fix(review): don't suppress a genuine mainstream 0 in the rows

Review feedback: the rankings/search rows treated any exactly-0 attainment as
not comparable regardless of school type, so a genuine 0 at a mainstream
school rendered as "—" (looks like missing data) and dropped its delta —
stricter and inconsistent with SchoolDetailView's placeholder check.

- SchoolRow: match SchoolDetailView's ks2Placeholder signature — suppress only
  when ALL of RWM + reading + writing + maths are 0 (special/suppressed
  signature), not on a bare rwm === 0. A genuine 0% combined (some pupils met
  individual subjects but not all three) is not all-zero, so it stays
  comparable and shows its real figure + trend.
- SecondarySchoolRow: Attainment 8 is a single 0–80 score with no subject
  breakdown to form an all-zero signature, so key off establishment type only
  (drop the bare att8 === 0 guard). A genuine (if extreme) 0.0 shows its value
  + LA delta.
- For consistency, apply the same to the detail views: drop the bare
  attainment_8_score === 0 guard (KS4 keys off isSpecial only); KS2 keeps the
  all-four-subjects-zero placeholder signature.

Special schools / PRUs / AP are still handled via isSpecialSchool everywhere.
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

@@ -237,19 +237,22 @@ export function SchoolDetailView({
   // 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)
+  // Belt-and-braces for KS2: a whole-row zero attainment (every subject 0 — a
-  // is a placeholder, not a real mainstream result — suppress its comparison
+  // special/suppressed signature) is a placeholder, not a real result. This
-  // too. A single 0 (e.g. 0% exceeding at a normal school) stays comparable.
+  // needs ALL of RWM + reading + writing + maths to be 0, so a genuine 0%
+  // combined (some pupils met individual subjects but not all three) stays
+  // comparable. Attainment 8 is a single 0–80 score with no subject breakdown
+  // to form such a signature, so KS4 keys off establishment type only — a
+  // genuine (if extreme) 0.0 still shows its real figure and comparison.
   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;
+  const suppressKs4Comparison = isSpecial;
 
   // Build section nav items dynamically — only sections with data.
   // Order is engagement-led (from section_nav_used analytics): the most-sought

nextjs-app/components/SchoolRow.tsx

@@ -40,12 +40,18 @@ export function SchoolRow({
 
   // Special schools / PRUs / AP: the mainstream RWM measure and its England
   // comparison aren't a fair judgement (their pupils have SEND), so a "0% ·
-  // −62 vs national" row misrepresents them. Treat the mainstream stat as not
+  // −62 vs national" row misrepresents them. Also guard a placeholder all-zero
-  // comparable — same for a placeholder all-zero value.
+  // row (every subject 0 — a special/suppressed signature), matching
+  // SchoolDetailView's ks2Placeholder. A genuine 0% combined (some pupils met
+  // individual subjects but not all three) is NOT all-zero, so it stays
+  // comparable and shows its real figure.
+  const rwmPlaceholder =
+    school.rwm_expected_pct === 0 &&
+    (school.reading_expected_pct ?? 0) === 0 &&
+    (school.writing_expected_pct ?? 0) === 0 &&
+    (school.maths_expected_pct ?? 0) === 0;
   const rwmComparable =
-    school.rwm_expected_pct != null &&
+    school.rwm_expected_pct != null && !rwmPlaceholder && !isSpecialSchool(school);
-    school.rwm_expected_pct !== 0 &&
-    !isSpecialSchool(school);
 
   // vs-national delta
   const rwmDelta =

nextjs-app/components/SecondarySchoolDetailView.tsx

@@ -110,10 +110,12 @@ export function SecondarySchoolDetailView({
   // 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
+  // them as failing against a benchmark that doesn't fit. Attainment 8 is a
-  // placeholder all-zero Attainment 8.)
+  // single 0–80 score with no subject breakdown to test for a placeholder, so
+  // this keys off establishment type only — a genuine (if extreme) 0.0 at a
+  // mainstream school still shows its real value and comparison.
   const isSpecial = isSpecialSchool(schoolInfo);
-  const suppressComparison = isSpecial || (latestResults != null && latestResults.attainment_8_score === 0);
+  const suppressComparison = isSpecial;
 
   const admissionsTag = (() => {
     const policy = schoolInfo.admissions_policy?.toLowerCase() ?? '';

nextjs-app/components/SecondarySchoolRow.tsx

@@ -57,8 +57,11 @@ export function SecondarySchoolRow({
   const att8 = school.attainment_8_score;
   // Special schools / PRUs / AP: Attainment 8 vs the LA average isn't a fair
   // comparison (their pupils have SEND), so drop the delta and the number
-  // rather than show them trailing "the average" by design.
+  // rather than show them trailing "the average" by design. Attainment 8 is a
-  const att8Comparable = att8 != null && att8 !== 0 && !isSpecialSchool(school);
+  // single 0–80 score with no subject breakdown to test for a placeholder, so
+  // this keys off establishment type only — a genuine (if extreme) 0.0 at a
+  // mainstream school still shows its real value.
+  const att8Comparable = att8 != null && !isSpecialSchool(school);
   const laDelta =
     att8Comparable && laAvgAttainment8 != null ? (att8 as number) - laAvgAttainment8 : null;