fix(date-range): compute the default range lazily to avoid a stale year

utils/dateRange.test.ts

@@ -1,5 +1,5 @@
-import { describe, it, expect } from 'vitest';
-import { formatDateRange, DEFAULT_DATE_RANGE } from './dateRange';
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import { formatDateRange, getDefaultDateRange, DEFAULT_DATE_RANGE } from './dateRange';
 
 describe('formatDateRange', () => {
   it('returns full date range for valid 4-digit year', () => {
@@ -105,9 +105,39 @@ describe('formatDateRange', () => {
     expect(typeof result.to).toBe('string');
   });
 
+  it('getDefaultDateRange uses the current UTC year', () => {
+    const currentYear = new Date().getUTCFullYear();
+    const range = getDefaultDateRange();
+    expect(range.from).toBe(`${currentYear}-01-01T00:00:00Z`);
+    expect(range.to).toBe(`${currentYear}-12-31T23:59:59Z`);
+  });
+
   it('DEFAULT_DATE_RANGE uses current UTC year', () => {
     const currentYear = new Date().getUTCFullYear();
     expect(DEFAULT_DATE_RANGE.from).toBe(`${currentYear}-01-01T00:00:00Z`);
     expect(DEFAULT_DATE_RANGE.to).toBe(`${currentYear}-12-31T23:59:59Z`);
   });
 });
+
+describe('getDefaultDateRange', () => {
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it('reflects the current year lazily rather than a value captured at module load', () => {
+    vi.useFakeTimers();
+
+    vi.setSystemTime(new Date('2030-06-15T00:00:00Z'));
+    expect(getDefaultDateRange()).toEqual({
+      from: '2030-01-01T00:00:00Z',
+      to: '2030-12-31T23:59:59Z',
+    });
+
+    // Crossing into a new year must be reflected on the next call.
+    vi.setSystemTime(new Date('2031-01-02T00:00:00Z'));
+    expect(getDefaultDateRange()).toEqual({
+      from: '2031-01-01T00:00:00Z',
+      to: '2031-12-31T23:59:59Z',
+    });
+  });
+});

utils/dateRange.ts

@@ -1,12 +1,3 @@
-/**
- * Default fallback date range when year is missing or invalid.
- * Uses current year as fallback.
- */
-export const DEFAULT_DATE_RANGE = {
-  from: `${new Date().getUTCFullYear()}-01-01T00:00:00Z`,
-  to: `${new Date().getUTCFullYear()}-12-31T23:59:59Z`,
-};
-
 /**
  * Date range with from and to ISO strings for GitHub API queries.
  */
@@ -15,6 +6,21 @@ export interface DateRange {
   to: string;
 }
 
+/**
+ * Default fallback date range when year is missing or invalid.
+ * Computed lazily so the current year stays correct after a New Year rollover.
+ */
+export function getDefaultDateRange(): DateRange {
+  const year = new Date().getUTCFullYear();
+  return {
+    from: `${year}-01-01T00:00:00Z`,
+    to: `${year}-12-31T23:59:59Z`,
+  };
+}
+
+/** Backward-compatible default range; runtime fallbacks use getDefaultDateRange() so they never go stale. */
+export const DEFAULT_DATE_RANGE: DateRange = getDefaultDateRange();
+
 /**
  * Formats a year into a date range for GitHub contributions query.
  * Returns fallback default ranges when year is missing, partial, or invalid.
@@ -25,17 +31,17 @@ export interface DateRange {
  * @example
  * formatDateRange("2024") // { from: "2024-01-01T00:00:00Z", to: "2024-12-31T23:59:59Z" }
  * formatDateRange("24") // { from: "2024-01-01T00:00:00Z", to: "2024-12-31T23:59:59Z" }
- * formatDateRange("") // returns DEFAULT_DATE_RANGE
- * formatDateRange(undefined) // returns DEFAULT_DATE_RANGE
+ * formatDateRange("") // returns the current-year default range
+ * formatDateRange(undefined) // returns the current-year default range
  */
 export function formatDateRange(year?: string | number | null): DateRange {
   if (year === undefined || year === null) {
-    return { ...DEFAULT_DATE_RANGE };
+    return getDefaultDateRange();
   }
 
   const trimmedYear = String(year).trim();
   if (trimmedYear === '') {
-    return { ...DEFAULT_DATE_RANGE };
+    return getDefaultDateRange();
   }
 
   // Handle partial years (1 or 2 digits): assume 20xx
@@ -56,7 +62,7 @@ export function formatDateRange(year?: string | number | null): DateRange {
   const isValidYear = !isNaN(fullYear) && fullYear >= 2008 && fullYear <= currentYear + 5;
 
   if (!isValidYear) {
-    return { ...DEFAULT_DATE_RANGE };
+    return getDefaultDateRange();
   }
 
   return {