fix(#558): migration幂等处理，phone字段已在029中存在

alembic/versions/049_wechat_login_phone.py

@@ -1,17 +1,18 @@
-"""#558 - 微信登录：用户手机号字段 + 验证码表
+"""#558 - 微信登录：手机号绑定字段 + 验证码表
 
 Revision ID: 049
 Revises: 048
 Create Date: 2026-07-21
 
 Changes:
-1. users 表新增 phone / phone_verified / binding_completed_at 字段
-2. 新建 verification_codes 表（统一管理邮箱+手机验证码）
+1. users 表新增 phone_verified / binding_completed_at 字段（phone 字段已在 029 中添加）
+2. users 表 phone 字段添加唯一索引（幂等）
+3. 新建 verification_codes 表（统一管理邮箱+手机验证码）
 """
 
 import sqlalchemy as sa
 
-from alembic import op
+from alembic import context, op
 
 revision = "049_wechat_login_phone"
 down_revision = "048_cleanup_result_count"
@@ -19,26 +20,59 @@ branch_labels = None
 depends_on = None
 
 
-def upgrade() -> None:
-    # 1. users 表新增手机号相关字段
-    op.add_column("users", sa.Column("phone", sa.String(32), nullable=True))
-    op.add_column(
-        "users",
-        sa.Column(
-            "phone_verified",
-            sa.Boolean,
-            nullable=False,
-            server_default=sa.text("false"),
+def _column_exists(table: str, column: str) -> bool:
+    """检查列是否已存在。离线模式下返回 False。"""
+    if context.is_offline_mode():
+        return False
+    conn = op.get_bind()
+    result = conn.execute(
+        sa.text(
+            "SELECT 1 FROM information_schema.columns "
+            "WHERE table_name = :table AND column_name = :column"
         ),
+        {"table": table, "column": column},
     )
-    op.add_column(
-        "users",
-        sa.Column("binding_completed_at", sa.DateTime, nullable=True),
-    )
-    # phone 唯一索引（已验证的手机号唯一，未验证的不做唯一约束）
-    op.create_index("ix_users_phone", "users", ["phone"], unique=True)
+    return result.first() is not None
 
-    # 2. verification_codes 表
+
+def _index_exists(index_name: str) -> bool:
+    """检查索引是否已存在。离线模式下返回 False。"""
+    if context.is_offline_mode():
+        return False
+    conn = op.get_bind()
+    result = conn.execute(
+        sa.text(
+            "SELECT 1 FROM pg_indexes WHERE indexname = :index_name"
+        ),
+        {"index_name": index_name},
+    )
+    return result.first() is not None
+
+
+def upgrade() -> None:
+    # 1. users 表新增手机号验证状态字段（幂等）
+    if not _column_exists("users", "phone_verified"):
+        op.add_column(
+            "users",
+            sa.Column(
+                "phone_verified",
+                sa.Boolean,
+                nullable=False,
+                server_default=sa.text("false"),
+            ),
+        )
+
+    if not _column_exists("users", "binding_completed_at"):
+        op.add_column(
+            "users",
+            sa.Column("binding_completed_at", sa.DateTime, nullable=True),
+        )
+
+    # 2. phone 字段唯一索引（幂等 - 029 加了字段但没加索引）
+    if not _index_exists("ix_users_phone"):
+        op.create_index("ix_users_phone", "users", ["phone"], unique=True)
+
+    # 3. verification_codes 表
     op.create_table(
         "verification_codes",
         sa.Column("id", sa.String(36), primary_key=True),
@@ -60,7 +94,9 @@ def upgrade() -> None:
 
 def downgrade() -> None:
     op.drop_table("verification_codes")
-    op.drop_index("ix_users_phone", table_name="users")
-    op.drop_column("users", "binding_completed_at")
-    op.drop_column("users", "phone_verified")
-    op.drop_column("users", "phone")
+    if _index_exists("ix_users_phone"):
+        op.drop_index("ix_users_phone", table_name="users")
+    if _column_exists("users", "binding_completed_at"):
+        op.drop_column("users", "binding_completed_at")
+    if _column_exists("users", "phone_verified"):
+        op.drop_column("users", "phone_verified")