fix(alembic): cps_v2_platforms 兼容 SQLite 且可重跑

batch_alter_table 包 ALTER(SQLite 无原生 ALTER COLUMN),server_default 按方言分叉(PG ::jsonb / SQLite 纯文本),add_column 加 _has_column 存在性守卫,让历史半应用的 SQLite 库自愈重跑。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

alembic/versions/cps_v2_platforms.py

@@ -23,39 +23,64 @@ branch_labels: Union[str, Sequence[str], None] = None
 depends_on: Union[str, Sequence[str], None] = None
 
 
+def _has_column(insp: sa.Inspector, table: str, column: str) -> bool:
+    return any(c["name"] == column for c in insp.get_columns(table))
+
+
 def upgrade() -> None:
+    bind = op.get_bind()
+    insp = sa.inspect(bind)
+    # SQLite 不认 ::jsonb cast(会报 "unrecognized token: :"),只有 PG 用显式 cast。
+    # 两边列类型都靠上面的 with_variant 区分,这里只管 server_default 文本。
+    platforms_default = (
+        sa.text("'[\"meituan\"]'::jsonb")
+        if bind.dialect.name == "postgresql"
+        else sa.text("'[\"meituan\"]'")
+    )
+
     # 活动:淘宝淘口令 / 京东链接
+    # 加 add_column 存在性守卫:本迁移历史上在 SQLite 第一次跑时加完 payload 即在
+    # platforms 那步炸掉(::jsonb),DDL 非事务不回滚 → 半应用状态。守卫让其可自愈重跑。
+    if not _has_column(insp, "cps_activity", "payload"):
         op.add_column("cps_activity", sa.Column("payload", sa.Text(), nullable=True))
 
-    # 群:多平台(现有群都是美团,server_default 回填)+ sid 可空
-    op.add_column(
-        "cps_group",
+    # 群:多平台(现有群都是美团,server_default 回填)+ sid 可空。
+    # SQLite 不支持 ALTER COLUMN,必须用 batch(重建表)才能改 nullable;PG 走原生 ALTER。
+    with op.batch_alter_table("cps_group") as batch_op:
+        if not _has_column(insp, "cps_group", "platforms"):
+            batch_op.add_column(
                 sa.Column(
                     "platforms",
                     sa.JSON().with_variant(postgresql.JSONB(), "postgresql"),
                     nullable=False,
-            server_default=sa.text("'[\"meituan\"]'::jsonb"),
-        ),
+                    server_default=platforms_default,
                 )
-    op.alter_column("cps_group", "sid", existing_type=sa.String(64), nullable=True)
+            )
+        batch_op.alter_column("sid", existing_type=sa.String(64), nullable=True)
 
     # link:sid 可空 + target 加长
-    op.alter_column("cps_link", "sid", existing_type=sa.String(64), nullable=True)
-    op.alter_column("cps_link", "target_url", existing_type=sa.String(1024), type_=sa.String(2048))
+    with op.batch_alter_table("cps_link") as batch_op:
+        batch_op.alter_column("sid", existing_type=sa.String(64), nullable=True)
+        batch_op.alter_column("target_url", existing_type=sa.String(1024), type_=sa.String(2048))
 
     # click:sid 可空 + 事件类型
-    op.alter_column("cps_click", "sid", existing_type=sa.String(64), nullable=True)
-    op.add_column(
-        "cps_click",
-        sa.Column("event_type", sa.String(16), nullable=False, server_default="visit"),
+    with op.batch_alter_table("cps_click") as batch_op:
+        batch_op.alter_column("sid", existing_type=sa.String(64), nullable=True)
+        if not _has_column(insp, "cps_click", "event_type"):
+            batch_op.add_column(
+                sa.Column("event_type", sa.String(16), nullable=False, server_default="visit")
             )
 
 
 def downgrade() -> None:
-    op.drop_column("cps_click", "event_type")
-    op.alter_column("cps_click", "sid", existing_type=sa.String(64), nullable=False)
-    op.alter_column("cps_link", "target_url", existing_type=sa.String(2048), type_=sa.String(1024))
-    op.alter_column("cps_link", "sid", existing_type=sa.String(64), nullable=False)
-    op.drop_column("cps_group", "platforms")
-    op.alter_column("cps_group", "sid", existing_type=sa.String(64), nullable=False)
-    op.drop_column("cps_activity", "payload")
+    with op.batch_alter_table("cps_click") as batch_op:
+        batch_op.drop_column("event_type")
+        batch_op.alter_column("sid", existing_type=sa.String(64), nullable=False)
+    with op.batch_alter_table("cps_link") as batch_op:
+        batch_op.alter_column("target_url", existing_type=sa.String(2048), type_=sa.String(1024))
+        batch_op.alter_column("sid", existing_type=sa.String(64), nullable=False)
+    with op.batch_alter_table("cps_group") as batch_op:
+        batch_op.drop_column("platforms")
+        batch_op.alter_column("sid", existing_type=sa.String(64), nullable=False)
+    with op.batch_alter_table("cps_activity") as batch_op:
+        batch_op.drop_column("payload")