diff --git a/src/server/services/round-engine.ts b/src/server/services/round-engine.ts
index 9e063f6..348085d 100644
--- a/src/server/services/round-engine.ts
+++ b/src/server/services/round-engine.ts
@@ -235,6 +235,42 @@ export async function closeRound(
       // Expire pending intents
       await expireIntentsForRound(roundId, actorId)
 
+      // Auto-close any preceding active rounds (lower sortOrder, same competition)
+      const precedingActiveRounds = await tx.round.findMany({
+        where: {
+          competitionId: round.competitionId,
+          sortOrder: { lt: round.sortOrder },
+          status: 'ROUND_ACTIVE',
+        },
+        orderBy: { sortOrder: 'asc' },
+      })
+
+      for (const prev of precedingActiveRounds) {
+        await tx.round.update({
+          where: { id: prev.id },
+          data: { status: 'ROUND_CLOSED' },
+        })
+        await tx.decisionAuditLog.create({
+          data: {
+            eventType: 'round.closed',
+            entityType: 'Round',
+            entityId: prev.id,
+            actorId,
+            detailsJson: {
+              roundName: prev.name,
+              roundType: prev.roundType,
+              previousStatus: 'ROUND_ACTIVE',
+              closedBy: 'cascade',
+              triggeringRoundId: roundId,
+            },
+            snapshotJson: {
+              timestamp: new Date().toISOString(),
+              emittedBy: 'round-engine',
+            },
+          },
+        })
+      }
+
       await tx.decisionAuditLog.create({
         data: {
           eventType: 'round.closed',
@@ -245,6 +281,7 @@ export async function closeRound(
             roundName: round.name,
             roundType: round.roundType,
             previousStatus: 'ROUND_ACTIVE',
+            cascadeClosed: precedingActiveRounds.map((r: any) => r.name),
           },
           snapshotJson: {
             timestamp: new Date().toISOString(),