diff --git a/apps/web/src/components/dashboard/widgets/calendar-widget.test.tsx b/apps/web/src/components/dashboard/widgets/calendar-widget.test.tsx
index df09a4a..ea968bd 100644
--- a/apps/web/src/components/dashboard/widgets/calendar-widget.test.tsx
+++ b/apps/web/src/components/dashboard/widgets/calendar-widget.test.tsx
@@ -26,6 +26,8 @@ vi.mock('next-intl', () => ({
         'calendar.upcomingTitle': 'Nächste Termine',
         'calendar.tooltipMore': 'Weitere Termine vorhanden',
         'calendar.allDay': 'ganztägig',
+        'calendar.dayEventsOne': '{date}: 1 Termin',
+        'calendar.dayEventsMany': '{date}: {count} Termine',
       },
     };
     const raw = map[ns]?.[key] ?? key;
@@ -514,4 +516,86 @@ describe('CalendarWidget', () => {
 
     await waitFor(() => expect(mockFetchEvents).toHaveBeenCalledTimes(1));
   });
+
+  // quick-260921-jt4 (D-01): Tage MIT Terminen sind echte Schaltflaechen und
+  // per Fokus bedienbar; Tage OHNE Termine bleiben Nicht-Tab-Stopps.
+  it('Test 11: Ein Tag MIT Terminen ist eine echte <button>-Schaltflaeche und zeigt beim Fokussieren dieselbe Einblendung wie beim Ueberfahren mit der Maus', async () => {
+    mockFetchEvents.mockResolvedValue([
+      ev('Team Meeting', new Date(2026, 6, 20, 9, 0), new Date(2026, 6, 20, 10, 0)),
+    ]);
+
+    const { CalendarWidget } = await import('./calendar-widget');
+    render(<CalendarWidget instanceId="cal-11" config={{}} isEditMode={false} />);
+
+    await waitFor(() => expect(screen.getByText('Juli 2026')).toBeInTheDocument());
+
+    const day20 = document.querySelector('[data-date="2026-07-20"]') as HTMLElement;
+    expect(day20.tagName).toBe('BUTTON');
+
+    fireEvent.focus(day20);
+    const tooltip = screen.getByTestId('calendar-day-tooltip');
+    expect(tooltip).toHaveTextContent('Team Meeting');
+
+    fireEvent.blur(day20);
+    expect(screen.queryByTestId('calendar-day-tooltip')).toBeNull();
+  });
+
+  it('Test 12: Ein Tag OHNE Termine bleibt eine <div> ohne Handler und ist kein Tab-Stopp', async () => {
+    mockFetchEvents.mockResolvedValue([]);
+
+    const { CalendarWidget } = await import('./calendar-widget');
+    render(<CalendarWidget instanceId="cal-12" config={{}} isEditMode={false} />);
+
+    await waitFor(() => expect(screen.getByText('Juli 2026')).toBeInTheDocument());
+
+    const day20 = document.querySelector('[data-date="2026-07-20"]') as HTMLElement;
+    expect(day20.tagName).toBe('DIV');
+  });
+
+  it('Test 13: die Schaltflaeche eines Tages mit Terminen traegt einen Namen, der Datum und Terminzahl nennt', async () => {
+    mockFetchEvents.mockResolvedValue([
+      ev('Team Meeting', new Date(2026, 6, 20, 9, 0), new Date(2026, 6, 20, 10, 0)),
+      ev('Lunch', new Date(2026, 6, 20, 14, 0), new Date(2026, 6, 20, 15, 0)),
+    ]);
+
+    const { CalendarWidget } = await import('./calendar-widget');
+    render(<CalendarWidget instanceId="cal-13" config={{}} isEditMode={false} />);
+
+    await waitFor(() => expect(screen.getByText('Juli 2026')).toBeInTheDocument());
+
+    const day20 = document.querySelector('[data-date="2026-07-20"]') as HTMLElement;
+    expect(day20.getAttribute('aria-label')).toContain('20.07');
+    expect(day20.getAttribute('aria-label')).toContain('2 Termine');
+  });
+
+  it('Test 14: die Schaltflaeche eines Tages mit genau einem Termin nutzt die Einzahl-Beschriftung', async () => {
+    mockFetchEvents.mockResolvedValue([
+      ev('Team Meeting', new Date(2026, 6, 20, 9, 0), new Date(2026, 6, 20, 10, 0)),
+    ]);
+
+    const { CalendarWidget } = await import('./calendar-widget');
+    render(<CalendarWidget instanceId="cal-14" config={{}} isEditMode={false} />);
+
+    await waitFor(() => expect(screen.getByText('Juli 2026')).toBeInTheDocument());
+
+    const day20 = document.querySelector('[data-date="2026-07-20"]') as HTMLElement;
+    expect(day20.getAttribute('aria-label')).toContain('1 Termin');
+    expect(day20.getAttribute('aria-label')).not.toContain('1 Termine');
+  });
+
+  it('Test 15: der Fokus landet tatsaechlich auf der Tages-Schaltflaeche (echter Tab-Stopp, nicht nur optisch)', async () => {
+    mockFetchEvents.mockResolvedValue([
+      ev('Team Meeting', new Date(2026, 6, 20, 9, 0), new Date(2026, 6, 20, 10, 0)),
+    ]);
+
+    const { CalendarWidget } = await import('./calendar-widget');
+    render(<CalendarWidget instanceId="cal-15" config={{}} isEditMode={false} />);
+
+    await waitFor(() => expect(screen.getByText('Juli 2026')).toBeInTheDocument());
+
+    const day20 = document.querySelector('[data-date="2026-07-20"]') as HTMLElement;
+    day20.focus();
+
+    expect(document.activeElement).toBe(day20);
+  });
 });
diff --git a/apps/web/src/components/dashboard/widgets/calendar-widget.tsx b/apps/web/src/components/dashboard/widgets/calendar-widget.tsx
