diff --git a/nextjs-app/__tests__/support/renderSchoolDetail.tsx b/nextjs-app/__tests__/support/renderSchoolDetail.tsx
index f8ca675..72deca2 100644
--- a/nextjs-app/__tests__/support/renderSchoolDetail.tsx
+++ b/nextjs-app/__tests__/support/renderSchoolDetail.tsx
@@ -37,8 +37,9 @@ export function renderSchoolDetail(fixture: any) {
   return render(
     withProviders(
       <SchoolDetailShell
-        {...fixture}
-        nationalAvg={nationalAveragesFixture}
+        schoolInfo={fixture.schoolInfo}
+        yearlyData={fixture.yearlyData}
+        census={fixture.census}
         navItems={navItems}
       >
         <PrimarySchoolSections
@@ -62,8 +63,9 @@ export function renderSecondarySchoolDetail(fixture: any) {
   return render(
     withProviders(
       <SchoolDetailShell
-        {...fixture}
-        nationalAvg={nationalAveragesFixture}
+        schoolInfo={fixture.schoolInfo}
+        yearlyData={fixture.yearlyData}
+        census={fixture.census}
         navItems={navItems}
       >
         <SecondarySchoolSections
diff --git a/nextjs-app/app/school/[slug]/page.tsx b/nextjs-app/app/school/[slug]/page.tsx
index 6e90198..56a3daf 100644
--- a/nextjs-app/app/school/[slug]/page.tsx
+++ b/nextjs-app/app/school/[slug]/page.tsx
@@ -218,14 +218,7 @@ export default async function SchoolPage({ params }: SchoolPageProps) {
         <SchoolDetailShell
           schoolInfo={school_info}
           yearlyData={yearly_data}
-          absenceData={absence_data}
-          ofsted={ofsted ?? null}
           census={census ?? null}
-          admissions={admissions ?? null}
-          admissionsHistory={admissions_history ?? []}
-          deprivation={deprivation ?? null}
-          finance={finance ?? null}
-          nationalAvg={nationalAvg}
           navItems={secondaryNavItems}
         >
           <SecondarySchoolSections
@@ -245,14 +238,7 @@ export default async function SchoolPage({ params }: SchoolPageProps) {
         <SchoolDetailShell
           schoolInfo={school_info}
           yearlyData={yearly_data}
-          absenceData={absence_data}
-          ofsted={ofsted ?? null}
           census={census ?? null}
-          admissions={admissions ?? null}
-          admissionsHistory={admissions_history ?? []}
-          deprivation={deprivation ?? null}
-          finance={finance ?? null}
-          nationalAvg={nationalAvg}
           navItems={primaryNavItems}
         >
           <PrimarySchoolSections
diff --git a/nextjs-app/components/school/SchoolDetailShell.tsx b/nextjs-app/components/school/SchoolDetailShell.tsx
index 9ab0500..04e7e52 100644
--- a/nextjs-app/components/school/SchoolDetailShell.tsx
+++ b/nextjs-app/components/school/SchoolDetailShell.tsx
@@ -20,34 +20,23 @@ import { useEffect, useRef, useState, type ReactNode } from 'react';
 import { useRouter } from 'next/navigation';
 import { useComparison } from '@/hooks/useComparison';
 import { SchoolHeroMap, type SchoolHeroMapHandle } from '../SchoolHeroMap';
-import type {
-  School, SchoolResult, AbsenceData,
-  OfstedInspection, SchoolCensus,
-  SchoolAdmissions,
-  SchoolDeprivation, SchoolFinance, NationalAverages,
-} from '@/lib/types';
-import {
-  formatPercentage, formatProgress, formatAcademicYear, formatAgeRange, isProposedToClose, ofstedLegacyAreas,
-} from '@/lib/utils';
-import { computeSchoolFlags, type NavItem } from '@/lib/schoolSections';
-
+import type { School, SchoolResult, SchoolCensus } from '@/lib/types';
+import { formatAgeRange, isProposedToClose } from '@/lib/utils';
+import type { NavItem } from '@/lib/schoolSections';
 import { track, getNavigationSource } from '@/lib/analytics';
 import styles from './SchoolDetailShell.module.css';
 
