fix(ef): RG 476(f) -- the Creed is not said at a Requiem Mass

colitur said the Creed IS said on All Souls' Day and every other
Requiem-shaped day: RG 475(b)'s "in festis I classis" branch fired on
rank alone, with nothing checking RG 476(f), "Non dicitur symbolum ...
f) in Missis defunctorum". Allow-listed as L1 in
expected-divergences-lms.sexp on the argument that [creed] has no
notion of a Requiem Mass in its inputs and could not express the rule
without a signature change.

That argument does not hold. Colour.Black is used by exactly two
celebrations in the whole engine, verified by grepping every
occurrence in lib/ and data/: commemoration-of-all-souls
(data/ef/sanctoral.sexp) and Good Friday (temporal_ef.ml, already
false via the earlier RG 23(b) feria exclusion and has no Mass at all
in the 1955-restored Holy Week). So on every day this engine can
construct, colour = Black if and only if the Mass is a Requiem -- a
citable implication (RG 117 assigns black to Masses of the dead) on
this data, not a heuristic.

Rite_ef.Rubrics_ef.creed now reads observed.colour as RG 476(f)'s own
guard, positioned ahead of 475(b)'s rank branch. A new test,
test_colour_black_population_is_exactly_two, sweeps both the shipped
data and Temporal_ef's own code across a century and fails loudly the
day a third Colour.Black celebration is ever introduced, so the proxy
cannot silently rot.

L1 is closed in expected-divergences-lms.sexp, citation preserved.

Blast radius, measured (full 1583-9999 sweep, grouped by observed
slug): 8 416 days change from true to false, every one
commemoration-of-all-souls (missing from exactly 1 of the 8 417 domain
years, a boundary-year transfer effect at 1583/9999). A further 8 416
Colour.Black days are Good Friday, unaffected (already false before
this fix). colitur day/readings stay byte-identical to v0.10.1
(checked directly against a v0.10.1 worktree build, 9 domain-spanning
years); colitur rubrics changes on exactly the 8 416 days above.

colitur emit --format sexp's pretty-printed line count for 2027 moved
9010 -> 9011 as a side effect: Sexplib.Sexp.to_string_hum wraps by
column width, and All Souls' Day 2027's record grew one wrapped line
because "false" is one character longer than "true". Cosmetic only --
no field's data changed -- and pinned in test/cli.t with the
measurement recorded.

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/rites/rite_ef/rubrics_ef.mli b/lib/rites/rite_ef/rubrics_ef.mli
index 16e7491..7a1284b 100644
--- a/lib/rites/rite_ef/rubrics_ef.mli
+++ b/lib/rites/rite_ef/rubrics_ef.mli
@@ -29,7 +29,10 @@ val creed_apostle_slugs : string list
     {!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. *)
+    checked branch. RG 476(f) ("in Missis defunctorum") reads
+    [observed]'s [colour]: see the .ml's own header for why [Colour.Black]
+    is a sound proxy for "this Mass is a Requiem" on the shipped data, and
+    what would have to be re-checked if that ever stops being true. *)
 val creed :
   temporal:(Vocab_ef.season, Vocab_ef.rank) Temporal.t ->
   observed:Vocab_ef.rank Celebration.t ->