ADR-0004 — pinky export: col_transform not exposed in YAML

Status: accepted Date: 2026-05-31

Context

create_workbook_from_df (pinky-snowpark) supports a col_transform callable for arbitrary value transformations at export time. The question was whether to expose this in export.yml so users could configure it without code.

Decision

col_transform is not exposed in export.yml. Complex value transformations must be done in SQL before the export query.

Consequences

export.yml stays purely declarative (formatting only: col_fmt, wrap_columns, fixed_column_widths, freeze_panes). Exposing a callable in YAML would require eval() or a plugin system — both are complexity and security traps. SQL is the right and already available layer for transformations.