Build the Paschaltide "Suffragium Paschale" mechanism

Throughout Paschaltide (Eastertide/Ascensiontide/Pentecost), two
things happen wherever they'd otherwise show: the ordinary
5-suffrage set (Cross/BVM/Joseph/Apostles/Peace) collapses into one
alleluia-form "Suffragium Paschale" (Lauds and Vespers each have
their own distinct antiphon here, unlike the ordinary suffrages,
which share identical text at both hours), and the ferial-Preces
litany drops entirely rather than being replaced. Live-verified
against the reference source's own [Suffragium] macro directly,
byte-identical between Monastic Tridentinum 1617 and Tridentine 1906.

Exported isPaschaltide(season) from resolve-common.ts (wraps the
pre-existing PASCHALTIDE_SEASONS set). resolveSuffrages gained a
third hourId parameter to pick the right antiphon; the Preces
omission is a small new check gated on the same isFerialOrVigil
predicate that already selects the ferial litany form.

Authored lauds-suffrage-paschale.yml and vespers-suffrage-
paschale.yml -- English on the Vespers antiphon is this project's own
translation (the reference engine leaves it untranslated) and marked
draft; everything else verified.

Closes the last item in TODO.md's "Mechanism gaps" priority tier.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AGjUyhUZJaSjiniEmnLdak

src/data/propers/common/lauds-suffrage-paschale.yml

@@ -0,0 +1,29 @@
+# Throughout Paschaltide (Eastertide/Ascensiontide/Pentecost), the whole
+# ordinary 5-suffrage set (Cross/BVM/Joseph/Apostles/Peace) collapses into
+# this single alleluia-form "Suffragium Paschale" instead — live-verified
+# against Divinum Officium (Monastic Tridentinum 1617 and Tridentine 1906,
+# byte-identical between the two tracks), Lauds live query, 2026-04-20 (a
+# plain Eastertide feria). Distinct antiphon from Vespers' own
+# (vespers-suffrage-paschale.yml, "Crucem sanctam súbiit..."); the
+# versicle/response and collect are shared between both hours.
+id: lauds-suffrage-paschale
+text:
+  la: |
+    Ant. Crucifíxus surréxit a mórtuis, et redémit nos, allelúja, allelúja.
+    V. Dícite in natiónibus, allelúja.
+    R. Quia Dóminus regnávit a ligno, allelúja.
+    Orémus.
+    Deus qui pro nobis Fílium tuum Crucis patíbulum subíre voluísti, ut inimíci a nobis expélleres potestátem: concéde nobis fámulis tuis; ut resurrectiónis grátiam consequámur.
+    Per eúmdem Dóminum nostrum Jesum Christum Fílium tuum, qui tecum vivit et regnat in unitáte Spíritus Sancti, Deus, per ómnia sǽcula sæculórum.
+    R. Amen.
+  en: |
+    Ant. He that was crucified is risen from the dead, and hath redeemed us. Alleluia, alleluia.
+    V. Say among the heathen, alleluia.
+    R. That the Lord reigneth from the tree, alleluia.
+    Let us pray.
+    O God, who didst send thy Son to suffer death for us upon the Cross, that thou mightest deliver us from the power of the enemy: grant unto us thy servants to be made partakers of his Resurrection.
+    Through the same Jesus Christ, thy Son, Our Lord, Who liveth and reigneth with thee in the unity of the Holy Ghost, God, world without end.
+    R. Amen.
+status:
+  la: verified
+  en: verified

