Document dual game date storage in CLAUDE.md

scoringEvents.eventDate and playoffMatchGames.scheduledAt both hold game
dates depending on the event type. Added a dedicated section under
Important Patterns explaining when each is used and the two-step
selectDistinct + findMany pattern required for correct date queries.

https://claude.ai/code/session_014zKK15o5RJfTaodLvnZpF5

CLAUDE.md

@@ -147,6 +147,20 @@ const league = await db.query.leagues.findFirst({...});
 - Check `clerkId` for ownership validation
 - Admin checks via `isAdmin` boolean on users table
 
+### Scoring Event Dates
+
+Game/event dates are stored in **two different places** depending on the event type, and any date-based query must account for both:
+
+1. **`scoringEvents.eventDate`** (`date` column, `YYYY-MM-DD` string) — set directly on the event. Used for non-bracket events (majors, final standings) and sometimes for bracket events when the admin sets a single date for the whole round.
+
+2. **`playoffMatchGames.scheduledAt`** (`timestamp` column) — set on individual games within a bracket match. Bracket events (e.g. a playoff series) often have `eventDate = null` on the scoring event itself, with each game's exact time stored here instead.
+
+**Pattern for date-range queries:** Use a two-step approach:
+1. `selectDistinct` event IDs via left joins through `playoffMatches → playoffMatchGames`, filtering with `eventDate IN [dates] OR (scheduledAt >= dayStart AND scheduledAt <= dayEnd)`
+2. `findMany` on the matched IDs to load full event data with relations
+
+See `getEventsForDates` and `getUpcomingEventsForDraftedParticipants` in `app/models/scoring-event.ts` for the reference implementation. All timestamp bounds use UTC (`T00:00:00.000Z` / `T23:59:59.999Z`).
+
 ### Draft Logic
 
 The draft system implements snake draft: