4 files changed, 43 insertions, 11 deletions
diff --git a/desktop/island/calendar/Cal.js b/desktop/island/calendar/Cal.js
index 6cf492d..6ec7bb3 100644
--- a/desktop/island/calendar/Cal.js
+++ b/desktop/island/calendar/Cal.js
@@ -112,14 +112,28 @@ function stepTime(s, minutes) {
     return pad(Math.floor(m / 60)) + ":" + pad(m % 60);
 }
 
-// A new event on `day`: the next whole hour, one hour long, alarm 1h (the
-// most common alarm in the live calendars). Capped at 22:00 so the end stays
-// on the same day.
-function newDraft(day, now, calendar) {
+// A new event on `day`: the next whole hour, `minutes` long (the island's
+// default event length), alarm 1h (the most common alarm in the live
+// calendars). Capped at 22:00 so a short event stays on the same day.
+function newDraft(day, now, calendar, minutes) {
     const h = Math.min(22, now.getHours() + 1);
-    return { uid: "", source: "", calendar: calendar, title: "", allDay: false,
-             startDay: day, endDay: day, startTime: pad(h) + ":00", endTime: pad(h + 1) + ":00",
-             repeat: "none", until: "", alarm: "1h", location: "", notes: "", override: false };
+    return withStart({ uid: "", source: "", calendar: calendar, title: "", allDay: false,
+             startDay: day, endDay: day, startTime: pad(h) + ":00", endTime: pad(h) + ":00",
+             repeat: "none", until: "", alarm: "1h", location: "", notes: "", override: false },
+             pad(h) + ":00", minutes);
+}
+
+// The draft with a new start time, as typed, the end following it `minutes` later,
+// into the next day if need be. A multi-day event keeps its end: snapping it
+// to the start's day would throw the other days away.
+function withStart(draft, time, minutes) {
+    const d = Object.assign({}, draft, { startTime: time });
+    const n = normTime(time);
+    if (!validTime(n) || d.startDay !== d.endDay) return d;
+    const t = +n.slice(0, 2) * 60 + +n.slice(3, 5) + (minutes > 0 ? minutes : 60);
+    d.endDay = addDays(d.startDay, Math.floor(t / 1440));
+    d.endTime = pad(Math.floor(t % 1440 / 60)) + ":" + pad(t % 60);
+    return d;
 }
 
 // calctl's event JSON as an editor draft. `source` is the calendar the event
diff --git a/desktop/island/calendar/CalendarPanel.qml b/desktop/island/calendar/CalendarPanel.qml
index 4a0a011..d28a856 100644
--- a/desktop/island/calendar/CalendarPanel.qml
+++ b/desktop/island/calendar/CalendarPanel.qml
@@ -82,7 +82,7 @@ Item {
     }
 
     function newEvent() {
-        editor.load(Cal.newDraft(panel.selected, new Date(), Calendar.defaultCalendar));
+        editor.load(Cal.newDraft(panel.selected, new Date(), Calendar.defaultCalendar, Prefs.island.eventMinutes));
         panel.editing = true;
     }
 
diff --git a/desktop/island/calendar/EventEditor.qml b/desktop/island/calendar/EventEditor.qml
index 41815e3..727e1df 100644
--- a/desktop/island/calendar/EventEditor.qml
+++ b/desktop/island/calendar/EventEditor.qml
@@ -55,7 +55,14 @@ Column {
 
     function setTime(key, value) {
         (key === "startTime" ? startTime : endTime).input.text = value;
-        ed.set(key, value);
+        if (key === "startTime") ed.setStart(value);
+        else ed.set(key, value);
+    }
+
+    // The end follows the start by the island's default event length.
+    function setStart(text) {
+        ed.draft = Cal.withStart(ed.draft, text, Prefs.island.eventMinutes);
+        endTime.input.text = ed.draft.endTime;
     }
 
     // A click in the time picker: an hour keeps the minutes, a minute keeps
@@ -195,7 +202,7 @@ Column {
             id: startTime
             width: 62
             visible: !ed.draft.allDay
-            input.onTextEdited: ed.set("startTime", input.text)
+            input.onTextEdited: ed.setStart(input.text)
             input.onEditingFinished: if (Cal.normTime(input.text) !== input.text) ed.setTime("startTime", Cal.normTime(input.text))
             MouseArea {
                 anchors.fill: parent
diff --git a/desktop/island/calendar/test_cal.js b/desktop/island/calendar/test_cal.js
index de3d1c7..853cbb6 100644
--- a/desktop/island/calendar/test_cal.js
+++ b/desktop/island/calendar/test_cal.js
@@ -17,7 +17,7 @@ const assert = require("assert");
 
 const src = fs.readFileSync(__dirname + "/Cal.js", "utf8").replace(/^\.pragma library$/m, "");
 const C = new Function(src + "\nreturn { pad, addDays, today, daysBetween, monthCells, shiftMonth," +
-    " lastDay, onDay, dayEvents, dots, timeLabel, validTime, normTime, stepTime, newDraft, fromEvent, pick," +
+    " lastDay, onDay, dayEvents, dots, timeLabel, validTime, normTime, stepTime, newDraft, withStart, fromEvent, pick," +
     " toPayload };")();
 
 // Dates are plain YYYY-MM-DD strings, arithmetic in UTC so DST never moves a day.
@@ -91,6 +91,17 @@ assert.strictEqual(d.alarm, "1h");
 assert.strictEqual(d.calendar, "home");
 assert.strictEqual(d.source, "");
 assert.strictEqual(C.newDraft("2026-10-20", new Date(2026, 9, 13, 23, 10), "home").startTime, "22:00");
+assert.strictEqual(C.newDraft("2026-10-20", new Date(2026, 9, 13, 9, 20), "home", 90).endTime, "11:30");
+
+// The end follows the start, by the default length, past midnight too.
+const w = C.withStart(d, "23:30", 60);
+assert.strictEqual(w.startTime, "23:30");
+assert.strictEqual(w.endTime, "00:30");
+assert.strictEqual(w.endDay, "2026-10-21");
+assert.strictEqual(C.withStart(d, "14:00", 45).endTime, "14:45");
+assert.strictEqual(C.withStart(d, "9.3", 60).endTime, "11:00");
+const multi = Object.assign({}, d, { endDay: "2026-10-22", endTime: "18:00" });
+assert.strictEqual(C.withStart(multi, "08:00", 60).endTime, "18:00");
 
 // From calctl's JSON.
 const fe = C.fromEvent({ uid: "u", calendar: "home", title: "Trip", allDay: true, start: "2026-10-14",