fix(places): phase links must stay in their own namespace

Every place page built its phase links as /schools/[slug]/[phase], the
shape that belongs to towns alone.

On an authority page that pointed into the town namespace. For 87 of the
151 authorities the target does not exist and the link 404s; for the
other 64 it resolves to the town of the same name — a different set of
schools, which is precisely the near-duplicate the two namespaces were
introduced to prevent. On an outcode page it 404s outright.

Two causes behind it, both a rule written twice and inherited by only
one of the places that needed it.

The authority phase route was in the spec and dropped by the plan, which
built the three bare routes and no fourth. The sitemap is generated from
the place registry, which was right about them all along, so 302
authority phase URLs have been submitted to Google and every one 404s.
Adding the route makes the sitemap true and serves a real query —
admissions are authority-run, so "primary schools in Kent" is how a
parent searches before they have settled on a town.

The outcode variants were the opposite: the registry computed phases for
outcodes although the spec gives them no route, and the sitemap knew to
skip them while the API did not. The registry now decides alone, and the
sitemap's duplicate of that rule is gone.

Also: an authority under the five-school threshold has no page, so the
API sends a null slug for it and the page names it without linking.
Two English authorities are in that position. It was unreachable in
today's data — verified across the EC and TR outcodes — but the thin
place redirect would have sent a reader to a 404 the year it isn't.

The e2e journey now walks every /schools link a page of each family
emits and requires a 200, which is the check that was missing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mWQnpye9F299NVRCCSRvj

nextjs-app/__tests__/components/PlaceView.test.tsx

@@ -276,3 +276,73 @@ describe('PlaceView list ordering', () => {
     expect(list.itemListOrder).toBe('https://schema.org/ItemListOrderAscending');
   });
 });
+
+describe('PlaceView phase links', () => {
+  const authority: PlaceDetail = {
+    place: { kind: 'authority', slug: 'barnet', name: 'Barnet', count: 156,
+             parent_authority: null, phases: ['primary', 'secondary'] },
+    schools: [
+      { urn: 1, school_name: 'Alpha Primary', phase: 'Primary',
+        rwm_expected_pct: 82, attainment_8_score: null } as never,
+    ],
+    averages: { rwm_expected_pct: 63, attainment_8_score: null },
+  };
+
+  it('keeps an authority phase link in the authority namespace', () => {
+    // The link was built as `/schools/${slug}/${phase}` for every kind, so an
+    // authority page pointed into the town namespace. For 87 of 151
+    // authorities that 404'd; for the other 64 it silently landed on the town
+    // page of the same name — a different set of schools, and exactly the
+    // duplicate the two namespaces exist to prevent. Barnet is one of the 64.
+    render(<PlaceView detail={authority} englandAverage={61} neighbours={[]} />);
+    expect(screen.getByRole('link', { name: /^Primary schools in Barnet$/ }))
+      .toHaveAttribute('href', '/schools/authority/barnet/primary');
+    expect(screen.getByRole('link', { name: /^Secondary schools in Barnet$/ }))
+      .toHaveAttribute('href', '/schools/authority/barnet/secondary');
+  });
+
+  it('still uses the bare namespace for a town', () => {
+    render(<PlaceView detail={detail} englandAverage={61} neighbours={[]} />);
+    expect(screen.getByRole('link', { name: /^Primary schools in Brentwood$/ }))
+      .toHaveAttribute('href', '/schools/brentwood/primary');
+  });
+
+  it('offers no phase link when the place publishes none', () => {
+    // Outcodes are the case: no phase route exists for them, so the registry
+    // reports no phases and the nav does not render.
+    const outcode = { ...detail,
+      place: { ...detail.place, kind: 'outcode', slug: 'cm13', name: 'CM13',
+               phases: [] } };
+    render(<PlaceView detail={outcode} englandAverage={61} neighbours={[]} />);
+    expect(screen.queryByRole('navigation', { name: 'By phase' }))
+      .not.toBeInTheDocument();
+  });
+});
+
+describe('PlaceView unlinkable authorities', () => {
+  const withUnpublished: PlaceDetail = {
+    place: { kind: 'outcode', slug: 'tr21', name: 'TR21', count: 8,
+             parent_authority: 'Cornwall', phases: [],
+             authorities: [
+               { name: 'Cornwall', slug: 'cornwall', count: 6 },
+               { name: 'Isles Of Scilly', slug: null, count: 2 },
+             ] },
+    schools: [
+      { urn: 1, school_name: 'Alpha Primary', phase: 'Primary',
+        rwm_expected_pct: 82, attainment_8_score: null } as never,
+    ],
+    averages: { rwm_expected_pct: 63, attainment_8_score: null },
+  };
+
+  it('names an authority with no page without linking it', () => {
+    // City of London and the Isles of Scilly hold fewer schools than a page
+    // needs. Saying where the place is stays right; linking there would 404.
+    const { container } = render(<PlaceView detail={withUnpublished}
+      englandAverage={61} neighbours={[]} />);
+    expect(screen.getByRole('link', { name: 'Cornwall' })).toBeInTheDocument();
+    expect(screen.queryByRole('link', { name: 'Isles Of Scilly' }))
+      .not.toBeInTheDocument();
+    expect(container.querySelector('header p')?.textContent)
+      .toContain('Isles Of Scilly');
+  });
+});

