fix: show one year instead of 12 months in relative timestamps

Yigtwxx · Yigtwxx · commit 39f424e9b06a · 2026-07-18T19:37:29.000+03:00
Listings updated 360-364 days ago rendered as "12mo ago" because 30-day
months do not tile a 365-day year, leaving a five-day gap that still
divided into twelve whole months.

Derive years from whole months so they roll over at 12, matching
formatRelativeUpdatedAt in routes/user/$handle.tsx, which already caps
months at 11.
diff --git a/src/lib/timeAgo.test.ts b/src/lib/timeAgo.test.ts
@@ -0,0 +1,63 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { timeAgo } from "./timeAgo";
+
+const MINUTE = 60_000;
+const HOUR = 60 * MINUTE;
+const DAY = 24 * HOUR;
+
+const NOW = Date.UTC(2026, 5, 23, 12, 0, 0);
+
+function agoByDays(days: number) {
+  return timeAgo(NOW - days * DAY);
+}
+
+describe("timeAgo", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.setSystemTime(NOW);
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("reports sub-minute gaps as just now", () => {
+    expect(timeAgo(NOW)).toBe("just now");
+    expect(timeAgo(NOW - 59_999)).toBe("just now");
+  });
+
+  it("formats minutes and hours", () => {
+    expect(timeAgo(NOW - MINUTE)).toBe("1m ago");
+    expect(timeAgo(NOW - 59 * MINUTE)).toBe("59m ago");
+    expect(timeAgo(NOW - HOUR)).toBe("1h ago");
+    expect(timeAgo(NOW - 23 * HOUR)).toBe("23h ago");
+  });
+
+  it("formats days and weeks", () => {
+    expect(agoByDays(1)).toBe("1d ago");
+    expect(agoByDays(6)).toBe("6d ago");
+    expect(agoByDays(7)).toBe("1w ago");
+    expect(agoByDays(29)).toBe("4w ago");
+  });
+
+  it("formats months", () => {
+    expect(agoByDays(30)).toBe("1mo ago");
+    expect(agoByDays(60)).toBe("2mo ago");
+    expect(agoByDays(180)).toBe("6mo ago");
+  });
+
+  // Regression: 30-day months divided into a 365-day year yielded "12mo ago"
+  // for gaps of 360-364 days. Months must roll over into years at 12.
+  it("rolls the last days before a year over into years", () => {
+    expect(agoByDays(330)).toBe("11mo ago");
+    expect(agoByDays(359)).toBe("11mo ago");
+    expect(agoByDays(360)).toBe("1y ago");
+    expect(agoByDays(364)).toBe("1y ago");
+  });
+
+  it("formats years", () => {
+    expect(agoByDays(365)).toBe("1y ago");
+    expect(agoByDays(400)).toBe("1y ago");
+    expect(agoByDays(730)).toBe("2y ago");
+  });
+});
diff --git a/src/lib/timeAgo.ts b/src/lib/timeAgo.ts
@@ -3,7 +3,6 @@ const HOUR = 60 * MINUTE;
 const DAY = 24 * HOUR;
 const WEEK = 7 * DAY;
 const MONTH = 30 * DAY;
-const YEAR = 365 * DAY;
 
 export function timeAgo(timestamp: number): string {
   const diff = Date.now() - timestamp;
@@ -24,10 +23,11 @@ export function timeAgo(timestamp: number): string {
     const w = Math.floor(diff / WEEK);
     return `${w}w ago`;
   }
-  if (diff < YEAR) {
-    const m = Math.floor(diff / MONTH);
-    return `${m}mo ago`;
-  }
-  const y = Math.floor(diff / YEAR);
-  return `${y}y ago`;
+  // Derive years from whole 30-day months rather than from a separate 365-day
+  // year: dividing a 365-day year by 30-day months leaves a 360-364 day gap
+  // that rendered as "12mo ago". Matches formatRelativeUpdatedAt in
+  // routes/user/$handle.tsx.
+  const months = Math.floor(diff / MONTH);
+  if (months < 12) return `${months}mo ago`;
+  return `${Math.floor(months / 12)}y ago`;
 }
