3 files changed, 79 insertions, 0 deletions
diff --git a/internal/calendar/oracle_ef_test.go b/internal/calendar/oracle_ef_test.go
index b765a34..79b31a5 100644
--- a/internal/calendar/oracle_ef_test.go
+++ b/internal/calendar/oracle_ef_test.go
@@ -128,6 +128,26 @@ type efAllow struct {
 
 var efAllowList = []efAllow{
 	{
+		// RG 87: "Litaniae minores seu Rogationes, per se, assignantur feriis
+		// II, III et IV ante festum Ascensionis Domini." The Monday and
+		// Tuesday before the Ascension are Rogation days, and RG 128(d) gives
+		// violet to "the procession and Mass of the Greater and Lesser
+		// Litanies" -- a penitential note inside white Paschaltide.
+		//
+		// missalemeum builds no Rogation days and shows a plain white
+		// paschaltide feria. It is the outlier here, not lectio: colitur has
+		// had these since its own v0.1 and the two engines now agree day for
+		// day. Rare in practice, because a III-class saint displaces them --
+		// in 2026 all three are impeded and none appears.
+		match: func(date string, day time.Time, o efOracleDay) bool {
+			e := calendar.Easter(day.Year())
+			off := int(day.Sub(e).Hours() / 24)
+			return off == 36 || off == 37
+		},
+		field:  "colour",
+		reason: "RG 87 + RG 128(d): the Rogation Monday and Tuesday before the Ascension are violet; missalemeum builds no Rogation days (colitur C8)",
+	},
+	{
 		// RG 124, "De coloribus paramentorum", section C "De colore rubro",
 		// both photographic scans word for word: 124(b) gives red to
 		// "Sanctorum Apostolorum et Evangelistarum, in eorum die natalicio,
diff --git a/internal/calendar/temporal_ef.go b/internal/calendar/temporal_ef.go
index 7d31b8b..a043179 100644
--- a/internal/calendar/temporal_ef.go
+++ b/internal/calendar/temporal_ef.go
@@ -276,6 +276,31 @@ func temporalEF(date time.Time) temporalDay {
 	// Unique ferial slug (season-week-weekday) so proper ferias (Lent, Advent,
 	// Holy Week, Ember days) can key their own readings; green-season ferias
 	// simply have no lectionary entry and fall back to the Sunday.
+	// RG 87: "Litaniae minores seu Rogationes, per se, assignantur feriis II,
+	// III et IV ante festum Ascensionis Domini" -- the Minor Litanies are
+	// assigned to the Monday, Tuesday and Wednesday before the Ascension.
+	// Easter+36 and +37 are that Monday and Tuesday; their colour is violet,
+	// RG 128(d) giving violet "for the procession and Mass of the Greater and
+	// Lesser Litanies", a penitential note inside white Paschaltide.
+	//
+	// The WEDNESDAY is deliberately absent. Easter+38 is by construction the
+	// Vigil of the Ascension, which is II class and wins the day outright, so
+	// there is no Rogation OFFICE to build there -- what the rubric asks for on
+	// that day is a commemoration, and that needs a channel this function does
+	// not have (it returns one office per day). colitur reaches it through a
+	// movable-date entry in its own sanctoral overlay; here it stays unbuilt
+	// rather than half-built, which is why this comment says so.
+	//
+	// The rank is left as the feria's: these are IV-class days per annum and
+	// any III-class saint displaces them, which is what makes the office rare
+	// -- in 2026 all three are impeded and none appears at all.
+	if rog := daysBetween(easter, date); rog == 36 || rog == 37 {
+		slug := "ef-rogation-monday"
+		if rog == 37 {
+			slug = "ef-rogation-tuesday"
+		}
+		return efCel(season, slug, Violet, rank, week)
+	}
 	// RG 78 (Caput IX, "De sancta Maria in sabbato"): "In sabbatis, in quibus
 	// occurrit Officium de feria IV classis, fit de sancta Maria in sabbato."
 	// On a Saturday whose office would otherwise be a IV-class feria, the
diff --git a/internal/calendar/temporal_ef_test.go b/internal/calendar/temporal_ef_test.go
index 1290a59..e8ef391 100644
--- a/internal/calendar/temporal_ef_test.go
+++ b/internal/calendar/temporal_ef_test.go
@@ -300,3 +300,37 @@ func TestTemporalEFBVMSaturday(t *testing.T) {
 		}
 	}
 }
+
+// TestTemporalEFRogationDays pins RG 87's Minor Litanies: "Litaniae minores seu
+// Rogationes, per se, assignantur feriis II, III et IV ante festum Ascensionis
+// Domini." Easter+36 and +37 are that Monday and Tuesday; RG 128(d) makes them
+// violet, "for the procession and Mass of the Greater and Lesser Litanies" --
+// a penitential note inside white Paschaltide.
+//
+// The Wednesday is asserted in the opposite direction on purpose. Easter+38 is
+// by construction the Vigil of the Ascension, II class, which wins the day; the
+// rubric asks for a COMMEMORATION there, which this function cannot express
+// since it returns one office per day. A change that extended the Rogation
+// branch to +38 to "complete" the rubric would silently displace the Vigil, and
+// this test is what stops it.
+func TestTemporalEFRogationDays(t *testing.T) {
+	// 2027: Easter is 28 March, so the Rogation days are 3-5 May and the
+	// Monday is unimpeded that year.
+	easter := d("2027-03-28")
+	for off, want := range map[int]string{36: "ef-rogation-monday", 37: "ef-rogation-tuesday"} {
+		day := easter.AddDate(0, 0, off)
+		got := temporalEF(day)
+		if got.Cel.Slug != want {
+			t.Errorf("Easter+%d (%s): slug = %q, want %q", off, day.Format("2006-01-02"), got.Cel.Slug, want)
+		}
+		if got.Cel.Colour != Violet {
+			t.Errorf("Easter+%d (%s): colour = %s, want violet (RG 128(d))",
+				off, day.Format("2006-01-02"), got.Cel.Colour)
+		}
+	}
+	// Easter+38 is the Ascension's Vigil and must stay so.
+	if got := temporalEF(easter.AddDate(0, 0, 38)); got.Cel.Slug != "ef-ascension-vigil" {
+		t.Errorf("Easter+38: slug = %q, want ef-ascension-vigil -- the Rogation Wednesday's "+
+			"commemoration cannot be built here without displacing the Vigil", got.Cel.Slug)
+	}
+}