nextjs-app/app/schools/[place]/page.tsx

@@ -74,9 +74,14 @@ export default async function PlacePage({ params }: Props) {
   // defers to its authority rather than publishing a thin page.
   if (detail.averages.rwm_expected_pct == null
       && detail.averages.attainment_8_score == null) {
-    if (detail.place.parent_authority) {
-      redirect(`/schools/authority/${authoritySlug(detail.place.parent_authority)}`);
-    }
+    // The API's own slug, which is null when that authority is itself under
+    // the threshold and has no page. Re-slugifying the name here would send
+    // the reader to a 404 instead of telling them the place has no page.
+    const target = detail.place.authorities?.[0]?.slug
+      ?? (detail.place.parent_authority
+        ? authoritySlug(detail.place.parent_authority)
+        : null);
+    if (target) redirect(`/schools/authority/${target}`);
     notFound();
   }
 

nextjs-app/app/schools/authority/[la]/[phase]/page.tsx

@@ -0,0 +1,65 @@
+/**
+ * Phase variants of an authority page.
+ *
+ * The spec called for these; the plan built the bare authority route and
+ * dropped them. Nothing caught it, because the sitemap is written from the
+ * place registry — which was right about them all along — while the routes
+ * were written by hand. 302 authority phase URLs were submitted to Google and
+ * every one 404'd, and every authority page linked to a phase page in the
+ * *town* namespace, which is a different set of schools entirely.
+ *
+ * "Primary schools in Kent" is the query these serve, and it is a real one:
+ * admissions are authority-run, so the authority is the unit a parent thinks
+ * in when they have not settled on a town.
+ */
+import { notFound } from 'next/navigation';
+import type { Metadata } from 'next';
+import { fetchPlace } from '@/lib/places';
+import { fetchNationalAverages } from '@/lib/api';
+import { PlaceView } from '@/components/places/PlaceView';
+import { absoluteUrl } from '@/lib/site';
+
+interface Props { params: Promise<{ la: string; phase: string }> }
+
+export const revalidate = 604800;
+export const dynamicParams = true;
+
+const PHASES = ['primary', 'secondary'] as const;
+type Phase = (typeof PHASES)[number];
+
+const isPhase = (v: string): v is Phase => (PHASES as readonly string[]).includes(v);
+
+export async function generateMetadata({ params }: Props): Promise<Metadata> {
+  const { la, phase } = await params;
+  if (!isPhase(phase)) return { title: 'Place Not Found' };
+  const detail = await fetchPlace('authority', la, phase);
+  if (!detail || detail.schools.length === 0) return { title: 'Place Not Found' };
+
+  const word = phase === 'secondary' ? 'Secondary' : 'Primary';
+  const { name } = detail.place;
+  return {
+    // "Local Authority" stays in the title for the same reason it is on the
+    // bare authority page: 67 town names collide with an authority name, and
+    // a reader landing on both needs to know which set each covers.
+    title: { absolute: `${word} Schools in ${name} — Local Authority | schoolcompare` },
+    description:
+      `Every ${phase} school in the ${name} local authority, with results, Ofsted `
+      + `grades and the authority average against England.`,
+    alternates: { canonical: absoluteUrl(`/schools/authority/${la}/${phase}`) },
+  };
+}
+
+export default async function AuthorityPhasePage({ params }: Props) {
+  const { la, phase } = await params;
+  if (!isPhase(phase)) notFound();
+  const detail = await fetchPlace('authority', la, phase);
+  if (!detail || detail.schools.length === 0) notFound();
+
+  const national = await fetchNationalAverages().catch(() => null);
+  const englandAverage = phase === 'secondary'
+    ? national?.secondary?.attainment_8_score ?? null
+    : national?.primary?.rwm_expected_pct ?? null;
+
+  return <PlaceView detail={detail} phase={phase}
+    englandAverage={englandAverage} neighbours={[]} />;
+}

