Embeds

Pipeline A does not support embeds. A YouTube/Twitter link inside an AUP format: "markdown" text field just renders as an ordinary <a> — there's no auto-detection. This page (283 files in the production corpus) is pipeline-B only.

There are three ways to get an embed, in order of how a real author is most likely to write one.

Auto-detection: a bare URL

A standalone paragraph containing nothing but a plain URL is auto-detected — no special syntax needed.

Source:

https://www.youtube.com/watch?v=jNQXAC9IVRw

Rendered:

Auto-detection relies on remark-gfm's autolink-literal extension turning the bare text into a real link node first; the paragraph must contain only that link (no other text) for it to become an embed instead of an ordinary clickable link — see the "stays a plain link" example below.

Auto-detection: a markdown link

Source:

[Watch the announcement](https://x.com/arc/status/12345678901)

Rendered:

The explicit embed directive

Useful when you want the embed without it also being the visible link text, or to be unambiguous about authoring intent.

Source:

::embed{url="https://youtu.be/jNQXAC9IVRw"}

Rendered:

A link with surrounding text stays a plain link

Only a standalone paragraph (or an explicit ::embed{}) becomes an embed. A supported URL that's part of a larger sentence stays an ordinary link — it does not suddenly turn into an iframe in the middle of a paragraph.

Source:

Read [this thread](https://x.com/i/status/12345678901) for the full context
before you continue.

Rendered:

Read this thread for the full context before you continue.

An unsupported URL degrades to a visible link

Only YouTube and Twitter/X hosts are recognized. Anything else — even via the explicit directive — degrades to a plain, visible link instead of a broken iframe or a silently dropped block.

Source:

::embed{url="https://a.example/v/1"}

Rendered:

https://a.example/v/1

Supported hosts

Every embedded frame is sandbox-restricted, loads lazy by default, and sends referrerpolicy="strict-origin-when-cross-origin" — the same safety posture as every other frame primitive in AUP, not a special case for embeds.