the rich text editor offers three heading levels

One button that toggled H2, so a document could hold exactly one weight of heading — and the levels the
site's sanitiser already accepted were unreachable from the editor that writes for it.

Three buttons rather than a dropdown: they are toggles like everything else on the bar, the active one
answers "what is this line", and a select would hide that behind a click.

A level is a rank in the outline and never a size. What each draws at is the site's — three of the four
type roles, in the prose rules — so the Layout section stays the one place type is sized.

`[open]` H1 is offered because it was asked for, and a page that already has a title now has two. That
is an outline a search engine reads as two documents, and it wants a rule about where H1 belongs before
this gets used much.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/RichText.tsx

@@ -9,7 +9,9 @@ import {
   AlignLeft,
   AlignRight,
   Bold,
+  Heading1,
   Heading2,
+  Heading3,
   Italic,
   Link2,
   List,
@@ -44,6 +46,24 @@ import {
  * somewhere that is not typing — see the effect below.
  */
 
+/**
+ * The heading levels the bar offers, in the order they nest.
+ *
+ * A level is a rank in the document's outline, and the SIZE it draws at is the site's — see the prose
+ * rules in styles.css, where each maps to one of the four type roles. So this list says what a heading
+ * means and never what it looks like, which is the only way the Layout section can go on being the
+ * place type is sized.
+ *
+ * `[open]` H1 is offered because it was asked for, and a page that already has a title now has two —
+ * which is an outline a search engine reads as two documents. Worth a rule about where H1 belongs
+ * before this is used much.
+ */
+const HEADINGS = [
+  { level: 1 as const, Icon: Heading1, label: 'Heading 1' },
+  { level: 2 as const, Icon: Heading2, label: 'Heading 2' },
+  { level: 3 as const, Icon: Heading3, label: 'Heading 3' },
+];
+
 const Tool = ({
   onClick,
   active,
@@ -107,13 +127,26 @@ const Toolbar = ({ editor }: { editor: Editor }) => (
 
     <span className="mx-1 h-4 w-px bg-border" />
 
-    <Tool
-      label="Heading"
-      onClick={() => editor.chain().focus().toggleHeading({ level: 2 }).run()}
-      active={editor.isActive('heading', { level: 2 })}
-    >
-      <Heading2 className="size-3.5" />
-    </Tool>
+    {/*
+      Three levels, not one.
+
+      It was a single button that toggled H2, so a document could hold exactly one weight of heading —
+      and the two levels the site's sanitiser already allowed were unreachable from the editor that
+      writes for it.
+
+      Three buttons rather than a dropdown: they are toggles like everything else on this bar, the
+      active one is the answer to "what is this line", and a select would hide that behind a click.
+    */}
+    {HEADINGS.map(({ level, Icon, label }) => (
+      <Tool
+        key={level}
+        label={label}
+        onClick={() => editor.chain().focus().toggleHeading({ level }).run()}
+        active={editor.isActive('heading', { level })}
+      >
+        <Icon className="size-3.5" />
+      </Tool>
+    ))}
     <Tool
       label="Bulleted list"
       onClick={() => editor.chain().focus().toggleBulletList().run()}