rite(ef): occurrence dispositions (RG 92-95, 33, 94)

Precedence_ef.disposition decides the loser's fate in an occurrence: a
Commemoration_only celebration is always commemorated (it can never win or
transfer); a I- or II-class vigil impeded by any Sunday or a I-class feast
is entirely omitted (RG 33), checked before the generic rule below or the
Nativity/Pentecost Vigil could wrongly transfer; any other I-class loser
transfers (RG 95 -- only I class has the right of translation); everything
else is commemorated, with the admit-or-omit decision left to RG 108-111's
admission count (Task 9). RG 94 needs no code: resolve always compares a
loser against the day's actual winner, never against a departed sibling, so
no commemoration can ride along with a transferred feast in this design.

This is the branch that completes Task 7's carried All Souls fix: once it
loses to an occurring Sunday, its untouched Class1 rank routes it to
Transfer via the generic rule, not a special case. Landing on 3 November is
Rite.transfer_target's job, not wired up yet.

Commemorate carries an interim Precedence.Ordinary privilege pending Task
9's RG 109 implementation, exposed as interim_privilege for that task to
replace.

Table-driven tests cover each rule, including RG 33's boundary from both
sides and a Commemoration_only loser that is also Class1 and vigil-shaped
to pin the branch ordering. Mutation-tested: disabling RG 33, either
direction of RG 95's rank condition, or the Commemoration_only priority
check each fail exactly the rows built to catch them.

