build as backups. Buy 2–3 cheap now, decide branding at launch.
Leaning
Team pricing
Flat per-org, unlimited viewers (category norm display.dev set at $49/mo Pro). Exact number needs a pricing pass against willingness-to-pay.
Open
Relationship to Sift
Separate open-source product/brand, or incubated under the company? Affects repo org, hiring, and how much time it can take from the core roadmap.
Open

Path to launch

From zero to public in four phases

Phase 1 · Build Private alpha M1–M3: publish + sandboxed render, versions, comments + MCP read-back. Dogfood internally — every plan and review doc we make ships through Atrium. exit: we prefer it to pasting files
Phase 2 · Harden Design partners M4–M5: auth/ACLs, audit log, compose + Helm, docs. 5–10 friendly teams, at least one with a real security review, to pressure-test self-host. exit: a stranger self-hosts unaided
Phase 3 · Open OSS launch Public repo + the Artifact Publish Protocol spec + Claude Code/Codex skills on day one. Launch on the strength of the loop demo: publish, comment, agent revises live. exit: external contributors + orgs in prod
Phase 4 · Monetize Hosted tier Same image, flat pricing, SSO gating. Enterprise motion follows bottom-up adoption: when usage hits a security review, the self-host answer is ready. exit: first paying team + support deal

Deliberately no calendar dates — this is an exploration plan. Sequencing and exit criteria are the commitments; timing follows staffing.

The bet in one line

The LLMs commoditize generation; the durable layer is where the output lives, who can comment on it, and how it changed over time. Own that as an open, neutral, self-hostable commons, and you become the default home no single model vendor is positioned to be.