blocks that draw whatever the page is about

`/collections/amadoras-mythology` and `/collections/70s` are the same page with a different subject.
Building each would be absurd; hard-coding the arrangement would put it out of reach of the admin. So
the arrangement is built once — a template page, composed exactly like any other — and every
collection is drawn through it.

Four blocks read the subject: its name, its description, its specs, its photographs. They hold nothing
at all, not even a reference. `collections` holds no content because the list is a query; these hold
none because the subject is the URL, and the same block draws a different collection on the next
request.

Offered only on a template, and HIDDEN rather than disabled elsewhere. A greyed-out row invites "why
not here", and the answer — this page has no subject — is not something a tooltip fixes. Available and
silently drawing nothing is the worse failure.

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

web/sections/AddComponentDialog.tsx

@@ -1,4 +1,4 @@
-import { Handshake, Image, Images, LayoutGrid, Mail, Type, type LucideIcon } from 'lucide-react';
+import { Handshake, Heading, Image, Images, LayoutGrid, Mail, Ruler, Type, type LucideIcon } from 'lucide-react';
 import { Dialog, DialogContent, DialogHeader, DialogTitle } from '@/components/ui/dialog';
 
 /**
@@ -23,7 +23,30 @@ import { Dialog, DialogContent, DialogHeader, DialogTitle } from '@/components/u
  * A kind the server would accept and this has never heard of is not creatable anyway.
  */
 
-export type ComponentKind = 'free-text' | 'media' | 'gallery' | 'contact-form' | 'partners' | 'collections';
+export type ComponentKind =
+  | 'free-text'
+  | 'media'
+  | 'gallery'
+  | 'contact-form'
+  | 'partners'
+  | 'collections'
+  | 'collection-title'
+  | 'collection-description'
+  | 'collection-specs'
+  | 'collection-gallery';
+
+/*
+  The blocks that draw whatever the page is ABOUT.
+
+  Only offered on a template. On an ordinary page they would render nothing, which is the worst kind of
+  block: one that is available, adds cleanly, and silently does nothing.
+*/
+export const SUBJECT_KINDS: ComponentKind[] = [
+  'collection-title',
+  'collection-description',
+  'collection-specs',
+  'collection-gallery',
+];
 
 type Choice = {
   kind: ComponentKind | null;
@@ -66,16 +89,36 @@ export const CHOICES: Choice[] = [
   { kind: 'contact-form', label: 'Contact form', hint: 'The site\'s form, as it is', Icon: Mail },
   { kind: 'partners', label: 'Partners', hint: 'The partner logos, from Site', Icon: Handshake },
   { kind: 'collections', label: 'Collections', hint: 'Every collection, as a grid', Icon: LayoutGrid },
+
+  /*
+    The four that draw THIS collection, on the template.
+
+    They hold nothing — not even a reference. The subject is the URL, so one block draws a different
+    collection on every request, and that is what lets one arrangement serve all of them.
+  */
+  { kind: 'collection-title', label: 'Its name', hint: 'The collection this page is about', Icon: Heading },
+  { kind: 'collection-description', label: 'Its description', hint: 'What was written about it', Icon: Type },
+  { kind: 'collection-specs', label: 'Its specs', hint: 'Measurement, material, colours, delivery', Icon: Ruler },
+  { kind: 'collection-gallery', label: 'Its photographs', hint: 'The gallery it points at', Icon: Images },
 ];
 
 export const AddComponentDialog = ({
   open,
   onCancel,
   onChoose,
+  template,
 }: {
   open: boolean;
   onCancel: () => void;
   onChoose: (kind: ComponentKind) => void;
+  /**
+   * Whether this page is a TEMPLATE, which decides whether the subject blocks are offered.
+   *
+   * Hidden rather than disabled elsewhere. A greyed-out row invites the question "why not here", and
+   * the answer — this page has no subject — is not something a tooltip fixes. On a page that has one
+   * they are the point; on any other they would render nothing at all.
+   */
+  template?: boolean;
 }) => (
   <Dialog open={open} onOpenChange={(next) => !next && onCancel()}>
     <DialogContent className="sm:max-w-lg">
@@ -84,7 +127,8 @@ export const AddComponentDialog = ({
       </DialogHeader>
 
       <div className="grid grid-cols-2 gap-2">
-        {CHOICES.map(({ kind, label, hint, Icon }) => (
+        {CHOICES.filter((choice) => template || !SUBJECT_KINDS.includes(choice.kind)).map(
+          ({ kind, label, hint, Icon }) => (
           <button
             key={label}
             type="button"
@@ -107,7 +151,8 @@ export const AddComponentDialog = ({
             </span>
             <span className="text-[11px] text-muted-foreground">{hint}</span>
           </button>
-        ))}
+          ),
+        )}
       </div>
     </DialogContent>
   </Dialog>

web/sections/PageBuilderPanel.tsx

@@ -1011,7 +1011,13 @@ export const PageBuilderPanel = () => {
         onCreate={(values) => void createSection(values)}
       />
 
-      <AddComponentDialog open={choosing !== null} onCancel={() => setChoosing(null)} onChoose={chooseKind} />
+      <AddComponentDialog
+        open={choosing !== null}
+        onCancel={() => setChoosing(null)}
+        onChoose={chooseKind}
+        // Which decides whether the subject blocks are offered — they render nothing anywhere else.
+        template={page?.is_template}
+      />
 
       <MediaPicker
         open={picking !== null}

web/usePages.ts

@@ -11,6 +11,14 @@ export type Page = {
   menu_label: string | null;
   position: number;
   is_home: boolean;
+  /**
+   * The arrangement a whole CLASS of pages is drawn with, rather than a page anybody visits.
+   *
+   * `collection` is the one today: every `/collections/<slug>` is drawn through it. Listed beside the
+   * pages because it is built exactly like one — a separate section for a single row would be a second
+   * place to learn — and marked so nothing offers to rename it, reorder it or put it in a menu.
+   */
+  is_template?: boolean;
 };
 
 /**