From a8232892b0ec94f8d077e3730143a09efcac452d Mon Sep 17 00:00:00 2001
From: Lukasz Kasprzak <lukas@labunix.xyz>
Date: Mon, 27 Jul 2026 12:24:24 +0200
Subject: fix(calendar): Christmas solemnity in temporal; feasts of the Lord
 band 5; Sunday band before solemnity-rank fallback

---
 internal/calendar/precedence.go  | 12 ++++++++----
 internal/calendar/refine_test.go | 30 ++++++++++++++++++++++++++++++
 internal/calendar/temporal.go    |  2 ++
 3 files changed, 40 insertions(+), 4 deletions(-)
 create mode 100644 internal/calendar/refine_test.go

(limited to 'internal')

diff --git a/internal/calendar/precedence.go b/internal/calendar/precedence.go
index 7919879..c27c5d3 100644
--- a/internal/calendar/precedence.go
+++ b/internal/calendar/precedence.go
@@ -26,12 +26,12 @@ func precedence(c candidate) int {
 			return 1
 		case c.Privileged:
 			return 2
+		case c.Sunday: // Ordinary/Christmas Sunday (checked before the solemnity-rank fallback)
+			return 6
 		case c.Cel.Rank == RankSolemnity: // Trinity, Corpus Christi, Sacred Heart, Christ the King
 			return 3
 		case c.Cel.Rank == RankFeast: // feasts of the Lord (Baptism, Holy Family)
 			return 5
-		case c.Sunday:
-			return 6
 		case c.PrivFeria:
 			return 9
 		default:
@@ -45,10 +45,14 @@ func precedence(c candidate) int {
 		}
 		return 3
 	case RankFeast:
-		if proper {
+		switch {
+		case proper:
 			return 8
+		case c.Cel.Class == ClassLord: // feasts of the Lord in the General Calendar
+			return 5
+		default:
+			return 7
 		}
-		return 7
 	case RankMemorial:
 		if proper {
 			return 11
diff --git a/internal/calendar/refine_test.go b/internal/calendar/refine_test.go
new file mode 100644
index 0000000..1f376c4
--- /dev/null
+++ b/internal/calendar/refine_test.go
@@ -0,0 +1,30 @@
+package calendar
+
+import "testing"
+
+func TestChristmasIsSolemnity(t *testing.T) {
+	got := Compute(d("2025-12-25"), DefaultSelection(), []Layer{universalTest()})
+	if got.Season != Christmas || got.Observed.Slug != "christmas" || got.Observed.Rank != RankSolemnity {
+		t.Errorf("2025-12-25 = %s/%s/%v, want christmas/solemnity", got.Season, got.Observed.Slug, got.Observed.Rank)
+	}
+}
+
+func TestFeastOfLordReplacesSunday(t *testing.T) {
+	// A feast of the Lord (band 5) must replace an Ordinary Sunday (band 6);
+	// a saint's feast (band 7) must not. 2025-08-10 is an Ordinary Sunday.
+	layer := Layer{ID: "universal", Cels: map[string]RawCelebration{
+		"transfiguration-test": {Fields: map[string]string{"date": "08-10", "rank": "feast", "class": "lord", "name.en": "L"}, Variants: map[string]map[string]string{}},
+	}}
+	got := Compute(d("2025-08-10"), DefaultSelection(), []Layer{layer})
+	if got.Observed.Slug != "transfiguration-test" {
+		t.Errorf("feast of the Lord did not replace the Sunday: observed %q", got.Observed.Slug)
+	}
+
+	saintLayer := Layer{ID: "universal", Cels: map[string]RawCelebration{
+		"a-saint": {Fields: map[string]string{"date": "08-10", "rank": "feast", "class": "saint", "name.en": "S"}, Variants: map[string]map[string]string{}},
+	}}
+	got2 := Compute(d("2025-08-10"), DefaultSelection(), []Layer{saintLayer})
+	if got2.Observed.Layer != "temporal" {
+		t.Errorf("a saint's feast must not replace the Sunday: observed %q", got2.Observed.Slug)
+	}
+}
diff --git a/internal/calendar/temporal.go b/internal/calendar/temporal.go
index 011e023..568efdc 100644
--- a/internal/calendar/temporal.go
+++ b/internal/calendar/temporal.go
@@ -150,6 +150,8 @@ func temporal(date time.Time, sel Selection) temporalDay {
 		return solemn(Ordinary, "sacred-heart", White, false)
 	case sameDay(date, christTheKing):
 		return solemn(Ordinary, "christ-the-king", White, false)
+	case sameDay(date, christmasThis):
+		return solemn(Christmas, "christmas", White, true)
 	case sameDay(date, epiphany(y, sel)):
 		return solemn(Christmas, "epiphany", White, true)
 	case sameDay(date, baptismThis):
-- 
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