1 files changed, 35 insertions, 0 deletions
diff --git a/frontend/lib/format.ts b/frontend/lib/format.ts
index 34bffd8..6a1fcc2 100644
--- a/frontend/lib/format.ts
+++ b/frontend/lib/format.ts
@@ -29,3 +29,38 @@ export function deltaClass(value?: number | null): string {
   if (value === null || value === undefined) return "neutral";
   return value >= 0 ? "positive" : "negative";
 }
+
+export function formatNewsTimestamp(iso: string): { display: string; iso: string } {
+  const date = new Date(iso);
+  const now = new Date();
+  const tz: Intl.DateTimeFormatOptions = { timeZone: "America/Los_Angeles" };
+  const diffMs = now.getTime() - date.getTime();
+  const diffMins = Math.floor(diffMs / 60_000);
+  const diffHours = Math.floor(diffMs / 3_600_000);
+
+  if (diffMins < 1) {
+    return { display: "Just now", iso };
+  }
+  if (diffMins < 60) {
+    return { display: `${diffMins}m ago`, iso };
+  }
+  if (diffHours < 24) {
+    return { display: `${diffHours}h ago`, iso };
+  }
+
+  const inTz = (options: Intl.DateTimeFormatOptions) =>
+    date.toLocaleString("en-US", { ...options, ...tz });
+
+  if (diffHours < 48) {
+    const time = inTz({ hour: "numeric", minute: "2-digit" });
+    return { display: `Yesterday ${time}`, iso };
+  }
+
+  const yearNow = Number(now.toLocaleString("en-US", { year: "numeric", ...tz }));
+  const yearDate = Number(inTz({ year: "numeric" }));
+
+  if (yearDate === yearNow) {
+    return { display: inTz({ month: "short", day: "numeric" }), iso };
+  }
+  return { display: inTz({ month: "short", day: "numeric", year: "numeric" }), iso };
+}