Merge branch 'fix/ef-precedence-defects': seven EF calendar defects

Fixes seven defects in the EF calendar, each found by differential and
oracle comparison against an independently-written engine and each
backed by a cited paragraph of the Rubricae Generales verified against
the 1962 Missal:

  RG 96  transfers must skip II-class days (the Precious Blood was
         landing on the Visitation)
  RG 91  a II-class privileged feria yields to an equal-class feast
         (St Matthew was losing to the September Ember Wednesday)
  RG 11  all Sundays of Advent, Lent and Passiontide are I class
         (only Advent I was), which also settles St Joseph on a Lent
         Sunday
  RG 131 Rose on Gaudete and Laetare, which the EF path never emitted
  RG 122 Holy Thursday is white

and the sanctoral generator itself, whose rank inference had tagged 15
III-class feasts as commemorations, dropped four entries to slug
collisions, and mis-tagged three class fields.

The EF oracle test asserted Season only, which is why none of this ever
failed. It now asserts rank and colour, with a cited allow-list.

Two commemorations had been deleted on a primary-source claim the
primary source contradicts: the Archivum Liturgicum transcription
silently drops commemoration lines where the photographic scans carry
them. Six of the seven affected dates are now present; the seventh
(25 December) is blocked by an ingestion limit that reads only the
first of three Christmas Masses, recorded at its cause.

Known gap, recorded in source: RG 95/97/98 chained transfers, where two
I-class feasts translate to the same day.

1 files changed, 63 insertions, 18 deletions

diff --git a/internal/calendar/temporal_ef.go b/internal/calendar/temporal_ef.go
index 7420ebd..c649405 100644
--- a/internal/calendar/temporal_ef.go
+++ b/internal/calendar/temporal_ef.go
@@ -74,6 +74,16 @@ func efCel(season Season, slug string, col Colour, rank Rank, week int) temporal
 	}
 }
 
+// efSunday is efCel plus the Sunday flag, for the temporal candidates that
+// are actual Sundays -- precedenceEF's tie-break needs to tell a Sunday (RG
+// 91 entry 15, wins its tie) apart from an equal-class privileged FERIA
+// (entry 18, the Ember/late-Advent days, which yields).
+func efSunday(season Season, slug string, col Colour, rank Rank, week int) temporalDay {
+	day := efCel(season, slug, col, rank, week)
+	day.Sunday = true
+	return day
+}
+
 // temporalEF computes the 1962 temporal identity of date. Season is exact
 // (oracle-validated); ranks/weeks are best-effort for display.
 func temporalEF(date time.Time) temporalDay {
@@ -87,6 +97,15 @@ func temporalEF(date time.Time) temporalDay {
 	if !date.Before(easter.AddDate(0, 0, 50)) && !date.After(easter.AddDate(0, 0, 55)) {
 		col = Red
 	}
+	// Holy Thursday (the Mass of Chrism and the Mass in Cena Domini) is white,
+	// a whole-Mass exception to Passiontide's violet -- RG 128(b)'s own named
+	// exception list, and RG 122 stating the same fact affirmatively in the
+	// White section. Good Friday and Holy Saturday, either side, are NOT
+	// exceptions here (RG 132's black for Good Friday's liturgical action is a
+	// separate, unmodelled gap -- see precedence_ef.go's doc comments).
+	if sameDay(date, easter.AddDate(0, 0, -3)) {
+		col = White
+	}
 	sun := date.Weekday() == time.Sunday
 
