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/SchoolDetailView.tsx

@@ -18,7 +18,7 @@ import type {
   SchoolDeprivation, SchoolFinance, NationalAverages,
 } from '@/lib/types';
 import {
-  formatPercentage, formatProgress, formatAcademicYear, isProposedToClose, ofstedLegacyAreas,
+  formatPercentage, formatProgress, formatAcademicYear, isProposedToClose, ofstedLegacyAreas, isSpecialSchool,
 } from '@/lib/utils';
 import { DeltaChip } from './DeltaChip';
 import { summariseAdmissions } from '@/lib/compareLogic';
@@ -233,6 +233,24 @@ export function SchoolDetailView({
   const hasKS4Results = latestResults != null && latestResults.attainment_8_score != null;
   const hasAnyResults = hasKS2Results || hasKS4Results;
 
+  // Special schools / PRUs / AP: their pupils sit the same tests but very few
+  // reach the mainstream "expected standard", so a 0% headline and an England
+  // comparison portray them as failing against a benchmark that doesn't fit.
+  const isSpecial = isSpecialSchool(schoolInfo);
+  // Belt-and-braces: a whole-row zero attainment (special or suppressed cohort)
+  // is a placeholder, not a real mainstream result — suppress its comparison
+  // too. A single 0 (e.g. 0% exceeding at a normal school) stays comparable.
+  const ks2Placeholder = latestResults != null
+    && latestResults.rwm_expected_pct === 0
+    && (latestResults.reading_expected_pct ?? 0) === 0
+    && (latestResults.writing_expected_pct ?? 0) === 0
+    && (latestResults.maths_expected_pct ?? 0) === 0;
+  const ks4Placeholder = latestResults != null && latestResults.attainment_8_score === 0;
+  // Whether to drop the England-average deltas / national markers / "below"
+  // framing on the attainment measures.
+  const suppressKs2Comparison = isSpecial || ks2Placeholder;
+  const suppressKs4Comparison = isSpecial || ks4Placeholder;
+
   // Build section nav items dynamically — only sections with data.
   // Order is engagement-led (from section_nav_used analytics): the most-sought
   // sections — results, admissions, inclusion, history — sit near the top,
@@ -624,13 +642,32 @@ export function SchoolDetailView({
             {isAllThrough ? 'SATs & GCSE Results' : isSecondary ? 'GCSE Results' : 'SATs Results'} ({formatAcademicYear(latestResults.year)})
           </h2>
           <p className={styles.sectionSubtitle}>
-            {isAllThrough
-              ? 'KS2 SATs (end of Year 6) and GCSE results (Year 11) — this school covers both. England averages shown for comparison.'
-              : isSecondary
-                ? 'GCSE results for Year 11 pupils. England averages shown for comparison.'
-                : 'End-of-primary-school tests taken by Year 6 pupils. England averages shown for comparison.'}
+            {isSpecial
+              ? (isSecondary
+                  ? 'GCSE results for Year 11 pupils.'
+                  : 'End-of-primary-school tests taken by Year 6 pupils.')
+              : isAllThrough
+                ? 'KS2 SATs (end of Year 6) and GCSE results (Year 11) — this school covers both. England averages shown for comparison.'
+                : isSecondary
+                  ? 'GCSE results for Year 11 pupils. England averages shown for comparison.'
+                  : 'End-of-primary-school tests taken by Year 6 pupils. England averages shown for comparison.'}
           </p>
 
