The type matrix as a roadmap: seven DuckDB types in two days
We started with a markdown table tracking which DuckDB types we could round-trip. The table became the roadmap. DECIMAL, LIST, STRUCT, MAP, ARRAY, ENUM, UNION each got their own MR. The surprises came from how DuckDB models the relationships: MAP is LIST<STRUCT>, UNION is STRUCT with a tag field, and DECIMAL packs four widths into one logical type.
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