Fix: Resolve leaderboard pagination duplicates (fixes #1913)

supabase/migrations/20260805000000_fix_leaderboard_pagination.sql

@@ -0,0 +1,53 @@
+-- Fix Issue 1913: Leaderboard pagination causes duplicate user entries between pages
+-- Adds l.id ASC to ORDER BY clauses in get_leaderboard to make sorting deterministic
+
+CREATE OR REPLACE FUNCTION public.get_leaderboard(
+  _timeframe text,
+  _limit int DEFAULT 100,
+  _offset int DEFAULT 0
+)
+RETURNS TABLE (
+  id uuid,
+  user_id uuid,
+  username text,
+  avatar_url text,
+  xp bigint,
+  streak int,
+  sessions_joined int,
+  badges text[],
+  updated_at text
+) LANGUAGE plpgsql SECURITY DEFINER SET search_path = public AS $$
+BEGIN
+  IF _timeframe = 'All Time' THEN
+    RETURN QUERY
+    SELECT l.id, l.user_id, l.username, l.avatar_url, l.xp::bigint, l.streak, l.sessions_joined, l.badges, ''::text AS updated_at
+    FROM public.leaderboard l
+    ORDER BY l.xp DESC, l.id ASC
+    LIMIT _limit OFFSET _offset;
+  ELSIF _timeframe = 'Weekly' THEN
+    RETURN QUERY
+    SELECT l.id, l.user_id, l.username, l.avatar_url, COALESCE(SUM(t.amount), 0)::bigint AS xp, l.streak, l.sessions_joined, l.badges, ''::text AS updated_at
+    FROM public.leaderboard l
+    JOIN public.xp_transactions t ON l.user_id = t.user_id
+    WHERE t.created_at >= date_trunc('week', now())
+    GROUP BY l.id, l.user_id, l.username, l.avatar_url, l.streak, l.sessions_joined, l.badges
+    ORDER BY xp DESC, l.id ASC
+    LIMIT _limit OFFSET _offset;
+  ELSIF _timeframe = 'Monthly' THEN
+    RETURN QUERY
+    SELECT l.id, l.user_id, l.username, l.avatar_url, COALESCE(SUM(t.amount), 0)::bigint AS xp, l.streak, l.sessions_joined, l.badges, ''::text AS updated_at
+    FROM public.leaderboard l
+    JOIN public.xp_transactions t ON l.user_id = t.user_id
+    WHERE t.created_at >= date_trunc('month', now())
+    GROUP BY l.id, l.user_id, l.username, l.avatar_url, l.streak, l.sessions_joined, l.badges
+    ORDER BY xp DESC, l.id ASC
+    LIMIT _limit OFFSET _offset;
+  ELSE
+    RETURN QUERY
+    SELECT l.id, l.user_id, l.username, l.avatar_url, l.xp::bigint, l.streak, l.sessions_joined, l.badges, ''::text AS updated_at
+    FROM public.leaderboard l
+    ORDER BY l.xp DESC, l.id ASC
+    LIMIT _limit OFFSET _offset;
+  END IF;
+END;
+$$;