feat(calendar): Compute — build celebrations, apply precedence + transfer, cycles

Also: deterministic pick tiebreak by slug.

1 files changed, 10 insertions, 2 deletions

diff --git a/internal/calendar/precedence.go b/internal/calendar/precedence.go
index b013b77..7919879 100644
--- a/internal/calendar/precedence.go
+++ b/internal/calendar/precedence.go
@@ -62,10 +62,18 @@ func precedence(c candidate) int {
 }
 
 // pick returns the highest-precedence candidate as observed and the rest as
-// others (commemorations / optional memorials), stably ordered by precedence.
+// others (commemorations / optional memorials). Ordering is deterministic:
+// by precedence band, then by slug, so equal-band collisions resolve the same
+// way on every run.
 func pick(cands []candidate) (candidate, []candidate) {
 	sorted := make([]candidate, len(cands))
 	copy(sorted, cands)
-	sort.SliceStable(sorted, func(i, j int) bool { return precedence(sorted[i]) < precedence(sorted[j]) })
+	sort.SliceStable(sorted, func(i, j int) bool {
+		pi, pj := precedence(sorted[i]), precedence(sorted[j])
+		if pi != pj {
+			return pi < pj
+		}
+		return sorted[i].Cel.Slug < sorted[j].Cel.Slug
+	})
 	return sorted[0], sorted[1:]
 }