diff --git a/apps/api/src/broker/expand.ts b/apps/api/src/broker/expand.ts
index d535674..12b8af3 100644
--- a/apps/api/src/broker/expand.ts
+++ b/apps/api/src/broker/expand.ts
@@ -19,6 +19,7 @@
  */
 
 import ICAL from 'ical.js';
+import { classifyValarms } from './vevent.js';
 
 /**
  * A concrete calendar event occurrence ready for UI consumption.
@@ -33,6 +34,11 @@ import ICAL from 'ical.js';
  * Color routing (D-06, CAL-02):
  *   The client routes calendarId for Schedule-X as: isShared ? 'shared' : String(ownerUserId)
  *   The DB calendarId is also present for reference but NOT used as the Schedule-X calendarId.
+ *
+ * Phase 11 Plan 03 (D-10): reminderLeadMinutes is a series-level property — all occurrences
+ * of a recurring master inherit the master's value. Derived from the VEVENT's VALARM via
+ * classifyValarms (same logic as sync.ts so the scheduler and the GET response agree).
+ * NULL-vs-0 is preserved (D-06): null = no reminder; 0 = same-day all-day; positive = lead.
  */
 export interface CalendarOccurrence {
   /** `ev-<sanitized-uid>-<epochMs>` — Schedule-X-safe stable id (see makeOccurrenceId) */
@@ -66,6 +72,14 @@ export interface CalendarOccurrence {
   description: string | null;
   /** True when this occurrence belongs to a recurring series (has RRULE). False for single events. */
   hasRrule: boolean;
+  /**
+   * Per-event reminder lead in minutes (Phase 11, CAL-13, D-06).
+   * Series-level: all occurrences inherit the master's value (D-10).
+   *   null     — no reminder / custom/absolute VALARM not reducible to a single lead
+   *   0        — same-day all-day (fire at 9 AM on event date)
+   *   positive — N minutes before event start (timed) or N/1440 days before (all-day)
+   */
+  reminderLeadMinutes: number | null;
 }
 
 /**
@@ -223,6 +237,16 @@ export function expandOccurrences(
   // Capture once — used in both the non-recurring and recurring branches to populate hasRrule.
   const isRecurring = event.isRecurring();
 
+  // Phase 11 Plan 03 (D-10): series-level reminderLeadMinutes — derived once from the master
+  // event's VALARM via classifyValarms. All occurrences inherit this value (series-level, D-10).
+  // preset/offlist → specific leadMinutes; custom/none → null (D-07/NOTIF-05).
+  // classifyValarms wraps ICAL.parse in try/catch (T-11-07 safe); safe on parse failure → null.
+  const alarmClass = classifyValarms(rawVevent);
+  const reminderLeadMinutes: number | null =
+    alarmClass.kind === 'preset' || alarmClass.kind === 'offlist'
+      ? alarmClass.leadMinutes
+      : null;
+
   // --- 4. Non-recurring event: single occurrence check ---
   if (!isRecurring) {
     if (dtstart.compare(rangeStart) >= 0 && dtstart.compare(rangeEnd) < 0) {
@@ -258,6 +282,7 @@ export function expandOccurrences(
         location: event.location ?? null,
         description: event.description ?? null,
         hasRrule: isRecurring, // always false in the non-recurring branch
+        reminderLeadMinutes, // series-level (D-10)
       });
     }
     return occurrences;
@@ -305,6 +330,7 @@ export function expandOccurrences(
       location: event.location ?? null,
       description: event.description ?? null,
       hasRrule: isRecurring, // always true in the recurring branch
+      reminderLeadMinutes, // series-level — all occurrences inherit the master's value (D-10)
     });
   }
 
diff --git a/apps/api/src/routes/events.ts b/apps/api/src/routes/events.ts
index 9a0432a..82d9b68 100644
--- a/apps/api/src/routes/events.ts
+++ b/apps/api/src/routes/events.ts
@@ -177,6 +177,8 @@ eventsRouter.get('/', zValidator('query', eventsQuerySchema), async (c) => {
         userId: users.id,
         userColor: users.color,
         ownerName: users.displayName,
+        // Phase 11 Plan 03: surface reminderLeadMinutes for edit-mode pre-population (D-06/D-10)
+        reminderLeadMinutes: calendarEvents.reminderLeadMinutes,
       })
       .from(calendarEvents)
       .innerJoin(calendars, eq(calendarEvents.calendarId, calendars.id))