fix(11-05): CR-01 surface reminderIsCustom to preserve custom VALARMs on edit

- expand.ts: add reminderIsCustom:boolean to CalendarOccurrence interface;
  derived from classifyValarms kind==='custom'; propagated to both
  non-recurring and recurring occurrence branches
- client.ts: mirror reminderIsCustom on CalendarOccurrence (atomic mirror)
- EventForm.tsx: extend deriveReminderValue to accept isCustom flag;
  returns '__custom__' when true, making the existing D-08 preserve branch
  live — editing a custom-alarm event now omits reminderLeadMinutes from
  the payload so outboxWorker extractValarms keeps the original VALARM
- Fix existing test fixtures (EventForm.test.tsx, EventDetailPopover.test.tsx)
  to include reminderIsCustom:false on all CalendarOccurrence literals

Fixes CAL-14 Pitfall 1: Apple Calendar absolute DATE-TIME / multi-VALARM
alarms no longer silently stripped on any edit round-trip from the PWA.

apps/pwa/src/components/EventDetailPopover.test.tsx

@@ -60,6 +60,7 @@ const TIMED_OCCURRENCE: CalendarOccurrence = {
   description: 'Daily team sync meeting',
   hasRrule: false,
   reminderLeadMinutes: null,
+  reminderIsCustom: false,
 };
 
 const OCCURRENCE_WITH_HTML: CalendarOccurrence = {
@@ -88,6 +89,7 @@ const ALLDAY_OCCURRENCE: CalendarOccurrence = {
   description: null,
   hasRrule: false,
   reminderLeadMinutes: null,
+  reminderIsCustom: false,
 };
 
 // ── Import component (after mocks are declared) ───────────────────────────────

apps/pwa/src/components/EventForm.test.tsx

@@ -125,6 +125,7 @@ const EDIT_OCCURRENCE: CalendarOccurrence = {
   description: 'Weekly sync',
   hasRrule: false,
   reminderLeadMinutes: null,
+  reminderIsCustom: false,
 };
 
 // ── Import component (after mocks) ────────────────────────────────────────────
@@ -511,6 +512,7 @@ const RECURRING_OCCURRENCE: CalendarOccurrence = {
   description: null,
   hasRrule: true,
   reminderLeadMinutes: null,
+  reminderIsCustom: false,
   // @ts-expect-error — recurrence is not on CalendarOccurrence type yet; the reset
   // effect reads it if present and defaults to 'none' when absent (WR-03, v1 comment)
   recurrence: 'weekly',
@@ -538,6 +540,7 @@ const LATE_OCCURRENCE: CalendarOccurrence = {
   description: null,
   hasRrule: false,
   reminderLeadMinutes: null,
+  reminderIsCustom: false,
 };
 
 describe('EventForm — Plan 03-12 gap closures', () => {
@@ -786,6 +789,7 @@ const ALL_DAY_OCCURRENCE: CalendarOccurrence = {
   description: null,
   hasRrule: false,
   reminderLeadMinutes: null,
+  reminderIsCustom: false,
 };
 
 describe('EventForm — Plan 06-06 end-tracking + recurrence-bound', () => {
@@ -1007,6 +1011,7 @@ const TIMED_REMINDER_OCCURRENCE: CalendarOccurrence = {
   title: 'Meeting with reminder',
   start: '2026-06-15T10:00:00-04:00',
   end: '2026-06-15T11:00:00-04:00',
+  reminderIsCustom: false,
   allDay: false,
   location: null,
   description: null,
@@ -1034,6 +1039,7 @@ const ALLDAY_REMINDER_OCCURRENCE: CalendarOccurrence = {
   description: null,
   hasRrule: false,
   reminderLeadMinutes: 1440,
+  reminderIsCustom: false,
 };
 
 /**
@@ -1056,6 +1062,7 @@ const OFFLIST_REMINDER_OCCURRENCE: CalendarOccurrence = {
   description: null,
   hasRrule: false,
   reminderLeadMinutes: 45,
+  reminderIsCustom: false,
 };
 
 describe('EventForm — Phase 11 reminder picker (Plan 04)', () => {
@@ -1315,10 +1322,8 @@ describe('EventForm — Phase 11 Plan 05 CR-01: custom alarm round-trip', () =>
       const callPayload = mockUpdateEvent.mock.calls[0][1] as Record<string, unknown>;
       // MUST be absent: the presence of reminderLeadMinutes:null would cause the outbox
       // worker to clear the VALARM — the CR-01 data-loss bug.
-      expect(Object.prototype.hasOwnProperty.call(callPayload, 'reminderLeadMinutes')).toBe(
-        false,
-        'reminderLeadMinutes must be absent from payload when alarm is custom (D-08 preserve path)',
-      );
+      // D-08: field must be absent — presence of reminderLeadMinutes:null clears the VALARM (CR-01)
+      expect(Object.prototype.hasOwnProperty.call(callPayload, 'reminderLeadMinutes')).toBe(false);
     });
   });
 });

apps/pwa/src/components/EventForm.tsx

@@ -75,12 +75,22 @@ function humanizeReminderLead(minutes: number): string {
 }
 
 /**
- * Derive the initial reminder picker value from an occurrence's reminderLeadMinutes.
- * Returns '__none__' for null, the matching preset string for a preset, or the numeric
- * string for an off-list value (synthetic option will be rendered for this case).
- * There is no '__custom__' path here — the occurrence only carries number|null.
+ * Derive the initial reminder picker value from an occurrence's reminder fields.
+ *
+ * CR-01 (Plan 11-05): When reminderIsCustom is true, the event carries an absolute
+ * DATE-TIME trigger or multiple VALARMs that cannot be reduced to a single lead.
+ * Returning '__custom__' makes the existing preserve branch live: the form emits an
+ * absent reminderLeadMinutes field, and the outboxWorker's D-08 preserve path keeps
+ * the original VALARM intact (no silent data loss on edit).
+ *
+ * Precedence: custom → '__custom__'; null → '__none__'; else preset/off-list string.
  */
-function deriveReminderValue(leadMinutes: number | null, isAllDay: boolean): string {
+function deriveReminderValue(
+  leadMinutes: number | null,
+  isAllDay: boolean,
+  isCustom = false,
+): string {
+  if (isCustom) return '__custom__';
   if (leadMinutes === null) return '__none__';
   const presets = isAllDay ? ALLDAY_REMINDER_PRESETS : TIMED_REMINDER_PRESETS;
   if (presets.has(leadMinutes)) return String(leadMinutes);
@@ -317,8 +327,13 @@ export function EventForm() {
       setLocation(occurrence?.location ?? '');
       setDescription(occurrence?.description ?? '');
       // Phase 11: derive reminder picker value from occurrence (edit-mode pre-population, D-01/D-07)
+      // CR-01 (Plan 11-05): pass reminderIsCustom so custom alarms initialize to '__custom__'
+      // instead of '__none__', making the D-08 preserve path reachable on edit.
       const occAllDay = occurrence?.allDay ?? false;
-      setReminderValue(deriveReminderValue(occurrence?.reminderLeadMinutes ?? null, occAllDay));
+      const occIsCustom = occurrence?.reminderIsCustom ?? false;
+      setReminderValue(
+        deriveReminderValue(occurrence?.reminderLeadMinutes ?? null, occAllDay, occIsCustom),
+      );
     }
   }, [eventFormOpen, eventFormMode, eventFormUid, occurrence?.uid]); // eslint-disable-line react-hooks/exhaustive-deps