merge: celebrant Mass rubrics, and four rubrical corrections

colitur now prints what a real ordo prints for the Mass: which formulary is
said and how it was reached, the Gloria, the Creed, the preface, and the
commemorations with their Low-Mass/sung distinction. colitur rubrics joins
day and readings.

Four defects were found and fixed on the way, each by an external witness
rather than by inspection: the Creed said at Requiem Masses (RG 476(f)),
the missing bissextile shift of St Matthias and St Gabriel (2 041 leap
years), Rogation Monday and Tuesday coloured violet in Paschaltide (RG
119(b)), and the ferias after the Ascension resuming the wrong Sunday's
Mass rather than the Ascension's.

Validation gained a sixth layer and then some: the preface is checked
against three independent publishers over seven witness-years (FIUV, three
LMS editions, three extraordinaryform.org editions), none of which shares
the Divinum Officium -> missalemeum -> lectio lineage the older layers all
descend from.

1 files changed, 44 insertions, 0 deletions

diff --git a/lib/kernel/precedence.mli b/lib/kernel/precedence.mli
index a0b4b1a..05022c5 100644
--- a/lib/kernel/precedence.mli
+++ b/lib/kernel/precedence.mli
@@ -145,3 +145,47 @@ type 'r resolution = {
 val resolve :
   ('s, 'r) rules -> 's context -> temporal:'r candidate ->
   sanctoral:'r candidate list -> 'r resolution
+
+(** RG 111(a) (EF; docs/research/rules-register.md; LT.txt, grep "Ratio
+    admittendi commemorationes"): {i "in diebus liturgicis I classis et in
+    Missis in cantu non conventualibus, nulla admittitur commemoratio,
+    praeter unam privilegiatam"} -- on a liturgical day of the first class,
+    AND at any non-conventual SUNG Mass regardless of the day's own class,
+    at most ONE commemoration is admitted, and only if it is privileged.
+    (b)/(c)/(d), immediately following in the same rubric, give the wider
+    caps -- two ordinary/privileged commemorations depending on class --
+    that apply everywhere else; {!rules.admit} already computes exactly
+    that wider set, which is why this function's own INPUT is the admitted
+    LOW-MASS list, not a fresh resolution: (a) is not a distinct admission
+    RULE with its own candidate-ranking logic, it is a narrower CAP applied
+    afterwards to the identical admitted, precedence-ordered list -- "at
+    most one, and it must be privileged" is exactly "keep the first
+    admitted entry, if any, that is privileged", nothing else in the list
+    can ever outrank it (RG 113: admission order already follows the
+    rite's own table of precedence, {!rules.admit}'s own citation).
+
+    Deliberately a pure post-hoc DERIVATION over
+    {!Liturgical_day.t.commemorations}, not a second stored field: the
+    input list is already validated (privilege-tagged, admission-capped);
+    this function adds no new information and can regress in no way the
+    input list itself could not already regress, so a second field would
+    only create a second place for the same fact to drift out of sync with
+    the first -- the identical reasoning {!Liturgical_day.t.temporal}'s own
+    "embedded, not flattened" comment gives for a different field. Exposed
+    here, at the kernel level, rather than left for an output layer to
+    reimplement: the filter is small but the RULE it encodes (RG 111(a))
+    is not obvious from the type alone, and a caller (the [rubrics] CLI
+    column, a future template, a differential test) should name the
+    rubric, not re-derive "privileged commemorations, capped at one" for
+    itself.
+
+    SCOPE: "non conventualibus" is read literally -- this models the
+    ordinary (non-conventual) sung Mass only. RG 111(a)'s own text implies
+    a CONVENTUAL sung Mass keeps the wider (b)/(c)/(d) caps even when sung
+    (a choir-obligation distinction), but this engine has no concept of
+    "conventual" at all (no community/choir dimension anywhere in
+    {!Celebration.t} or {!Liturgical_day.t}), so this function's result
+    should be read as "what a normal parish/private Low OR sung Mass
+    admits", never "what every sung Mass, everywhere, admits" -- a
+    documented scope limit, not an oversight. *)
+val sung_mass_commemorations : ('a * privilege) list -> ('a * privilege) list