diff --git a/src/decisions/decisions.service.ts b/src/decisions/decisions.service.ts
index 911a1a2..1c40a2f 100644
--- a/src/decisions/decisions.service.ts
+++ b/src/decisions/decisions.service.ts
@@ -26,49 +26,53 @@ export class DecisionsService {
   }
 
   async create(session: AuthenticatedSession, dto: CreateDecisionDto) {
-    const [row] = await db
-      .insert(decisions)
-      .values({
+    return db.transaction(async (tx) => {
+      const [row] = await tx
+        .insert(decisions)
+        .values({
+          tenantId: session.tenantId,
+          ownerUserId: session.userId,
+          context: dto.context,
+          options: (dto.options ?? []) as unknown[],
+          assumptions: (dto.assumptions ?? []) as unknown[],
+          evidence: (dto.evidence ?? []) as unknown[],
+          reviewDueAt: dto.reviewDueAt ? new Date(dto.reviewDueAt) : undefined,
+        })
+        .returning();
+      await this.audit.record(tx, {
         tenantId: session.tenantId,
-        ownerUserId: session.userId,
-        context: dto.context,
-        options: (dto.options ?? []) as unknown[],
-        assumptions: (dto.assumptions ?? []) as unknown[],
-        evidence: (dto.evidence ?? []) as unknown[],
-        reviewDueAt: dto.reviewDueAt ? new Date(dto.reviewDueAt) : undefined,
-      })
-      .returning();
-    await this.audit.record(null, {
-      tenantId: session.tenantId,
-      actorId: session.userId,
-      action: 'decision.created',
-      resource: `decision:${row.id}`,
+        actorId: session.userId,
+        action: 'decision.created',
+        resource: `decision:${row.id}`,
+      });
+      return row;
     });
-    return row;
   }
 
   async update(session: AuthenticatedSession, id: string, dto: UpdateDecisionDto) {
     await this.getById(session, id);
-    const [row] = await db
-      .update(decisions)
-      .set({
-        ...(dto.context !== undefined ? { context: dto.context } : {}),
-        ...(dto.options !== undefined ? { options: dto.options as unknown[] } : {}),
-        ...(dto.assumptions !== undefined ? { assumptions: dto.assumptions as unknown[] } : {}),
-        ...(dto.evidence !== undefined ? { evidence: dto.evidence as unknown[] } : {}),
-        ...(dto.selectedOption !== undefined ? { selectedOption: dto.selectedOption } : {}),
-        ...(dto.outcomeReview !== undefined ? { outcomeReview: dto.outcomeReview } : {}),
-        ...(dto.reviewDueAt !== undefined ? { reviewDueAt: new Date(dto.reviewDueAt) } : {}),
-        updatedAt: new Date(),
-      })
-      .where(and(eq(decisions.id, id), eq(decisions.tenantId, session.tenantId)))
-      .returning();
-    await this.audit.record(null, {
-      tenantId: session.tenantId,
-      actorId: session.userId,
-      action: dto.selectedOption !== undefined ? 'decision.option_selected' : 'decision.updated',
-      resource: `decision:${id}`,
+    return db.transaction(async (tx) => {
+      const [row] = await tx
+        .update(decisions)
+        .set({
+          ...(dto.context !== undefined ? { context: dto.context } : {}),
+          ...(dto.options !== undefined ? { options: dto.options as unknown[] } : {}),
+          ...(dto.assumptions !== undefined ? { assumptions: dto.assumptions as unknown[] } : {}),
+          ...(dto.evidence !== undefined ? { evidence: dto.evidence as unknown[] } : {}),
+          ...(dto.selectedOption !== undefined ? { selectedOption: dto.selectedOption } : {}),
+          ...(dto.outcomeReview !== undefined ? { outcomeReview: dto.outcomeReview } : {}),
+          ...(dto.reviewDueAt !== undefined ? { reviewDueAt: new Date(dto.reviewDueAt) } : {}),
+          updatedAt: new Date(),
+        })
+        .where(and(eq(decisions.id, id), eq(decisions.tenantId, session.tenantId)))
+        .returning();
+      await this.audit.record(tx, {
+        tenantId: session.tenantId,
+        actorId: session.userId,
+        action: dto.selectedOption !== undefined ? 'decision.option_selected' : 'decision.updated',
+        resource: `decision:${id}`,
+      });
+      return row;
     });
-    return row;
   }
 }