merge: RG 33's third omission trigger

The last unbuilt clause in the EF module. A II/III-class vigil is omitted
entirely when the feast it precedes fails to keep its own day -- 1 744 days
across 1583-9999, three verified shapes, zero unexplained.

Rule and vigil inventory independently confirmed by O'Connell 1964, outside
the Divinum Officium -> missalemeum -> lectio lineage. The 10 affected days
in 2005-2050 are allow-listed as C39; no external day-level witness exists,
which the note states rather than glosses.

1 files changed, 35 insertions, 0 deletions

diff --git a/lib/rites/rite_ef/precedence_ef.mli b/lib/rites/rite_ef/precedence_ef.mli
index 419613a..4c2523a 100644
--- a/lib/rites/rite_ef/precedence_ef.mli
+++ b/lib/rites/rite_ef/precedence_ef.mli
@@ -217,6 +217,41 @@ val disposition :
   loser:Vocab_ef.rank Precedence.candidate ->
   Precedence.disposition
 
+(** RG 33's third omission trigger. Given a candidate, the feast it is a
+    VIGIL of, when that vigil is one this rule can omit; [None] otherwise --
+    which is every candidate that is not one of the five II/III-class vigils
+    in the 1962 universal calendar.
+
+    Answers only the identity question. Whether the feast actually kept its
+    own day is {!Colitur_kernel.Calendar}'s to determine, because only the
+    kernel holds the settled post-transfer placement of the whole year; see
+    {!Colitur_kernel.Precedence.rules.vigil_feast} for the division of labour
+    and for why the feast is NAMED here rather than inferred there.
+
+    The I-class vigils (Nativity Eve, Pentecost Vigil) are outside this rule
+    by RG 33's own wording and outside losing at all by RG 30, so they are
+    absent from the table and this returns [None] for them -- the same
+    argument {!is_omissible_vigil} already makes for the rule's other two
+    triggers. *)
+val vigil_feast : Vocab_ef.rank Precedence.candidate -> Slug.t option
+
+(** The (vigil slug, feast slug) pairs {!vigil_feast} answers from, exposed so
+    the test suite can assert both directions against the shipped sanctoral
+    data: that every slug named here exists, and that no II/III-class vigil in
+    the data is missing from it. Neither is checkable by a type, and both fail
+    SILENTLY -- an unmatched slug simply makes RG 33 inert for that entry. *)
+val vigil_feast_table : (string * Slug.t) list
+
+(** Whether a slug names a vigil, by either of the two conventions this
+    calendar's data uses (a "-vigil" suffix from the temporal cycle, a
+    "vigil-of-" prefix from the sanctoral bootstrap). Exposed for the same
+    table-drift assertions as {!vigil_feast_table}. *)
+val is_vigil : string -> bool
+
+(** Whether a rank is one RG 33 can omit -- II or III class. I-class vigils are
+    outside the rule (RG 30). Exposed alongside {!is_vigil}. *)
+val is_omissible_vigil : Vocab_ef.rank -> bool
+
 (** Slug prefix marking a celebration as one of RG 91 entry 17's days within
     the Octave of the Nativity (29-31 Dec -- 26-28 Dec are Stephen, John, the
     Innocents, sanctoral, never this prefix). Also colitur's own convention