src/data/propers/common/vespers-suffrage-paschale.yml

@@ -0,0 +1,30 @@
+# Vespers' own antiphon for the same "Suffragium Paschale" substitution
+# described in lauds-suffrage-paschale.yml's own header — shares that
+# file's versicle/response and collect, but its own distinct antiphon
+# ("Crucem sanctam súbiit..."), live-verified against Divinum Officium
+# (Monastic Tridentinum 1617), Vespers live query, 2026-04-20 (a plain
+# Eastertide feria). English antiphon translation is this project's own
+# (the reference engine's own English-language render leaves this
+# particular antiphon untranslated, Latin-only) — status left `draft`
+# for the English text specifically pending a better-sourced translation.
+id: vespers-suffrage-paschale
+text:
+  la: |
+    Ant. Crucem sanctam súbiit, qui inférnum confrégit; accínctus est poténtia, surréxit die tértia, allelúja.
+    V. Dícite in natiónibus, allelúja.
+    R. Quia Dóminus regnávit a ligno, allelúja.
+    Orémus.
+    Deus qui pro nobis Fílium tuum Crucis patíbulum subíre voluísti, ut inimíci a nobis expélleres potestátem: concéde nobis fámulis tuis; ut resurrectiónis grátiam consequámur.
+    Per eúmdem Dóminum nostrum Jesum Christum Fílium tuum, qui tecum vivit et regnat in unitáte Spíritus Sancti, Deus, per ómnia sǽcula sæculórum.
+    R. Amen.
+  en: |
+    Ant. He bore the holy Cross, who broke the gates of hell; he was girded with power, and rose again on the third day, alleluia.
+    V. Say among the heathen, alleluia.
+    R. That the Lord reigneth from the tree, alleluia.
+    Let us pray.
+    O God, who didst send thy Son to suffer death for us upon the Cross, that thou mightest deliver us from the power of the enemy: grant unto us thy servants to be made partakers of his Resurrection.
+    Through the same Jesus Christ, thy Son, Our Lord, Who liveth and reigneth with thee in the unity of the Holy Ghost, God, world without end.
+    R. Amen.
+status:
+  la: verified
+  en: draft

src/hours/lauds.ts

@@ -26,6 +26,7 @@ import {
   resolveResponsory,
   resolveOfficeBundle,
   resolveSuffrages,
+  isPaschaltide,
 } from './resolve-common';
 import laudsDefinitionData from '../data/hours/lauds.yml';
 import laudsAntiphonsData from '../data/hours/lauds-antiphons.yml';
@@ -366,7 +367,7 @@ function resolvePart(part: HourPart, day: LiturgicalDay): ResolvedPart[] {
     case 'day-collects':
       return getDayCollects(day);
     case 'suffrages':
-      return resolveSuffrages(day, part.omitOnDouble);
+      return resolveSuffrages(day, part.omitOnDouble, 'lauds');
     case 'versicle':
     case 'chapter':
     case 'responsory':
@@ -377,6 +378,15 @@ function resolvePart(part: HourPart, day: LiturgicalDay): ResolvedPart[] {
       return [{ kind: 'preces', text: resolveCommon(id), label: getMarianAntiphonLabel(id) }];
     }
     case 'lauds-preces': {
+      // Throughout Paschaltide, the whole ferial-Preces litany drops
+      // entirely rather than being replaced by anything — live-verified
+      // ("Preces Feriales{omittitur}" against both Monastic Tridentinum
+      // 1617 and Tridentine 1906, a plain Eastertide feria, 2026-04-20).
+      // Sunday/feast's own short litany is untouched — that's a separate,
+      // universal collect-opening dialogue, not this ferial-specific one.
+      if (isFerialOrVigil(day) && isPaschaltide(day.season)) {
+        return [];
+      }
       const id = isFerialOrVigil(day) ? 'lauds-preces-feriales' : 'lauds-short-litany';
       return [{ kind: 'preces', text: resolveCommon(id) }];
     }

src/hours/resolve-common.ts

@@ -306,6 +306,15 @@ export function getMinorHourOverrideId(day: LiturgicalDay): string | undefined {
  */
 const PASCHALTIDE_SEASONS = new Set(['eastertide', 'ascensiontide', 'pentecost']);
 
