diff --git a/backend/migrations/000051_user_token_version.sql b/backend/migrations/000051_user_token_version.sql
deleted file mode 100644
index 2febaf3..0000000
--- a/backend/migrations/000051_user_token_version.sql
+++ /dev/null
@@ -1,10 +0,0 @@
--- +goose Up
-
--- 用户会话版本：冻结、改密和退出时递增，立即撤销旧 access/refresh token。
-ALTER TABLE users
-  ADD COLUMN token_version BIGINT NOT NULL DEFAULT 1 COMMENT '用户令牌版本';
-
--- +goose Down
-
-ALTER TABLE users
-  DROP COLUMN token_version;
diff --git a/backend/migrations/000053_file_upload_owners_cleanup_index.sql b/backend/migrations/000053_file_upload_owners_cleanup_index.sql
deleted file mode 100644
index 9ac010a..0000000
--- a/backend/migrations/000053_file_upload_owners_cleanup_index.sql
+++ /dev/null
@@ -1,10 +0,0 @@
--- +goose Up
-
--- 为长期未关联上传归属记录的定时清理提供索引。
-ALTER TABLE file_upload_owners
-  ADD KEY idx_file_upload_owners_created_at (created_at);
-
--- +goose Down
-
-ALTER TABLE file_upload_owners
-  DROP INDEX idx_file_upload_owners_created_at;
diff --git a/backend/migrations/000050_order_list_least_privilege.sql b/backend/migrations/000067_order_list_least_privilege.sql
similarity index 100%
rename from backend/migrations/000050_order_list_least_privilege.sql
rename to backend/migrations/000067_order_list_least_privilege.sql
diff --git a/backend/migrations/000052_file_upload_owners.sql b/backend/migrations/000068_file_upload_owners.sql
similarity index 92%
rename from backend/migrations/000052_file_upload_owners.sql
rename to backend/migrations/000068_file_upload_owners.sql
index 51f5cfe..f340093 100644
--- a/backend/migrations/000052_file_upload_owners.sql
+++ b/backend/migrations/000068_file_upload_owners.sql
@@ -1,7 +1,7 @@
 -- +goose Up
 
 -- 私有文件上传归属：在业务记录写入前，仅允许上传者预览自己的临时文件。
-CREATE TABLE file_upload_owners (
+CREATE TABLE IF NOT EXISTS file_upload_owners (
   id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
   user_id BIGINT UNSIGNED NOT NULL,
   object_key VARCHAR(512) NOT NULL,
diff --git a/backend/migrations/000069_file_upload_owners_cleanup_index.sql b/backend/migrations/000069_file_upload_owners_cleanup_index.sql
new file mode 100644
index 0000000..3f5b6c1
--- /dev/null
+++ b/backend/migrations/000069_file_upload_owners_cleanup_index.sql
@@ -0,0 +1,21 @@
+-- +goose Up
+
+-- 为长期未关联上传归属记录的定时清理提供索引。
+-- 兼容历史上已按旧编号执行过该索引的数据库，重复执行时跳过。
+SET @idx_exists := (
+  SELECT COUNT(*) FROM information_schema.statistics
+  WHERE table_schema = DATABASE()
+    AND table_name = 'file_upload_owners'
+    AND index_name = 'idx_file_upload_owners_created_at'
+);
+SET @ddl := IF(@idx_exists > 0,
+  'SELECT 1',
+  'ALTER TABLE file_upload_owners ADD KEY idx_file_upload_owners_created_at (created_at)');
+PREPARE stmt FROM @ddl;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+-- +goose Down
+
+ALTER TABLE file_upload_owners
+  DROP INDEX idx_file_upload_owners_created_at;