Fix event time save off-by-one using bundled tz data.

Use moment-timezone in parseEventDatetime so naive America/Asuncion wall-clock times convert correctly regardless of the host Node tz database. Also normalize user registration date filters with toDbDate for Postgres.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/package.json

@@ -25,6 +25,7 @@
     "hono": "^4.4.7",
     "ioredis": "^5.11.1",
     "jose": "^5.4.0",
+    "moment-timezone": "^0.6.2",
     "nanoid": "^5.0.7",
     "nodemailer": "^7.0.13",
     "pdfkit": "^0.17.2",

backend/src/lib/utils.ts

@@ -1,5 +1,6 @@
 import { nanoid } from 'nanoid';
 import { randomUUID } from 'crypto';
+import moment from 'moment-timezone';
 
 /**
  * Get database type (reads env var each time to handle module loading order)
@@ -59,17 +60,10 @@ export function parseEventDatetime(
     return new Date(datetime);
   }
 
-  // Treat the digits as UTC so we have a stable reference instant.
-  const fakeUTC = new Date(datetime + 'Z');
-
-  // Ask Intl what that UTC instant looks like in both UTC and the target tz.
-  const utcStr = fakeUTC.toLocaleString('en-US', { timeZone: 'UTC' });
-  const tzStr  = fakeUTC.toLocaleString('en-US', { timeZone: timezone });
-
-  // The gap between the two tells us the tz offset at this point in time.
-  const offsetMs = new Date(utcStr).getTime() - new Date(tzStr).getTime();
-
-  return new Date(fakeUTC.getTime() + offsetMs);
+  // Interpret the wall-clock digits as local time in `timezone` using
+  // moment-timezone's bundled IANA data. This keeps the conversion correct
+  // regardless of the host Node runtime's (possibly stale) tz database.
+  return moment.tz(datetime, timezone).toDate();
 }
 
 /**

backend/src/routes/users.ts

@@ -4,7 +4,7 @@ import { z } from 'zod';
 import { db, dbGet, dbAll, users, tickets, events, payments, magicLinkTokens, userSessions, invoices, auditLogs, emailLogs, paymentOptions, legalPages, siteSettings } from '../db/index.js';
 import { eq, desc, sql, and, gte, lte } from 'drizzle-orm';
 import { requireAuth } from '../lib/auth.js';
-import { getNow } from '../lib/utils.js';
+import { getNow, toDbDate } from '../lib/utils.js';
 
 interface UserContext {
   id: string;
@@ -39,8 +39,8 @@ usersRouter.get('/', requireAuth(['admin']), async (c) => {
   const conditions: any[] = [];
   if (role) conditions.push(eq((users as any).role, role));
   if (accountStatus) conditions.push(eq((users as any).accountStatus, accountStatus));
-  if (registeredAfter) conditions.push(gte((users as any).createdAt, registeredAfter));
-  if (registeredBefore) conditions.push(lte((users as any).createdAt, registeredBefore));
+  if (registeredAfter) conditions.push(gte((users as any).createdAt, toDbDate(registeredAfter)));
+  if (registeredBefore) conditions.push(lte((users as any).createdAt, toDbDate(registeredBefore)));
   if (search) {
     const like = `%${search.toLowerCase()}%`;
     conditions.push(sql`(