fix: invalidate unchanged alias cache when updating feeds (#492)

* fix: invalidate unchanged alias cache when updating feeds

* fix: resolve main conflicts for issue 429

* chore: drop obsolete feed-cache helper

* fix: re-export clearFeedCache for server consumers

Author: ThankRain

server/src/services/__tests__/clear-feed-cache.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, it } from 'bun:test';
+
+import { clearFeedCache } from '../clear-feed-cache';
+
+describe('clearFeedCache', () => {
+    it('deletes alias cache when alias is unchanged', async () => {
+        const deletedPrefixes: string[] = [];
+        const deletedKeys: Array<{ key: string; save: boolean | undefined }> = [];
+        const cache = {
+            async deletePrefix(prefix: string) {
+                deletedPrefixes.push(prefix);
+            },
+            async delete(key: string, save?: boolean) {
+                deletedKeys.push({ key, save });
+            }
+        } as any;
+
+        await clearFeedCache(cache, 42, 'about', 'about');
+
+        expect(deletedPrefixes).toEqual([
+            'feeds_',
+            'search_',
+            '42_previous_feed',
+            '42_next_feed'
+        ]);
+        expect(deletedKeys).toEqual([
+            { key: 'feed_42', save: false },
+            { key: 'feed_about', save: false }
+        ]);
+    });
+
+    it('deletes both old and new alias cache keys when alias changes', async () => {
+        const deletedKeys: Array<{ key: string; save: boolean | undefined }> = [];
+        const cache = {
+            async deletePrefix() {},
+            async delete(key: string, save?: boolean) {
+                deletedKeys.push({ key, save });
+            }
+        } as any;
+
+        await clearFeedCache(cache, 42, 'about', 'about-us');
+
+        expect(deletedKeys).toEqual([
+            { key: 'feed_42', save: false },
+            { key: 'feed_about', save: false },
+            { key: 'feed_about-us', save: false }
+        ]);
+    });
+});

server/src/services/clear-feed-cache.ts

@@ -0,0 +1,11 @@
+import type { CacheImpl } from "../core/hono-types";
+
+export async function clearFeedCache(cache: CacheImpl, id: number, alias: string | null, newAlias: string | null) {
+    await cache.deletePrefix('feeds_');
+    await cache.deletePrefix('search_');
+    await cache.delete(`feed_${id}`, false);
+    await cache.deletePrefix(`${id}_previous_feed`);
+    await cache.deletePrefix(`${id}_next_feed`);
+    if (alias) await cache.delete(`feed_${alias}`, false);
+    if (newAlias && newAlias !== alias) await cache.delete(`feed_${newAlias}`, false);
+}

server/src/services/feed.ts

@@ -1,12 +1,14 @@
 import { and, asc, count, desc, eq, gt, like, lt, or } from "drizzle-orm";
 import { Hono } from "hono";
-import type { Variables, CacheImpl } from "../core/hono-types";
+import type { Variables } from "../core/hono-types";
 import { profileAsync } from "../core/server-timing";
 import { feeds, visits, visitStats } from "../db/schema";
 import { HyperLogLog } from "../utils/hyperloglog";
 import { extractImageWithMetadata } from "../utils/image";
 import { syncFeedAISummaryQueueState } from "./feed-ai-summary";
 import { bindTagToPost } from "./tag";
+import { clearFeedCache } from "./clear-feed-cache";
+export { clearFeedCache } from "./clear-feed-cache";
 
 // Lazy-loaded modules for WordPress import
 let XMLParser: any;
@@ -659,13 +661,3 @@ type FeedItem = {
     tags?: string[];
 }
 
-export async function clearFeedCache(cache: CacheImpl, id: number, alias: string | null, newAlias: string | null) {
-    await cache.deletePrefix('feeds_');
-    await cache.deletePrefix('search_');
-    await cache.delete(`feed_${id}`, false);
-    await cache.deletePrefix(`${id}_previous_feed`);
-    await cache.deletePrefix(`${id}_next_feed`);
-    if (alias === newAlias) return;
-    if (alias) await cache.delete(`feed_${alias}`, false);
-    if (newAlias) await cache.delete(`feed_${newAlias}`, false);
-}