Corrects and completes the occurrence rules, based on a design discussion
plus one concrete data point: St. Anthony Abbot (plain Duplex) was found
outright winning against an ordinary Sunday in the real Monastic 1617
engine, which the old duplex-1-classis-only threshold got wrong.
- FeastClass gains `vigil`, inserted between `simplex` and `semiduplex` —
one ordering that correctly serves both "does this win against a Sunday"
(vigil behaves like simplex there) and "which of two saints wins a
landing-day collision" (vigil beats simplex, loses to semiduplex).
- LiturgicalDay.occurring (a flat OccurringFeast[] that could only ever
express a losing *sanctoral* candidate) is replaced by `winner:
DayWinner` + `commemorations: Commemoration[]` — a discriminated list
that can hold the temporal day itself, one or more sanctoral entries, or
(not built yet, but the shape already accommodates it) a future octave
kind.
- commemorations.ts: ordinary Sundays let Duplex+ win outright (Sunday
commemorated in return), Semiduplex/Vigil transfer elsewhere (too
substantial a feast to cheapen with a bare commemoration), Simplex stays
and is commemorated. Privileged Sundays never displace; Duplex-majus+
commemorated, everything else transfers.
- collision.ts (new): resolves two sanctoral candidates wanting the same
day (a transfer landing on an already-occupied day, or two native
saints sharing a date) — duplex > semiduplex > vigil > simplex, loser
always commemorated, ties favor the native occupant.
- temporal-id.ts (new): maps any date to one of the 52 real Sunday-collect
ids from the previous commit, so a temporal winner/commemoration can
actually be looked up, not just labeled "temporal" in the abstract.
- index.ts's resolveDay orchestrates all of it, including the actual
Monday/Saturday transfer mechanism. Landing on a privileged feria (the
concrete case: Holy Week, right after Palm Sunday) is explicitly
deferred rather than guessed at — it needs its own Easter-keyed lookup
table, the same way the reference engine handles it.
Added the Vigil of St. Lawrence (Aug 9) as real content specifically to
exercise the backward-transfer rule end-to-end: Aug 9, 2026 is a Sunday,
so the vigil transfers cleanly back to Saturday, verified by a new
integration test alongside the unit-level rule and collision tests.