+          {/* Special schools sit the same national assessments but teach pupils
+              with SEND, so very few reach the mainstream "expected standard".
+              Explain that up front and drop the England comparison below, so a
+              0% headline never reads as a failing grade against a benchmark
+              that doesn't fit the school. */}
+          {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 national tests, but
+              very few reach the mainstream &ldquo;expected standard&rdquo; these measures report,
+              so a comparison with the England average isn&rsquo;t a meaningful guide to the
+              school. Where available, the progress pupils make (below) is a fairer measure.
+            </div>
+          )}
+
           {/* ── Primary / KS2 content ── */}
           {hasKS2Results && (
             <>
@@ -646,7 +683,7 @@ export function SchoolDetailView({
                     </div>
                     <div className={styles.heroStatValue}>
                       {formatPercentage(latestResults.rwm_expected_pct)}
-                      {primaryAvg.rwm_expected_pct != null && (
+                      {!suppressKs2Comparison && primaryAvg.rwm_expected_pct != null && (
                         <DeltaChip
                           value={latestResults.rwm_expected_pct}
                           baseline={primaryAvg.rwm_expected_pct}
@@ -655,7 +692,7 @@ export function SchoolDetailView({
                         />
                       )}
                     </div>
-                    {primaryAvg.rwm_expected_pct != null && (
+                    {!suppressKs2Comparison && primaryAvg.rwm_expected_pct != null && (
                       <div className={styles.heroStatHint}>England avg: {primaryAvg.rwm_expected_pct.toFixed(0)}%</div>
                     )}
                   </div>
@@ -668,7 +705,7 @@ export function SchoolDetailView({
                     </div>
                     <div className={styles.heroStatValue}>
                       {formatPercentage(latestResults.rwm_high_pct)}
-                      {primaryAvg.rwm_high_pct != null && (
+                      {!suppressKs2Comparison && primaryAvg.rwm_high_pct != null && (
                         <DeltaChip
                           value={latestResults.rwm_high_pct}
                           baseline={primaryAvg.rwm_high_pct}
@@ -677,14 +714,15 @@ export function SchoolDetailView({
                         />
                       )}
                     </div>
-                    {primaryAvg.rwm_high_pct != null && (
+                    {!suppressKs2Comparison && primaryAvg.rwm_high_pct != null && (
                       <div className={styles.heroStatHint}>England avg: {primaryAvg.rwm_high_pct.toFixed(0)}%</div>
                     )}
                   </div>
                 )}
               </div>
 
-              {latestResults.rwm_expected_pct != null &&
+              {!suppressKs2Comparison &&
+                latestResults.rwm_expected_pct != null &&
                 latestResults.reading_expected_pct != null &&
                 latestResults.writing_expected_pct != null &&
                 latestResults.maths_expected_pct != null && (
@@ -708,28 +746,34 @@ export function SchoolDetailView({
                   </div>
                 )}
 
-              <SatsChart
-                subjects={[
-                  {
-                    name: 'Reading',
-                    expectedPct: latestResults.reading_expected_pct,
-                    exceedingPct: latestResults.reading_high_pct,
-                    nationalExpectedPct: primaryAvg.reading_expected_pct,
-                  },
-                  {
-                    name: 'Writing',
-                    expectedPct: latestResults.writing_expected_pct,
-                    exceedingPct: latestResults.writing_high_pct,
-                    nationalExpectedPct: primaryAvg.writing_expected_pct,
-                  },
-                  {
-                    name: 'Maths',
-                    expectedPct: latestResults.maths_expected_pct,
-                    exceedingPct: latestResults.maths_high_pct,
-                    nationalExpectedPct: primaryAvg.maths_expected_pct,
-                  },
-                ]}
-              />
+              {/* All-zero placeholder rows (special / suppressed) would render as
+                  three empty bars against the national markers — misleading, so
+                  skip the chart. For a special school with some non-zero
+                  subjects, keep the bars but drop the national markers. */}
+              {!ks2Placeholder && (
+                <SatsChart
+                  subjects={[
+                    {
+                      name: 'Reading',
+                      expectedPct: latestResults.reading_expected_pct,
+                      exceedingPct: latestResults.reading_high_pct,
+                      nationalExpectedPct: suppressKs2Comparison ? null : primaryAvg.reading_expected_pct,
+                    },
+                    {
+                      name: 'Writing',
+                      expectedPct: latestResults.writing_expected_pct,
+                      exceedingPct: latestResults.writing_high_pct,
+                      nationalExpectedPct: suppressKs2Comparison ? null : primaryAvg.writing_expected_pct,
+                    },
+                    {
+                      name: 'Maths',
+                      expectedPct: latestResults.maths_expected_pct,
+                      exceedingPct: latestResults.maths_high_pct,
+                      nationalExpectedPct: suppressKs2Comparison ? null : primaryAvg.maths_expected_pct,
+                    },
+                  ]}
+                />
+              )}
 
