Report the latest feed entry when fetching a feed for the first time

changelog.d/809.feature

@@ -0,0 +1 @@
+Report the latest feed item when subscribing to a new feed

src/Stores/MemoryStorageProvider.ts

@@ -19,6 +19,10 @@ export class MemoryStorageProvider extends MSP implements IBridgeStorageProvider
         super();
     }
 
+    get isPersistent(): boolean {
+        return false;
+    }
+
     async storeFeedGuids(url: string, ...guids: string[]): Promise<void> {
         let set = this.feedGuids.get(url);
         if (!set) {

src/Stores/RedisStorageProvider.ts

@@ -79,6 +79,10 @@ export class RedisStorageProvider extends RedisStorageContextualProvider impleme
         });
     }
 
+    get isPersistent(): boolean {
+        return true;
+    }
+
     public async connect(): Promise<void> {
         try {
             await this.redis.ping();

src/Stores/StorageProvider.ts

@@ -11,6 +11,7 @@ import { SerializedGitlabDiscussionThreads } from "../Gitlab/Types";
 export const MAX_FEED_ITEMS = 10_000;
 
 export interface IBridgeStorageProvider extends IAppserviceStorageProvider, IStorageProvider, ProvisioningStore {
+    get isPersistent(): boolean;
     connect?(): Promise<void>;
     disconnect?(): Promise<void>;
     setGithubIssue(repo: string, issueNumber: string, data: IssuesGetResponseData, scope?: string): Promise<void>;

src/feeds/FeedReader.ts

@@ -6,7 +6,7 @@ import { MessageQueue } from "../MessageQueue";
 import axios from "axios";
 import Metrics from "../Metrics";
 import { randomUUID } from "crypto";
-import { readFeed } from "../libRs";
+import { FeedItem, readFeed } from "../libRs";
 import { IBridgeStorageProvider } from "../Stores/StorageProvider";
 import UserAgent from "../UserAgent";
 
@@ -204,6 +204,8 @@ export class FeedReader {
                 // If undefined, we got a not-modified.
                 log.debug(`Found ${feed.items.length} entries in ${url}`);
 
+                const newEntries: FeedEntry[] = [];
+
                 for (const item of feed.items) {
                     // Some feeds have a nasty habit of leading a empty tag there, making us parse it as garbage.
                     if (!item.hashId) {
@@ -212,11 +214,7 @@ export class FeedReader {
                     }
                     const hashId = `md5:${item.hashId}`;
                     newGuids.push(hashId);
-
-                    if (initialSync) {
-                        log.debug(`Skipping entry ${item.id ?? hashId} since we're performing an initial sync`);
-                        continue;
-                    }
+
                     if (await this.storage.hasSeenFeedGuid(url, hashId)) {
                         log.debug('Skipping already seen entry', item.id ?? hashId);
                         continue;
@@ -235,9 +233,22 @@ export class FeedReader {
                     };
 
                     log.debug('New entry:', entry);
+                    newEntries.push(entry);
                     seenEntriesChanged = true;
+                }
 
-                    this.queue.push<FeedEntry>({ eventName: 'feed.entry', sender: 'FeedReader', data: entry });
+                if (initialSync) {
+                    if (this.storage.isPersistent) {
+                        try {
+                            const latest = newEntries.sort((a, b) => new Date(b.pubdate!).getTime() - new Date(a.pubdate!).getTime())[0];
+                            this.queue.push<FeedEntry>({ eventName: 'feed.entry', sender: 'FeedReader', data: latest });
+                        } catch (err: unknown) {
+                            // no pubdates available, or they parse incorrectly. Null sweat
+                            log.debug(`Could not determine the latest entry in ${url} (${err}), won't report anything`);
+                        }
+                    }
+                } else {
+                    newEntries.forEach(entry => this.queue.push<FeedEntry>({ eventName: 'feed.entry', sender: 'FeedReader', data: entry }));
                 }
 
                 if (seenEntriesChanged) {