When Advent 4's own Sunday lands on Dec 24, the Vigil of Christmas's
identity (rank, collect, Lauds antiphons, Matins Gospel nocturn) now
governs the day, matching the reference engine's own rule that a
privileged Sunday never displaces it. Unlike the reference engine's own
"no commemoratio" for this exact collision, Advent 4 is deliberately
still commemorated — the Sundays of Advent have real standing of their
own. Matins' three-nocturn Sunday psalmody is untouched either way,
since it's driven by weekday, not by which id wins.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ME8QNPdEmHSbSx1r6VmDRG
Non-Sunday Dec 24 previously just inherited Advent 4's ferial collect and
antiphons with nothing of its own. Import the Vigil's real proper content
from the reference engine (Duplex I classis): its own collect, all 5 Lauds
antiphons, the Benedictus antiphon, and Matins' Gospel (Matt 1:18-21) +
St. Jerome homily, wired via a new `vigil-of-christmas` temporal id scoped
to non-Sunday Dec 24 only. Advent IV landing on Dec 24 itself is untouched,
left as its own separate design question.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ME8QNPdEmHSbSx1r6VmDRG
Post-Pentecost overflow years (early Easter, fewer than 6 Sundays after
Epiphany fit before Septuagesima) previously clamped every excess Sunday
to post-pentecost-24 instead of resuming the skipped post-Epiphany
Sundays' own content, per the traditional rubric. Ported directly from
the reference engine's own DivinumOfficium/Date.pm getweek().
Also adds the Epiphany VI Saturday-before-Septuagesima commemoration
(only when Epiphany V was the last Sunday to actually occur), and fixes
day-label.ts's on-screen display to track the same resumed-Sunday
content instead of a raw elapsed-week count — including a correction so
the fixed final Sunday of the year always reads "23rd Sunday after
Trinity", not a per-year-varying number.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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.
will