rite(ef): ferias, Ember days, Rogations and the temporal entry point

Ferial ranks per RG 91: I class in Holy Week and the privileged octaves
(entries 7, 10), II class for Advent 17-23 and the Ember days (entry 18), III
class for Advent to 16 December and Lent/Passiontide (entries 22, 25), IV class
per annum (entry 28). Two further divergences from lectio, both from the table:
Advent 17-23 are II class, and the Lenten Ember days are II class rather than
ordinary Lenten ferias. Rogations (RG 80/87) exist at all, which lectio does
not compute. Gaudete and Laetare are rose.

Two corrections against the primary source beyond the task brief's draft.
Entry 7 (verified against the Latin: "feria IV cinerum et II, III et IV
Hebdomadae sanctae") covers only Ash Wednesday and Monday-Wednesday of Holy
Week; Thursday-Saturday are the Sacred Triduum, entry 2, cited separately.
Rogation Monday and Tuesday keep the ordinary ferial rank of their season
(RG 88: "de Litaniis minoribus nihil fit in Officio") rather than a fixed
class, since no RG 91 entry ranks them specially.

A module-type constraint proves Temporal_ef satisfies the kernel RITE contract.

1 files changed, 101 insertions, 1 deletions

diff --git a/test/test_temporal_ef.ml b/test/test_temporal_ef.ml
index 96c7761..aa84014 100644
--- a/test/test_temporal_ef.ml
+++ b/test/test_temporal_ef.ml
@@ -162,6 +162,100 @@ let test_resumed_sundays () =
   in
   Alcotest.(check bool) "2035 has resumed Epiphany Sundays" true (resumed <> [])
 
