Feature 21: Home Dashboard (#181)

Co-authored-by: dev_agent <dev_agent@cubecraftlabs.com>

web/src/plan/week.test.ts

@@ -1,5 +1,17 @@
 import { describe, expect, it } from 'vitest'
-import { addDays, dayAndDate, dayOfMonth, defaultWeek, localNow, weekdayKicker, weekdayName, weekLabel, weekStart } from './week.ts'
+import {
+  addDays,
+  dayAndDate,
+  dayOfMonth,
+  defaultWeek,
+  isMonday,
+  localNow,
+  untilLocalMidnight,
+  weekdayKicker,
+  weekdayName,
+  weekLabel,
+  weekStart,
+} from './week.ts'
 
 // SCHEDULE drafts the plan on Fridays (Sunday = 0) at 09:00 in New York.
 const SCHEDULE = { timezone: 'America/New_York', plan_draft_dow: 5, plan_draft_time: '09:00' }
@@ -72,4 +84,45 @@ describe('week helpers', () => {
     expect(defaultWeek(sunday, new Date('2026-10-10T16:00:00Z'))).toBe('2026-10-05') // Sat
     expect(defaultWeek(sunday, new Date('2026-10-11T22:00:00Z'))).toBe('2026-10-12') // Sun 18:00
   })
+
+  it('says whether a date is a real Monday', () => {
+    expect(isMonday('2026-10-05')).toBe(true)
+    expect(isMonday('2026-10-07')).toBe(false)
+    expect(isMonday('2026-02-30')).toBe(false)
+    expect(isMonday('next week')).toBe(false)
+  })
+
+  it('counts the time to the next midnight in the household zone, not UTC', () => {
+    // 23:59:30.250 in New York is already 03:59 the next day in UTC.
+    expect(untilLocalMidnight('America/New_York', new Date('2026-10-03T03:59:30.250Z'))).toBe(29_750)
+    // At midnight itself the next is a day away.
+    expect(untilLocalMidnight('America/New_York', new Date('2026-10-03T04:00:00Z'))).toBe(24 * 60 * 60 * 1000)
+    // The same instant is 13:00 in Tokyo: eleven hours to go.
+    expect(untilLocalMidnight('Asia/Tokyo', new Date('2026-10-03T04:00:00Z'))).toBe(11 * 60 * 60 * 1000)
+  })
+
+  it('counts a day shortened by the spring clock change as 23 hours', () => {
+    const hour = 60 * 60 * 1000
+    // 01:30 EST on Sunday March 8, 2026: clocks go forward at 02:00, so the
+    // next midnight is 00:00 EDT on March 9 (04:00Z), 21.5 hours away.
+    expect(untilLocalMidnight('America/New_York', new Date('2026-03-08T06:30:00Z'))).toBe(21.5 * hour)
+    // 03:30 EDT, after the change: 20.5 hours to midnight.
+    expect(untilLocalMidnight('America/New_York', new Date('2026-03-08T07:30:00Z'))).toBe(20.5 * hour)
+    // At midnight starting the 23-hour day, the next midnight is 23 hours away.
+    expect(untilLocalMidnight('America/New_York', new Date('2026-03-08T05:00:00Z'))).toBe(23 * hour)
+    // Noon EST the day before: the change is after the coming midnight.
+    expect(untilLocalMidnight('America/New_York', new Date('2026-03-07T17:00:00Z'))).toBe(12 * hour)
+  })
+
+  it('counts a day lengthened by the autumn clock change as 25 hours', () => {
+    const hour = 60 * 60 * 1000
+    // Midnight EDT on Sunday November 1, 2026: clocks go back at 02:00.
+    expect(untilLocalMidnight('America/New_York', new Date('2026-11-01T04:00:00Z'))).toBe(25 * hour)
+  })
+
+  it('starts the next day at the clock change when the clocks skip midnight', () => {
+    // Santiago goes from 24:00 -04 to 01:00 -03 on September 6, 2026 (04:00Z);
+    // at 23:00 -04 on September 5 the next day starts an hour later.
+    expect(untilLocalMidnight('America/Santiago', new Date('2026-09-06T03:00:00Z'))).toBe(60 * 60 * 1000)
+  })
 })