Omit the year from dateToReadable within the current year

dateToReadable now formats current-year dates without the year (e.g.
"June 8th") and includes it otherwise (e.g. "February 3rd, 2024"). This
keeps the mention menu subtitle compact while the relative title shows
"Today"/"Tomorrow".

shared/utils/date.test.ts

@@ -19,8 +19,16 @@ describe("toISODate / parseISODate", () => {
 });
 
 describe("dateToReadable", () => {
-  it("formats an absolute, human-readable date", () => {
-    expect(dateToReadable("2024-02-03")).toBe("February 3rd, 2024");
+  it("includes the year outside the current year", () => {
+    expect(dateToReadable("2020-02-03")).toBe("February 3rd, 2020");
+  });
+
+  it("omits the year within the current year", () => {
+    const date = new Date();
+    date.setMonth(date.getMonth() === 0 ? 6 : 0);
+    date.setDate(15);
+    const result = dateToReadable(toISODate(date));
+    expect(result).not.toContain(`${date.getFullYear()}`);
   });
 
   it("returns the original string when invalid", () => {

shared/utils/date.ts

@@ -328,8 +328,9 @@ export function parseISODate(iso: string): Date | null {
 
 /**
  * Formats a date mention's stored ISO value into an absolute, localized,
- * human-readable label (e.g. "January 2nd, 2024"). Suitable for plaintext
- * and markdown serialization where a stable, unambiguous value is required.
+ * human-readable label. The year is omitted within the current year (e.g.
+ * "January 2nd") and included otherwise (e.g. "February 3rd, 2024"). Suitable
+ * for plaintext and markdown serialization.
  *
  * @param iso The date-only ISO string.
  * @param language The user's language preference.
@@ -343,7 +344,11 @@ export function dateToReadable(
   if (!date) {
     return iso;
   }
-  return format(date, "MMMM do, yyyy", { locale: dateLocale(language) });
+  const locale = dateLocale(language);
+  if (isSameYear(date, new Date())) {
+    return format(date, "MMMM do", { locale });
+  }
+  return format(date, "MMMM do, yyyy", { locale });
 }
 
 /**