fix: don't portray special schools as failing the mainstream benchmark

Special schools, PRUs and alternative provision teach pupils with SEND who
sit the same KS2/KS4 assessments but very few reach the mainstream "expected
standard". Their headline attainment is therefore ~0% (or a very low
Attainment 8), and the site was comparing that to the England average and
painting it red — e.g. Greenmead School (a community special school) rendered
as "0.0% — −62 pts below England average" with three 0% red SATs bars. That
portrays a special school as catastrophically failing against a benchmark
that doesn't fit it.

Add a shared `isSpecialSchool()` helper (detects every DfE special-school
establishment type — all contain "special" — plus PRUs / alternative
provision) and drop the mainstream England comparison + "below" framing for
these schools across every surface:

- Detail (primary + secondary): a plain-English context note explaining the
  school is special and why the comparison isn't shown; England-average delta
  chips, "England avg" hints, the SATs national markers, the Attainment-8
  "vs national" bar and the trend chart's England overlay are all suppressed.
  An all-zero placeholder SATs row hides the (empty) subject bar chart and the
  "why is combined lower" bridge.
- Rankings / search rows (primary + secondary): the mainstream RWM / Attainment
  8 stat shows "—" with no "vs national" delta, instead of "0% · −62 vs
  national".
- Compare: special schools' attainment values are dropped (no misleading dot
  at 0% / no "Below England average" chip); progress banding, which IS a fair
  measure for special schools, is kept.

Belt-and-braces zero-guard: a whole-row zero attainment (special or a
suppressed cohort) is also treated as not-comparable, while a legitimate
single 0 (e.g. 0% exceeding at a mainstream school) stays comparable.

Tests: new isSpecialSchool unit tests (every DfE special type matched, no
mainstream false positives); an e2e journey asserts Greenmead shows the
special-school note and no England-average comparison. tsc clean; 108/108 unit.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0146VHeLAWjDVE2B5uU67jCB

nextjs-app/components/SecondarySchoolDetailView.tsx

@@ -23,7 +23,7 @@ import type {
   SchoolAdmissions, SenDetail, Phonics,
   SchoolDeprivation, SchoolFinance, NationalAverages,
 } from '@/lib/types';
-import { formatPercentage, formatProgress, formatAcademicYear, formatAgeRange, isProposedToClose, ofstedLegacyAreas } from '@/lib/utils';
+import { formatPercentage, formatProgress, formatAcademicYear, formatAgeRange, isProposedToClose, ofstedLegacyAreas, isSpecialSchool } from '@/lib/utils';
 import { DeltaChip } from './DeltaChip';
 import { track, getNavigationSource } from '@/lib/analytics';
 import styles from './SecondarySchoolDetailView.module.css';
@@ -107,6 +107,14 @@ export function SecondarySchoolDetailView({
   const p8Suspended = latestResults != null && latestResults.year >= 202425;
   const hasResults = latestResults?.attainment_8_score != null;
 
+  // Special schools / PRUs / AP sit the same GCSEs but teach pupils with SEND,
+  // so their headline attainment is far below the mainstream average by design.
+  // Drop the England comparison + "below" framing so the page doesn't portray
+  // them as failing against a benchmark that doesn't fit. (Also guards a
+  // placeholder all-zero Attainment 8.)
+  const isSpecial = isSpecialSchool(schoolInfo);
+  const suppressComparison = isSpecial || (latestResults != null && latestResults.attainment_8_score === 0);
+
   const admissionsTag = (() => {
     const policy = schoolInfo.admissions_policy?.toLowerCase() ?? '';
     if (policy.includes('selective')) return 'Selective';
@@ -452,9 +460,18 @@ export function SecondarySchoolDetailView({
             GCSE Results ({formatAcademicYear(latestResults.year)})
           </h2>
           <p className={styles.sectionSubtitle}>
-            GCSE results for Year 11 pupils. England averages shown for comparison.
+            GCSE results for Year 11 pupils.{!suppressComparison && ' England averages shown for comparison.'}
           </p>
 
