feat(expiry): KST util — todayInKstString + nextKstMidnightMs (#5 v0.2.3)

src/main/util/kstDate.ts

@@ -0,0 +1,28 @@
+const KST_OFFSET_MS = 9 * 60 * 60 * 1000;
+
+/**
+ * Calendar date (YYYY-MM-DD) in Asia/Seoul timezone for the given instant.
+ *
+ * v0.2.3 #5 — used by NoteRepository.findExpiredCandidates to compare against
+ * notes.due_date (also stored as YYYY-MM-DD per slice §F1).
+ */
+export function todayInKstString(now: Date): string {
+  const k = new Date(now.getTime() + KST_OFFSET_MS);
+  return new Date(
+    Date.UTC(k.getUTCFullYear(), k.getUTCMonth(), k.getUTCDate())
+  ).toISOString().slice(0, 10);
+}
+
+/**
+ * Epoch ms of the next 00:00 KST strictly after `now`.
+ *
+ * v0.2.3 #5 — used by store.snoozeExpired to compute the in-memory snooze
+ * deadline ("오늘 그만").
+ */
+export function nextKstMidnightMs(now: number): number {
+  const kstNow = now + KST_OFFSET_MS;
+  // Floor to KST midnight, then add one day.
+  const kstMidnightFloor = Math.floor(kstNow / 86_400_000) * 86_400_000;
+  const nextKstMidnight = kstMidnightFloor + 86_400_000;
+  return nextKstMidnight - KST_OFFSET_MS;
+}

tests/unit/kstDate.test.ts

@@ -0,0 +1,37 @@
+import { describe, it, expect } from 'vitest';
+import { todayInKstString, nextKstMidnightMs } from '@main/util/kstDate.js';
+
+describe('todayInKstString', () => {
+  it('returns KST calendar date as YYYY-MM-DD', () => {
+    // 2026-05-01 12:00 UTC = 2026-05-01 21:00 KST
+    expect(todayInKstString(new Date('2026-05-01T12:00:00Z'))).toBe('2026-05-01');
+  });
+
+  it('handles UTC→KST date rollover (UTC 23:30 → KST next day 08:30)', () => {
+    expect(todayInKstString(new Date('2026-05-01T23:30:00Z'))).toBe('2026-05-02');
+  });
+
+  it('handles KST midnight exactly (UTC 15:00 = KST 00:00 next day)', () => {
+    expect(todayInKstString(new Date('2026-05-01T15:00:00Z'))).toBe('2026-05-02');
+  });
+});
+
+describe('nextKstMidnightMs', () => {
+  it('returns the next KST 00:00 epoch ms (UTC 12:00 → +12h to KST midnight)', () => {
+    // 2026-05-01 12:00 UTC = 2026-05-01 21:00 KST → 다음 KST 자정 = 2026-05-02 00:00 KST
+    // = 2026-05-01 15:00 UTC
+    const now = Date.parse('2026-05-01T12:00:00Z');
+    const next = nextKstMidnightMs(now);
+    expect(new Date(next).toISOString()).toBe('2026-05-01T15:00:00.000Z');
+  });
+
+  it('returns 24h-from-now-ish when called shortly after KST midnight', () => {
+    // 2026-05-01 15:01 UTC = 2026-05-02 00:01 KST → 다음 KST 자정 = 2026-05-03 00:00 KST
+    // = 2026-05-02 15:00 UTC (≈ 23h59m later)
+    const now = Date.parse('2026-05-01T15:01:00Z');
+    const next = nextKstMidnightMs(now);
+    expect(new Date(next).toISOString()).toBe('2026-05-02T15:00:00.000Z');
+    expect(next - now).toBeGreaterThan(23 * 60 * 60 * 1000);
+    expect(next - now).toBeLessThan(24 * 60 * 60 * 1000);
+  });
+});