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When someone shares your site’s link or finds it in search, what they see — the title, the one-line description, the little icon, and the preview image — comes from your site’s SEO settings. Mythos lets you set all of these on the SEO step of the publish wizard, and applies them to your live site without rebuilding it. The mental model: your site’s files are one thing; the SEO details are layered on top when the site is served. That’s why changing them is instant — there’s nothing to rebuild.
SEO settings are part of publishing. You set them on the SEO step of the publish wizard (and can edit them later from the published panel). They don’t apply to the private preview — only to the public *.r21.dev site.

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What you can set

FieldWhat it controlsLimit
TitleThe page title shown in browser tabs, search results, and link previews60 characters
DescriptionThe one-line summary under the title in search and link previews160 characters
IconThe small favicon next to the title (browser tab, bookmarks)PNG, JPEG, WebP, or ICO
Social imageThe large preview image when the link is shared (the og:image)An image you upload or generate

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Why set them

  • Better link previews. A shared link with a clear title, description, and image gets more clicks than a bare URL.
  • Search and discovery. The title and description are what search engines show.
  • Recognizable in a tab. A favicon and social image replace the default Mythos icon and preview.

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How to set SEO

1

Open the SEO step

On the publish wizard it’s the Add info to help people find your site step (step 2). If your site is already live, open the Publish panel and choose Website info under settings.
2

Set the icon and title

Upload an icon (favicon) and type a title — keep it under 60 characters so it isn’t truncated.
3

Write a description

Add a one-line description under 160 characters. Mythos pre-fills a suggested one from your site’s content — edit it or keep it as is.
4

Add a social image

Upload an image or select Generate to capture a screenshot of your site. This is the large preview that shows when your link is shared.
5

Save

Continue through the wizard, or select Done if your site is already live. The preview card on the step shows roughly how your link will appear.

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Editing SEO after publishing — no rebuild

SEO settings are applied to your live site when it’s served, not baked into the build. So you can change your title, description, icon, or social image on an already-live site and the change takes effect almost immediately — without rebuilding or republishing the site itself.
Got the wording wrong on a shared link? Fix the description in the published panel and re-share. The update is near-instant — no need to run Update site.

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Auto-filled defaults

You don’t have to start from a blank form. Mythos pre-fills sensible defaults so a published site always has reasonable preview information:
  • Title and description are suggested from your site’s content, in the site’s own language.
  • The social image defaults to a screenshot of your site.
You can accept these as-is or replace any of them.

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Examples

Good SEO copy is specific and human. For a bakery site: 
Title:       Flour & Stone — artisan sourdough in Portland
Description: Small-batch sourdough, pastries, and morning coffee. Order ahead for weekend pickup.
For a freelance portfolio: 
Title:       Maya Okafor — product designer
Description: Portfolio of UX and product design work across fintech and health apps. Open for projects.

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Limitations & good to know

  • Title and description limits. Titles cap at 60 characters and descriptions at 160 — longer text is truncated in search and previews anyway.
  • Icon formats. The icon accepts raster images (PNG, JPEG, WebP) and ICO. SVG icons aren’t accepted.
  • The social image isn’t AI-generated. You upload one or use a screenshot of your site — Mythos doesn’t generate a brand image for you.
  • SEO applies to the published site only. The private preview keeps the default Mythos title and icon.

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Troubleshooting

Mythos serves the updated SEO almost immediately, but social platforms and messaging apps (Twitter/X, Telegram, Facebook, Slack) cache link previews on their side. The old preview can linger until their cache expires. Re-share into a fresh chat, or use the platform’s own debugger (e.g. Facebook’s Sharing Debugger) to force a re-fetch.

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FAQ

No. Mythos pre-fills a title, description, and screenshot so your site has reasonable preview info even if you skip the fields. Customizing them just makes the result sharper.
No. SEO settings update on the live site near-instantly — there’s nothing to rebuild. Just save the change.
No. The icon accepts PNG, JPEG, WebP, and ICO. Use one of those formats.
It’s the large preview that appears when your link is shared on social platforms and messaging apps (the og:image). You can upload one or generate a screenshot of your site.