diff --git a/video-gen-api/alembic/versions/2026070902_add_generated_date_expression_indexes.py b/video-gen-api/alembic/versions/2026070902_add_generated_date_expression_indexes.py
new file mode 100644
index 00000000..8520a8c6
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+++ b/video-gen-api/alembic/versions/2026070902_add_generated_date_expression_indexes.py
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+"""2026070902_add_generated_date_expression_indexes
+
+Revision ID: 2026070902
+Revises: 2026070901
+Create Date: 2026-07-09 00:00:00.000000
+
+该文件包含 2026-07-09 的数据库迁移内容：
+1. chat_generation_tasks 表增加 generated_at 日期表达式索引，优化按日期分组/筛选
+2. generation_records 表增加 generated_at 日期表达式索引，优化按日期分组/筛选
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision: str = '2026070902'
+down_revision: Union[str, None] = '2026070901'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ========================================
+    # 2026-07-09 - 生成记录表增加日期表达式索引
+    # ========================================
+    op.create_index(
+        'idx_chat_generation_tasks_generated_date',
+        'chat_generation_tasks',
+        [sa.text("date(generated_at)")],
+        unique=False,
+    )
+    op.create_index(
+        'idx_generation_records_generated_date',
+        'generation_records',
+        [sa.text("date(generated_at)")],
+        unique=False,
+    )
+
+
+def downgrade() -> None:
+    # ========================================
+    # 2026-07-09 - 生成记录表增加日期表达式索引（回滚）
+    # ========================================
+    op.drop_index('idx_generation_records_generated_date', table_name='generation_records')
+    op.drop_index('idx_chat_generation_tasks_generated_date', table_name='chat_generation_tasks')