preserving navigation

site/src/components/ActivityFeed.svelte

@@ -34,6 +34,7 @@
   let shown = PAGE_SIZE;
   let loading = true;
   let error = '';
+  let mounted = false;
 
   $: filtered = sport === 'all' ? all : all.filter(a => a.sport === sport);
   $: visible = filtered.slice(0, shown);
@@ -41,7 +42,16 @@
 
   $: if (sport) shown = PAGE_SIZE; // reset pagination on filter change
 
+  $: if (mounted) {
+    const params = new URLSearchParams(window.location.search);
+    if (sport === 'all') params.delete('sport'); else params.set('sport', sport);
+    const qs = params.toString();
+    history.replaceState(null, '', qs ? `?${qs}` : window.location.pathname);
+  }
+
   onMount(async () => {
+    sport = (new URLSearchParams(window.location.search).get('sport') as Sport | 'all') ?? 'all';
+    mounted = true;
     try {
       const res = await fetch(`${import.meta.env.BASE_URL}data/index.json`);
       if (!res.ok) throw new Error(`HTTP ${res.status}`);

site/src/components/AthleteView.svelte

@@ -13,10 +13,20 @@
 
   type Tab = 'power' | 'records' | 'profile';
   let activeTab: Tab = 'power';
+  let mounted = false;
 
   const editUrl = import.meta.env.PUBLIC_EDIT_URL ?? '';
 
+  $: if (mounted) {
+    const params = new URLSearchParams(window.location.search);
+    if (activeTab === 'power') params.delete('tab'); else params.set('tab', activeTab);
+    const qs = params.toString();
+    history.replaceState(null, '', qs ? `?${qs}` : window.location.pathname);
+  }
+
   onMount(async () => {
+    activeTab = (new URLSearchParams(window.location.search).get('tab') as Tab) ?? 'power';
+    mounted = true;
     try {
       const [athleteRes, indexRes] = await Promise.all([
         fetch(`${import.meta.env.BASE_URL}data/athlete.json`),

site/src/components/RecordsView.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+  import { onMount } from 'svelte';
   import type { AthleteJson } from '../lib/types';
   import { formatDate, sportIcon, sportColor } from '../lib/format';
 
@@ -48,6 +49,20 @@
   ];
 
   let activeTab: SportTab = 'running';
+  let mounted = false;
+
+  $: if (mounted) {
+    const params = new URLSearchParams(window.location.search);
+    if (activeTab === 'running') params.delete('sport'); else params.set('sport', activeTab);
+    const qs = params.toString();
+    history.replaceState(null, '', qs ? `?${qs}` : window.location.pathname);
+  }
+
+  onMount(() => {
+    const sp = new URLSearchParams(window.location.search).get('sport') as SportTab | null;
+    if (sp && TABS.some(t => t.key === sp)) activeTab = sp;
+    mounted = true;
+  });
 
   // Tabs that have at least one record
   function hasRecords(sport: SportTab): boolean {

site/src/components/StatsView.svelte

@@ -7,8 +7,18 @@
   let sport: Sport | 'all' = 'all';
   let loading = true;
   let theme = 'dark';
+  let mounted = false;
+
+  $: if (mounted) {
+    const params = new URLSearchParams(window.location.search);
+    if (sport === 'all') params.delete('sport'); else params.set('sport', sport);
+    const qs = params.toString();
+    history.replaceState(null, '', qs ? `?${qs}` : window.location.pathname);
+  }
 
   onMount(async () => {
+    sport = (new URLSearchParams(window.location.search).get('sport') as Sport | 'all') ?? 'all';
+    mounted = true;
     const res = await fetch(`${import.meta.env.BASE_URL}data/index.json`);
     const index: BASIndex = await res.json();
     all = index.activities.filter(a => a.privacy !== 'private' && a.distance_m);