Fix business date rollover and make timezone a setting

src/lib/business-date.test.ts

@@ -0,0 +1,121 @@
+import { describe, it, expect } from 'vitest';
+import { businessDate, defaultShift, isValidTimeZone, DEFAULT_TIMEZONE } from './business-date';
+
+const PACIFIC = 'America/Los_Angeles';
+
+// Helper: build a Date from a UTC instant so tests are independent of the
+// machine's local timezone (CI runs in UTC).
+const at = (iso: string) => new Date(iso);
+
+describe('businessDate', () => {
+  it('defaults to America/Los_Angeles', () => {
+    expect(DEFAULT_TIMEZONE).toBe(PACIFIC);
+  });
+
+  it('reproduces the reported bug: 8 PM Pacific stays the same calendar day', () => {
+    // 8:00 PM PDT on 2026-07-13 is 2026-07-14T03:00:00Z. The old UTC-based
+    // code showed 2026-07-14; the business date must still be 2026-07-13.
+    expect(businessDate(at('2026-07-14T03:00:00Z'), PACIFIC)).toBe('2026-07-13');
+  });
+
+  it('does not advance to the next day at closing time (1 AM Pacific)', () => {
+    // 1:00 AM PDT on 2026-07-14 is 2026-07-14T08:00:00Z — still the prior
+    // business day because the restaurant day rolls over at 3 AM.
+    expect(businessDate(at('2026-07-14T08:00:00Z'), PACIFIC)).toBe('2026-07-13');
+  });
+
+  it('stays on the prior day just before the 3 AM rollover (2:59 AM Pacific)', () => {
+    expect(businessDate(at('2026-07-14T09:59:00Z'), PACIFIC)).toBe('2026-07-13');
+  });
+
+  it('advances to the new day exactly at 3 AM Pacific', () => {
+    expect(businessDate(at('2026-07-14T10:00:00Z'), PACIFIC)).toBe('2026-07-14');
+  });
+
+  it('stays on the new day after 3 AM Pacific', () => {
+    expect(businessDate(at('2026-07-14T10:30:00Z'), PACIFIC)).toBe('2026-07-14');
+    expect(businessDate(at('2026-07-14T19:00:00Z'), PACIFIC)).toBe('2026-07-14'); // noon
+  });
+
+  it('late evening Pacific stays on the same calendar day', () => {
+    // 11:30 PM PDT on 2026-07-13 → 2026-07-14T06:30:00Z
+    expect(businessDate(at('2026-07-14T06:30:00Z'), PACIFIC)).toBe('2026-07-13');
+  });
+
+  it('rolls back across a month boundary', () => {
+    // 12:30 AM PDT on 2026-08-01 → 2026-08-01T07:30:00Z → prior day 2026-07-31
+    expect(businessDate(at('2026-08-01T07:30:00Z'), PACIFIC)).toBe('2026-07-31');
+  });
+
+  it('rolls back across a year boundary', () => {
+    // 1:00 AM PST on 2026-01-01 → 2026-01-01T09:00:00Z → 2025-12-31
+    expect(businessDate(at('2026-01-01T09:00:00Z'), PACIFIC)).toBe('2025-12-31');
+  });
+
+  it('handles the spring-forward DST day correctly', () => {
+    // 2026-03-08: clocks jump 2 AM PST → 3 AM PDT. 1:00 AM PST = 09:00Z (prior day),
+    // 3:00 AM PDT = 10:00Z (new day, exactly at rollover).