2 files changed, 141 insertions, 0 deletions

diff --git a/lib/rites/rite_ef/precedence_ef.ml b/lib/rites/rite_ef/precedence_ef.ml
index 0716177..d8d64a8 100644
--- a/lib/rites/rite_ef/precedence_ef.ml
+++ b/lib/rites/rite_ef/precedence_ef.ml
@@ -214,3 +214,98 @@ let band (ctx : Vocab_ef.season Precedence.context) (c : Vocab_ef.rank Precedenc
        "feria" that is also a vigil is not a feria RG 91 describes. *)
   else if (not is_vigil) && rank = Class4 then 28
   else unclassified
+
+(* Task 8: what happens to the day's LOSING candidate (docs/research/
+   rules-register.md §4, "Occurrence" RG 92-95 and "Vigils" RG 33, plus RG
+   94). [band] above decides who wins; this decides the loser's fate, which
+   turns on the LOSER's own rank and status (RG 95), except RG 33's vigil
+   omission, which also has to read the winner. Nothing here ever returns
+   [Precedence.Repose]: that disposition denotes RG 100-102's *repositio*
+   (perpetual impediment from a proper/diocesan calendar), out of this
+   plan's scope -- see calendar.mli's own note that nothing in the EF
+   ruleset currently emits it. *)
+
+(* RG 33 (register line 383-384): a I- or II-class vigil falling on any
+   Sunday or a I-class feast is entirely omitted. Every Sunday slug this
+   rite's temporal cycle produces -- named (temporal_ef.ml's [named], e.g.
+   "ef-easter-sunday") or the generic "ef-<season>-sunday-<n>" fallback
+   ([sunday_slug]) -- contains this marker; nothing else [band] classifies
+   does. Not an RG citation itself -- see [universal_layer]'s note on this
+   file's own naming conventions -- exposed for the same reason as
+   {!vigil_suffix}: a future rename of temporal_ef's Sunday-slug format has
+   somewhere to be caught other than a silently-wrong RG 33 disposition. *)
+let sunday_marker = "-sunday"
+
+let contains_substring s ~needle =
+  let ls = String.length s and ln = String.length needle in
+  let rec at i = i + ln <= ls && (String.sub s i ln = needle || at (i + 1)) in
+  ln = 0 || at 0
+
+let is_sunday_slug slug = contains_substring slug ~needle:sunday_marker
+
+(* RG 33's "any Sunday or a I-class feast": every RG 91 entry that can ever
+   outrank a II-class vigil (entry 21) without itself being a Sunday is I
+   class by the table's own structure (entries 1-13), so [rank = Class1]
+   alone already covers every way a I-class vigil (entries 5, 9 -- Nativity,
+   Pentecost) can be impeded at all; the slug check is what a II-class vigil
+   impeded by an ordinary Sunday (entry 15, rank Class2) needs, since that
+   winner's own rank is not Class1. *)
+let impedes_vigil (winner : Vocab_ef.rank Precedence.candidate) =
+  let cel = winner.Precedence.cel in
+  cel.Celebration.rank = Vocab_ef.Class1
+  || is_sunday_slug (Slug.to_string cel.Celebration.slug)
+
+(* Not yet RG 109 (Task 9's job: the closed list of privileged commemorations
+   and RG 108-111's admission counts). Every [Commemorate] this function
+   returns carries this one placeholder rather than a silent default, so the
+   choice is visible and grep-able. [Ordinary] chosen over [Privileged]
+   deliberately: it grants no admission entitlement RG 111 has not earned,
+   so code that trusts this value before Task 9 replaces it under-privileges
+   a commemoration rather than over-privileges one -- the safer direction to
+   be wrong in. *)
+let interim_privilege = Precedence.Ordinary
+
+let disposition ~(winner : Vocab_ef.rank Precedence.candidate)
+    ~(loser : Vocab_ef.rank Precedence.candidate) : Precedence.disposition =
+  let open Vocab_ef in
+  let cel = loser.Precedence.cel in
+  if cel.Celebration.status = Celebration.Commemoration_only then
+    (* Always -- checked before RG 33's omission and RG 95's transfer so
+       neither can override it: a Commemoration_only entry can never win
+       (Precedence.resolve holds it out of the band contest entirely, see
+       that module's [resolve]) and, per the brief, can never transfer
+       either. *)
+    Precedence.Commemorate interim_privilege
+  else if
+    (cel.Celebration.rank = Class1 || cel.Celebration.rank = Class2)
+    && is_vigil (Slug.to_string cel.Celebration.slug)
+    && impedes_vigil winner
+  then
+    (* RG 33. Checked before the generic Class1 -> Transfer rule below, or a
+       I-class vigil (Nativity, Pentecost) impeded on its own Sunday/
+       I-class-feast terms would wrongly transfer instead of vanishing. *)
+    Precedence.Omit
+  else if cel.Celebration.rank = Class1 then
+    (* RG 95: only I-class feasts have the right of translation. This is the
+       branch that completes Task 7's All Souls fix (register line 334, RG
+       91 entry 8): All Souls is I class and not a vigil, so once it loses
+       to an occurring Sunday it reaches here and transfers -- to 3
+       November per the register, but WHERE it lands is
+       Rite.transfer_target's job (RG 96), not this function's; disposition
+       only says THAT it moves. *)
+    Precedence.Transfer
+  else
+    (* RG 95's other branch, for everything below I class: "aut
+       commemorantur aut penitus omittuntur" -- commemorated or wholly
+       omitted. Which of the two survives is RG 108-111's admission count
+       (Task 9's [admit]), not this function's decision; this only opens the
+       commemoration.
+
+       RG 94 (a fixed-day commemoration is not carried along with a
+       transferred feast) needs no code here: [Precedence.resolve] calls
+       this function once per loser, always against the day's actual
+       [observed] winner -- never against a fellow loser that itself
+       transferred away -- so no mechanism exists by which a commemoration
+       could ride along with a departing feast in the first place; there is
+       nothing to suppress. *)
+    Precedence.Commemorate interim_privilege
diff --git a/lib/rites/rite_ef/precedence_ef.mli b/lib/rites/rite_ef/precedence_ef.mli
index 63fb0a1..9fe8789 100644
--- a/lib/rites/rite_ef/precedence_ef.mli
+++ b/lib/rites/rite_ef/precedence_ef.mli
@@ -56,3 +56,49 @@ val unclassified : int
     including shapes the 1962 table itself does not describe (see
     {!unclassified}). *)
 val band : Vocab_ef.season Precedence.context -> Vocab_ef.rank Precedence.candidate -> int
+
+(** RG 33's marker: every Sunday slug this rite's temporal cycle produces
+    (temporal_ef.ml's [named] and [sunday_slug]) contains this substring;
+    nothing else {!band} classifies does. Also colitur's own convention, not
+    an RG citation -- see {!universal_layer} -- exposed for the same reason
+    as {!vigil_suffix}: a rename of temporal_ef's Sunday-slug format has
+    somewhere to be caught other than a silently-wrong RG 33 disposition. *)
+val sunday_marker : string
+
+(** The placeholder {!Precedence.privilege} every [Commemorate] disposition
+    below carries until Task 9 implements RG 109's closed list of privileged
+    commemorations and RG 108-111's admission counts. Exposed so Task 9 (and
+    any test wanting to assert on it explicitly) does not have to duplicate
+    the literal [Precedence.Ordinary]. *)
+val interim_privilege : Precedence.privilege
+
+(** [disposition ~winner ~loser]: RG 92-95, 33, 94 (docs/research/
+    rules-register.md §4, "Occurrence" and "Vigils"). What becomes of a
+    losing candidate, decided by the LOSER's own rank and status (RG 95),
+    except RG 33's vigil omission, which also reads the winner:
+    - a {!Celebration.status} of [Commemoration_only] is always
+      [Commemorate] (checked first: it can never win -- see
+      {!Precedence.resolve} -- and, by that same status's own definition,
+      already denotes an office with nothing left to translate, so it never
+      transfers either; not itself a further RG citation beyond RG 93's
+      general four-mechanism statement above);
+    - a [Class1] or [Class2] loser whose slug marks it a vigil ({!vigil_suffix})
+      is [Omit] when the winner is any Sunday ({!sunday_marker}) or itself
+      [Class1] (RG 33 -- entirely omitted, not merely commemorated);
+    - any other [Class1] loser is [Transfer] (RG 95 -- only I class has the
+      right of translation; this is also what moves All Souls, register
+      line 334, once it loses to an occurring Sunday -- WHERE it lands is
+      {!Rite.t.transfer_target}'s job, not this function's);
+    - everything else is [Commemorate], carrying {!interim_privilege} until
+      Task 9 replaces it with RG 109's real per-day computation.
+
+    Total over every winner/loser pair {!Precedence.resolve} or {!Calendar}
+    can construct: [Vocab_ef.rank] (RG 8) and {!Celebration.status} are both
+    closed variants, so the four cases above exhaust every representable
+    shape -- there is no fifth, "unclassified" case the way {!band} needs
+    one, because this function's own return type has no such slot to fall
+    into by accident. *)
+val disposition :
+  winner:Vocab_ef.rank Precedence.candidate ->
+  loser:Vocab_ef.rank Precedence.candidate ->
+  Precedence.disposition