perf: batch video updates in subscribeVideos to reduce UI thrashing

Updates `NostrClient.subscribeVideos` to buffer incoming events and invoke the `onVideo` callback once per flush cycle with an array of updates, instead of once per video. This significantly reduces redundant sorting, filtering, and persistence operations in `NostrService`.

Also optimizes `populateNip71MetadataForVideos` to run as a single batched request per flush cycle.

BREAKING CHANGE: `subscribeVideos` callback now receives `Video[]` instead of `Video`. All internal consumers have been updated.

Co-authored-by: PR0M3TH3AN <[email protected]>

js/nostr/client.js

@@ -7750,6 +7750,7 @@ export class NostrClient {
 
       const toProcess = eventBuffer;
       eventBuffer = [];
+      const updatedVideos = [];
 
       for (const evt of toProcess) {
         try {
@@ -7805,25 +7806,32 @@ export class NostrClient {
           const prevActive = this.activeMap.get(activeKey);
           if (!prevActive || video.created_at > prevActive.created_at) {
             this.activeMap.set(activeKey, video);
-            onVideo(video); // Trigger the callback that re-renders
-
-            // Fetch NIP-71 metadata (categorization tags) in the background
-            this.populateNip71MetadataForVideos([video])
-              .then(() => {
-                this.applyRootCreatedAt(video);
-              })
-              .catch((error) => {
-                devLogger.warn(
-                  "[nostr] Failed to hydrate NIP-71 metadata for live video:",
-                  error
-                );
-              });
+            updatedVideos.push(video);
           }
         } catch (err) {
           devLogger.error("[subscribeVideos] Error processing event:", err);
         }
       }
 
+      if (updatedVideos.length > 0) {
+        // Trigger the callback once per batch to avoid UI thrashing
+        onVideo(updatedVideos);
+
+        // Fetch NIP-71 metadata (categorization tags) in the background for the whole batch
+        this.populateNip71MetadataForVideos(updatedVideos)
+          .then(() => {
+            for (const video of updatedVideos) {
+              this.applyRootCreatedAt(video);
+            }
+          })
+          .catch((error) => {
+            devLogger.warn(
+              "[nostr] Failed to hydrate NIP-71 metadata for live video batch:",
+              error
+            );
+          });
+      }
+
       // Persist processed events after each flush so reloads warm quickly.
       this.saveLocalData("subscribeVideos:flush");
     };

tests/nostr-delete-flow.test.mjs

@@ -196,8 +196,10 @@ await (async function testDeleteFlowPublishesDeletionFlag() {
     },
   };
 
-  client.subscribeVideos((videoUpdate) => {
-    seenUpdates.push(videoUpdate);
+  client.subscribeVideos((videos) => {
+    if (Array.isArray(videos)) {
+      seenUpdates.push(...videos);
+    }
   });
 
   const deleteEvent = {
@@ -300,8 +302,10 @@ await (async function testSubscribeVideosSkipsOlderThanTombstone() {
     },
   };
 
-  client.subscribeVideos((videoUpdate) => {
-    seenUpdates.push(videoUpdate);
+  client.subscribeVideos((videos) => {
+    if (Array.isArray(videos)) {
+      seenUpdates.push(...videos);
+    }
   });
 
   const pubkey = "PUBKEY789";

tests/nostr/client.test.mjs

@@ -148,8 +148,11 @@ describe("NostrClient", () => {
       client.pool.sub.mock.mockImplementation(() => subMock);
 
       let capturedVideo = null;
-      const sub = client.subscribeVideos((video) => {
-        capturedVideo = video;
+      const sub = client.subscribeVideos((videos) => {
+        // Callback receives an array of updates
+        if (Array.isArray(videos) && videos.length > 0) {
+          capturedVideo = videos[0];
+        }
       });
       assert.ok(sub);