index df2a001..6554767 100644
--- a/apps/web/src/components/dashboard/widgets/calendar-widget.tsx
+++ b/apps/web/src/components/dashboard/widgets/calendar-widget.tsx
@@ -249,20 +249,8 @@ export function CalendarWidget({ config }: WidgetProps) {
                 .filter(Boolean)
                 .join(' ');
 
-              return (
-                <div
-                  key={day.key}
-                  data-testid="calendar-day"
-                  data-date={day.key}
-                  data-today={day.isToday || undefined}
-                  data-outside={!day.inCurrentMonth || undefined}
-                  className={cellClass}
-                  onMouseEnter={(e) =>
-                    hasEvents &&
-                    setHover({ key: day.key, rect: e.currentTarget.getBoundingClientRect() })
-                  }
-                  onMouseLeave={() => setHover(null)}
-                >
+              const cellContent = (
+                <>
                   <span>{day.date.getDate()}</span>
                   {hasEvents && (
                     // Wrapper traegt die Positionierung, die einzelnen Kreise nicht
@@ -298,6 +286,61 @@ export function CalendarWidget({ config }: WidgetProps) {
                       })}
                     </span>
                   )}
+                </>
+              );
+
+              // Nur Tage MIT Terminen werden zu Tab-Stopps (D-01) — ein
+              // Widget mit 42 zusaetzlichen Tab-Stopps waere eine
+              // Verschlechterung. Wer nicht mit der Maus arbeitet, bekam
+              // die Termin-Einblendung bislang gar nicht zu sehen; die
+              // Schaltflaeche traegt deshalb zusaetzlich onFocus/onBlur mit
+              // demselben Rumpf wie onMouseEnter/onMouseLeave.
+              if (hasEvents) {
+                const dayLabel = new Intl.DateTimeFormat('de-DE', {
+                  weekday: 'short',
+                  day: '2-digit',
+                  month: '2-digit',
+                }).format(day.date);
+                const eventCount = day.events.length;
+                const ariaLabel =
+                  eventCount === 1
+                    ? t('calendar.dayEventsOne', { date: dayLabel })
+                    : t('calendar.dayEventsMany', { date: dayLabel, count: eventCount });
+
+                return (
+                  <button
+                    key={day.key}
+                    type="button"
+                    data-testid="calendar-day"
+                    data-date={day.key}
+                    data-today={day.isToday || undefined}
+                    data-outside={!day.inCurrentMonth || undefined}
+                    className={`${cellClass} w-full text-left`}
+                    aria-label={ariaLabel}
+                    onMouseEnter={(e) =>
+                      setHover({ key: day.key, rect: e.currentTarget.getBoundingClientRect() })
+                    }
+                    onMouseLeave={() => setHover(null)}
+                    onFocus={(e) =>
+                      setHover({ key: day.key, rect: e.currentTarget.getBoundingClientRect() })
+                    }
+                    onBlur={() => setHover(null)}
+                  >
+                    {cellContent}
+                  </button>
+                );
+              }
+
+              return (
+                <div
+                  key={day.key}
+                  data-testid="calendar-day"
+                  data-date={day.key}
+                  data-today={day.isToday || undefined}
+                  data-outside={!day.inCurrentMonth || undefined}
+                  className={cellClass}
+                >
+                  {cellContent}
                 </div>
               );
             })}
diff --git a/apps/web/src/messages/de.json b/apps/web/src/messages/de.json
index 1550802..05d1f59 100644
--- a/apps/web/src/messages/de.json
+++ b/apps/web/src/messages/de.json
@@ -244,6 +244,8 @@
       "upcomingTitle": "Nächste Termine",
       "tooltipMore": "Weitere Termine vorhanden",
       "allDay": "ganztägig",
+      "dayEventsOne": "{date}: 1 Termin",
+      "dayEventsMany": "{date}: {count} Termine",
       "configShowMonth": "Monatsansicht anzeigen",
       "configMaxEvents": "Anzahl Termine",
       "configMaxEventsNone": "Ausblenden",
diff --git a/apps/web/src/messages/en.json b/apps/web/src/messages/en.json
index f7ca6bb..4b24374 100644
--- a/apps/web/src/messages/en.json
+++ b/apps/web/src/messages/en.json
@@ -244,6 +244,8 @@
       "upcomingTitle": "Upcoming events",
       "tooltipMore": "More events available",
       "allDay": "all day",
+      "dayEventsOne": "{date}: 1 event",
+      "dayEventsMany": "{date}: {count} events",
       "configShowMonth": "Show month view",
       "configMaxEvents": "Number of events",
       "configMaxEventsNone": "Hide",