Decouple scopes from tenancy schema

alembic/versions/4f2a9c8e7b6d_rename_tenancy_tenants_to_core_scopes.py

@@ -0,0 +1,76 @@
+"""rename tenancy scope table to core scopes
+
+Revision ID: 4f2a9c8e7b6d
+Revises: 3f4a5b6c7d8e
+Create Date: 2026-07-10 00:00:00.000000
+"""
+from __future__ import annotations
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "4f2a9c8e7b6d"
+down_revision = "3f4a5b6c7d8e"
+branch_labels = None
+depends_on = None
+
+LEGACY_SCOPE_TABLE = "tenancy_tenants"
+CORE_SCOPE_TABLE = "core_scopes"
+LEGACY_SLUG_INDEX = "ix_tenancy_tenants_slug"
+CORE_SLUG_INDEX = "ix_core_scopes_slug"
+
+
+def _row_count(bind: sa.Connection, table_name: str) -> int:
+    quoted = bind.dialect.identifier_preparer.quote(table_name)
+    return int(bind.execute(sa.text(f"SELECT COUNT(*) FROM {quoted}")).scalar_one())
+
+
+def _scope_tables(bind: sa.Connection) -> set[str]:
+    return set(sa.inspect(bind).get_table_names())
+
+
+def _drop_table_if_empty(bind: sa.Connection, table_name: str) -> bool:
+    if _row_count(bind, table_name) != 0:
+        return False
+    op.drop_table(table_name)
+    return True
+
+
+def _ensure_slug_index(bind: sa.Connection, table_name: str, index_name: str, old_index_name: str) -> None:
+    indexes = {index["name"] for index in sa.inspect(bind).get_indexes(table_name)}
+    if old_index_name in indexes:
+        op.drop_index(old_index_name, table_name=table_name)
+        indexes.remove(old_index_name)
+    if index_name not in indexes:
+        op.create_index(op.f(index_name), table_name, ["slug"], unique=True)
+
+
+def _rename_scope_table(old_name: str, new_name: str) -> None:
+    bind = op.get_bind()
+    tables = _scope_tables(bind)
+    if old_name not in tables:
+        if new_name in tables:
+            _ensure_slug_index(bind, new_name, CORE_SLUG_INDEX if new_name == CORE_SCOPE_TABLE else LEGACY_SLUG_INDEX, LEGACY_SLUG_INDEX if new_name == CORE_SCOPE_TABLE else CORE_SLUG_INDEX)
+        return
+
+    if new_name in tables:
+        if _drop_table_if_empty(bind, new_name):
+            tables.remove(new_name)
+        elif _drop_table_if_empty(bind, old_name):
+            _ensure_slug_index(bind, new_name, CORE_SLUG_INDEX if new_name == CORE_SCOPE_TABLE else LEGACY_SLUG_INDEX, LEGACY_SLUG_INDEX if new_name == CORE_SCOPE_TABLE else CORE_SLUG_INDEX)
+            return
+        else:
+            raise RuntimeError(f"Cannot reconcile non-empty {old_name} over non-empty {new_name}")
+
+    if old_name in tables and new_name not in tables:
+        op.rename_table(old_name, new_name)
+        _ensure_slug_index(bind, new_name, CORE_SLUG_INDEX if new_name == CORE_SCOPE_TABLE else LEGACY_SLUG_INDEX, LEGACY_SLUG_INDEX if new_name == CORE_SCOPE_TABLE else CORE_SLUG_INDEX)
+
+
+def upgrade() -> None:
+    _rename_scope_table(LEGACY_SCOPE_TABLE, CORE_SCOPE_TABLE)
+
+
+def downgrade() -> None:
+    _rename_scope_table(CORE_SCOPE_TABLE, LEGACY_SCOPE_TABLE)