+    expect(businessDate(at('2026-03-08T09:00:00Z'), PACIFIC)).toBe('2026-03-07');
+    expect(businessDate(at('2026-03-08T10:00:00Z'), PACIFIC)).toBe('2026-03-08');
+  });
+
+  it('works for other timezones (America/New_York)', () => {
+    const NY = 'America/New_York';
+    // 1:00 AM EDT on 2026-07-14 → 2026-07-14T05:00:00Z → prior day
+    expect(businessDate(at('2026-07-14T05:00:00Z'), NY)).toBe('2026-07-13');
+    // 3:00 AM EDT on 2026-07-14 → 2026-07-14T07:00:00Z → new day
+    expect(businessDate(at('2026-07-14T07:00:00Z'), NY)).toBe('2026-07-14');
+  });
+
+  it('respects a custom rollover hour', () => {
+    // With a 6 AM rollover, 5 AM Pacific still belongs to the prior day.
+    // 5:00 AM PDT on 2026-07-14 → 2026-07-14T12:00:00Z
+    expect(businessDate(at('2026-07-14T12:00:00Z'), PACIFIC, 6)).toBe('2026-07-13');
+    expect(businessDate(at('2026-07-14T13:00:00Z'), PACIFIC, 6)).toBe('2026-07-14'); // 6 AM
+  });
+});
+
+describe('defaultShift', () => {
+  const LUNCH_CUTOFF = '15:00';
+
+  it('is Dinner during late-night closing (before the 3 AM rollover)', () => {
+    // 1:00 AM PDT — you are closing out dinner, not lunch.
+    expect(defaultShift(at('2026-07-14T08:00:00Z'), PACIFIC, LUNCH_CUTOFF)).toBe('Dinner');
+  });
+
+  it('is Lunch in the morning after the rollover', () => {
+    // 10:00 AM PDT → 2026-07-14T17:00:00Z
+    expect(defaultShift(at('2026-07-14T17:00:00Z'), PACIFIC, LUNCH_CUTOFF)).toBe('Lunch');
+  });
+
+  it('is Dinner in the evening', () => {
+    // 8:00 PM PDT → 2026-07-14T03:00:00Z (next UTC day, but 8 PM local)
+    expect(defaultShift(at('2026-07-14T03:00:00Z'), PACIFIC, LUNCH_CUTOFF)).toBe('Dinner');
+  });
+
+  it('switches to Dinner exactly at the lunch cutoff', () => {
+    // 3:00 PM PDT → 2026-07-14T22:00:00Z
+    expect(defaultShift(at('2026-07-14T22:00:00Z'), PACIFIC, LUNCH_CUTOFF)).toBe('Dinner');
+    // 2:59 PM PDT → 2026-07-14T21:59:00Z is still Lunch
+    expect(defaultShift(at('2026-07-14T21:59:00Z'), PACIFIC, LUNCH_CUTOFF)).toBe('Lunch');
+  });
+
+  it('is Lunch just after the rollover (3:30 AM Pacific)', () => {
+    // 3:30 AM PDT → 2026-07-14T10:30:00Z
+    expect(defaultShift(at('2026-07-14T10:30:00Z'), PACIFIC, LUNCH_CUTOFF)).toBe('Lunch');
+  });
+});
+
+describe('isValidTimeZone', () => {
+  it('accepts valid IANA zones', () => {
+    expect(isValidTimeZone('America/Los_Angeles')).toBe(true);
+    expect(isValidTimeZone('America/New_York')).toBe(true);
+    expect(isValidTimeZone('UTC')).toBe(true);
+  });
+
+  it('rejects invalid zones', () => {
+    expect(isValidTimeZone('Not/AZone')).toBe(false);
+    expect(isValidTimeZone('')).toBe(false);
+    expect(isValidTimeZone('Pacific Time')).toBe(false);
+  });
+});

