~30 Seconds Turns Tiny: Flarum's Litedown Subscript Trap

I maintain a Flarum forum and ran into a problem posters kept complaining about — they would type "wait ~30 seconds" and 30 would turn into a tiny subscript hanging at the end of the line instead of normal text. At first I thought the theme was broken. It actually comes down to the syntax of the markdown parser Flarum uses, which Thai users often run into because of their typing habits, so I wanted to write it up.

Flarum Does Not Use CommonMark

Flarum renders with Litedown (part of the s9e/TextFormatter family), rather than the familiar CommonMark. They look similar but have some differences. The biggest troublemaker is ~.

How to Avoid It When Typing

The easiest way is to avoid ~ altogether when you mean "approximately":

• Use Thai words directly: "ราว 30 วินาที", "ประมาณ 5 GB"
• Use another symbol: ≈ 30
• If you really need ~, wrap it in inline code: `~30` will display ~30 literally.

Fixing Old Posts Through the DB — Know That It Stores s9e XML

If you want to fix many old posts directly through the database, there is an important trap: Flarum does not store raw markdown in posts.content; it stores parsed s9e XML.

# ดูของจริงในคอลัมน์ content — จะเห็นเป็น XML ไม่ใช่ ~30
# <r><SUB>...</SUB></r> ประมาณนี้ ไม่ใช่ข้อความดิบ

A direct REPLACE needs to account for the XML structure, rather than searching for "~30", because that is no longer what it looks like in the database — after fixing it, remember to clear the cache so it renders again.

php flarum cache:clear

Summary

1. Flarum uses Litedown, not CommonMark — ~ = subscript, ^ = superscript
2. Thai users run into this often because they use ~ for "approximately" — avoid it with Thai words or inline code
3. When fixing content through the DB, remember it stores s9e XML rather than raw markdown, then run cache:clear
4. ModSec blocks PATCH -> use X-HTTP-Method-Override; to hide a post, set hidden_at in 2 tables

This is a small issue, but it comes up a lot, especially on forums where people write a lot of Thai. Once you know that ~ has a special meaning, it is easy to avoid. And if you need to fix a large number of old posts, remember that the database contains XML, not what you typed. If you maintain a Flarum forum with a lot of Thai content, keep this handy to save yourself some confusion. If I have left anything out or made a typo, I will come back and fix it later.