merge: celebrant Mass rubrics, and four rubrical corrections

colitur now prints what a real ordo prints for the Mass: which formulary is
said and how it was reached, the Gloria, the Creed, the preface, and the
commemorations with their Low-Mass/sung distinction. colitur rubrics joins
day and readings.

Four defects were found and fixed on the way, each by an external witness
rather than by inspection: the Creed said at Requiem Masses (RG 476(f)),
the missing bissextile shift of St Matthias and St Gabriel (2 041 leap
years), Rogation Monday and Tuesday coloured violet in Paschaltide (RG
119(b)), and the ferias after the Ascension resuming the wrong Sunday's
Mass rather than the Ascension's.

Validation gained a sixth layer and then some: the preface is checked
against three independent publishers over seven witness-years (FIUV, three
LMS editions, three extraordinaryform.org editions), none of which shares
the Divinum Officium -> missalemeum -> lectio lineage the older layers all
descend from.

1 files changed, 59 insertions, 0 deletions

diff --git a/lib/kernel/preface.ml b/lib/kernel/preface.ml
new file mode 100644
index 0000000..08d00b4
--- /dev/null
+++ b/lib/kernel/preface.ml
@@ -0,0 +1,59 @@
+(* RG 482-499 -- see the .mli for the rubric quoted in full and the
+   placement rationale. Argument-less variants only, so no
+   [Sexplib0.Sexp_conv] open is needed -- see CLAUDE.md's own gotcha note. *)
+type t =
+  | Nativity
+  | Epiphany
+  | Lent
+  | Holy_cross
+  | Easter
+  | Ascension
+  | Sacred_heart
+  | Christ_the_king
+  | Holy_spirit
+  | Trinity
+  | Bvm
+  | St_joseph
+  | Apostles
+  | Common
+  | Requiem
+[@@deriving sexp]
+
+let all =
+  [ Nativity; Epiphany; Lent; Holy_cross; Easter; Ascension; Sacred_heart; Christ_the_king;
+    Holy_spirit; Trinity; Bvm; St_joseph; Apostles; Common; Requiem ]
+
+let to_string = function
+  | Nativity -> "nativity"
+  | Epiphany -> "epiphany"
+  | Lent -> "lent"
+  | Holy_cross -> "holy-cross"
+  | Easter -> "easter"
+  | Ascension -> "ascension"
+  | Sacred_heart -> "sacred-heart"
+  | Christ_the_king -> "christ-the-king"
+  | Holy_spirit -> "holy-spirit"
+  | Trinity -> "trinity"
+  | Bvm -> "bvm"
+  | St_joseph -> "st-joseph"
+  | Apostles -> "apostles"
+  | Common -> "common"
+  | Requiem -> "requiem"
+
+let of_string = function
+  | "nativity" -> Some Nativity
+  | "epiphany" -> Some Epiphany
+  | "lent" -> Some Lent
+  | "holy-cross" -> Some Holy_cross
+  | "easter" -> Some Easter
+  | "ascension" -> Some Ascension
+  | "sacred-heart" -> Some Sacred_heart
+  | "christ-the-king" -> Some Christ_the_king
+  | "holy-spirit" -> Some Holy_spirit
+  | "trinity" -> Some Trinity
+  | "bvm" -> Some Bvm
+  | "st-joseph" -> Some St_joseph
+  | "apostles" -> Some Apostles
+  | "common" -> Some Common
+  | "requiem" -> Some Requiem
+  | _ -> None