Stable, unique column names across schema snapshots

You receive successive snapshots of table schemas and must give every column an effective name. Dots in an original name become underscores, and effective names must be unique within a table regardless of letter case; collisions get suffixes _1, _2 and so on. A column that already has an effective name must keep it in later snapshots even as other columns come and go. Implement the renaming across calls and explain how you keep names stable.