[kvlonge]

Why

Runtime-dynamic pivots produce a closed set of fixed columns plus data-derived column names, but exact static column lists cannot represent that shape. Enforced contracts need first-class metadata and compiler proof for those generated families without weakening wildcard, type, or runtime validation.

Changes

• add closed, typed contract declarations for runtime-generated pivot column families
• prove supported Snowflake and DuckDB/MotherDuck dynamic pivots from authoritative input schemas
• propagate family semantics through runtime validation, planning, manifests, contract inspection/generation, and Rules
• reject unsupported adapters, static pivots, modified wildcards, incomplete schemas, ambiguous family matches, and unproven types

Verification

• uv sync --all-extras
• make check-ci
• focused Python suite: 166 passed
• native Rust suite: 38 passed
• DuckDB end-to-end build with runtime-generated typed columns
• release wheel build
• cache-free compile against a large downstream project, including negative wildcard and type cases
• public repository hygiene scan