fix(search): start postcode searches at half a mile

New postcode searches, the near-me button and URLs without a radius now
use 0.5 miles. A postcode URL with no radius used to show "1 mile" in the
Distance control while the API applied its own 5-mile default; the page
and the map fetch now send the same default the control displays.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

e2e/tests/journeys.spec.ts

@@ -270,6 +270,9 @@ test('searching by name returns school results', async ({ page }) => {
 test('searching by postcode returns nearby schools', async ({ page }) => {
   await searchByName(page, 'B1 1BB');
   await expect(schoolLinks(page).first()).toBeVisible({ timeout: 15_000 });
+  // A new postcode search starts at half a mile.
+  await expect(page).toHaveURL(/[?&]radius=0\.5(&|$)/);
+  await expect(page.getByRole('combobox', { name: 'Distance' })).toHaveValue('0.5');
 });
 
 test('the phase filter switches straight from secondary to primary', async ({ page }) => {

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

@@ -0,0 +1,41 @@
+import { render, screen, waitFor } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { FilterBar } from '@/components/FilterBar';
+
+const push = jest.fn();
+let searchParams = new URLSearchParams();
+jest.mock('next/navigation', () => ({
+  useRouter: () => ({ push, replace: jest.fn(), prefetch: jest.fn() }),
+  usePathname: () => '/',
+  useSearchParams: () => searchParams,
+}));
+
+const FILTERS = {
+  local_authorities: [], school_types: [], years: [], phases: [],
+  genders: [], admissions_policies: [],
+};
+
+beforeEach(() => {
+  push.mockClear();
+  searchParams = new URLSearchParams();
+});
+
+describe('FilterBar default distance', () => {
+  it('searches a new postcode within half a mile', async () => {
+    render(<FilterBar filters={FILTERS} />);
+    await userEvent.type(screen.getByPlaceholderText(/School name or postcode/i), 'SW19 6AR{Enter}');
+    await waitFor(() => expect(push).toHaveBeenCalledWith(expect.stringContaining('radius=0.5')));
+  });
+
+  it('shows half a mile when the URL carries a postcode but no radius', () => {
+    searchParams = new URLSearchParams('postcode=SW196AR');
+    render(<FilterBar filters={FILTERS} />);
+    expect(screen.getByRole('combobox', { name: 'Distance' })).toHaveValue('0.5');
+  });
+
+  it('keeps a distance the user already chose', async () => {
+    searchParams = new URLSearchParams('postcode=SW196AR&radius=3');
+    render(<FilterBar filters={FILTERS} />);
+    expect(screen.getByRole('combobox', { name: 'Distance' })).toHaveValue('3');
+  });
+});

nextjs-app/app/(frontend)/page.tsx

@@ -6,7 +6,7 @@
 import { absoluteUrl } from '@/lib/site';
 import type { Metadata } from 'next';
 import { fetchSchools, fetchFilters, fetchDataInfo } from '@/lib/api';
-import { formatAcademicYear } from '@/lib/utils';
+import { DEFAULT_RADIUS_MILES, formatAcademicYear } from '@/lib/utils';
 import { HomeView } from '@/components/HomeView';
 import { getFlags } from '@/lib/flags';
 import { HowItWorksSection } from '@/components/HowItWorksSection';
@@ -71,7 +71,9 @@ export default async function HomePage({ searchParams }: HomePageProps) {
 
   // Parse search params
   const page = parseInt(params.page || '1');
-  const radius = params.radius ? parseFloat(params.radius) : undefined;
+  // Without this the API applies its own 5-mile default while the Distance
+  // control shows DEFAULT_RADIUS_MILES.
+  const radius = params.radius ? parseFloat(params.radius) : DEFAULT_RADIUS_MILES;
 
   // Check if user has performed a search
   const hasSearchParams = !!(

nextjs-app/components/FilterBar.tsx

@@ -3,7 +3,7 @@
 import { useState, useCallback, useTransition, useRef, useEffect } from "react";
 import type { ReactNode } from "react";
 import { useRouter, useSearchParams, usePathname } from "next/navigation";
-import { isValidPostcode, schoolUrl } from "@/lib/utils";
+import { DEFAULT_RADIUS_MILES, isValidPostcode, schoolUrl } from "@/lib/utils";
 import { track } from "@/lib/analytics";
 import { useSchoolSuggest } from "@/hooks/useSchoolSuggest";
 import { SuggestList, suggestOptionId } from "./SuggestList";
@@ -70,7 +70,7 @@ export function FilterBar({
 
   const currentSearch = searchParams.get("search") || "";
   const currentPostcode = searchParams.get("postcode") || "";
-  const currentRadius = searchParams.get("radius") || "1";
+  const currentRadius = searchParams.get("radius") || String(DEFAULT_RADIUS_MILES);
   const initialOmniValue = currentPostcode || currentSearch;
 
   const [omniValue, setOmniValue] = useState(initialOmniValue);
@@ -269,7 +269,7 @@ export function FilterBar({
     if (isPostcode) {
       updateURL({
         postcode: cleaned.toUpperCase(),
-        radius: currentRadius || "1",
+        radius: currentRadius,
         search: "",
       });
     } else {

nextjs-app/components/HomeView.tsx

@@ -17,6 +17,7 @@ import { useComparisonContext } from '@/context/ComparisonContext';
 import { fetchSchools, fetchLAaverages, fetchNationalAverages } from '@/lib/api';
 import type { SchoolsResponse, Filters, School } from '@/lib/types';
 import { track } from '@/lib/analytics';
+import { DEFAULT_RADIUS_MILES } from '@/lib/utils';
 import styles from './HomeView.module.css';
 
 interface HomeViewProps {
@@ -340,6 +341,7 @@ export function HomeView({ initialSchools, filters, totalSchools, howItWorks, ed
     setIsLoadingMap(true);
     const params: Record<string, any> = {};
     searchParams.forEach((value, key) => { params[key] = value; });
+    params.radius ??= DEFAULT_RADIUS_MILES;
     params.page = 1;
     params.page_size = 500;
     fetchSchools(params, { cache: 'no-store', signal: controller.signal })
@@ -419,7 +421,7 @@ export function HomeView({ initialSchools, filters, totalSchools, howItWorks, ed
             setGeoState('idle');
             track('near_me_used', { outcome: 'granted' });
             track('search_submitted', { query: postcode, via: 'near_me', has_postcode: true, filters_active: '', filters_count: 0 });
-            router.push(`/?postcode=${encodeURIComponent(postcode)}&radius=1`);
+            router.push(`/?postcode=${encodeURIComponent(postcode)}&radius=${DEFAULT_RADIUS_MILES}`);
           } else {
             track('near_me_used', { outcome: 'no_postcode' });
             setGeoState('error');

nextjs-app/lib/utils.ts

@@ -235,6 +235,9 @@ export function getVariabilityLabel(stdDev: number | null): string {
 // Validation
 // ============================================================================
 
+/** Radius a postcode search uses until the user picks another. */
+export const DEFAULT_RADIUS_MILES = 0.5;
+
 /**
  * Validate UK postcode format
  */