Improve timestamp handling and event navigation

web/src/lib/format.ts

@@ -1,7 +1,34 @@
-export function fmtDate(iso?: string | null): string {
+export const DEFAULT_TIME_ZONE = "UTC";
+
+export function normalizeTimeZone(timeZone?: string | null): string {
+  const value = timeZone?.trim();
+  if (!value) return DEFAULT_TIME_ZONE;
+  try {
+    new Intl.DateTimeFormat("en-US", { timeZone: value }).format(new Date(0));
+    return value;
+  } catch {
+    return DEFAULT_TIME_ZONE;
+  }
+}
+
+export function fmtDate(iso?: string | null, timeZone = DEFAULT_TIME_ZONE): string {
   if (!iso) return "—";
   const d = new Date(iso);
-  return Number.isNaN(d.getTime()) ? iso : d.toISOString().replace("T", " ").replace(/\..+$/, "Z");
+  if (Number.isNaN(d.getTime())) return iso;
+
+  const parts = new Intl.DateTimeFormat("en-CA", {
+    timeZone: normalizeTimeZone(timeZone),
+    year: "numeric",
+    month: "2-digit",
+    day: "2-digit",
+    hour: "2-digit",
+    minute: "2-digit",
+    second: "2-digit",
+    hour12: false,
+    timeZoneName: "short",
+  }).formatToParts(d);
+  const get = (type: string) => parts.find((p) => p.type === type)?.value ?? "";
+  return `${get("year")}-${get("month")}-${get("day")} ${get("hour")}:${get("minute")}:${get("second")} ${get("timeZoneName")}`;
 }
 
 export function statusBadgeClass(s: string): string {

web/src/lib/timezone.ts

@@ -0,0 +1,7 @@
+import "server-only";
+
+import { DEFAULT_TIME_ZONE, normalizeTimeZone } from "@/lib/format";
+
+export function getUiTimeZone(): string {
+  return normalizeTimeZone(process.env.MONLET_WEB_TIME_ZONE ?? process.env.TZ ?? DEFAULT_TIME_ZONE);
+}