 
+/**
+ * Only what the chrome itself renders. Everything the sections need — Ofsted,
+ * admissions, deprivation, finance, national averages — goes straight to the
+ * section composers in page.tsx and never reaches the client.
+ */
 export interface SchoolDetailShellProps {
   schoolInfo: School;
+  /** Only for the header's pupil-count fallback. */
   yearlyData: SchoolResult[];
-  absenceData: AbsenceData | null;
-  ofsted: OfstedInspection | null;
   census: SchoolCensus | null;
-  admissions: SchoolAdmissions | null;
-  admissionsHistory: SchoolAdmissions[];
-  deprivation: SchoolDeprivation | null;
-  finance: SchoolFinance | null;
-  /** Fetched on the server so the England-comparison deltas are in the
-   *  initial HTML; null when the endpoint is unavailable. */
-  nationalAvg: NationalAverages | null;
   /** Section list for the sticky nav, computed on the server. */
   navItems: NavItem[];
   /** The server-rendered sections. */
@@ -55,9 +44,7 @@ export interface SchoolDetailShellProps {
 }
 
 export function SchoolDetailShell({
-  schoolInfo, yearlyData, absenceData,
-  ofsted, census, admissions, admissionsHistory, deprivation, finance,
-  nationalAvg, navItems, children,
+  schoolInfo, yearlyData, census, navItems, children,
 }: SchoolDetailShellProps) {
   const router = useRouter();
   const { addSchool, removeSchool, isSelected } = useComparison();
@@ -135,21 +122,14 @@ export function SchoolDetailShell({
     return () => window.removeEventListener('keydown', onKey);
   }, [sectionsOpen]);
 
-  // Derived data-shape logic lives in lib/schoolSections so the server route
-  // can compute the section list without importing this client component.
-  const flags = computeSchoolFlags({
-    schoolInfo, yearlyData, absenceData, census, deprivation, finance,
-  });
-  const {
-    latestResults, isAllThrough, isSecondary, isPrimary,
-    hasGenderSplit, hasInclusionData, hasSchoolLife, hasDeprivation,
-    hasFinance, hasLocation, hasKS2Results, hasKS4Results, hasAnyResults,
-    isSpecial, ks2Placeholder, suppressKs2Comparison, suppressKs4Comparison,
-  } = flags;
+  // The chrome needs only these four. The section-shape flags are computed
+  // once on the server (lib/schoolSections) and consumed by the section
+  // composers; recomputing them here would duplicate that work for values
+  // this component never renders.
+  const latestResults = yearlyData.length > 0 ? yearlyData[yearlyData.length - 1] : null;
   const phase = schoolInfo.phase ?? '';
-
-  const primaryAvg = nationalAvg?.primary ?? {};
-  const secondaryAvg = nationalAvg?.secondary ?? {};
+  const isAllThrough = phase.toLowerCase() === 'all-through';
+  const hasLocation = schoolInfo.latitude != null && schoolInfo.longitude != null;
 
   const handleComparisonToggle = () => {
     if (isInComparison) {
@@ -172,13 +152,6 @@ export function SchoolDetailShell({
   // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [schoolInfo.urn]);
 
-  const deprivationDesc = (decile: number) => {
-    if (decile <= 3) return `This school is in one of England's most deprived areas (decile ${decile}/10). Many pupils may face additional challenges at home.`;
-    if (decile <= 7) return `This school is in an area with average levels of deprivation (decile ${decile}/10).`;
-    return `This school is in one of England's less deprived areas (decile ${decile}/10).`;
-  };
-
-
   // Track active section as user scrolls
   useEffect(() => {
     const ids = navItems.map(n => n.id);
@@ -211,29 +184,6 @@ export function SchoolDetailShell({
   // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [navItems.map(n => n.id).join(',')]);
 
-  // A report card is identified by the presence of report-card area
-  // judgements, NOT by `framework` — the API sets `framework` to the raw
-  // event grouping (e.g. "Schools - S5") even for report-card schools, so
-  // the old `framework === 'ReportCard'` test never matched and report cards
-  // were rendered as legacy ratings dated to a pre-Nov-2025 inspection.
-  const isReportCard = !!(
-    ofsted?.report_card && Object.keys(ofsted.report_card).length > 0
-  );
-  // A report card is dated by its own inspection (rc_inspection_date); the
-  // legacy inspection_date belongs to an older inspection and must never
-  // date a report card (report cards exist only from Nov 2025).
-  const ofstedInspectedDate = isReportCard
-    ? ofsted?.rc_inspection_date ?? null
-    : ofsted?.inspection_date ?? null;
-
-  // ── Ofsted: detect if all OEIF sub-grades match the overall ───────────
-  const oeifAreas = ofsted ? ofstedLegacyAreas(ofsted) : [];
-  const oeifAllSameGrade =
-    !!ofsted &&
-    !isReportCard &&
-    oeifAreas.length >= 3 &&
-    oeifAreas.every((a) => a.value === ofsted.overall_effectiveness);
-
   // Label shown in the mobile "section" menu button — the section in view.
   const activeNavLabel = (navItems.find((n) => n.id === activeSection) ?? navItems[0])?.label ?? '';