feat(ef): the Creed, RG 475-476

Whether the Creed is said at Mass. New Rubrics_ef.creed, reached through
a new Rite.t.creed field and a new Liturgical_day.t.creed bool (false,
not an option, for a rite that has not implemented the rule); colitur
rubrics gains a fourth TAB-separated column.

475(a) reads the TEMPORAL cycle's own weekday, not the observed day: a
Sunday impeded by a Feast of the Lord (RG 16a) still says the Creed.
475(d)'s three octaves (Nativity, Easter, Pentecost) are pure date/
Easter-offset windows, checked first, since a saint's feast winning the
day inside one of them still says the Creed ("etiam in festis
occurrentibus") -- St Stephen, 26 December, is the live witness.

RG 23 classifies Ash Wednesday and every feria of Holy Week (including
the Sacred Triduum) as feriae, not festa, however high their rank, so
475(b)/(c)'s "in festis" never reaches them; this single check subsumes
476(a)'s own naming of the Chrism/Lord's-Supper Mass and the Easter
Vigil. RG 28-34 vigils are a third liturgical-day category, also
excluded from "in festis" regardless of rank -- reuses the already-
exported Precedence_ef.is_vigil rather than a new list.

475(e)'s Apostle/Evangelist natalicia list (creed_apostle_slugs) was
derived by grepping data/ef/sanctoral.sexp directly and checking each
candidate's own date against whether it is that saint's dies natalis --
not copied from any list supplied with the task. The Conversion of St
Paul and the 30 June Commemoration of St Paul are excluded (neither is
a natalicium); the Chair of St Peter and St Barnabas are included only
because the clause names them explicitly, which is exactly why it has
to: neither is a natalicium either.

475(c)'s BVM half reuses Precedence_ef.marian_slugs (newly exported)
rather than the subject field alone: checked against the shipped data,
almost every Marian sanctoral entry ships subject=Saint, not Bvm.

man/colitur.1's rubrics section is updated to match the new column;
test/cli.t repinned via dune promote for the same reason. Verified
day/readings output byte-identical to v0.10.1 across the whole
1583-9999 domain (both binaries' concatenated day+readings output,
6,148,492 lines each, zero diff). Domain-wide: 882,996 days say the
Creed, 2,191,250 do not; every one of the domain's 439,178 Sundays says
it, zero exceptions.

1 files changed, 37 insertions, 0 deletions

diff --git a/lib/rites/rite_ef/rubrics_ef.mli b/lib/rites/rite_ef/rubrics_ef.mli
new file mode 100644
index 0000000..16e7491
--- /dev/null
+++ b/lib/rites/rite_ef/rubrics_ef.mli
@@ -0,0 +1,37 @@
+(** RG 475-476 (docs/research/LT.txt, grep "dicitur symbolum") -- whether the
+    Creed is said at Mass. The first rubric in this phase governing a PART OF
+    MASS rather than occurrence/precedence, hence its own module: see the
+    .ml's own header for the rubric quoted in full and every branch's
+    citation. *)
+
+open Colitur_kernel
+
+(** RG 475(e)'s "festis nataliciis Apostolorum et Evangelistarum, necnon in
+    festis Cathedrae S. Petri et S. Barnabae Ap." -- see the .ml's own
+    citation for how each entry was derived from and verified against
+    data/ef/sanctoral.sexp, and for what was deliberately excluded. Exposed
+    so the test suite can assert completeness against the shipped data the
+    same way {!Precedence_ef.vigil_feast_table} already lets it. *)
+val creed_apostle_slugs : string list
+
+(** Whether the Creed is said, post-Gospel/homily, at the Mass this day
+    resolves to.
+
+    [temporal] is read for exactly one fact -- RG 475(a)'s own "in qualibet
+    dominica, ETSI EIUS OFFICIUM ALICUI FESTO LOCUM CEDAT" ("on any Sunday,
+    EVEN WHEN a feast displaces its own Office"): a Sunday impeded by a
+    Feast of the Lord (RG 16(a)) still says the Creed, so this reads the
+    TEMPORAL cycle's own weekday, never [observed]'s. Every other clause
+    reads [observed] -- the celebration whose Mass is actually said -- and
+    [date], read once against the rite's own (Gregorian) Easter for the two
+    Easter-relative window questions (RG 475(d)'s three octaves, RG 23's
+    Ash-Wednesday-and-Holy-Week feriae). [creed] never reads
+    {!Liturgical_day.t.commemorations}: RG 476(e), "ratione alicuius
+    commemorationis in Missa occurrentis" [never say the Creed merely
+    because of a commemoration], holds by construction rather than by a
+    checked branch. *)
+val creed :
+  temporal:(Vocab_ef.season, Vocab_ef.rank) Temporal.t ->
+  observed:Vocab_ef.rank Celebration.t ->
+  date:Date.t ->
+  bool