refactor: reorganize startup persistence boundaries

app/startup/composition/database.py

@@ -0,0 +1,63 @@
+"""数据库治理能力的宿主组合根。"""
+
+from __future__ import annotations
+
+from app.adapters.system.backup.database import (
+    PostgreSQLBackupBackend,
+    SQLiteBackupBackend,
+)
+from app.application.backup import BackupPolicy, DatabaseBackupService
+from app.application.database import (
+    DatabaseGovernance,
+    DatabaseHealthService,
+    configure_database_governance,
+)
+from app.application.maintenance import (
+    DataCleanupService,
+    read_cleanup_policy,
+)
+from app.db.engine import get_engine
+from app.db.health import probe_database
+from app.db.maintenance import DatabaseCleanupRepository
+from app.db.session import SessionFactory
+from app.runtime.settings import RuntimeSettingsCompat
+
+settings = RuntimeSettingsCompat()
+
+
+def build_database_governance() -> DatabaseGovernance:
+    """以缓存同步引擎为事实源构造一个完整数据库治理门面。"""
+    engine = get_engine()
+    dialect = engine.dialect.name
+    if dialect == "sqlite":
+        backup_backend = SQLiteBackupBackend(engine)
+    elif dialect == "postgresql":
+        backup_backend = PostgreSQLBackupBackend(engine)
+    else:
+        raise RuntimeError(f"不支持的数据库类型：{dialect}")
+
+    return DatabaseGovernance(
+        health=DatabaseHealthService(probe_database),
+        cleanup=DataCleanupService(
+            repository=DatabaseCleanupRepository(session_factory=SessionFactory),
+            policy_reader=read_cleanup_policy,
+        ),
+        backup=DatabaseBackupService(
+            backend=backup_backend,
+            policy_reader=read_backup_policy,
+        ),
+    )
+
+
+def configure_database() -> None:
+    """构造并登记宿主进程唯一的数据库治理门面。"""
+    configure_database_governance(build_database_governance())
+
+
+def read_backup_policy() -> BackupPolicy:
+    """读取一次可热更新的数据库备份目录与保留策略。"""
+    return BackupPolicy(
+        root=settings.DATABASE_BACKUP_PATH,
+        retention_days=settings.DB_BACKUP_RETENTION_DAYS,
+        max_count=settings.DB_BACKUP_MAX_COUNT,
+    )