fix(caldav): expand RRULE for recurring events

internal/web/ics_detail_test.go

@@ -74,9 +74,9 @@ func TestICSDetailRouteRendersReadonlyEvent(t *testing.T) {
 	handler := s.Handler(emptyStaticFS{})
 	cookie := loginAs(t, handler, "alice", "password")
 
-	id := icssub.EventID(mustParseICS(t, icsDetailSample))
+	id := seriesID(t, icsDetailSample)
 	if id == "" {
-		t.Fatal("EventID must be non-empty")
+		t.Fatal("series ID must be non-empty")
 	}
 
 	req := httptest.NewRequest(http.MethodGet, "/calendar/"+url.PathEscape("!holidays")+"/"+id, nil)
@@ -147,7 +147,7 @@ func TestMonthGridLinksICSEventToDetailPage(t *testing.T) {
 	if !strings.Contains(body, "ICS detail event") {
 		t.Fatalf("month grid should list ICS events, got:\n%s", body)
 	}
-	id := icssub.EventID(mustParseICS(t, icsDetailSample))
+	id := seriesID(t, icsDetailSample)
 	// The grid renders the detail link with a "/web/calendar/!<ref>/<id>"
 	// shape (see eventLinkURL in calendar.templ). The "!" in the ref is
 	// not %-escaped by templ.URL — we observed un-escaped output in the
@@ -161,6 +161,102 @@ func TestMonthGridLinksICSEventToDetailPage(t *testing.T) {
 	}
 }
 
+// TestEventOccurrenceDaysExpandsRRule verifies that a recurring event
+// (RRULE) is placed on every in-window occurrence day, not just its base
+// date — the core of the "recurring series events missing" fix.
+func TestEventOccurrenceDaysExpandsRRule(t *testing.T) {
+	const raw = "BEGIN:VCALENDAR\r\n" +
+		"VERSION:2.0\r\n" +
+		"PRODID:-//nidus//test//EN\r\n" +
+		"BEGIN:VEVENT\r\n" +
+		"UID:rec1@nidus.test\r\n" +
+		"DTSTAMP:20260101T000000Z\r\n" +
+		"DTSTART:20260803T090000Z\r\n" + // a Monday
+		"DTEND:20260803T100000Z\r\n" +
+		"RRULE:FREQ=WEEKLY;COUNT=4\r\n" +
+		"SUMMARY:weekly meeting\r\n" +
+		"END:VEVENT\r\n" +
+		"END:VCALENDAR\r\n"
+
+	ev := mustParseICS(t, raw)
+	loc := time.UTC
+
+	// Window covering the whole of August 2026 (the 4 weekly occurrences:
+	// Aug 3, 10, 17, 24 are all within range).
+	gridStart := time.Date(2026, 8, 1, 0, 0, 0, 0, loc)
+	gridEnd := time.Date(2026, 8, 31, 0, 0, 0, 0, loc)
+
+	dayIndex := make(map[string]int)
+	for d, i := gridStart, 0; !d.After(gridEnd); d, i = d.AddDate(0, 0, 1), i+1 {
+		dayIndex[d.Format(dateLayout)] = i
+	}
+
+	got := eventOccurrenceDays(ev, gridStart, gridEnd, loc, dayIndex)
+
+	wantDates := []string{"2026-08-03", "2026-08-10", "2026-08-17", "2026-08-24"}
+	for _, ws := range wantDates {
+		if _, ok := got[dayIndex[ws]]; !ok {
+			t.Errorf("expected recurring occurrence on %s, got days %v", ws, got)
+		}
+	}
+	if len(got) != 4 {
+		t.Errorf("expected exactly 4 in-window occurrence days, got %d (%v)", len(got), got)
+	}
+}
+
+// TestEventOccurrenceDaysSingleEvent verifies a non-recurring event occupies
+// only its own day(s) (no spurious expansion).
+func TestEventOccurrenceDaysSingleEvent(t *testing.T) {
+	const raw = "BEGIN:VCALENDAR\r\n" +
+		"VERSION:2.0\r\n" +
+		"PRODID:-//nidus//test//EN\r\n" +
+		"BEGIN:VEVENT\r\n" +
+		"UID:single1@nidus.test\r\n" +
+		"DTSTAMP:20260101T000000Z\r\n" +
+		"DTSTART:20260805T090000Z\r\n" +
+		"DTEND:20260805T100000Z\r\n" +
+		"SUMMARY:one off\r\n" +
+		"END:VEVENT\r\n" +
+		"END:VCALENDAR\r\n"
+
+	ev := mustParseICS(t, raw)
+	loc := time.UTC
+	gridStart := time.Date(2026, 8, 1, 0, 0, 0, 0, loc)
+	gridEnd := time.Date(2026, 8, 31, 0, 0, 0, 0, loc)
+
+	dayIndex := make(map[string]int)
+	for d, i := gridStart, 0; !d.After(gridEnd); d, i = d.AddDate(0, 0, 1), i+1 {
+		dayIndex[d.Format(dateLayout)] = i
+	}
+
+	got := eventOccurrenceDays(ev, gridStart, gridEnd, loc, dayIndex)
+	if len(got) != 1 {
+		t.Fatalf("expected exactly 1 occurrence day, got %d (%v)", len(got), got)
+	}
+	if _, ok := got[dayIndex["2026-08-05"]]; !ok {
+		t.Errorf("expected event on 2026-08-05, got days %v", got)
+	}
+}
+
+// seriesID returns the stable ID that addICSEvents/icsEventForDisplay
+// advertise for the (single) series in raw — GroupSeries(raw)[0].ID().
+// ICS-subscription grid cells and detail links are keyed by the series,
+// not by individual VEVENTs, so this is what the href/ID in assertions
+// must match.
+func seriesID(t *testing.T, raw string) string {
+	t.Helper()
+	_ = t
+	cal, err := ical.NewDecoder(strings.NewReader(raw)).Decode()
+	if err != nil {
+		t.Fatalf("seriesID: ical decode: %v", err)
+	}
+	series := icssub.GroupSeries(cal)
+	if len(series) == 0 {
+		t.Fatal("seriesID: no series")
+	}
+	return series[0].ID()
+}
+
 // mustParseICS parses raw and returns its first VEVENT (panic on error).
 func mustParseICS(t *testing.T, raw string) ical.Event {
 	t.Helper()