fix: ensure watch history is sorted by most recent first

- Enforce descending month order in `js/nostr/watchHistory.js` by explicitly sorting keys before flattening buckets.
- Update `js/feedEngine/watchHistoryFeed.js` and `js/historyView.js` to use `video.created_at` as a fallback sort key when `watchedAt` is missing or equal.
- Verified logic with `tests/verify_sort.mjs`.

js/feedEngine/watchHistoryFeed.js

@@ -195,8 +195,19 @@ function createWatchHistorySource({ service = watchHistoryService } = {}) {
     }
 
     results.sort((a, b) => {
-      if (a.watchedAt !== b.watchedAt) {
-        return b.watchedAt - a.watchedAt;
+      const watchedA = a?.watchedAt || 0;
+      const watchedB = b?.watchedAt || 0;
+      if (watchedA !== watchedB) {
+        return watchedB - watchedA;
+      }
+      const createdA = Number.isFinite(a?.video?.created_at)
+        ? a.video.created_at
+        : 0;
+      const createdB = Number.isFinite(b?.video?.created_at)
+        ? b.video.created_at
+        : 0;
+      if (createdA !== createdB) {
+        return createdB - createdA;
       }
       return a.pointerKey.localeCompare(b.pointerKey);
     });
@@ -488,8 +499,19 @@ function createWatchHistorySorter() {
     }
     const copy = [...items];
     copy.sort((a, b) => {
-      if (a?.watchedAt !== b?.watchedAt) {
-        return (b?.watchedAt || 0) - (a?.watchedAt || 0);
+      const watchedA = a?.watchedAt || 0;
+      const watchedB = b?.watchedAt || 0;
+      if (watchedA !== watchedB) {
+        return watchedB - watchedA;
+      }
+      const createdA = Number.isFinite(a?.video?.created_at)
+        ? a.video.created_at
+        : 0;
+      const createdB = Number.isFinite(b?.video?.created_at)
+        ? b.video.created_at
+        : 0;
+      if (createdA !== createdB) {
+        return createdB - createdA;
       }
       const aKey = typeof a?.pointerKey === "string" ? a.pointerKey : "";
       const bKey = typeof b?.pointerKey === "string" ? b.pointerKey : "";

js/historyView.js

@@ -240,6 +240,15 @@ function normalizeHistoryItems(rawItems) {
     if (a.watchedAt !== b.watchedAt) {
       return b.watchedAt - a.watchedAt;
     }
+    const createdA = Number.isFinite(a?.video?.created_at)
+      ? a.video.created_at
+      : 0;
+    const createdB = Number.isFinite(b?.video?.created_at)
+      ? b.video.created_at
+      : 0;
+    if (createdA !== createdB) {
+      return createdB - createdA;
+    }
     return a.pointerKey.localeCompare(b.pointerKey);
   });
   return normalized;

js/nostr/watchHistory.js

@@ -526,7 +526,11 @@ async function computeWatchHistoryFingerprintForItems(itemsOrBuckets) {
   if (Array.isArray(itemsOrBuckets)) {
     flatItems = itemsOrBuckets;
   } else if (itemsOrBuckets && typeof itemsOrBuckets === "object") {
-    flatItems = Object.values(itemsOrBuckets).flat();
+    flatItems = Object.keys(itemsOrBuckets)
+      .sort()
+      .reverse()
+      .map((k) => itemsOrBuckets[k])
+      .flat();
   }
 
   // Sort for deterministic fingerprint
@@ -1617,7 +1621,11 @@ class WatchHistoryManager {
     // Existing items - try to get records, fallback to items
     let existingItems = [];
     if (cachedEntry.records && typeof cachedEntry.records === "object") {
-        existingItems = Object.values(cachedEntry.records).flat();
+      existingItems = Object.keys(cachedEntry.records)
+        .sort()
+        .reverse()
+        .map((k) => cachedEntry.records[k])
+        .flat();
     } else if (Array.isArray(cachedEntry.items)) {
         existingItems = cachedEntry.items;
     }
@@ -1959,7 +1967,11 @@ class WatchHistoryManager {
       mergedItems,
       WATCH_HISTORY_MAX_ITEMS,
     );
-    const flatItems = Object.values(records).flat();
+    const flatItems = Object.keys(records)
+      .sort()
+      .reverse()
+      .map((k) => records[k])
+      .flat();
 
     const fingerprint = await this.getFingerprint(
       resolvedActor,
@@ -2038,7 +2050,11 @@ class WatchHistoryManager {
       merged.items || [],
       batchLimit,
     );
-    const flatItems = Object.values(records).flat();
+    const flatItems = Object.keys(records)
+      .sort()
+      .reverse()
+      .map((k) => records[k])
+      .flat();
 
     const fingerprint = await this.getFingerprint(
       resolvedActor,