fix: 限制有效签名名称唯一并保留批量导入补资料

api/prisma/migrations/20260917120000_signature_active_name_unique/migration.sql

@@ -0,0 +1,24 @@
+BEGIN;
+
+-- Preserve every historical record. A conflicting installation must be reviewed before release.
+LOCK TABLE "SmsSignature" IN SHARE ROW EXCLUSIVE MODE;
+DO $$
+BEGIN
+  IF EXISTS (
+    SELECT 1 FROM "SmsSignature"
+    WHERE "auditStatus" NOT IN ('deleted', 'disabled')
+    GROUP BY "tenantId", "applicationId", "name" HAVING count(*) > 1
+  ) THEN
+    RAISE EXCEPTION 'Cannot enforce signature uniqueness: duplicate active signatures exist; review tenantId/applicationId/name groups without deleting or merging automatically';
+  END IF;
+END $$;
+
+CREATE UNIQUE INDEX "SmsSignature_active_application_name_key"
+  ON "SmsSignature" ("tenantId", "applicationId", "name")
+  WHERE "applicationId" IS NOT NULL AND "auditStatus" NOT IN ('deleted', 'disabled');
+
+CREATE UNIQUE INDEX "SmsSignature_active_unbound_name_key"
+  ON "SmsSignature" ("tenantId", "name")
+  WHERE "applicationId" IS NULL AND "auditStatus" NOT IN ('deleted', 'disabled');
+
+COMMIT;

api/prisma/schema.prisma

@@ -776,6 +776,8 @@ model ReportNotificationRead {
 }
 
 model SmsSignature {
+  // Active name uniqueness (including null applicationId) is enforced by two partial SQL indexes.
+  // Owned by migration 20260917120000_signature_active_name_unique; do not replace with @@unique.
   id              String   @id @default(cuid())
   tenantId        String
   applicationId   String?