+module Cel = Colitur_kernel.Celebration
+module Sl = Colitur_kernel.Slug
+module Colr = Colitur_kernel.Colour
+
+let office dt = (T.temporal dt).Colitur_kernel.Temporal.office
+let slug_of dt = Sl.to_string (office dt).Cel.slug
+let rank_of dt = V.rank_to_string (office dt).Cel.rank
+let colour_of dt = Colr.to_string (office dt).Cel.colour
+
+let test_ferial_slugs_and_ranks () =
+  (* Ferias key on season-week-weekday, matching lectio's lectionary keys. *)
+  Alcotest.(check string) "Lent feria" "ef-lent-3-monday" (slug_of (d 2026 3 9));
+  (* RG 91 entry 22: Lent and Passiontide ferias are III class. *)
+  Alcotest.(check string) "Lent feria is III class" "class-3" (rank_of (d 2026 3 9));
+  (* RG 91 entry 25: Advent ferias to 16 December are III class ... *)
+  Alcotest.(check string) "Advent 15 Dec is III class" "class-3" (rank_of (d 2026 12 15));
+  (* ... entry 18: Advent 17-23 December are II class. lectio marks all Advent
+     ferias III class; this is a deliberate divergence. 21 Dec (not 18 Dec) is
+     used deliberately: 18 Dec 2026 is also the Advent Ember Friday, which
+     would independently be II class via the Ember rule and so would not
+     isolate this one. *)
+  Alcotest.(check string) "Advent 21 Dec is II class" "class-2" (rank_of (d 2026 12 21));
+  (* RG 91 entry 28: per annum ferias are IV class. *)
+  Alcotest.(check string) "per annum feria is IV class" "class-4" (rank_of (d 2026 7 15));
+  (* RG 91 entries 7 and 10: Holy Week and the privileged octaves are I class. *)
+  Alcotest.(check string) "Holy Monday is I class" "class-1" (rank_of (d 2026 3 30));
+  (* Good Friday: RG 91 entry 7 covers only Ash Wed and Mon-Wed of Holy Week --
+     Thursday-Saturday are the Sacred Triduum, entry 2, still I class. *)
+  Alcotest.(check string) "Good Friday is I class" "class-1" (rank_of (d 2026 4 3));
+  Alcotest.(check string) "Easter Monday is I class" "class-1" (rank_of (d 2026 4 6));
+  Alcotest.(check string) "Whit Monday is I class" "class-1" (rank_of (d 2026 5 25))
+
+let test_after_ashes () =
+  Alcotest.(check string) "Thursday after Ash Wednesday" "ef-lent-after-ashes-thursday"
+    (slug_of (d 2026 2 19));
+  Alcotest.(check (option int)) "outside a numbered week" None
+    (T.temporal (d 2026 2 19)).Colitur_kernel.Temporal.week
+
+let test_ember_days () =
+  (* September Ember days: Wed/Fri/Sat after the third Sunday of September.
+     Third Sunday of September 2026 = 20 September. *)
+  Alcotest.(check string) "September Ember Wed" "ef-september-ember-wed" (slug_of (d 2026 9 23));
+  Alcotest.(check string) "September Ember Sat" "ef-september-ember-sat" (slug_of (d 2026 9 26));
+  Alcotest.(check string) "September Ember is II class" "class-2" (rank_of (d 2026 9 23));
+  (* Advent Ember days: after Advent III (2026: 13 December). *)
+  Alcotest.(check string) "Advent Ember Wed" "ef-advent-ember-wed" (slug_of (d 2026 12 16));
+  (* Lenten Ember days: after Lent I (2026: 22 February). RG 91 entry 18 makes
+     them II class -- entry 22 excepts them from the III-class Lenten ferias.
+     lectio treats them as ordinary Lenten ferias. *)
+  Alcotest.(check string) "Lent Ember Wed" "ef-lent-ember-wed" (slug_of (d 2026 2 25));
+  Alcotest.(check string) "Lent Ember is II class" "class-2" (rank_of (d 2026 2 25));
+  (* Whitsun Ember days sit inside the I-class Pentecost octave. *)
+  Alcotest.(check string) "Whit Ember Wed" "ef-pentecost-ember-wed" (slug_of (d 2026 5 27));
+  Alcotest.(check string) "Whit Ember is I class" "class-1" (rank_of (d 2026 5 27));
+  (* Thursday is not an Ember day: the [day_of] guard matches only Wed/Fri/Sat
+     (3/5/6 days after the anchor), never day 4. 24 Sept 2026 is the Thursday
+     after the September anchor and must fall back to an ordinary IV-class
+     per annum feria, not an Ember slug. *)
+  Alcotest.(check string) "Thursday after the September anchor is not Ember" "class-4"
+    (rank_of (d 2026 9 24))
+
+let test_rogations () =
+  (* RG 80/87: Minor Litanies on the Monday and Tuesday before Ascension. The
+     Wednesday is the Ascension vigil (see Task 11). *)
+  Alcotest.(check string) "Rogation Monday" "ef-rogation-monday" (slug_of (d 2026 5 11));
+  Alcotest.(check string) "Rogation Tuesday" "ef-rogation-tuesday" (slug_of (d 2026 5 12));
+  Alcotest.(check string) "Wednesday is the vigil" "ef-ascension-vigil" (slug_of (d 2026 5 13));
+  (* RG 88: "de Litaniis minoribus nihil fit in Officio" -- the Rogation
+     changes the Mass, not the Office, and no RG 91 table entry ranks these
+     days specially, so they keep the ordinary IV-class rank of an unprivileged
+     Paschaltide feria (entry 28's catch-all). *)
+  Alcotest.(check string) "Rogation Monday keeps the ordinary ferial rank" "class-4"
+    (rank_of (d 2026 5 11))
+
+let test_colours () =
+  Alcotest.(check string) "Advent is violet" "violet" (colour_of (d 2026 12 1));
+  Alcotest.(check string) "per annum is green" "green" (colour_of (d 2026 7 15));
+  Alcotest.(check string) "Paschaltide is white" "white" (colour_of (d 2026 4 20));
+  Alcotest.(check string) "Pentecost octave is red" "red" (colour_of (d 2026 5 25));
+  (* Gaudete = Advent III, Laetare = Lent IV. *)
+  Alcotest.(check string) "Gaudete is rose" "rose" (colour_of (d 2026 12 13));
+  Alcotest.(check string) "Laetare is rose" "rose" (colour_of (d 2026 3 15))
+
+let test_totality () =
+  (* Every day of 2026 yields an office, and every slug is well-formed. *)
+  let jan1 = d 2026 1 1 in
+  for i = 0 to 364 do
+    let dt = D.add_days jan1 i in
+    let s = slug_of dt in
+    match Sl.of_string s with
+    | Ok _ -> ()
+    | Error e -> Alcotest.failf "%s: %s" (D.to_iso8601 dt) e
+  done
+
 let suite_extra =
   [ Alcotest.test_case "advent start" `Quick test_advent_start;
     Alcotest.test_case "seasons" `Quick test_seasons;
@@ -171,7 +265,13 @@ let suite_extra =
     Alcotest.test_case "week numbers" `Quick test_week_numbers;
     Alcotest.test_case "sunday slugs" `Quick test_sunday_slugs;
     Alcotest.test_case "week/sunday_slug agree" `Quick test_week_sunday_slug_agree;
-    Alcotest.test_case "resumed sundays" `Quick test_resumed_sundays ]
+    Alcotest.test_case "resumed sundays" `Quick test_resumed_sundays;
+    Alcotest.test_case "ferial slugs and ranks" `Quick test_ferial_slugs_and_ranks;
+    Alcotest.test_case "after ashes" `Quick test_after_ashes;
+    Alcotest.test_case "ember days" `Quick test_ember_days;
+    Alcotest.test_case "rogations" `Quick test_rogations;
+    Alcotest.test_case "colours" `Quick test_colours;
+    Alcotest.test_case "totality" `Quick test_totality ]
 
 let suite =
   ( "Rite_ef",