nextjs-app/components/places/PlaceView.tsx

@@ -181,11 +181,18 @@ export function PlaceView({ detail, phase, englandAverage, neighbours }: Props)
                   and a third of towns cross a boundary: SW19 is mostly Merton
                   but partly Wandsworth, and naming one asserts otherwise. */}
               {authorities.map((a, i) => (
-                <span key={a.slug}>
+                <span key={a.name}>
                   {i > 0 && (i === authorities.length - 1 ? ' and ' : ', ')}
-                  <Link href={`/schools/authority/${a.slug}`} className={styles.inlineLink}>
-                    {a.name}
-                  </Link>
+                  {/* No slug means no page: City of London and the Isles of
+                      Scilly hold too few schools for one. Saying where the
+                      place is stays right; linking there would 404. */}
+                  {a.slug
+                    ? (
+                      <Link href={`/schools/authority/${a.slug}`} className={styles.inlineLink}>
+                        {a.name}
+                      </Link>
+                    )
+                    : a.name}
                 </span>
               ))}
             </>
@@ -196,7 +203,11 @@ export function PlaceView({ detail, phase, englandAverage, neighbours }: Props)
       {!phase && (place.phases ?? []).length > 0 && (
         <nav className={styles.phaseLinks} aria-label="By phase">
           {(place.phases ?? []).map((ph) => (
-            <Link key={ph} href={`/schools/${place.slug}/${ph}`} className={styles.phaseLink}>
+            /* placeUrl, not a template: the bare `/schools/[slug]/[phase]`
+               shape belongs to towns alone, and using it everywhere sent
+               every authority page into the town namespace. */
+            <Link key={ph} href={placeUrl(place.kind, place.slug, ph)}
+              className={styles.phaseLink}>
               {ph === 'secondary' ? 'Secondary schools' : 'Primary schools'} in {place.name}
             </Link>
           ))}

nextjs-app/lib/places.ts

@@ -20,7 +20,9 @@ export interface PlaceSummary {
 
 export interface PlaceAuthority {
   name: string;
-  slug: string;
+  /** null when that authority has no page of its own — two English
+   *  authorities hold fewer schools than the threshold. */
+  slug: string | null;
   count: number;
 }
 
@@ -46,9 +48,20 @@ export function placeUrl(kind: string, slug: string, phase?: string): string {
   return phase ? `${base}/${phase}` : base;
 }
 
-/** An authority name as it appears in a URL. */
+/**
+ * An authority name as it appears in a URL.
+ *
+ * Only a fallback: the API sends the slug it built, and that is what should
+ * be used. This mirrors `_slugify` in backend/app.py, collapsed runs and
+ * trimmed hyphens included, so the two cannot disagree about a name like
+ * "Bristol, City of".
+ */
 export function authoritySlug(name: string): string {
-  return name.toLowerCase().trim().replace(/[^\w\s-]/g, '').replace(/\s+/g, '-');
+  return name.toLowerCase().trim()
+    .replace(/[^\w\s-]/g, '')
+    .replace(/\s+/g, '-')
+    .replace(/-+/g, '-')
+    .replace(/^-|-$/g, '');
 }
 
 const API = process.env.FASTAPI_URL || process.env.NEXT_PUBLIC_API_URL