src/lib/business-date.ts

@@ -0,0 +1,106 @@
+// Business-day date handling.
+//
+// A restaurant's "business day" is not the same as the calendar day: service
+// that runs past midnight still belongs to the previous day's books. We roll
+// the business date over at 3 AM local time, so late-night close-outs record
+// against the day the shift started rather than jumping to tomorrow.
+//
+// All wall-clock reasoning is done in a configurable IANA timezone (default
+// America/Los_Angeles) so the app is correct regardless of the server's own
+// clock — the previous code used UTC and showed tomorrow's date after ~5 PM
+// Pacific.
+
+export const DEFAULT_TIMEZONE = 'America/Los_Angeles';
+
+/** Hour (local time) at which the business day rolls over to the next date. */
+export const DEFAULT_ROLLOVER_HOUR = 3;
+
+export interface LocalParts {
+  year: number;   // full year, e.g. 2026
+  month: number;  // 1-12
+  day: number;    // 1-31
+  hour: number;   // 0-23
+  minute: number; // 0-59
+}
+
+/** Wall-clock parts of `now` as observed in `timeZone`. */
+export function localParts(now: Date, timeZone: string): LocalParts {
+  const parts = new Intl.DateTimeFormat('en-US', {
+    timeZone,
+    year: 'numeric',
+    month: '2-digit',
+    day: '2-digit',
+    hour: '2-digit',
+    minute: '2-digit',
+    hourCycle: 'h23', // 00-23; avoids the "24" that hour12:false can emit at midnight
+  }).formatToParts(now);
+  const get = (type: string) => parts.find((p) => p.type === type)!.value;
+  return {
+    year: parseInt(get('year'), 10),
+    month: parseInt(get('month'), 10),
+    day: parseInt(get('day'), 10),
+    hour: parseInt(get('hour'), 10),
+    minute: parseInt(get('minute'), 10),
+  };
+}
+
+function pad2(n: number): string {
+  return String(n).padStart(2, '0');
+}
+
+/**
+ * The current business date (YYYY-MM-DD) in `timeZone`. Between midnight and
+ * `rolloverHour` local time the date is still the previous calendar day.
+ *
+ * Day subtraction is done as pure calendar arithmetic (via UTC on the plain
+ * Y/M/D components), so month/year boundaries and DST transitions are handled
+ * without offset math.
+ */
+export function businessDate(
+  now: Date,
+  timeZone: string,
+  rolloverHour: number = DEFAULT_ROLLOVER_HOUR,
+): string {
+  const { year, month, day, hour } = localParts(now, timeZone);
+  let y = year;
+  let m = month;
+  let d = day;
+  if (hour < rolloverHour) {
+    const prev = new Date(Date.UTC(year, month - 1, day));
+    prev.setUTCDate(prev.getUTCDate() - 1);
+    y = prev.getUTCFullYear();
+    m = prev.getUTCMonth() + 1;
+    d = prev.getUTCDate();
+  }
+  return `${y}-${pad2(m)}-${pad2(d)}`;
+}
+
+/**
+ * Which shift to default the tip-entry form to, based on the wall clock in
+ * `timeZone`. Between the lunch cutoff and the 3 AM rollover (i.e. dinner
+ * service and the late-night close-out) it's Dinner; the rest of the day is
+ * Lunch.
+ */
+export function defaultShift(
+  now: Date,
+  timeZone: string,
+  lunchCutoff: string,
+  rolloverHour: number = DEFAULT_ROLLOVER_HOUR,
+): 'Lunch' | 'Dinner' {
+  const { hour, minute } = localParts(now, timeZone);
+  const [cutoffH, cutoffM] = (lunchCutoff || '15:00').split(':').map(Number);
+  const afterLunchCutoff = hour > cutoffH || (hour === cutoffH && minute >= cutoffM);
+  const beforeRollover = hour < rolloverHour;
+  return afterLunchCutoff || beforeRollover ? 'Dinner' : 'Lunch';
+}
+
+/** True if `tz` is an IANA timezone the runtime understands. */
+export function isValidTimeZone(tz: string): boolean {
+  if (!tz) return false;
+  try {
+    new Intl.DateTimeFormat('en-US', { timeZone: tz });
+    return true;
+  } catch {
+    return false;
+  }
+}

src/lib/server/db.ts

@@ -2,6 +2,7 @@ import Database from 'better-sqlite3';
 import { mkdirSync } from 'fs';
 import { dirname } from 'path';
 import bcrypt from 'bcryptjs';
+import { DEFAULT_TIMEZONE } from '../business-date';
 
 const dbPath = process.env.DATABASE_PATH ?? './data/tipsplit.db';
 
@@ -144,6 +145,7 @@ for (const [key, value] of [
   ['bar_liquor_pct',               '10'],
   ['busser_rate',                  '20'],
   ['lunch_cutoff',                 '15:00'],
+  ['timezone',                     DEFAULT_TIMEZONE],
   ['restaurant_name',              'My Restaurant'],
   ['google_sheets_spreadsheet_id', ''],
   ['google_sheets_sheet_name',     'Tip History'],

src/routes/calculate/+page.server.ts

@@ -3,6 +3,7 @@ import { fail, redirect } from '@sveltejs/kit';
 import db from '$lib/server/db';
 import { getSettings } from '$lib/server/auth';
 import { calculate, dollarsToCents } from '$lib/calculator';
+import { businessDate, defaultShift, DEFAULT_TIMEZONE } from '$lib/business-date';
 import type { StaffRow } from '$lib/server/db';
 
 export const load: PageServerLoad = ({ locals }) => {
@@ -13,21 +14,14 @@ export const load: PageServerLoad = ({ locals }) => {
   ).all() as StaffRow[];
 
   const settings = getSettings();
-  const today = new Date().toISOString().split('T')[0];
-  const [cutoffH, cutoffM] = (settings.lunch_cutoff ?? '15:00').split(':').map(Number);
-  const parts = new Intl.DateTimeFormat('en-US', {
-    timeZone: 'America/Los_Angeles',
-    hour: '2-digit',
-    minute: '2-digit',
-    hour12: false,
-  }).formatToParts(new Date());
-  const localHour   = parseInt(parts.find(p => p.type === 'hour')!.value,   10);
-  const localMinute = parseInt(parts.find(p => p.type === 'minute')!.value, 10);
-  const defaultShift = localHour > cutoffH || (localHour === cutoffH && localMinute >= cutoffM)
-    ? 'Dinner'
-    : 'Lunch';
-
-  return { staff, settings, today, defaultShift, user: locals.user };
+  const timeZone = settings.timezone ?? DEFAULT_TIMEZONE;
+  const now = new Date();
+  // Business day, not calendar day: late-night close-outs stay on the prior
+  // date until 3 AM local time (see $lib/business-date).
+  const today = businessDate(now, timeZone);
+  const shift = defaultShift(now, timeZone, settings.lunch_cutoff ?? '15:00');
+
+  return { staff, settings, today, defaultShift: shift, user: locals.user };
 };
 
