What a post's content says about it, worked out once, when the content is written — reading a post works out neither:

• content_components — the components its markers name (MishkaCmsCore.Runtime.ContentComponents.names/1), nil when it names none. A site's stylesheet is built from them — see MishkaBlog.Plugins.ContentComponents.
• content_icons — the icon classes it names, in a marker's attribute or in its HTML (MishkaCmsCore.Runtime.ContentComponents.icons/1), nil when it names none. The site's stylesheet carries a rule for each — see MishkaBlog.Plugins.ContentComponents.
• content_classes — the classes it writes: its HTML's class lists, a marker's class and *_class attributes, and the attributes its component takes a class string in (MishkaCmsCore.Runtime.ContentComponents.site_classes/2), nil when it writes none. The site's stylesheet is built with each — see MishkaBlog.Plugins.ContentComponents.
• reading_time_minutes — its words at 200 a minute, rounded up, never under 1.

All four are worked out in a before_action hook, which runs after every change an action lists — the guardedstruct sanitizer and MishkaBlog.Resources.Changes.HighlightCode included — so they are read off the content that is stored. A write that leaves content alone leaves them alone, unless the post has no reading time yet — a row this change never saw — which any save fills.

The stylesheet

A write that makes a name, an icon or a class live on its site — a published post names it now and did not before, and no other published post of the site names it — rebuilds the site's stylesheet, through MishkaCmsCore.Runtime.Compilers.TailwindCompiler.schedule/1. The job is enqueued in the write's own transaction, so a write rolled back asks for nothing. A name, an icon or a class dropped, or a post unpublished, rebuilds nothing.

Usage

update :update do
  change MishkaBlog.Resources.Changes.HighlightCode
  change MishkaBlog.Resources.Changes.ContentFacts
end

On an action that writes no content — :publish — only the stylesheet half has anything to do.