diff --git a/src/calendar/day-label.ts b/src/calendar/day-label.ts
index f5db2d2..117830e 100644
--- a/src/calendar/day-label.ts
+++ b/src/calendar/day-label.ts
@@ -476,6 +476,22 @@ const TEMPORAL_CATEGORY_RANK_LABELS: Record<TemporalCategory, Bi> = {
   'privileged-feria-major': bi('Feria', 'Feria'),
 };
 
+/**
+ * Explicit "which Vespers is this" status, for the Vespers hour header —
+ * distinct from `getDayLabel`'s name/rank/commemoration text, which is
+ * silent about *why* a given identity governs tonight (a reader has to
+ * already know, e.g., that St. Zephyrinus falls on tomorrow's date to
+ * realize this evening is anticipating him). Pass the result of
+ * `calendar/vespers.ts`'s `resolveEveningDay`, not a plain `resolveDay` —
+ * only that carries the `vespersFrom` tag this reads.
+ */
+export function getVespersStatusLabel(day: LiturgicalDay): Bi {
+  if (day.winner.kind === 'sanctoral' && day.winner.vespersFrom === 'firstVespersOfTomorrow') {
+    return bi('First Vespers (of tomorrow)', 'Vesperæ de sequenti');
+  }
+  return bi('Second Vespers (of today)', 'Vesperæ de hodierno');
+}
+
 /**
  * The full "day being celebrated" label: the day's own primary identity
  * (a sanctoral winner, a named temporal feast, a season's own anchor day,
diff --git a/src/ui/day-nav.ts b/src/ui/day-nav.ts
index 0f454c6..cdfb8be 100644
--- a/src/ui/day-nav.ts
+++ b/src/ui/day-nav.ts
@@ -1,6 +1,7 @@
 import { getState, shiftDate, goToToday, addDays, todayIso } from '../app-state';
 import { resolveDay } from '../calendar';
-import { getDayLabel } from '../calendar/day-label';
+import { resolveEveningDay } from '../calendar/vespers';
+import { getDayLabel, getVespersStatusLabel } from '../calendar/day-label';
 import { urlFor } from '../router';
 import { formatDateLong, renderBilingual } from './format';
 
@@ -8,14 +9,21 @@ import { formatDateLong, renderBilingual } from './format';
  * weekday and the liturgical day-being-celebrated, together in one place
  * — previously the date lived here while the day-being-celebrated text
  * was repeated separately inside every hour's own view. The day-being-
- * celebrated text is hour-independent (the same LiturgicalDay for every
- * hour on a given date), so it's resolved directly here via `resolveDay`
- * rather than through any particular hour's `resolveOrdo`. */
+ * celebrated text is hour-independent for the daytime hours (the same
+ * `LiturgicalDay` for every hour on a given date) but NOT for Vespers/
+ * Compline: those two can belong to *tomorrow's* identity instead (First
+ * Vespers anticipation — see `calendar/vespers.ts`'s `resolveEveningDay`),
+ * so this header must resolve through that function for those two hours
+ * specifically, or it shows the wrong saint (previously always used plain
+ * `resolveDay`, silently mismatched against what the hour itself was
+ * actually rendering). */
 export function renderDayNav(container: HTMLElement): void {
   const { date, selectedHour, languages } = getState();
-  const day = resolveDay(date);
+  const isEveningHour = selectedHour === 'vespers' || selectedHour === 'compline';
+  const day = isEveningHour ? resolveEveningDay(date) : resolveDay(date);
   const dateLabel = formatDateLong(date);
   const dayLabel = getDayLabel(day);
+  const vespersStatus = selectedHour === 'vespers' ? getVespersStatusLabel(day) : undefined;
   const prevUrl = urlFor(addDays(date, -1), selectedHour, languages);
   const nextUrl = urlFor(addDays(date, 1), selectedHour, languages);
   const todayUrl = urlFor(todayIso(), selectedHour, languages);
@@ -26,6 +34,7 @@ export function renderDayNav(container: HTMLElement): void {
       <div class="day-nav-header">
         ${renderBilingual(dateLabel, languages, 'day-nav-date')}
         ${renderBilingual(dayLabel, languages, 'day-nav-label')}
+        ${vespersStatus ? renderBilingual(vespersStatus, languages, 'day-nav-vespers-status') : ''}
       </div>
       <a href="${nextUrl}" class="day-nav-btn" data-action="next" aria-label="Next day">&rarr;</a>
     </nav>
diff --git a/src/ui/styles.css b/src/ui/styles.css
index bbd39f0..8bb1054 100644
--- a/src/ui/styles.css
+++ b/src/ui/styles.css
@@ -185,6 +185,12 @@ button:focus-visible {
   color: var(--color-brass);
 }
 
+.day-nav-vespers-status {
+  font-family: var(--font-ui);
+  font-size: 0.75rem;
+  color: var(--color-muted, var(--color-brass));
+}
+
 /* --------------------------------------------------------------------------
    Layout: hour list + hour view
    -------------------------------------------------------------------------- */
diff --git a/tests/ui/shell.test.ts b/tests/ui/shell.test.ts
index 5a6f713..69945dc 100644
--- a/tests/ui/shell.test.ts
+++ b/tests/ui/shell.test.ts
@@ -41,6 +41,34 @@ describe('shell', () => {
     expect(root.querySelectorAll('.ordo-part-psalm').length).toBeGreaterThan(0);
   });
 
+  it('shows tomorrow\'s saint (not today\'s) in the header when Vespers/Compline anticipate First Vespers', () => {
+    // Live-verified case (calendar/vespers.ts): Aug 25, 2026 is St. Louis
+    // (Simplex), but St. Zephyrinus (Aug 26, also Simplex) claims First
+    // Vespers over him -- the evening's real identity is tomorrow's, not
+    // today's. The header previously always used the daytime `resolveDay`
+    // regardless of selected hour, so it kept showing St. Louis even while
+    // the hour content itself had already switched to St. Zephyrinus.
+    setDate('2026-08-25');
+    setSelectedHour('vespers');
+    window.history.replaceState(null, '', '/vu/2026-08-25/vespers');
+    const root = document.getElementById('app')!;
+    mountShell(root);
+
+    expect(root.querySelector('.day-nav-label')?.textContent).toContain('Zephyrinus');
+    expect(root.querySelector('.day-nav-label')?.textContent).not.toContain('Louis');
+    expect(root.querySelector('.day-nav-vespers-status')?.textContent).toContain('First Vespers');
+  });
+
+  it('shows a plain Second Vespers status when Vespers is not anticipating tomorrow', () => {
+    setDate('2026-08-09');
+    setSelectedHour('vespers');
+    window.history.replaceState(null, '', '/vu/2026-08-09/vespers');
+    const root = document.getElementById('app')!;
+    mountShell(root);
+
+    expect(root.querySelector('.day-nav-vespers-status')?.textContent).toContain('Second Vespers');
+  });
+
   it('switches to Matins and shows its real content, not the pending message', () => {
     const root = document.getElementById('app')!;
     mountShell(root);