fix: improve moments clustering

apps/web/app/lib/moments.ts

@@ -0,0 +1,84 @@
+export type MomentAsset = {
+  id: string;
+  capture_ts_utc: string;
+};
+
+export type MomentCluster = {
+  day: string;
+  start: string;
+  end: string;
+  count: number;
+  assets: MomentAsset[];
+};
+
+const MOMENT_WINDOW_MINUTES = 30;
+const MOMENT_WINDOW_MS = MOMENT_WINDOW_MINUTES * 60 * 1000;
+
+function dayKeyFromIso(iso: string) {
+  const d = new Date(iso);
+  const yyyy = d.getUTCFullYear();
+  const mm = String(d.getUTCMonth() + 1).padStart(2, "0");
+  const dd = String(d.getUTCDate()).padStart(2, "0");
+  return `${yyyy}-${mm}-${dd}`;
+}
+
+export function clusterMoments(input: MomentAsset[]): MomentCluster[] {
+  const byDay = new Map<string, MomentAsset[]>();
+
+  for (const asset of input) {
+    if (!asset.capture_ts_utc) continue;
+    const key = dayKeyFromIso(asset.capture_ts_utc);
+    const list = byDay.get(key);
+    if (list) list.push(asset);
+    else byDay.set(key, [asset]);
+  }
+
+  const clusters: MomentCluster[] = [];
+
+  for (const [day, assets] of byDay) {
+    const sorted = [...assets].sort((a, b) =>
+      a.capture_ts_utc.localeCompare(b.capture_ts_utc),
+    );
+
+    let current: MomentAsset[] = [];
+    let lastTs: number | null = null;
+
+    for (const asset of sorted) {
+      const ts = new Date(asset.capture_ts_utc).getTime();
+      if (!Number.isFinite(ts)) continue;
+
+      if (lastTs === null || ts - lastTs <= MOMENT_WINDOW_MS) {
+        current.push(asset);
+      } else {
+        const start = current[0]?.capture_ts_utc;
+        const end = current[current.length - 1]?.capture_ts_utc;
+        if (start && end) {
+          clusters.push({
+            day,
+            start,
+            end,
+            count: current.length,
+            assets: current,
+          });
+        }
+        current = [asset];
+      }
+
+      lastTs = ts;
+    }
+
+    if (current.length) {
+      const start = current[0].capture_ts_utc;
+      const end = current[current.length - 1].capture_ts_utc;
+      clusters.push({
+        day,
+        start,
+        end,
+        count: current.length,
+        assets: current,
+      });
+    }
+  }
+
+  return clusters;
+}