cross mix knockout seeds

src/features/tournaments/server.ts

@@ -502,12 +502,30 @@ export const generateKnockoutBracket = createServerFn()
 
       const orderedTeamIds: string[] = [];
       const maxRank = tournament.group_config.advance_per_group;
+      const numGroups = tournament.group_config.num_groups;
 
-      for (let rank = 1; rank <= maxRank; rank++) {
-        const teamsAtRank = qualifiedTeams
-          .filter(t => t.rank === rank)
-          .sort((a, b) => a.groupOrder - b.groupOrder);
-        orderedTeamIds.push(...teamsAtRank.map(t => t.teamId));
+      const teamsByGroup: string[][] = [];
+      for (let g = 0; g < numGroups; g++) {
+        teamsByGroup[g] = [];
+      }
+
+      for (const qualified of qualifiedTeams) {
+        teamsByGroup[qualified.groupOrder][qualified.rank - 1] = qualified.teamId;
+      }
+
+      const totalTeams = numGroups * maxRank;
+      for (let i = 0; i < totalTeams / 2; i++) {
+        const group1 = i % numGroups;
+        const rankIndex1 = Math.floor(i / numGroups);
+
+        const group2 = (i + 1) % numGroups;
+        const rankIndex2 = maxRank - 1 - rankIndex1;
+
+        const team1 = teamsByGroup[group1]?.[rankIndex1];
+        const team2 = teamsByGroup[group2]?.[rankIndex2];
+
+        if (team1) orderedTeamIds.push(team1);
+        if (team2) orderedTeamIds.push(team2);
       }
 
       const teamCount = orderedTeamIds.length;
@@ -673,6 +691,7 @@ export const generateGroupStage = createServerFn()
         createdGroups.push(group);
 
         const teamIds = assignment.teamIds;
+
         for (let i = 0; i < teamIds.length; i++) {
           for (let j = i + 1; j < teamIds.length; j++) {
             groupStageMatches.push({