feat(daily): adjust cache to be until next timezone relative time

Author: capJavert

__tests__/common/date.ts

@@ -1,6 +1,62 @@
-import { isWeekend, DayOfWeek } from '../../src/common/date';
+import { formatInTimeZone } from 'date-fns-tz';
+import {
+  isWeekend,
+  DayOfWeek,
+  secondsUntilNextHourInTimezone,
+} from '../../src/common/date';
+import { ONE_DAY_IN_SECONDS } from '../../src/common/constants';
 
 describe('date', () => {
+  describe('secondsUntilNextHourInTimezone', () => {
+    const expiryAt = (now: Date, ttl: number): Date =>
+      new Date(now.getTime() + ttl * 1000);
+
+    it('should expire at the next 9am in the given timezone', () => {
+      const now = new Date('2026-06-19T06:00:00Z');
+
+      ['Etc/UTC', 'America/New_York', 'Asia/Tokyo'].forEach((timezone) => {
+        const ttl = secondsUntilNextHourInTimezone({ hour: 9, timezone, now });
+
+        expect(ttl).toBeGreaterThan(0);
+        expect(ttl).toBeLessThanOrEqual(ONE_DAY_IN_SECONDS);
+        expect(formatInTimeZone(expiryAt(now, ttl), timezone, 'HH:mm')).toBe(
+          '09:00',
+        );
+        expect(expiryAt(now, ttl).getTime()).toBeGreaterThan(now.getTime());
+      });
+    });
+
+    it('should roll to the next day once 9am has passed in the timezone', () => {
+      // 23:00 UTC is already past 9am UTC today, so it targets tomorrow.
+      const now = new Date('2026-06-19T23:00:00Z');
+      const ttl = secondsUntilNextHourInTimezone({
+        hour: 9,
+        timezone: 'Etc/UTC',
+        now,
+      });
+
+      expect(
+        formatInTimeZone(expiryAt(now, ttl), 'Etc/UTC', 'yyyy-MM-dd HH:mm'),
+      ).toBe('2026-06-20 09:00');
+    });
+
+    it('should shift with the timezone for the same instant', () => {
+      const now = new Date('2026-06-19T06:00:00Z');
+      const utc = secondsUntilNextHourInTimezone({
+        hour: 9,
+        timezone: 'Etc/UTC',
+        now,
+      });
+      const tokyo = secondsUntilNextHourInTimezone({
+        hour: 9,
+        timezone: 'Asia/Tokyo',
+        now,
+      });
+
+      expect(utc).not.toEqual(tokyo);
+    });
+  });
+
   describe('isWeekend', () => {
     it('should return true for Saturday and Sunday when the week starts on Monday', () => {
       expect(isWeekend(new Date('2024-08-10'), DayOfWeek.Monday)).toBe(true); // Saturday

src/common/date.ts

@@ -1,3 +1,5 @@
+import { zonedTimeToUtc } from 'date-fns-tz';
+
 export enum DayOfWeek {
   Sunday = 0,
   Monday = 1,
@@ -27,6 +29,25 @@ export const isWeekend = (
   }
 };
 
+export const secondsUntilNextHourInTimezone = ({
+  hour,
+  timezone,
+  now = new Date(),
+}: {
+  hour: number;
+  timezone: string;
+  now?: Date;
+}): number => {
+  const target = new Date(now);
+  target.setHours(hour, 0, 0, 0);
+  let targetUtc = zonedTimeToUtc(target, timezone);
+  if (targetUtc.getTime() <= now.getTime()) {
+    target.setDate(target.getDate() + 1);
+    targetUtc = zonedTimeToUtc(target, timezone);
+  }
+  return Math.max(60, Math.ceil((targetUtc.getTime() - now.getTime()) / 1000));
+};
+
 export const getSecondsTimestamp = (ms: number | Date): number => {
   const msValue = ms instanceof Date ? ms.getTime() : ms;
 

src/config.ts

@@ -43,6 +43,7 @@ export enum StorageTopic {
   RedisCounter = 'redis_counter',
   Cron = 'cron',
   LiveRoom = 'live_room',
+  Feed = 'feeds',
 }
 
 export enum StorageKey {
@@ -57,6 +58,7 @@ export enum StorageKey {
   UserLastOnline = 'ulo',
   ParticipantCount = 'participant_count',
   HasLiveRooms = 'has_live_rooms',
+  DailyFeed = 'daily',
 }
 
 export const generateStorageKey = (

src/remoteConfig.ts

@@ -54,6 +54,7 @@ export type RemoteConfigValue = {
     onboarding_funnel_id: string;
   }>;
   dailyBriefLimit: number;
+  dailyFeedCacheKey: string;
   superAgentTrial: SuperAgentTrialConfig;
   digestPostEnabled: boolean;
   newViewLogs: boolean;

src/schema/feeds.ts

@@ -72,7 +72,12 @@ import {
   getForYouByTagFeedGenerator,
 } from '../integrations/feed/generators';
 import { getRedisObject, setRedisObjectWithExpiry } from '../redis';
-import { ONE_DAY_IN_SECONDS } from '../common/constants';
+import { remoteConfig } from '../remoteConfig';
+import { generateStorageKey, StorageKey, StorageTopic } from '../config';
+import {
+  DEFAULT_TIMEZONE,
+  secondsUntilNextHourInTimezone,
+} from '../common/date';
 import type { FeedResponse } from '../integrations/feed';
 import {
   AuthenticationError,
@@ -1695,7 +1700,19 @@ const dailyFeedResolver = feedResolver<
   (ctx, args, page, builder) => builder,
   {
     fetchQueryParams: async (ctx, args: FeedArgs, page) => {
-      const cacheKey = `feeds:daily:${ctx.userId ?? ctx.trackingId}:${page.limit}:${page.cursor ?? ''}:${(args.supportedTypes ?? []).join(',')}`;
+      const cacheKey = generateStorageKey(
+        StorageTopic.Feed,
+        StorageKey.DailyFeed,
+        [
+          remoteConfig.vars.dailyFeedCacheKey,
+          ctx.userId ?? ctx.trackingId,
+          page.limit,
+          page.cursor,
+          args.supportedTypes?.join(','),
+        ]
+          .filter(Boolean)
+          .join(':'),
+      );
       const cached = await getRedisObject(cacheKey);
       if (cached) {
         return JSON.parse(cached) as FeedResponse;
@@ -1717,12 +1734,20 @@ const dailyFeedResolver = feedResolver<
         config,
         extraMetadata,
       );
-      // Don't cache empty responses so a not-yet-generated feed isn't pinned for a day.
       if (response.data.length) {
+        const user = ctx.userId
+          ? await ctx.dataLoader.user.load({
+              userId: ctx.userId,
+              select: ['timezone'],
+            })
+          : null;
         await setRedisObjectWithExpiry(
           cacheKey,
           JSON.stringify(response),
-          ONE_DAY_IN_SECONDS,
+          secondsUntilNextHourInTimezone({
+            hour: 9,
+            timezone: user?.timezone || DEFAULT_TIMEZONE,
+          }),
         );
       }
       return response;