fix alembic migration

api/app/core/alembic_revision_repair.py

@@ -0,0 +1,33 @@
+"""修复已撤回 migration 写入的 alembic_version（跨环境一次性兼容）。"""
+
+from __future__ import annotations
+
+from sqlalchemy import Connection, text
+
+_WITHDRAWN_0020_REVISIONS = frozenset(
+    {
+        "0020_add_tts_audio_urls_column",
+        "0020_backfill_missing_schema",
+        "0020_backfill_all_missing_columns",
+    }
+)
+_REPAIR_TARGET_REVISION = "0018_users_language_preference"
+
+
+def try_repair_withdrawn_0020_revision(conn: Connection) -> bool:
+    """
+    若当前 stamp 为已撤回的 0020_*，回退到 0018 以便重新执行 0019_align_legacy_schema。
+
+    返回 True 表示已执行 UPDATE；调用方负责 commit。
+    """
+    row = conn.execute(text("SELECT version_num FROM alembic_version")).fetchone()
+    if row is None:
+        return False
+    current = row[0]
+    if current not in _WITHDRAWN_0020_REVISIONS:
+        return False
+    conn.execute(
+        text("UPDATE alembic_version SET version_num = :target"),
+        {"target": _REPAIR_TARGET_REVISION},
+    )
+    return True