+/** Whether `season` falls within the same broad Paschaltide window
+ * `PASCHALTIDE_SEASONS` already governs elsewhere in this file (Marian
+ * antiphon, Common-category text, hymn doxology) — exported so
+ * hours/lauds.ts's and hours/vespers.ts's own ferial-Preces omission can
+ * share the identical boundary rather than redeclaring it. */
+export function isPaschaltide(season: string): boolean {
+  return PASCHALTIDE_SEASONS.has(season);
+}
+
 /**
  * Which seasonal office-content suffix (if any) a day's season maps to —
  * shared by Lauds' and Vespers' own resolveOffice, both of which fall
@@ -789,7 +798,11 @@ const SUFFRAGE_LABELS: Record<string, string> = {
  * the caveat on what real practice also suppresses them for that isn't
  * modeled.
  */
-export function resolveSuffrages(day: LiturgicalDay, omitOnDouble: boolean | undefined): ResolvedPart[] {
+export function resolveSuffrages(
+  day: LiturgicalDay,
+  omitOnDouble: boolean | undefined,
+  hourId: 'lauds' | 'vespers' = 'lauds',
+): ResolvedPart[] {
   // isDoubleOrHigher only ever looks at a sanctoral rank — Christ the
   // King is modeled as a named temporal winner (see
   // ALWAYS_OVERRIDE_TEMPORAL_IDS above) with no FeastClass to check at
@@ -812,6 +825,18 @@ export function resolveSuffrages(day: LiturgicalDay, omitOnDouble: boolean | und
   if (omitOnDouble && (isDoubleOrHigher(day.winner) || isChristTheKing || isSeasonallyExcluded || isWithinAnOctave)) {
     return [];
   }
+  // Throughout the rest of Paschaltide, the whole ordinary 5-suffrage set
+  // below collapses into a single alleluia-form "Suffragium Paschale" —
+  // live-verified against both Monastic Tridentinum 1617 and Tridentine
+  // 1906 directly (a plain Eastertide feria, 2026-04-20), byte-identical
+  // between the two tracks. Checked after the omit-entirely gate above
+  // (an active octave/Double+/Advent-Christmastide-Passiontide already
+  // drops suffrages regardless of season, unaffected by this) but before
+  // the ordinary per-suffrage filtering below, since this replaces that
+  // filtering outright rather than adjusting it.
+  if (isPaschaltide(day.season)) {
+    return [{ kind: 'preces', text: resolveCommon(`${hourId}-suffrage-paschale`) }];
+  }
   // "Of the Holy Cross" is the real *ferial*-office suffrage, sourced
   // from Tridentine 1906/1910 (a different track than the other four,
   // which come from Monastic 1617 -- that track has no Cross suffrage

src/hours/vespers.ts

@@ -26,6 +26,7 @@ import {
   resolveResponsory,
   resolveOfficeBundle,
   resolveSuffrages,
+  isPaschaltide,
 } from './resolve-common';
 import vespersDefinitionData from '../data/hours/vespers.yml';
 import vespersAntiphonsData from '../data/hours/vespers-antiphons.yml';
@@ -275,13 +276,19 @@ function resolvePart(part: HourPart, day: LiturgicalDay, weekday: Weekday): Reso
       ];
     }
     case 'vespers-preces': {
+      // Throughout Paschaltide, the whole ferial-Preces litany drops
+      // entirely rather than being replaced by anything — see lauds.ts's
+      // identical 'lauds-preces' case for the live-verification detail.
+      if (isFerialOrVigil(day) && isPaschaltide(day.season)) {
+        return [];
+      }
       const id = isFerialOrVigil(day) ? 'vespers-preces-feriales' : 'lauds-short-litany';
       return [{ kind: 'preces', text: resolveCommon(id) }];
     }
     case 'day-collects':
       return getDayCollects(day);
     case 'suffrages':
-      return resolveSuffrages(day, part.omitOnDouble);
+      return resolveSuffrages(day, part.omitOnDouble, 'vespers');
     case 'preces':
       return [{ kind: 'preces', text: resolveCommon(part.textRef.id), label: part.label }];
     case 'versicle':