Feed: eager-load only the year shards needed for the active date filter

site/src/components/ActivityFeed.svelte

@@ -132,19 +132,41 @@
 
   $: if (sport || datePre || query || customFrom || customTo) shown = PAGE_SIZE; // reset pagination on filter change
 
-  // When a search query or any date filter is active, eagerly load all
+  // Eager-load shards / feed-pages when a filter needs data not yet in memory.
-  // remaining shards so results aren't limited to the initially-loaded year.
-  // Use only primary let-variables here — Svelte 5 doesn't reliably track
-  // derived $: variables as dependencies of side-effect $: blocks.
   let loadingAllShards    = false;
   let loadingAllFeedPages = false;
 
-  $: if ((query.trim() || customFrom || customTo || datePre !== 'all') && pendingShards.length > 0 && !loadingAllShards) {
+  function _yearFromShard(url: string): number | null {
+    const m = url.match(/index-(\d{4})\.json$/);
+    return m ? parseInt(m[1], 10) : null;
+  }
+
+  // Returns [minYear, maxYear] for year-specific filters (year preset or custom
+  // date range).  Returns null for open-ended filters (all, 7d, 30d, 6mo).
+  function _neededYearRange(pre: string, from: string, to: string): [number, number] | null {
+    if (from || to) {
+      const fy = from ? parseInt(from.slice(0, 4), 10) : 0;
+      const ty = to   ? parseInt(to.slice(0, 4),   10) : 9999;
+      return [fy, ty];
+    }
+    if (/^\d{4}$/.test(pre)) { const y = parseInt(pre, 10); return [y, y]; }
+    return null;
+  }
+
+  $: {
+    const yr = _neededYearRange(datePre, customFrom, customTo);
+    const needEager = !!query.trim() || yr !== null;
+    if (needEager && pendingShards.length > 0 && !loadingAllShards) {
       loadingAllShards = true;
+      // When year-specific filter (no search), load only shards that cover
+      // the needed range; unneeded shards stay in pendingShards for "Load more".
+      // When search is active, load everything so full-text search works.
+      const toLoad = (yr && !query.trim())
+        ? pendingShards.filter(url => { const y = _yearFromShard(url); return y !== null && y >= yr[0] && y <= yr[1]; })
+        : [...pendingShards];
       (async () => {
-      while (pendingShards.length > 0) {
+        for (const url of toLoad) {
-        const url = pendingShards[0];
+          pendingShards = pendingShards.filter(u => u !== url);
-        pendingShards = pendingShards.slice(1);
           try {
             const fresh = await loadShardActivities(url);
             const existing = new Map(all.map(a => [a.id, a]));
@@ -157,12 +179,15 @@
         loadingAllShards = false;
       })();
     }
+  }
 
-  $: if ((query.trim() || customFrom || customTo || datePre !== 'all') && feedNextPage > 0 && !loadingAllFeedPages) {
+  $: {
+    const yr = _neededYearRange(datePre, customFrom, customTo);
+    if ((!!query.trim() || yr !== null) && feedNextPage > 0 && !loadingAllFeedPages) {
       loadingAllFeedPages = true;
+      // Capture at loop start — dateFrom is reactive and may change mid-fetch.
+      const effectiveFrom = dateFrom;
       (async () => {
-      // Snapshot at loop start — customFrom may change while we're fetching.
-      const fromFilter = customFrom;
         while (feedNextPage > 0) {
           const page = feedNextPage;
           feedNextPage = page < feedTotalPages ? page + 1 : 0;
@@ -175,15 +200,16 @@
             );
             // Feed is sorted newest-first. Once the oldest activity in this page
             // predates our from-filter, everything needed is already loaded.
-          if (fromFilter && fresh.length > 0) {
+            if (effectiveFrom && fresh.length > 0) {
               const oldest = fresh.reduce((m, a) => (a.started_at ?? '') < (m.started_at ?? '') ? a : m);
-            if ((oldest.started_at ?? '') < fromFilter) { feedNextPage = 0; break; }
+              if ((oldest.started_at ?? '') < effectiveFrom) { feedNextPage = 0; break; }
             }
           } catch { /* ignore — partial results still useful */ }
         }
         loadingAllFeedPages = false;
       })();
     }
+  }
 
   $: if (mounted) {
     const params = new URLSearchParams(window.location.search);