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Publishing takes the project you’ve been building and puts it on the internet at a public address like your-name.r21.dev. It runs a fresh production build of the project’s repository, deploys the result, and hands you a link you can share. A short three-step wizard walks you through it — pick the address, fill in how the site looks when shared, then review and publish. This is different from the preview you see while building. The preview is a private, temporary sandbox only you can reach. Publishing produces a separate, durable build that anyone with the link can open.
Preview vs published site. The preview in the workspace is private and tied to your build session. The published site is a separate production build served from a stable *.r21.dev URL that anyone can visit. Editing your project does not change the published site until you publish again.
Publishing is free — it doesn’t spend credits. Only building (3) and editing (2) do.
Publishing makes your site public. Once published, anyone with the link can open it — there’s no password or sign-in gate. Don’t publish a site that shows private data, and check the secret scan (below) before you share the link.

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Why publish

  • Share a real link. Send your-name.r21.dev to anyone — no Mythos account needed to view it.
  • A stable address. The published URL doesn’t change when you edit the project; it only updates when you publish again.
  • A true production build. Publishing runs a fresh production build, separate from the dev preview.

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Prerequisites

  • A generated project with a repository. If you’ve built something and can see a preview, you’re ready. A project that hasn’t been generated yet has nothing to build, so publishing is blocked until then.
  • That’s it — publishing itself does not spend credits (see Credits & pricing).

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How to publish

The wizard itself is three steps — the panel header shows Step 1 of 3 through Step 3 of 3. Opening the panel and waiting for the build bracket those steps.
1

Open the Publish panel

In the workspace, open Publish from the top of the right panel. The wizard opens on the URL step.
2

Step 1 — Pick your URL

Choose the subdomain for your site — this becomes your-name.r21.dev. Edit it and Mythos checks availability as you type; a green Available means it’s yours. Then select Continue.
3

Step 2 — Add site info (SEO)

Set the title, description, icon, and social image that show when your link is shared or found in search. Mythos pre-fills a suggested title and description from your site’s content — accept them or edit. Select Continue. See SEO & social previews for what each field does.
4

Step 3 — Review

Check the URL, the site info, and the secret-scan note, then select Publish.
5

Wait for the build

Mythos builds and deploys your site. This usually takes under a minute. When it finishes you see Your app is live! with the URL, a View app button, and a Share action.

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What you see while it builds

Publishing is a build-and-deploy step, so there’s a short wait. The panel reflects the state:
StateWhat you seeWhat you do
Building”Publishing your site” with a spinnerWait — usually under a minute
Live”Your app is live!” with the URL and View/ShareOpen the link, copy it, share it
FailedAn error message on the review step with a retryFix the issue, then publish again

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Updating a published site

Editing your project after publishing does not change the live site automatically — the published build is a separate snapshot. To push your latest changes live, open the Publish panel and select Update site. It rebuilds from your current code and replaces the live version at the same URL.
Editing in chat never touches the live site — it stays on its last published build until you select Update site.

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Renaming and unpublishing

  • Rename anytime. Change the subdomain from the URL step whenever you like. The new address is live almost immediately and the old one stops resolving — no rebuild needed.
  • Unpublish. Select Unpublish from the published panel. The site stops resolving and its files become unreachable, making it private again. You can publish it again later.
Renaming frees the old subdomain and the old link stops working within seconds. Anyone holding the old URL will get a “not found” page — re-share the new address.

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The secret scan

Every publish runs an automatic scan of the built site for high-signal leaked credentials. It checks six categories, reporting the matched label (never the value): 
AWS access key
OpenAI secret key
Stripe live secret key
GitHub token
Slack token
Private key
The result appears on the review and live screens:
  • No leaked secrets detected — you’re clear to share.
  • Potential secrets in your bundle — it lists the category above (never the value). Remove the secret from your code and publish again before sharing.
The scan reports categories, not the secret itself, and it doesn’t block publishing — it’s a warning so you can fix a leak before handing out the link. It deliberately ignores public keys (like a Supabase anon key) that are safe to ship in a frontend.

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Limitations & good to know

  • Frontend builds only. A project that needs a live server — server-side rendering, API routes, or server actions — can’t be served as a static site and the build will fail. Mythos apps are frontend-first (data lives in your connected Supabase), so most projects publish cleanly.
  • One live build per project. Each project has one published site at one URL. Publishing again replaces it; it doesn’t create a second copy.
  • No password protection. A published site is fully public. There’s no view gate — use Unpublish to take it down.
  • Custom domains aren’t available yet. Published sites live on *.r21.dev for now. See Custom domains.

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Troubleshooting

The review step shows the error and a way to retry. The most common cause is a project that needs a live server (API routes or server-side rendering), which can’t be served as a static site. Adjust the project to be frontend-only, then publish again.
Editing the project doesn’t update the live site on its own. Open the Publish panel and select Update site to rebuild and push your latest changes.
Open the Publish panel and select Unpublish. The site becomes unreachable. Remove the private content, then publish again when ready.

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FAQ

No. Publishing and updating a published site are free. Only building and editing the project itself spend credits.
Yes — a published site is public. Anyone with the link can open it, no Mythos account required.
Yes, anytime. Edit the subdomain on the URL step; the new address goes live within seconds and the old one stops working.
Usually under a minute. The panel shows a “Publishing your site” state while it builds, then switches to “Your app is live!”.
Yes. Both build and deploy as static sites. A Next.js project that depends on a server (API routes, SSR, server actions) won’t publish — those need a live backend Mythos doesn’t host.