 	// Major feasts of the Lord (I class): nice titles + colour.
@@ -129,8 +148,20 @@ func temporalEF(date time.Time) temporalDay {
 	if sun {
 		week := efWeek(date, season, y, easter)
 		rank := RankClass2
-		if season == Advent && sameDay(date, adventStart(y)) {
-			rank = RankClass1 // 1st Sunday of Advent
+		sundayColour := col
+		if season == Advent || season == Lent {
+			// RG 11-12 / RG 91 entry 6: every Sunday of Advent and every Sunday
+			// of Lent is I class -- not only Advent I, the sole case previously
+			// handled (Passiontide's own two Sundays, Passion and Palm, are
+			// already I class via the named-feast switch above; Low Sunday
+			// likewise).
+			rank = RankClass1
+			switch {
+			case season == Advent && week == 3:
+				sundayColour = Rose // Gaudete -- RG 131, that Sunday's Office/Mass only
+			case season == Lent && week == 4:
+				sundayColour = Rose // Laetare -- RG 131, that Sunday's Office/Mass only
+			}
 		}
 		// Resumed Sundays after Pentecost (1960 Rubrics): when Easter is early
 		// there are more than 24 Sundays after Pentecost. The LAST Sunday before
@@ -140,17 +171,17 @@ func temporalEF(date time.Time) temporalDay {
 		if season == TimeAfterPentecost {
 			lastSun := adventStart(y).AddDate(0, 0, -7)
 			if sameDay(date, lastSun) {
-				return efCel(TimeAfterPentecost, "ef-time-after-pentecost-sunday-24", col, rank, 24)
+				return efSunday(TimeAfterPentecost, "ef-time-after-pentecost-sunday-24", col, rank, 24)
 			}
 			if week > 23 {
 				p := daysBetween(easter.AddDate(0, 0, 49), lastSun) / 7 // total Sundays after Pentecost
 				e := week - p + 7                                       // resumed Sunday after Epiphany
 				// Season stays time-after-pentecost (calendrical); the Epiphany
 				// slug only routes the readings to the resumed Mass.
-				return efCel(TimeAfterPentecost, "ef-time-after-epiphany-sunday-"+strconv.Itoa(e), Green, rank, e)
+				return efSunday(TimeAfterPentecost, "ef-time-after-epiphany-sunday-"+strconv.Itoa(e), Green, rank, e)
 			}
 		}
-		return efCel(season, "ef-"+string(season)+"-sunday-"+strconv.Itoa(week), col, rank, week)
+		return efSunday(season, "ef-"+string(season)+"-sunday-"+strconv.Itoa(week), sundayColour, rank, week)
 	}
 	// The days between Ash Wednesday and the 1st Sunday of Lent have their own
 	// proper Masses (not part of a numbered Lenten week).
@@ -166,6 +197,17 @@ func temporalEF(date time.Time) temporalDay {
 		// saint (e.g. the Conversion of St Paul, Jan 25) displaces them.
 		rank = RankClass3
 	}
+	if season == Advent && date.Month() == time.December && date.Day() >= 17 && date.Day() <= 23 {
+		// RG 91 entry 18: the late-Advent ferias (17-23 Dec) are II class
+		// privileged ferias, not the ordinary III class of the rest of Advent.
+		rank = RankClass2
+	}
+	if season == Christmas && date.Month() == time.December && date.Day() >= 26 {
+		// RG 67/68: "Dies infra octavam sunt II classis" -- days within the
+		// Octave of the Nativity (26-31 Dec) are II class; the octave day
+		// itself (1 Jan) is I class, already handled above as a named feast.
+		rank = RankClass2
+	}
 	if efPrivilegedFeria(date, easter) {
 		// The days of Holy Week and the privileged octaves of Easter and
 		// Pentecost are I class; no saint's feast is admitted (the feast is
@@ -173,12 +215,11 @@ func temporalEF(date time.Time) temporalDay {
 		// the temporal office win, matching the 1962 occurrence rules.
 		rank = RankClass1
 	}
-	// The Ember Days of September and Advent (Wednesday, Friday, Saturday after
-	// the third Sunday of the month/season) are II class privileged ferias in
-	// violet; they displace a III class saint (only commemorated). The Lenten
-	// Ember days are already III class Lenten ferias, and the Whitsun Ember days
-	// fall inside the I class Pentecost octave handled above.
-	if es, ok := efEmberSlug(date, y); ok {
+	// The Ember Days of September, Advent and Lent (Wednesday, Friday, Saturday
+	// after the anchor Sunday) are II class privileged ferias in violet; they
+	// displace a III class saint (only commemorated) -- RG 91 entry 18. The
+	// Whitsun Ember days fall inside the I class Pentecost octave handled above.
+	if es, ok := efEmberSlug(date, y, easter); ok {
 		return efCel(season, es, Violet, RankClass2, week)
 	}
 	// Unique ferial slug (season-week-weekday) so proper ferias (Lent, Advent,
@@ -197,22 +238,26 @@ func thirdSundayOfSeptember(y int) time.Time {
 }
 
 // efEmberSlug returns the Ember-day slug for date, if it is an Ember Wednesday,
-// Friday or Saturday of September or Advent (the day after the third Sunday +
-// 3/5/6). Returns ("", false) otherwise.
-func efEmberSlug(date time.Time, y int) (string, bool) {
+// Friday or Saturday of September, Advent or Lent (the day after the anchor
+// Sunday + 3/5/6: the third Sunday of September, Advent III, or Lent I --
+// MR1962, "De anno et eius partibus", Quatuor Tempora). Returns ("", false)
+// otherwise. The Whitsun Ember days are not listed here: they fall inside the
+// I class Pentecost octave, handled separately by efPrivilegedFeria.
+func efEmberSlug(date time.Time, y int, easter time.Time) (string, bool) {
 	for _, e := range []struct {
-		third  time.Time
+		anchor time.Time
 		season string
 	}{
 		{thirdSundayOfSeptember(y), "september"},
 		{adventStart(y).AddDate(0, 0, 14), "advent"}, // 3rd Sunday of Advent
+		{easter.AddDate(0, 0, -42), "lent"},          // 1st Sunday of Lent
 	} {
 		switch {
-		case sameDay(date, e.third.AddDate(0, 0, 3)):
+		case sameDay(date, e.anchor.AddDate(0, 0, 3)):
 			return "ef-" + e.season + "-ember-wed", true
-		case sameDay(date, e.third.AddDate(0, 0, 5)):
+		case sameDay(date, e.anchor.AddDate(0, 0, 5)):
 			return "ef-" + e.season + "-ember-fri", true
-		case sameDay(date, e.third.AddDate(0, 0, 6)):
+		case sameDay(date, e.anchor.AddDate(0, 0, 6)):
 			return "ef-" + e.season + "-ember-sat", true
 		}
 	}