feat: add selected task reset actions

app/db.py

@@ -518,6 +518,16 @@ def list_tasks(batch_id=None, stage=None, status=None, alias=None, path=None, co
         return _fetch_all(database, sql, params, Task)
 
 
+def get_task(task_id, path=None, conn=None):
+    with _connection(conn, path) as database:
+        return _fetch_one(
+            database,
+            "SELECT * FROM tasks WHERE id = ?",
+            (int(task_id),),
+            Task,
+        )
+
+
 def mark_running(task_id, phase, path=None, conn=None) -> None:
     _attempt_field(phase)
     with _connection(conn, path) as database:
@@ -639,6 +649,71 @@ def set_applied(task_id, committed, error=None, path=None, conn=None) -> None:
                 )
 
 
+def reset_generated(task_id, delete_file=False, path=None, conn=None) -> dict:
+    """Clear local AI result and move the task back to collected state."""
+
+    with _connection(conn, path) as database:
+        before = get_task(task_id, conn=database)
+        if before is None:
+            raise DbError(f"任务不存在: {task_id}")
+        new_cover_path = before.new_cover_path
+        deleted_file = None
+        if delete_file:
+            raise DbError("重置生成结果默认不删除本地新封面文件，请手动确认后清理")
+        now = _now()
+        with database:
+            database.execute(
+                """
+                UPDATE tasks
+                SET new_title = NULL,
+                    new_cover_path = NULL,
+                    stage = 'collected',
+                    status = 'success',
+                    last_error = NULL,
+                    generated_at = NULL,
+                    updated_at = ?
+                WHERE id = ?
+                """,
+                (now, int(task_id)),
+            )
+        after = get_task(task_id, conn=database)
+    return {
+        "task_id": int(task_id),
+        "before": before,
+        "after": after,
+        "new_cover_path": new_cover_path,
+        "deleted_file": deleted_file,
+    }
+
+
+def reset_apply_status(task_id, path=None, conn=None) -> dict:
+    """Move a generated/applied local task back to pending update state."""
+
+    with _connection(conn, path) as database:
+        before = get_task(task_id, conn=database)
+        if before is None:
+            raise DbError(f"任务不存在: {task_id}")
+        now = _now()
+        with database:
+            database.execute(
+                """
+                UPDATE tasks
+                SET stage = 'generated',
+                    status = 'pending',
+                    last_error = NULL,
+                    updated_at = ?
+                WHERE id = ?
+                """,
+                (now, int(task_id)),
+            )
+        after = get_task(task_id, conn=database)
+    return {
+        "task_id": int(task_id),
+        "before": before,
+        "after": after,
+    }
+
+
 def create_run_log(
     run_type,
     dry_run=False,