[Fix] PR analytics misses local-day records on non-UTC servers

apps/docs/cost-analytics.mdx

@@ -34,6 +34,11 @@ model and provider. The source also appears in the detail drilldown. Choose a
 time range before comparing periods so the chart and breakdown use the same
 window.
 
+Analytics date presets and daily chart buckets use the web server's timezone,
+including daylight-saving transitions. Costs, Tasks, and PR analytics use the
+same calendar-day boundaries; these are not based on each viewer's browser
+timezone or the deployment's automation scheduling timezone.
+
 ## Exporting data
 
 Select **Download data** to export the currently filtered detail rows as a CSV

apps/web/src/lib/server/analytics/time-buckets.ts

@@ -35,14 +35,7 @@ export function getRequestTimeBootstrapCutoff(
   timePeriod: TimePeriodFilter | undefined,
   now: Date,
 ): Date | null {
-  if (!timePeriod || timePeriod === 'all') {
-    return null;
-  }
-
-  const cutoff = new Date(now);
-  cutoff.setUTCHours(0, 0, 0, 0);
-  cutoff.setUTCDate(cutoff.getUTCDate() - (timePeriod - 1));
-  return cutoff;
+  return getTimeCutoff(timePeriod, now);
 }
 
 export function getResolvedGranularity(

apps/web/src/lib/server/pull-request-facts.ts

@@ -10,20 +10,7 @@ import {
 } from '@roomote/db/server';
 
 import type { TimePeriodFilter } from '@/types';
-
-function getTimeCutoff(
-  timePeriod: TimePeriodFilter | undefined,
-  now: Date,
-): Date | null {
-  if (!timePeriod || timePeriod === 'all') {
-    return null;
-  }
-
-  const cutoff = new Date(now);
-  cutoff.setUTCHours(0, 0, 0, 0);
-  cutoff.setUTCDate(cutoff.getUTCDate() - (timePeriod - 1));
-  return cutoff;
-}
+import { getTimeCutoff } from './analytics/time-buckets';
 
 export async function getStoredPullRequestsForAnalytics(params: {
   repositoryIds: string[];