+          {isSpecial && (
+            <div className={styles.specialNote} role="note">
+              <strong>This is a special school.</strong> Its pupils have special educational
+              needs and work towards individual targets. They sit the same GCSEs, but their
+              headline attainment is far below the mainstream average by design, so a comparison
+              with the England average isn&rsquo;t a meaningful guide to the school.
+            </div>
+          )}
+
           {p8Suspended && (
             <div className={styles.p8Banner}>
               Progress 8 isn&apos;t published for 2024/25: this GCSE year group sat no KS2 tests
@@ -472,7 +489,7 @@ export function SecondarySchoolDetailView({
                 </div>
                 <div className={styles.heroStatValue}>
                   {latestResults.attainment_8_score.toFixed(1)}
-                  {secondaryAvg.attainment_8_score != null && (
+                  {!suppressComparison && secondaryAvg.attainment_8_score != null && (
                     <DeltaChip
                       value={latestResults.attainment_8_score}
                       baseline={secondaryAvg.attainment_8_score}
@@ -481,7 +498,7 @@ export function SecondarySchoolDetailView({
                     />
                   )}
                 </div>
-                {secondaryAvg.attainment_8_score != null && (
+                {!suppressComparison && secondaryAvg.attainment_8_score != null && (
                   <div className={styles.heroStatHint}>England avg: {secondaryAvg.attainment_8_score.toFixed(1)}</div>
                 )}
               </div>
@@ -512,7 +529,7 @@ export function SecondarySchoolDetailView({
                 </div>
                 <div className={styles.heroStatValue}>
                   {formatPercentage(latestResults.english_maths_strong_pass_pct)}
-                  {secondaryAvg.english_maths_strong_pass_pct != null && (
+                  {!suppressComparison && secondaryAvg.english_maths_strong_pass_pct != null && (
                     <DeltaChip
                       value={latestResults.english_maths_strong_pass_pct}
                       baseline={secondaryAvg.english_maths_strong_pass_pct}
@@ -521,7 +538,7 @@ export function SecondarySchoolDetailView({
                     />
                   )}
                 </div>
-                {secondaryAvg.english_maths_strong_pass_pct != null && (
+                {!suppressComparison && secondaryAvg.english_maths_strong_pass_pct != null && (
                   <div className={styles.heroStatHint}>England avg: {secondaryAvg.english_maths_strong_pass_pct.toFixed(0)}%</div>
                 )}
               </div>
@@ -534,7 +551,7 @@ export function SecondarySchoolDetailView({
                 </div>
                 <div className={styles.heroStatValue}>
                   {formatPercentage(latestResults.english_maths_standard_pass_pct)}
-                  {secondaryAvg.english_maths_standard_pass_pct != null && (
+                  {!suppressComparison && secondaryAvg.english_maths_standard_pass_pct != null && (
                     <DeltaChip
                       value={latestResults.english_maths_standard_pass_pct}
                       baseline={secondaryAvg.english_maths_standard_pass_pct}
@@ -543,15 +560,17 @@ export function SecondarySchoolDetailView({
                     />
                   )}
                 </div>
-                {secondaryAvg.english_maths_standard_pass_pct != null && (
+                {!suppressComparison && secondaryAvg.english_maths_standard_pass_pct != null && (
                   <div className={styles.heroStatHint}>England avg: {secondaryAvg.english_maths_standard_pass_pct.toFixed(0)}%</div>
                 )}
               </div>
             )}
           </div>
 
-          {/* Attainment 8 visual bar (0–80 scale) */}
-          {latestResults.attainment_8_score != null && (
+          {/* Attainment 8 visual bar (0–80 scale). This viz is explicitly
+              "school vs national", so it's dropped for special schools where
+              that comparison isn't meaningful. */}
+          {!suppressComparison && latestResults.attainment_8_score != null && (
             <div className={styles.att8Viz}>
               <div className={styles.att8VizLabel}>Attainment 8 — school vs national</div>
               <div className={styles.att8VizTrack}>
@@ -743,8 +762,8 @@ export function SecondarySchoolDetailView({
                   data={yearlyData}
                   schoolName={schoolInfo.school_name}
                   isSecondary={true}
-                  nationalAtt8Avg={heroAtt8Nat}
-                  nationalByYear={nationalAvg?.by_year}
+                  nationalAtt8Avg={suppressComparison ? null : heroAtt8Nat}
+                  nationalByYear={suppressComparison ? undefined : nationalAvg?.by_year}
                 />
               </div>
             </>