diff --git a/apps/pwa/src/components/CalendarShell.tsx b/apps/pwa/src/components/CalendarShell.tsx
index 5cf0a0d..b244c0e 100644
--- a/apps/pwa/src/components/CalendarShell.tsx
+++ b/apps/pwa/src/components/CalendarShell.tsx
@@ -6,11 +6,13 @@
  *   → hydrateEvents (ISO → Temporal) → eventsService.set() → Schedule-X render
  *
  * Critical constraints:
- *   - Plugins (eventsService, eventModal) created once via useState stable initialiser
+ *   - Plugins (eventsService) created once via useState stable initialiser
  *   - onRangeUpdate fires on navigation; initial fetch uses Zustand default range (A4/Q2)
  *   - DateRange.start/end are Temporal.ZonedDateTime → converted to 'YYYY-MM-DD' for Zustand
  *   - calendarId routing: 'shared' | String(ownerUserId) — produced by hydrateEvents, consumed
  *     by buildCalendarConfig; never the DB calendar-row id
+ *   - Event popover: driven exclusively by Zustand openEventId via onEventClick → standalone
+ *     EventDetailPopover; createEventModalPlugin and customComponents.eventModal are NOT used
  *   - Threat T-02d-01: all event fields are plain-text JSX children — no raw HTML injection
  *
  * Layout:
@@ -35,7 +37,6 @@ import {
   type CalendarType,
 } from '@schedule-x/calendar'
 import { createEventsServicePlugin } from '@schedule-x/events-service'
-import { createEventModalPlugin } from '@schedule-x/event-modal'
 
 import { fetchMe, fetchEvents } from '../api/client.js'
 import { hydrateEvents } from '../lib/hydrateEvents.js'
@@ -88,7 +89,6 @@ export function CalendarShell() {
 
   // Create plugins once (stable across renders)
   const eventsService = useState(() => createEventsServicePlugin())[0]
-  const eventModal = useState(() => createEventModalPlugin())[0]
 
   // Build members list from /api/me for AppNav + ColorLegend
   const members = useMemo(() => {
@@ -124,11 +124,13 @@ export function CalendarShell() {
       calendars: calendarsConfig,
       callbacks: {
         onRangeUpdate(range) {
-          // range.start / range.end are Temporal.ZonedDateTime
-          // Convert to ISO date strings ('YYYY-MM-DD') for the Zustand range
+          // range.start / range.end are Temporal.ZonedDateTime.
+          // Set end to the day AFTER range.end (exclusive window end) so that:
+          //   - Day view: start === day N, end === day N+1 → 1-day window (avoids 400 on 0-day span)
+          //   - Week/Month: end includes the last visible day instead of dropping it
           setCalendarRange({
             start: range.start.toPlainDate().toString(),
-            end: range.end.toPlainDate().toString(),
+            end: range.end.toPlainDate().add({ days: 1 }).toString(),
           })
         },
         onEventClick(event) {
@@ -138,7 +140,7 @@ export function CalendarShell() {
         },
       },
     },
-    [eventsService, eventModal],
+    [eventsService],
   )
 
   // Sync TanStack Query result into Schedule-X eventsService (Pitfall 4 guard)
@@ -263,10 +265,7 @@ export function CalendarShell() {
             <EmptyState />
           ) : (
             // Normal: Schedule-X calendar (primary focal point)
-            <ScheduleXCalendar
-              calendarApp={calendar}
-              customComponents={{ eventModal: EventDetailPopover }}
-            />
+            <ScheduleXCalendar calendarApp={calendar} />
           )}
         </div>
 
diff --git a/apps/pwa/src/components/EventDetailPopover.test.tsx b/apps/pwa/src/components/EventDetailPopover.test.tsx
index 762aa0d..e9197ef 100644
--- a/apps/pwa/src/components/EventDetailPopover.test.tsx
+++ b/apps/pwa/src/components/EventDetailPopover.test.tsx
@@ -190,4 +190,27 @@ describe('EventDetailPopover', () => {
     expect(descEl.innerHTML).not.toContain('<b>')
     expect(descEl.textContent).toContain('<b>Bold</b> description')
   })
+
+  it('BUG-3 regression: IANA-bracketed start/end does not produce "Invalid Date" in rendered output', () => {
+    // Fastmail events are serialized with IANA bracket notation e.g. '2026-06-18T08:00:00-04:00[America/Toronto]'.
+    // new Date() cannot parse the bracket, so the date/time line showed "Invalid Date, Invalid Date – Invalid Date".
+    // After the fix, the bracket is stripped before parsing.
+    const occurrence: CalendarOccurrence = {
+      ...TIMED_OCCURRENCE,
+      id: 'iana-bracket-uid::1718712000000',
+      uid: 'iana-bracket-uid',
+      start: '2026-06-18T08:00:00-04:00[America/Toronto]',
+      end: '2026-06-18T09:00:00-04:00[America/Toronto]',
+    }
+    renderPopover(occurrence)
+
+    // The date/time text must not contain 'Invalid Date'
+    const dialogEl = screen.getByRole('dialog')
+    expect(dialogEl.textContent).not.toContain('Invalid Date')
+
+    // It must contain recognizable date content (month name or a digit)
+    // toLocaleDateString output varies by locale; check for a digit at minimum
+    const dateTimeText = dialogEl.textContent ?? ''
+    expect(dateTimeText).toMatch(/\d/)
+  })
 })
diff --git a/apps/pwa/src/components/EventDetailPopover.tsx b/apps/pwa/src/components/EventDetailPopover.tsx
index c6411f4..05f0c2d 100644
--- a/apps/pwa/src/components/EventDetailPopover.tsx
+++ b/apps/pwa/src/components/EventDetailPopover.tsx
@@ -48,7 +48,11 @@ interface ScheduleXEventModalProps {
 
 /**
  * Format a start/end pair for display.
- * Handles both timed (ISO with tz) and all-day (YYYY-MM-DD) strings.
+ * Handles both timed (IANA-annotated ISO e.g. '2026-06-18T08:00:00-04:00[America/Toronto]')
+ * and all-day ('YYYY-MM-DD') strings.
+ *
+ * The IANA bracket suffix '[Zone]' is stripped before passing to new Date() because
+ * the built-in Date constructor cannot parse it and returns Invalid Date (BUG 3).
  */
 function formatDateTime(start: string, end: string, allDay: boolean): string {
   if (allDay) {
@@ -65,10 +69,14 @@ function formatDateTime(start: string, end: string, allDay: boolean): string {
       return start
     }
   }
-  // Timed — parse offset-aware ISO string
+  // Timed — parse offset-aware ISO string.
+  // Strip trailing IANA bracket e.g. '[America/Toronto]' before passing to new Date():
+  // new Date() cannot parse the bracket notation and returns Invalid Date.
   try {
-    const startDate = new Date(start)
-    const endDate = new Date(end)
+    const cleanStart = start.replace(/\[[^\]]*\]$/, '')
+    const cleanEnd = end.replace(/\[[^\]]*\]$/, '')
+    const startDate = new Date(cleanStart)
+    const endDate = new Date(cleanEnd)
     const dateStr = startDate.toLocaleDateString(undefined, {
       weekday: 'short',
       month: 'long',