Settings never told the user which days "Auto" turns each seasonal theme on.
Extracted the date windows out of getActiveSeason into a shared SEASON_SCHEDULE
(seasonSchedule.ts) — the single source of truth for both the runtime Auto
selector and the settings UI, so displayed dates can't drift from real activation.
- seasonal/types.ts: SeasonTheme + SeasonalOverlayProps (leaf module).
- seasonal/seasonSchedule.ts: priority-ordered SEASON_SCHEDULE with human date
ranges + SEASON_DATE_RANGES + getActiveSeason (behavior-preserving refactor).
- SeasonalEffect.tsx: consume the shared type/selector; re-export SeasonTheme.
- General.tsx: per-theme date caption under each swatch ("Oct 15 – Nov 1"), Auto
reads "By calendar", and the section description explains it.
- seasonSchedule.test.ts (6): representative day per theme, overlap priority
(Deep Space > Autumn, New Year > Lunar), inclusive boundaries, off-season null.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
