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, 6 insertions, 0 deletions

diff --git a/lib/kernel/precedence.ml b/lib/kernel/precedence.ml
index 2c55817..c207117 100644
--- a/lib/kernel/precedence.ml
+++ b/lib/kernel/precedence.ml
@@ -25,6 +25,12 @@ type ('s, 'r) rules = {
           has no [context] of its own to compute it with) -- see [resolve]'s
           own comment for why this is a KERNEL-level policy, not a rite-
           specific rule threaded in as data. *)
+  vigil_feast : 'r candidate -> Slug.t option;
+      (** RG 33's third omission trigger: the slug of the feast this candidate
+          is a vigil OF, when the rite subjects that vigil to omission;
+          [None] for every other candidate. See the .mli for the contract and
+          for why the kernel asks the rite to NAME the feast rather than infer
+          it. *)
 }
 
 type 'r resolution = {