 export const actions: Actions = {

src/routes/calculate/+page.svelte

@@ -9,6 +9,8 @@
   let shift = $state(data.defaultShift);
   let date = $state(data.today);
 
+  const SHIFTS = ['Lunch', 'Dinner'] as const;
+
   // Live staff list — starts from server data, updated when new person is added
   let staff = $state<StaffRow[]>(data.staff);
 
@@ -78,7 +80,7 @@
         <div>
           <label class="label">Shift</label>
           <div style="display:grid;grid-template-columns:1fr 1fr;gap:0.5rem;">
-            {#each ['Lunch', 'Dinner'] as s}
+            {#each SHIFTS as s}
               <button type="button"
                 onclick={() => shift = s}
                 style="

src/routes/settings/+page.server.ts

@@ -2,6 +2,7 @@ import type { Actions, PageServerLoad } from './$types';
 import { fail, redirect } from '@sveltejs/kit';
 import db from '$lib/server/db';
 import { getSettings } from '$lib/server/auth';
+import { isValidTimeZone, DEFAULT_TIMEZONE } from '$lib/business-date';
 
 export const load: PageServerLoad = ({ locals }) => {
   if (!locals.user) redirect(303, '/');
@@ -33,12 +34,17 @@ export const actions: Actions = {
     if (kitchenPct + barLiquorPct > 100)
       return fail(400, { error: 'Kitchen % and bar liquor % cannot exceed 100% combined' });
 
+    const timezone = String(fd.get('timezone') ?? DEFAULT_TIMEZONE);
+    if (!isValidTimeZone(timezone))
+      return fail(400, { error: 'Invalid timezone' });
+
     const updates: [string, string][] = [
       ['cc_fee_rate',                  String(ccFeeRate)],
       ['kitchen_pct',                  String(kitchenPct)],
       ['bar_liquor_pct',               String(barLiquorPct)],
       ['busser_rate',                  String(busserRate)],
       ['lunch_cutoff',                 String(fd.get('lunch_cutoff') ?? '15:00')],
+      ['timezone',                     timezone],
       ['restaurant_name',              String(fd.get('restaurant_name') ?? '')],
       ['google_sheets_spreadsheet_id', String(fd.get('google_sheets_spreadsheet_id') ?? '')],
       ['google_sheets_sheet_name',     String(fd.get('google_sheets_sheet_name') ?? '')],

src/routes/settings/+page.svelte

@@ -4,6 +4,17 @@
 
   let { data, form }: { data: PageData; form: ActionData } = $props();
   let saving = $state(false);
+
+  // Common US restaurant timezones. Business day rolls over at 3 AM local time.
+  const TIMEZONES = [
+    { id: 'America/Los_Angeles', label: 'Pacific (Los Angeles)' },
+    { id: 'America/Denver',      label: 'Mountain (Denver)' },
+    { id: 'America/Phoenix',     label: 'Arizona (no DST)' },
+    { id: 'America/Chicago',     label: 'Central (Chicago)' },
+    { id: 'America/New_York',    label: 'Eastern (New York)' },
+    { id: 'America/Anchorage',   label: 'Alaska (Anchorage)' },
+    { id: 'Pacific/Honolulu',    label: 'Hawaii (Honolulu)' },
+  ];
 </script>
 
 <div class="page" style="padding-top:0;">
@@ -47,7 +58,16 @@
         </label>
 
         <label class="field">
-          <span>Lunch Cutoff (Pacific, 24h)</span>
+          <span>Timezone</span>
+          <select class="input" name="timezone">
+            {#each TIMEZONES as tz}
+              <option value={tz.id} selected={tz.id === (data.settings.timezone ?? 'America/Los_Angeles')}>{tz.label}</option>
+            {/each}
+          </select>
+        </label>
+
+        <label class="field">
+          <span>Lunch Cutoff (local, 24h)</span>
           <input class="input" type="time" name="lunch_cutoff"
             value={data.settings.lunch_cutoff ?? '15:00'} />
         </label>