fix: show the scheduled time rounded to the minute and with its date

components/email/email-viewer.tsx

@@ -16,6 +16,7 @@ import { useCopyLink } from "@/hooks/use-copy-link";
 import { Button } from "@/components/ui/button";
 import { Avatar } from "@/components/ui/avatar";
 import { formatFileSize, cn, MailboxNode, formatDate, formatDateTime, generateUUID } from "@/lib/utils";
+import { formatScheduledSendAt } from "@/lib/scheduled-send-label";
 import { buildMoveTargets, resolveMoveOwnerAccountId } from "@/lib/move-targets";
 import { emailDisplayDate } from "@/lib/email-date";
 import { TagBadge } from "./tag-badge";
@@ -4722,7 +4723,7 @@ export function EmailViewer({
               <div className="flex items-center gap-2 text-primary">
                 <CalendarClock className="w-4 h-4" />
                 <span className="text-sm font-medium">
-                  {t('scheduled_banner', { date: email.scheduledSendAt ? formatDateTime(email.scheduledSendAt, timeFormat) : '' })}
+                  {t('scheduled_banner', { date: email.scheduledSendAt ? formatScheduledSendAt(email.scheduledSendAt, timeFormat) : '' })}
                 </span>
               </div>
               <div className="flex flex-wrap items-center gap-2">

components/email/thread-list-item.tsx

@@ -1,7 +1,8 @@
 "use client";
 
 import React, { useCallback } from "react";
-import { cleanPreview, formatDate, formatDateTime } from "@/lib/utils";
+import { cleanPreview, formatDate } from "@/lib/utils";
+import { formatScheduledSendAt } from "@/lib/scheduled-send-label";
 import { Email, ThreadGroup } from "@/lib/jmap/types";
 import { cn } from "@/lib/utils";
 import { ListAttachmentChips, useListHasAttachment } from "./attachment-chips";
@@ -324,7 +325,7 @@ const SingleEmailItem = React.forwardRef<HTMLDivElement, SingleEmailItemProps>(
     const subjectSnippet = email.searchSnippet?.subject ?? null;
     const previewSnippet = showPreview ? (email.searchSnippet?.preview ?? null) : null;
     const scheduledSendLabel = email.isScheduled && email.scheduledSendAt
-      ? formatDateTime(email.scheduledSendAt, timeFormat)
+      ? formatScheduledSendAt(email.scheduledSendAt, timeFormat)
       : null;
 
     const tagIds = sortTagIds(getEmailTagIds(email.keywords));
@@ -825,7 +826,7 @@ export const ThreadListItem = React.forwardRef<HTMLDivElement, ThreadListItemPro
     const subjectSnippet = threadSnippet?.subject ?? null;
     const previewSnippet = showPreview ? (threadSnippet?.preview ?? null) : null;
     const scheduledSendLabel = latestEmail.isScheduled && latestEmail.scheduledSendAt
-      ? formatDateTime(latestEmail.scheduledSendAt, timeFormat)
+      ? formatScheduledSendAt(latestEmail.scheduledSendAt, timeFormat)
       : null;
 
     const { selectedMailbox, mailboxes, selectedEmailKeys, toggleEmailSelection, selectRangeEmails, clearSelection, isUnifiedView, unifiedRole } = useEmailStore();

lib/__tests__/scheduled-send-label.test.ts

@@ -0,0 +1,25 @@
+import { describe, expect, it } from 'vitest';
+import { formatScheduledSendAt } from '../scheduled-send-label';
+
+// Local times, so the expectations do not depend on the machine's time zone.
+const at = (y: number, mo: number, d: number, h: number, mi: number, s = 0) => new Date(y, mo - 1, d, h, mi, s);
+
+describe('formatScheduledSendAt', () => {
+  const today = at(2026, 10, 11, 18, 0);
+
+  it('shows 08:00 for a release one second before eight', () => {
+    const label = formatScheduledSendAt(at(2026, 10, 11, 19, 59, 59).toISOString(), '24h', today);
+    expect(label).toContain('20:00');
+    expect(label).not.toContain('19:59');
+  });
+
+  it('shows only the time for a release later today', () => {
+    expect(formatScheduledSendAt(at(2026, 10, 11, 21, 30).toISOString(), '24h', today)).toBe('21:30');
+  });
+
+  it('includes the date for a release on another day', () => {
+    const label = formatScheduledSendAt(at(2026, 10, 12, 7, 59, 59).toISOString(), '24h', today);
+    expect(label).toContain('08:00');
+    expect(label).toMatch(/12/);
+  });
+});

lib/scheduled-send-label.ts

@@ -0,0 +1,23 @@
+import { formatDateTime } from '@/lib/utils';
+
+/**
+ * The release time of a scheduled message, for lists and banners.
+ *
+ * The server can land a second before the minute the user picked (08:00
+ * showed as 07:59), so the time is rounded to the nearest minute. A message
+ * that is not due today also shows its date; a bare "07:59" for tomorrow
+ * morning read like a time that had already passed.
+ */
+export function formatScheduledSendAt(
+  sendAt: string,
+  timeFormat: '12h' | '24h',
+  now: Date = new Date(),
+): string {
+  const ms = Date.parse(sendAt);
+  if (!Number.isFinite(ms)) return sendAt;
+  const rounded = new Date(Math.round(ms / 60_000) * 60_000);
+  const sameDay = rounded.toDateString() === now.toDateString();
+  return sameDay
+    ? formatDateTime(rounded, timeFormat)
+    : formatDateTime(rounded, timeFormat, { weekday: 'short', month: 'short', day: 'numeric' });
+}