优化结构

internal/data/README.md

@@ -3,12 +3,29 @@
 `data` owns database clients, persistence models, migrations, configuration
 watching, and repository implementations.
 
-- `repository/`: system repositories and table persistence
-- `payment/`: payment configuration and payment-order persistence
+- `system/`: system repositories and system table persistence
+- `task/`: timed-task tables and task persistence
+- `integration/`: `sys_integration_configs` and integration configuration persistence
+- `payment/`: payment-order persistence
 - each subpackage owns its Wire `ProviderSet`; the root package only binds the
-  shared `Data` infrastructure and aggregates those sets
-- root files: shared database lifecycle, runtime clients, integration-config
-  storage, data-scope auditing, and migration orchestration
+  shared `Data` infrastructure and aggregates those sets, mirroring `biz`
+- root files: shared database lifecycle, runtime clients, configuration
+  orchestration, data-scope auditing, and migration orchestration
+
+新增数据模块时创建 `internal/data/<module>`，提供 `ProviderSet()` 和
+`Migrations()`，再在 `internal/modules/<module>/definition.go` 注册迁移与
+管理面，最后在根 `data.ProviderSet` 中注册该模块。根 `data` 不应直接
+拥有业务表 PO，也不应让一个模块引用另一个模块的私有 PO。
 
 Root files intentionally stay in one package because they share `Data` state and
 reload locks. Do not split them into packages only to reduce file count.
+
+当前内置数据模块为 `system`、`integration`、`task` 和 `payment`。其中：
+
+- `system` 只拥有 `sys_*` 系统表、系统仓储、种子和系统维护清理；
+- `integration` 唯一拥有 `sys_integration_configs` 表模型、配置仓储和通信默认值；
+- `task` 只拥有定时任务与任务日志表；
+- `payment` 只拥有 `pay_orders` 等支付持久化，读取集成配置时复用 integration 的表模型。
+
+配置文件迁移、数据库切换、Redis/Mongo/对象存储重载仍属于根 data 的生命周期编排，
+不等同于某个业务模块的表仓储。