feat: 完善 MVP-2 演示和进度体验

app/db.py

@@ -1,5 +1,7 @@
 from collections.abc import Generator
 from pathlib import Path
+from shutil import copy2
+from datetime import UTC, datetime
 
 from sqlalchemy import Engine, create_engine, event
 from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker
@@ -30,6 +32,16 @@ def create_sqlite_engine(database_url: str):
     return engine
 
 
+def sqlite_file_path(target_engine: Engine = None) -> Path | None:
+    target_engine = target_engine or engine
+    if target_engine.url.get_backend_name() != "sqlite":
+        return None
+    database = target_engine.url.database
+    if not database or database == ":memory:":
+        return None
+    return Path(database)
+
+
 engine = create_sqlite_engine(get_settings().database_url)
 SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False)
 
@@ -63,10 +75,39 @@ def checkpoint_sqlite_wal(target_engine: Engine = engine) -> bool:
     return True
 
 
+def ensure_sqlite_schema_compat(target_engine: Engine = engine) -> None:
+    if target_engine.url.get_backend_name() != "sqlite":
+        return
+    with target_engine.begin() as connection:
+        task_columns = {row[1] for row in connection.exec_driver_sql("PRAGMA table_info(tasks)").all()}
+        if "current_stage" not in task_columns:
+            connection.exec_driver_sql("ALTER TABLE tasks ADD COLUMN current_stage VARCHAR(64)")
+        if "last_progress_at" not in task_columns:
+            connection.exec_driver_sql("ALTER TABLE tasks ADD COLUMN last_progress_at DATETIME")
+
+
+def backup_sqlite_files(target_engine: Engine = engine) -> list[Path]:
+    db_path = sqlite_file_path(target_engine)
+    if db_path is None:
+        return []
+    backup_dir = db_path.parent / "corrupt-backups"
+    backup_dir.mkdir(parents=True, exist_ok=True)
+    timestamp = datetime.now(UTC).strftime("%Y%m%d-%H%M%S")
+    copied: list[Path] = []
+    for source in [db_path, db_path.with_name(f"{db_path.name}-wal"), db_path.with_name(f"{db_path.name}-shm")]:
+        if not source.exists():
+            continue
+        target = backup_dir / f"{source.name}.{timestamp}.bak"
+        copy2(source, target)
+        copied.append(target)
+    return copied
+
+
 def init_db() -> None:
     import app.models  # noqa: F401
 
     Base.metadata.create_all(engine)
+    ensure_sqlite_schema_compat(engine)
     check_database_integrity(engine)
     checkpoint_sqlite_wal(engine)