               {/* Progress scores row */}
               {(latestResults.reading_progress != null || latestResults.writing_progress != null || latestResults.maths_progress != null) && (
@@ -786,7 +830,7 @@ export function SchoolDetailView({
                       <MetricTooltip metricKey="attainment_8_score" />
                     </div>
                     <div className={styles.metricValue}>{latestResults.attainment_8_score.toFixed(1)}</div>
-                    {secondaryAvg.attainment_8_score != null && (
+                    {!suppressKs4Comparison && secondaryAvg.attainment_8_score != null && (
                       <div className={styles.metricHint}>England avg: {secondaryAvg.attainment_8_score.toFixed(1)}</div>
                     )}
                   </div>
@@ -810,7 +854,7 @@ export function SchoolDetailView({
                       <MetricTooltip metricKey="english_maths_standard_pass_pct" />
                     </div>
                     <div className={styles.metricValue}>{formatPercentage(latestResults.english_maths_standard_pass_pct)}</div>
-                    {secondaryAvg.english_maths_standard_pass_pct != null && (
+                    {!suppressKs4Comparison && secondaryAvg.english_maths_standard_pass_pct != null && (
                       <div className={styles.metricHint}>England avg: {secondaryAvg.english_maths_standard_pass_pct.toFixed(0)}%</div>
                     )}
                   </div>
@@ -822,7 +866,7 @@ export function SchoolDetailView({
                       <MetricTooltip metricKey="english_maths_strong_pass_pct" />
                     </div>
                     <div className={styles.metricValue}>{formatPercentage(latestResults.english_maths_strong_pass_pct)}</div>
-                    {secondaryAvg.english_maths_strong_pass_pct != null && (
+                    {!suppressKs4Comparison && secondaryAvg.english_maths_strong_pass_pct != null && (
                       <div className={styles.metricHint}>England avg: {secondaryAvg.english_maths_strong_pass_pct.toFixed(0)}%</div>
                     )}
                   </div>
@@ -1076,8 +1120,8 @@ export function SchoolDetailView({
                       data={yearlyData}
                       schoolName={schoolInfo.school_name}
                       isSecondary={false}
-                      nationalRwmAvg={primaryAvg.rwm_expected_pct ?? null}
-                      nationalByYear={nationalAvg?.by_year}
+                      nationalRwmAvg={suppressKs2Comparison ? null : (primaryAvg.rwm_expected_pct ?? null)}
+                      nationalByYear={suppressKs2Comparison ? undefined : nationalAvg?.by_year}
                     />
                   </div>
                 </>
@@ -1090,8 +1134,8 @@ export function SchoolDetailView({
                       data={yearlyData}
                       schoolName={schoolInfo.school_name}
                       isSecondary={true}
-                      nationalAtt8Avg={secondaryAvg.attainment_8_score ?? null}
-                      nationalByYear={nationalAvg?.by_year}
+                      nationalAtt8Avg={suppressKs4Comparison ? null : (secondaryAvg.attainment_8_score ?? null)}
+                      nationalByYear={suppressKs4Comparison ? undefined : nationalAvg?.by_year}
                     />
                   </div>
                 </>
@@ -1103,9 +1147,9 @@ export function SchoolDetailView({
                 data={yearlyData}
                 schoolName={schoolInfo.school_name}
                 isSecondary={isSecondary}
-                nationalRwmAvg={isPrimary ? (primaryAvg.rwm_expected_pct ?? null) : null}
-                nationalAtt8Avg={isSecondary ? (secondaryAvg.attainment_8_score ?? null) : null}
-                nationalByYear={nationalAvg?.by_year}
+                nationalRwmAvg={isPrimary && !suppressKs2Comparison ? (primaryAvg.rwm_expected_pct ?? null) : null}
+                nationalAtt8Avg={isSecondary && !suppressKs4Comparison ? (secondaryAvg.attainment_8_score ?? null) : null}
+                nationalByYear={(isPrimary ? suppressKs2Comparison : suppressKs4Comparison) ? undefined : nationalAvg?.by_year}
               />
             </div>
           )}